SVG – CSS-Tricks https://css-tricks.com Tips, Tricks, and Techniques on using Cascading Style Sheets. Tue, 17 Jan 2023 13:51:30 +0000 en-US hourly 1 https://wordpress.org/?v=6.5.5 https://i0.wp.com/css-tricks.com/wp-content/uploads/2021/07/star.png?fit=32%2C32&ssl=1 SVG – CSS-Tricks https://css-tricks.com 32 32 45537868 6 Common SVG Fails (and How to Fix Them) https://css-tricks.com/6-common-svg-fails-and-how-to-fix-them/ https://css-tricks.com/6-common-svg-fails-and-how-to-fix-them/#comments Tue, 17 Jan 2023 13:51:20 +0000 https://css-tricks.com/?p=376352 Someone recently asked me how I approach debugging inline SVGs. Because it is part of the DOM, we can inspect any inline SVG in any browser DevTools. And because of that, we have the ability to scope things out and …


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Someone recently asked me how I approach debugging inline SVGs. Because it is part of the DOM, we can inspect any inline SVG in any browser DevTools. And because of that, we have the ability to scope things out and uncover any potential issues or opportunities to optimize the SVG.

But sometimes, we can’t even see our SVGs at all. In those cases, there are six specific things that I look for when I’m debugging.

1. The viewBox values

The viewBox is a common point of confusion when working with SVG. It’s technically fine to use inline SVG without it, but we would lose one of its most significant benefits: scaling with the container. At the same time, it can work against us when improperly configured, resulting in unwanted clipping.

The elements are there when they’re clipped — they’re just in a part of the coordinate system that we don’t see. If we were to open the file in some graphics editing program, it might look like this:

Cat line art with part of the drawing outside the artwork area in Illustrator.
Screenshot of SVG opened in Illustrator.

The easiest way to fix this? Add overflow="visible" to the SVG, whether it’s in our stylesheet, inline on the style attribute or directly as an SVG presentation attribute. But if we also apply a background-color to the SVG or if we have other elements around it, things might look a little bit off. In this case, the best option will be to edit the viewBox to show that part of the coordinate system that was hidden:

Demo applying overflow="hidden" and editing the viewBox.

There are a few additional things about the viewBox that are worth covering while we’re on the topic:

How does the viewBox work?

SVG is an infinite canvas, but we can control what we see and how we see it through the viewport and the viewBox.

The viewport is a window frame on the infinite canvas. Its dimensions are defined by width and height attributes, or in CSS with the corresponding width and height properties. We can specify any length unit we want, but if we provide unitless numbers, they default to pixels.

The viewBox is defined by four values. The first two are the starting point at the upper-left corner (x and y values, negative numbers allowed). I’m editing these to reframe the image. The last two are the width and height of the coordinate system inside the viewport — this is where we can edit the scale of the grid (which we’ll get into in the section on Zooming).

Here’s simplified markup showing the SVG viewBox and the width and height attributes both set on the <svg>:

<svg viewBox="0 0 700 700" width="700" height="700">
  <!-- etc. -->
</svg>

Reframing

So, this:

<svg viewBox="0 0 700 700">

…maps to this:

<svg viewBox="start-x-axis start-y-axis width height">

The viewport we see starts where 0 on the x-axis and 0 on the y-axis meet.

By changing this:

<svg viewBox="0 0 700 700">

…to this:

<svg viewBox="300 200 700 700">

…the width and height remain the same (700 units each), but the start of the coordinate system is now at the 300 point on the x-axis and 200 on the y-axis.

In the following video I’m adding a red <circle> to the SVG with its center at the 300 point on the x-axis and 200 on the y-axis. Notice how changing the viewBox coordinates to the same values also changes the circle’s placement to the upper-left corner of the frame while the rendered size of the SVG remains the same (700×700). All I did was “reframe” things with the viewBox.

Zooming

We can change the last two values inside the viewBox to zoom in or out of the image. The larger the values, the more SVG units are added to fit in the viewport, resulting in a smaller image. If we want to keep a 1:1 ratio, our viewBox width and height must match our viewport width and height values.

Let’s see what happens in Illustrator when we change these parameters. The artboard is the viewport which is represented by a white 700px square. Everything else outside that area is our infinite SVG canvas and gets clipped by default.

Figure 1 below shows a blue dot at 900 along the x-axis and 900 along the y-axis. If I change the last two viewBox values from 700 to 900 like this:

<svg viewBox="300 200 900 900" width="700" height="700">

…then the blue dot is almost fully back in view, as seen in Figure 2 below. Our image is scaled down because we increased the viewBox values, but the SVG’s actual width and height dimensions remained the same, and the blue dot made its way back closer to the unclipped area.

Figure 1.
Figure 1
Figure 2

There is a pink square as evidence of how the grid scales to fit the viewport: the unit gets smaller, and more grid lines fit into the same viewport area. You can play with the same values in the following Pen to see that work in action:

2. Missing width and height

Another common thing I look at when debugging inline SVG is whether the markup contains the width or height attributes. This is no big deal in many cases unless the SVG is inside a container with absolute positioning or a flexible container (as Safari computes the SVG width value with 0px instead of auto). Excluding width or height in these cases prevents us from seeing the full image, as we can see by opening this CodePen demo and comparing it in Chrome, Safari, and Firefox (tap images for larger view).

Chrome
Safari
Firefox

The solution? Add a width or height, whether as a presentation attribute, inline in the style attribute, or in CSS. Avoid using height by itself, particularly when it is set to 100% or auto. Another workaround is to set the right and left values.

You can play around with the following Pen and combine the different options.

3. Inadvertent fill and stroke colors

It may also be that we are applying color to the <svg> tag, whether it’s an inline style or coming from CSS. That’s fine, but there could be other color values throughout the markup or styles that conflict with the color set on the <svg>, causing parts to be invisible.

That’s why I tend to look for the fill and stroke attributes in the SVG’s markup and wipe them out. The following video shows an SVG I styled in CSS with a red fill. There are a couple of instances where parts of the SVG are filled in white directly in the markup that I removed to reveal the missing pieces.

4. Missing IDs

This one might seem super obvious, but you’d be surprised how often I see it come up. Let’s say we made an SVG file in Illustrator and were very diligent about naming our layers so that you get nice matching IDs in the markup when exporting the file. And let’s say we plan to style that SVG in CSS by hooking into those IDs.

That’s a nice way to do things. But there are plenty of times where I’ve seen the same SVG file exported a second time to the same location and the IDs are different, usually when copy/pasting the vectors directly. Maybe a new layer was added, or one of the existing ones was renamed or something. Whatever the case, the CSS rules no longer match the IDs in the SVG markup, causing the SVG to render differently than you’d expect.

Underscores with numbers after the element IDs
Pasting Illustrator’s exported SVG file into SVGOMG.

In large SVG files we might find it difficult to find those IDs. This is a good time to open the DevTools, inspect that part of the graphic that’s not working, and see if those IDs are still matching.

So, I’d say it’s worth opening an exported SVG file in a code editor and comparing it to the original before swapping things out. Apps like Illustrator, Figma, and Sketch are smart, but that doesn’t mean we aren’t responsible for vetting them.

5. Checklist for clipping and masking

If an SVG is unexpectedly clipped and the viewBox checks out alright, I usually look at the CSS for clip-path or mask properties that might interfere with the image. It’s tempting to keep looking at the inline markup, but it’s good to remember that an SVG’s styling might be happening elsewhere.

CSS clipping and masking allow us to “hide” parts of an image or element. In SVG, <clipPath> is a vector operation that cuts parts of an image with no halfway results. The <mask> tag is a pixel operation that allows transparency, semi-transparency effects, and blurred edges.

This is a small checklist for debugging cases where clipping and masking are involved:

  • Make sure the clipping path (or mask) and the graphic overlap one another. The overlapping parts are what gets displayed.
  • If you have a complex path that is not intersecting your graphic, try applying transforms until they match.
  • You can still inspect the inner code with the DevTools even though the <clipPath> or <mask> are not rendered, so use it!
  • Copy the markup inside <clipPath> and <mask> and paste it before closing the </svg> tag. Then add a fill to those shapes and check the SVG’s coordinates and dimensions. If you still do not see the image, try adding overflow="hidden" to the <svg> tag.
  • Check that a unique ID is used for the <clipPath> or <mask>, and that the same ID is applied to the shapes or group of shapes that are clipped or masked. A mismatched ID will break the appearance.
  • Check for typos in the markup between the <clipPath> or <mask> tags.
  • fill, stroke, opacity, or some other styles applied to the elements inside <clipPath> are useless — the only useful part is the fill-region geometry of those elements. That’s why if you use a <polyline> it will behave as a <polygon> and if you use a <line> you won’t see any clipping effect.
  • If you don’t see your image after applying a <mask>, make sure that the fill of the masking content is not entirely black. The luminance of the masking element determines the opacity of the final graphic. You’ll be able to see through the brighter parts, and the darker parts will hide your image’s content.

You can play with masked and clipped elements in this Pen.

6. Namespaces

Did you know that SVG is an XML-based markup language? Well, it is! The namespace for SVG is set on the xmlns attribute:

<svg xmlns="http://www.w3.org/2000/svg">
  <!-- etc. -->
</svg>

There’s a lot to know about namespacing in XML and MDN has a great primer on it. Suffice to say, the namespace provides context to the browser, informing it that the markup is specific to SVG. The idea is that namespaces help prevent conflicts when more than one type of XML is in the same file, like SVG and XHTML. This is a much less common issue in modern browsers but could help explain SVG rendering issues in older browsers or browsers like Gecko that are strict when defining doctypes and namespaces.

The SVG 2 specification does not require namespacing when using HTML syntax. But it’s crucial if support for legacy browsers is a priority — plus, it doesn’t hurt anything to add it. That way, when the <html> element’s xmlns attribute is defined, it will not conflict in those rare cases.

<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
  <body>
    <svg xmlns="http://www.w3.org/2000/svg" width="700px" height="700px">
      <!-- etc. -->
    </svg>
  </body>
</html>

This is also true when using inline SVG in CSS, like setting it as a background image. In the following example, a checkmark icon appears on the input after successful validation. This is what the CSS looks like:

textarea:valid {
 background: white url('data:image/svg+xml,\
    <svg xmlns="http://www.w3.org/2000/svg" width="26" height="26">\
    <circle cx="13" cy="13" r="13" fill="%23abedd8"/>\
    <path fill="none" stroke="white" stroke-width="2" d="M5 15.2l5 5 10-12"/>\
    </svg>') no-repeat 98% 5px;
}

When we remove the namespace inside the SVG in the background property, the image disappears:

Another common namespace prefix is xlink:href. We use it a lot when referencing other parts of the SVG like: patterns, filters, animations or gradients. The recommendation is to start replacing it with href as the other one is being deprecated since SVG 2, but there might be compatibility issues with older browsers. In that case, we can use both. Just remember to include the namespace xmlns:xlink="http://www.w3.org/1999/xlink" if you are still using xlink:href.

Level up your SVG skills!

I hope these tips help save you a ton of time if you find yourself troubleshooting improperly rendered inline SVGs. These are just the things I look for. Maybe you have different red flags you watch for — if so, tell me in the comments!

The bottom line is that it pays to have at least a basic understanding of the various ways SVG can be used. CodePen Challenges often incorporate SVG and offer good practice. Here are a few more resources to level up:

There are a few people I suggest following for SVG-related goodness:


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How I Made an Icon System Out of CSS Custom Properties https://css-tricks.com/how-i-made-an-icon-system-out-of-css-custom-properties/ https://css-tricks.com/how-i-made-an-icon-system-out-of-css-custom-properties/#comments Thu, 22 Sep 2022 15:17:21 +0000 https://css-tricks.com/?p=373111 SVG is the best format for icons on a website, there is no doubt about that. It allows you to have sharp icons no matter the screen pixel density, you can change the styles of the SVG on hover …


How I Made an Icon System Out of CSS Custom Properties originally published on CSS-Tricks, which is part of the DigitalOcean family. You should get the newsletter.

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SVG is the best format for icons on a website, there is no doubt about that. It allows you to have sharp icons no matter the screen pixel density, you can change the styles of the SVG on hover and you can even animate the icons with CSS or JavaScript.

There are many ways to include an SVG on a page and each technique has its own advantages and disadvantages. For the last couple of years, I have been using a Sass function to import directly my icons in my CSS and avoid having to mess up my HTML markup.

I have a Sass list with all the source codes of my icons. Each icon is then encoded into a data URI with a Sass function and stored in a custom property on the root of the page.

TL;DR

What I have for you here is a Sass function that creates a SVG icon library directly in your CSS.

The SVG source code is compiled with the Sass function that encodes them in data URI and then stores the icons in CSS custom properties. You can then use any icon anywhere in your CSS like as if it was an external image.

This is an example pulled straight from the code of my personal site:

.c-filters__summary h2:after {
  content: var(--svg-down-arrow);
  position: relative;
  top: 2px;
  margin-left: auto;
  animation: closeSummary .25s ease-out;
}

Demo

Sass structure

/* All the icons source codes */
$svg-icons: (
  burger: '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0...'
);

/* Sass function to encode the icons */
@function svg($name) {
  @return url('data:image/svg+xml, #{$encodedSVG} ');
}

/* Store each icon into a custom property */
:root {
  @each $name, $code in $svg-icons {
    --svg-#{$name}: #{svg($name)};
  }
}

/* Append a burger icon in my button */
.menu::after {
  content: var(--svg-burger);
}		

This technique has both pros and cons, so please take them into account before implementing this solution on your project:

Pros

  • There are no HTTP requests for the SVG files.
  • All of the icons are stored in one place.
  • If you need to update an icon, you don’t have to go over each HTML templates file.
  • The icons are cached along with your CSS.
  • You can manually edit the source code of the icons.
  • It does not pollute your HTML by adding extra markup.
  • You can still change the color or some aspect of the icon with CSS.

Cons

  • You cannot animate or update a specific part of the SVG with CSS.
  • The more icons you have, the heavier your CSS compiled file will be.

I mostly use this technique for icons rather than logos or illustrations. An encoded SVG is always going to be heavier than its original file, so I still load my complex SVG with an external file either with an <img> tag or in my CSS with url(path/to/file.svg).

Encoding SVG into data URI

Encoding your SVG as data URIs is not new. In fact Chris Coyier wrote a post about it over 10 years ago to explain how to use this technique and why you should (or should not) use it.

There are two ways to use an SVG in your CSS with data URI:

  • As an external image (using background-image,border-image,list-style-image,…)
  • As the content of a pseudo element (e.g. ::before or ::after)

Here is a basic example showing how you how to use those two methods:

The main issue with this particular implementation is that you have to convert the SVG manually every time you need a new icon and it is not really pleasant to have this long string of unreadable code in your CSS.

This is where Sass comes to the rescue!

Using a Sass function

By using Sass, we can make our life simpler by copying the source code of our SVG directly in our codebase, letting Sass encode them properly to avoid any browser error.

This solution is mostly inspired by an existing function developed by Threespot Media and available in their repository.

Here are the four steps of this technique:

  • Create a variable with all your SVG icons listed.
  • List all the characters that needs to be skipped for a data URI.
  • Implement a function to encode the SVGs to a data URI format.
  • Use your function in your code.

1. Icons list

/**
* Add all the icons of your project in this Sass list
*/
$svg-icons: (
  burger: '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24.8 18.92" width="24.8" height="18.92"><path d="M23.8,9.46H1m22.8,8.46H1M23.8,1H1" fill="none" stroke="#000" stroke-linecap="round" stroke-width="2"/></svg>'
);

2. List of escaped characters

/**
* Characters to escape from SVGs
* This list allows you to have inline CSS in your SVG code as well
*/
$fs-escape-chars: (
  ' ': '%20',
  '\'': '%22',
  '"': '%27',
  '#': '%23',
  '/': '%2F',
  ':': '%3A',
  '(': '%28',
  ')': '%29',
  '%': '%25',
  '<': '%3C',
  '>': '%3E',
  '\\': '%5C',
  '^': '%5E',
  '{': '%7B',
  '|': '%7C',
  '}': '%7D',
);

3. Encode function

/**
* You can call this function by using `svg(nameOfTheSVG)`
*/
@function svg($name) {
  // Check if icon exists
  @if not map-has-key($svg-icons, $name) {
    @error 'icon “#{$name}” does not exists in $svg-icons map';
    @return false;
  }

  // Get icon data
  $icon-map: map-get($svg-icons, $name);

  $escaped-string: '';
  $unquote-icon: unquote($icon-map);
  // Loop through each character in string
  @for $i from 1 through str-length($unquote-icon) {
    $char: str-slice($unquote-icon, $i, $i);

    // Check if character is in symbol map
    $char-lookup: map-get($fs-escape-chars, $char);

    // If it is, use escaped version
    @if $char-lookup != null {
        $char: $char-lookup;
    }

    // Append character to escaped string
    $escaped-string: $escaped-string + $char;
  }

  // Return inline SVG data
  @return url('data:image/svg+xml, #{$escaped-string} ');
}		

4. Add an SVG in your page

button {
  &::after {
    /* Import inline SVG */
    content: svg(burger);
  }
}

If you have followed those steps, Sass should compile your code properly and output the following:

button::after {
  content: url("data:image/svg+xml, %3Csvg%20xmlns=%27http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%27%20viewBox=%270%200%2024.8%2018.92%27%20width=%2724.8%27%20height=%2718.92%27%3E%3Cpath%20d=%27M23.8,9.46H1m22.8,8.46H1M23.8,1H1%27%20fill=%27none%27%20stroke=%27%23000%27%20stroke-linecap=%27round%27%20stroke-width=%272%27%2F%3E%3C%2Fsvg%3E ");
}		

Custom properties

The now-implemented Sass svg() function works great. But its biggest flaw is that an icon that is needed in multiple places in your code will be duplicated and could increase your compiled CSS file weight by a lot!

To avoid this, we can store all our icons into CSS variables and use a reference to the variable instead of outputting the encoded URI every time.

We will keep the same code we had before, but this time we will first output all the icons from the Sass list into the root of our webpage:

/**
  * Convert all icons into custom properties
  * They will be available to any HTML tag since they are attached to the :root
  */

:root {
  @each $name, $code in $svg-icons {
    --svg-#{$name}: #{svg($name)};
  }
}

Now, instead of calling the svg() function every time we need an icon, we have to use the variable that was created with the --svg prefix.

button::after {
  /* Import inline SVG */
  content: var(--svg-burger);
}

Optimizing your SVGs

This technique does not provide any optimization on the source code of the SVG you are using. Make sure that you don’t leave unnecessary code; otherwise they will be encoded as well and will increase your CSS file size.

You can check this great list of tools and information on how to optimize properly your SVG. My favorite tool is Jake Archibald’s SVGOMG — simply drag your file in there and copy the outputted code.

Bonus: Updating the icon on hover

With this technique, we cannot select with CSS specific parts of the SVG. For example, there is no way to change the fill color of the icon when the user hovers the button. But there are a few tricks we can use with CSS to still be able to modify the look of our icon.

For example, if you have a black icon and you want to have it white on hover, you can use the invert() CSS filter. We can also play with the hue-rotate() filter.

Bonus #2: Updating the icon using CSS mask-image property

Another trick to be able to change the color of your icon, is to use it as a mask on your pseudo-element with a background. Set your pseudo-element as inline-block with a background-color and define a width & height for the size needed.

Once you have a rectangle with the color needed, apply those four values to only keep the shape of the SVG needed:

  • mask-image: var(--svg-burger): The reference to our icon.
  • mask-repeat: no-repeat: To prevent the mask to be duplicated.
  • mask-size: contain: To make the icon fit perfectly in the rectangle.
  • mask-position: center: To center our icon in the pseudo-element.

Don’t forget that all CSS mask properties still need to be prefixed with -webkit- for most browsers as of September 2022.

Thanks to Christopher and Mike for letting me know about this trick in the comments!

That’s it!

I hope you find this little helper function handy in your own projects. Let me know what you think of the approach — I’d be interested to know how you’d make this better or tackle it differently!


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How stroke-dasharray Patterns Work https://css-tricks.com/how-stroke-dasharray-patterns-work/ https://css-tricks.com/how-stroke-dasharray-patterns-work/#comments Fri, 15 Jul 2022 19:43:40 +0000 https://css-tricks.com/?p=366993 Say you have a line in SVG:

<svg<line x1="0" y1="30" x2="500" y2="30" stroke-color="#f8a100" /</svg

You can use the stroke-dasharray property in CSS to make dashes:

line {
  stroke-dasharray: 5;
}

That 5 value is a relative unit based …


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]]>
Say you have a line in SVG:

<svg>
  <line x1="0" y1="30" x2="500" y2="30" stroke-color="#f8a100" />
</svg>

You can use the stroke-dasharray property in CSS to make dashes:

line {
  stroke-dasharray: 5;
}

That 5 value is a relative unit based on the size of the SVG’s viewBox. We could use any CSS length, really. But what it does is make a pattern of dashes that are 5 units long with 5 unit gaps between them.

So far, so good. We can use two values where the second value individually sets the gap length:

Now we have dashes that are 5 units and gaps that are 10. Let’s try a third value:

See how we’re forming a pattern here? It goes:

  • Dash: 5 units
  • Gap: 10 units
  • Dash: 15 units

You’d think it repeats after that in the exact same cadence. But no! It if did, we’d have dashes bumping into one another:

  • Dash: 5 units
  • Gap: 10 units
  • Dash: 15 units
  • Dash: 5 units
  • Gap: 10 units
  • Dash: 15 units
  • …and so on.

Instead, stroke-dasharray gets all smart and duplicates the pattern if there are an odd number of values So…

stroke-dasharray: 5 10 15;

/* is the same as */
stroke-dasharray: 5 10 15 5 10 15;

That’s actually why a single value works! Earlier, we declared a single 5 value. That’s really the same as saying stroke-dasharray: 5 5. Without the second value, stroke-dasharray implicitly duplicates the first value to get a repeatable pattern. Otherwise, it’d just be a solid line of dashes that are 5 units long, but no gaps between them!

The pattern also depends on the size of the shape itself. Our SVG line is 500 units. Let’s set larger stroke-dasharray values and add them up:

stroke-dasharray: 10 20 30 40 50; /* 150 units */

If the pattern runs four times (150 units ⨉ 4 iterations), we’re dealing with 600 total units. That additional 100 units is lopped off to prevent the pattern from overflowing itself.

That’s all.

🎩 Hat tip to Joshua Dance for calling this out!


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Mastering SVG’s stroke-miterlimit Attribute https://css-tricks.com/mastering-svgs-stroke-miterlimit-attribute/ https://css-tricks.com/mastering-svgs-stroke-miterlimit-attribute/#respond Tue, 24 May 2022 14:04:17 +0000 https://css-tricks.com/?p=365828 So, SVG has this stroke-miterlimit presentation attribute. You’ve probably seen it when exporting an SVG from a graphic editor program, or perhaps you find out you could remove it without noticing any change to the visual appearance.

After a good …


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So, SVG has this stroke-miterlimit presentation attribute. You’ve probably seen it when exporting an SVG from a graphic editor program, or perhaps you find out you could remove it without noticing any change to the visual appearance.

After a good amount of research, one of the first things I discovered is that the attribute works alongside stroke-linejoin, and I’ll show you how as well as a bunch of other things I learned about this interesting (and possibly overlooked) SVG attribute.

TLDR;

stroke-miterlimit depends on stroke-linejoin: if we use round or bevel for joins, then there’s no need to declare stroke-miterlimit. But if we use miter instead, we can still delete it and maybe the default value will be enough. Beware that many graphic software editors will add this attribute even when is not necessary.

What is stroke-linejoin?

I know, we’re actually here to talk about stroke-miterlimit, but I want to start with stroke-linejoin because of how tightly they work together. This is the definition for stroke-linejoin pulled straight from the SVG Working Group (SVGWG):

stroke-linejoin specifies the shape to be used at the corners of paths or basic shapes when they are stroked.

This means we can define how the corner looks when two lines meet at a point. And this attribute accepts five possible values, though two of them have no browser implementation and are identified by the spec as at risk of being dropped. So, I’ll briefly present the three supported values the attribute accepts.

miter is the default value and it just so happens to be the most important one of the three we’re looking at. If we don’t explicitly declare stroke-linejoin in the SVG code, then miter is used to shape the corner of a path. We know a join is set to miter when both edges meet at a sharp angle.

But we can also choose round which softens the edges with — you guessed it — rounded corners.

The bevel value, meanwhile, produces a flat edge that sort of looks like a cropped corner.

What is stroke-miterlimit?

OK, now that we know what stroke-linejoin is, let’s get back to the topic at hand and pick apart the definition of stroke-miterlimit from the book Using SVG with CSS3 and HTML5:

[…] on really tight corners, you have to extend the stroke for quite a distance, before the two edges meet. For that reason, there is a secondary property: stroke-miterlimit. It defines how far you can extend the point when creating a miter corner.

In other words, stroke-miterlimit sets how far the stroke of the edges goes before they can meet at a point. And only when the stroke-linejoin is miter.

Miter join with miter limit in grey.

So, the stroke-miterlimit value can be any positive integer, where 4 is the default value. The higher the value, the further the corner shape is allowed to go.

How they work together

You probably have a good conceptual understanding now of how stroke-linejoin and stroke-miterlimit work together. But depending on the stroke-miterlimit value, you might get some seemingly quirky results.

Case in point: if stroke-linejoin is set to miter, it can actually wind up looking like the bevel value instead when the miter limit is too low. Here’s the spec again to help us understand why:

If the miter length divided by the stroke width exceeds the stroke-miterlimit then [the miter value] is converted to a bevel.

So, mathematically we could say that this:

[miter length] / [stroke width] > [stroke-miterlimit] = miter
[miter length] / [stroke width] < [stroke-miterlimit] = bevel

That makes sense, right? If the miter is unable to exceed the width of the stroke, then it ought to be a flat edge. Otherwise, the miter can grow and form a point.

Sometimes seeing is believing, so here’s Ana Tudor with a wonderful demo showing how the stroke-miterlimit value affects an SVG’s stroke-linejoin:

Setting miter limits in design apps

Did you know that miter joins and limits are available in many of the design apps we use in our everyday work? Here’s where to find them in Illustrator, Figma, and Inkscape.

Setting miter limits in Adobe Illustrator

Illustrator has a way to modify the miter value when configuring a path’s stroke. You can find it in the “Stroke” settings on a path. Notice how — true to the spec — we are only able to set a value for the “Limit” when the path’s “Corner” is set to “Miter Join”.

Applying stroke-miterlimit in Adobe Illustrator.

One nuance is that Illustrator has a default miter limit of 10 rather than the default 4. I’ve noticed this every time I export the SVG file or copy and paste the resulting SVG code. That could be confusing when you open up the code because even if you do not change the miter limit value, Illustrator adds stroke-miterlimit="10" where you might expect 4 or perhaps no stroke-miterlimit at all.

And that’s true even if we choose a different stroke-linejoin value other than “Miter Join”. Here is the code I got when exporting an SVG with stroke-linejoin="round".

<svg viewBox="0 0 16 10"><path stroke-width="2" stroke-linejoin="round" stroke-miterlimit="10" d="M0 1h15.8S4.8 5.5 2 9.5" fill="none" stroke="#000"/></svg>

The stroke-miterlimit shouldn’t be there as it only works with stroke-linejoin="miter". Here are a couple of workarounds for that:

  • Set the “Limit” value to 4, as it is the default in SVG and is the only value that doesn’t appear in the code.
  • Use the “Export As” or “Export for Screen” options instead of “Save As” or copy-pasting the vectors directly.

If you’d like to see that fixed, join me and upvote the request to make it happen.

Setting miter limits in Figma

Miter joins and limits are slightly different in Figma. When we click the node of an angle on a shape, under the three dots of the Stroke section, we can find a place to set the join of a corner. The option “Miter angle” appears by default, but only when the join is set to miter:

Applying stroke-miterlimit in Figma.

This part works is similar to Illustrator except for how Figma allows us to set the miter angle in degree units instead of decimal values. There are some other specific nuances to point out:

  • The angle is 7.17° by default and there is no way to set a lower value. When exporting the SVG, that value is becomes stroke-miterlimit='16‘ in the markup, which is different from both the SVG spec and the Illustrator default.
  • The max value is 180°, and when drawing with this option, the join is automatically switched to bevel.
  • When exporting with bevel join, the stroke-miterlimit is there in the code, but it keeps the value that was set when the miter angle was last active (Illustrator does the same thing).
  • When exporting the SVG with a round join, the path is expanded and we no longer have a stroke, but a path with a fill color.

I was unable to find a way to avoid the extra code that ends up in the exported SVG when stroke-miterlimit is unneeded.

Setting miter limits in Inkscape

Inkscape works exactly the way I’d expect a design app to manage miter joins and limits. When selecting a a miter join, the default value is 4, exactly what it is in the spec. Better yet, stroke-miterlimit is excluded from the exported SVG code when it is the default value!

Applying stroke-miterlimit in Inkscape.

Still, if we export any path with bevel or round after the limit was modified, the stroke-miterlimit will be back in the code, unless we keep the 4 units of the default in the Limit box. Same trick as Illustrator.

These examples will work nicely if we choose the Save AsOptimized SVG option. Inkscape is free and open source and, at the end of the day, has the neatest code as far as stroke-miterlimit goes and the many options to optimize the code for exporting.

But if you are more familiar with Illustrator (like I am), there is a workaround to keep in mind. Figma, because of the degree units and the expansion of the strokes, feels like the more distant from the specs and expected behavior.

Wrapping up

And that’s what I learned about SVG’s stroke-miterlimit attribute. It’s another one of those easy-to-overlook things we might find ourselves blindly cutting out, particularly when optimizing an SVG file. So, now when you find yourself setting stroke-miterlimit you’ll know what it does, how it works alongside stroke-linejoin, and why the heck you might get a beveled join when setting a miter limit value.


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Optimizing SVG Patterns to Their Smallest Size https://css-tricks.com/optimizing-svg-patterns/ https://css-tricks.com/optimizing-svg-patterns/#comments Fri, 18 Mar 2022 22:31:22 +0000 https://css-tricks.com/?p=364090 I recently created a brick wall pattern as part of my #PetitePatterns series, a challenge where I create organic-looking patterns or textures in SVG within 560 bytes (or approximately the size of two tweets). To fit this constraint, I have …


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I recently created a brick wall pattern as part of my #PetitePatterns series, a challenge where I create organic-looking patterns or textures in SVG within 560 bytes (or approximately the size of two tweets). To fit this constraint, I have gone through a journey that has taught me some radical ways of optimizing SVG patterns so that they contain as little code as possible without affecting the overall image quality.

I want to walk you through the process and show you how we can take an SVG pattern that starts at 197 bytes all the way down to a mere 44 bytes — a whopping 77.7% reduction!

The SVG pattern

This is what’s called a “running bond” brick pattern. It’s the most common brick pattern out there, and one you’ve surely seen before: each row of bricks is offset by one half the length of a brick, creating a repeating staggered pattern. The arrangement is pretty simple, making SVG’s <pattern> element a perfect fit to reproduce it in code.

The SVG <pattern> element uses a pre-defined graphic object which can be replicated (or “tiled”) at fixed intervals along the horizontal and vertical axes. Essentially, we define a rectangular tile pattern and it gets repeated to paint the fill area.

First, let’s set the dimensions of a brick and the gap between each brick. For the sake of simplicity, let’s use clean, round numbers: a width of 100 and a height of 30 for the brick, and 10 for the horizontal and vertical gaps between them.

Showing a highlighted portion of a brick wall pattern, which is the example we are using for optimizing SVG patterns.

Next, we have to identify our “base” tile. And by “tile” I’m talking about pattern tiles rather than physical tiles, not to be confused with the bricks. Let’s use the highlighted part of the image above as our pattern tile: two whole bricks in the first row, and one whole sandwiched between two half bricks in the second row. Notice how and where the gaps are included, because those need to be included in the repeated pattern tile.

When using <pattern>, we have to define the pattern’s width and height, which correspond to the width and height of the base tile. To get the dimensions, we need a little math:

Tile Width  = 2(Brick Width) + 2(Gap) = 2(100) + 2(10) = 220
Tile Height = 2(Bright Height) + 2(Gap) = 2(30) + 2(10) = 80

Alright, so our pattern tile is 220✕80. We also have to set the patternUnits attribute, where the value userSpaceOnUse essentially means pixels. Finally, adding an id to the pattern is necessary so that it can be referenced when we are painting another element with it.

<pattern id="p" width="220" height="80" patternUnits="userSpaceOnUse">
  <!-- pattern content here -->
</pattern>

Now that we have established the tile dimensions, the challenge is to create the code for the tile in a way that renders the graphic with the smallest number of bytes possible. This is what we hope to end up with at the very end:

The bricks (in black) and gaps (in white) of the final running bond pattern

Initial markup (197 bytes)

The simplest and most declarative approach to recreate this pattern that comes to my mind is to draw five rectangles. By default, the fill of an SVG element is black and the stroke is transparent. This works well for optimizing SVG patterns, as we don’t have to explicitly declare those in the code.

Each line in the code below defines a rectangle. The width and height are always set, and the x and y positions are only set if a rectangle is offset from the 0 position.

<rect width="100" height="30"/>
<rect x="110" width="100" height="30"/>
<rect y="40" width="45" height="30"/>
<rect x="55" y="40" width="100" height="30"/>
<rect x="165" y="40" width="55" height="30"/>

The top row of the tile contained two full-width bricks, the second brick is positioned to x="110" allowing 10 pixels of gap before the brick. Similarly there’s 10 pixels of gap after, because the brick ends at 210 pixels (110 + 100 = 210) on the horizontal axis even though the <pattern> width is 220 pixels. We need that little bit of extra space; otherwise the second brick would merge with the first brick in the adjacent tile.

The bricks in the second (bottom) row are offset so the row contains two half bricks and one whole brick. In this case, we want the half-width bricks to merge so there’s no gap at the start or the end, allowing them to seamlessly flow with the bricks in adjoining pattern tiles. When offsetting these bricks, we also have to include half gaps, thus the x values are 55 and 165, respectively.

Element reuse, (-43B, 154B total)

It seems inefficient to define each brick so explicitly. Isn’t there some way to optimize SVG patterns by reusing the shapes instead?

I don’t think it’s widely known that SVG has a <use> element. You can reference another element with it and render that referenced element wherever <use> is used. This saves quite a few bytes because we can omit specifying the widths and heights of each brick, except for the first one.

That said, <use> does come with a little price. That is, we have to add an id for the element we want to reuse.

<rect id="b" width="100" height="30"/>
<use href="#b" x="110"/>
<use href="#b" x="-55" y="40"/>
<use href="#b" x="55" y="40"/>
<use href="#b" x="165" y="40"/>

The shortest id possible is one character, so I chose “b” for brick. The <use> element can be positioned similarly to <rect>, with the x and y attributes as offsets. Since each brick is full-width now that we’ve switched to <use> (remember, we explicitly halved the bricks in the second row of the pattern tile), we have to use a negative x value in the second row, then make sure the last brick overflows from the tile for that seamless connection between bricks. These are okay, though, because anything that falls outside of the pattern tile is automatically cut off.

Can you spot some repeating strings that can be written more efficiently? Let’s work on those next.

Rewriting to path (-54B, 100B total)

<path> is probably the most powerful element in SVG. You can draw just about any shape with “commands” in its d attribute. There are 20 commands available, but we only need the simplest ones for rectangles.

Here’s where I landed with that:

<path d="M0 0h100v30h-100z
         M110 0h100v30h-100
         M0 40h45v30h-45z
         M55 40h100v30h-100z
         M165 40h55v30h-55z"/>

I know, super weird numbers and letters! They all have meaning, of course. Here’s what’s happening in this specific case:

  • M{x} {y}: Moves to a point based on coordinates.
  • z: Closes the current segment.
  • h{x}: Draws a horizontal line from the current point, with the length of x in the direction defined by the sign of x. Lowercase x indicates a relative coordinate.
  • v{y}: Draws a vertical line from the current point, with the length of y in the direction defined by the sign of y. Lowercase y indicates a relative coordinate.

This markup is much more terse than the previous one (line breaks and indentation whitespace is only for readability). And, hey, we’ve managed to cut out half of the initial size, arriving at 100 bytes. Still, something makes me feel like this could be smaller…

Tile revision (-38B, 62B total)

Doesn’t our pattern tile have repeating parts? It’s clear that in the first row a whole brick is repeated, but what about the second row? It’s a bit harder to see, but if we cut the middle brick in half it becomes obvious.

The left half preceding the red line is the same as the right side.

Well, the middle brick isn’t exactly cut in half. There’s a slight offset because we also have to account for the gap. Anyways, we just found a simpler base tile pattern, which means fewer bytes! This also means we have to halve the width of our <pattern> element from 220 to 110.

<pattern id="p" width="110" height="80" patternUnits="userSpaceOnUse">
  <!-- pattern content here -->
</pattern>

Now let’s see how the simplified tile is drawn with <path>:

<path d="M0 0h100v30h-100z
         M0 40h45v30h-45z
         M55 40h55v30h-55z"/>

The size is reduced to 62 bytes, which is already less than a third of the original size! But why stop here when there’s even more we can do!

Shortening path commands (-9B, 53B total)

It’s worth getting a little deeper into the <path> element because it provides more hints for optimizing SVG patterns. One misconception I’ve had when working with <path> is regarding how the fill attribute works. Having played a lot with MS Paint in my childhood, I’ve learned that any shape I want to fill with a solid color has to be closed, i.e. have no open points. Otherwise, the paint will leak out of the shape and spill over everything.

In SVG, however, this is not true. Let me quote the spec itself:

The fill operation fills open subpaths by performing the fill operation as if an additional “closepath” command were added to the path to connect the last point of the subpath with the first point of the subpath.

This means we can omit the close path commands (z), because the subpaths are considered automatically closed when filled.

Another useful thing to know about path commands is that they come in uppercase and lowercase variations. Lowercase letters mean that relative coordinates are used; uppercase letters mean absolute coordinates are used instead.

It’s a little trickier than that with the H and V commands because they only include one coordinate. Here’s how I would describe these two commands:

  • H{x}: Draws a horizontal line from the current point to coordinate x.
  • V{y}: Draws a vertical line from the current point to coordinate y.

When we are drawing the first brick in the pattern tile, we start from the (0,0) coordinates. We then draw a horizontal line to (100,0) and a vertical line to (100,30), and finally, draw a horizontal line to (0,30). We used the h-100 command in the last line, but it is the equivalent of H0, which is two bytes instead of five. We can replace two similar occurrences and pare the code of our <path> down to this:

<path d="M0 0h100v30H0
         M0 40h45v30H0
         M55 40h55v30H55"/>

Another 9 bytes shaved off — how much smaller can we go?

Bridging (-5B, 48B total)

The longest commands standing in our way of a fully-optimized SVG pattern are the “move to” commands which take up 4, 5, and 6 bytes, respectively. One constraint we have is that:

A path data segment (if there is one) must begin with a “moveto” command.

But that’s okay. The first one is the shortest anyways. If we swap the rows, we can come up with a path definition where we only have to move either horizontally or vertically between the bricks. What if we could use the h and v commands there instead of M?

The path starts from the red dot in the top-left corner. Red are the path commands supported with arrows, black are the coordinates the arrows point to.

The above diagram shows how the three shapes can be drawn with a single path. Note that we are leveraging the fact that the fill operation automatically closes the open part between (110,0) and (0,0). With this rearrangement, we also moved the gap to the left of the full-width brick in the second row. Here’s how the code looks, still broken into one brick per line:

<path d="M0 0v30h50V0
         h10v30h50
         v10H10v30h100V0"/>

Surely, we’ve found the absolute smallest solution now that we’re down to 48 bytes, right?! Well…

Digit trimming (-4B, 44B total)

If you can be a bit flexible with the dimensions, there’s another little way we can optimize SVG patterns. We’ve been working with a brick width of 100 pixels, but that’s three bytes. Changing it to 90 means one less byte whenever we need to write it. Similarly, we used a gap of 10 pixels — but if we change it to 8 instead, we save a byte on each of those occurrences.

<path d="M0 0v30h45V0
         h8v30h45
         v8H8v30h90V0"/>

Of course, this also means we have to adjust the pattern dimensions accordingly. Here’s the final optimized SVG pattern code:

<pattern id="p" width="98" height="76" patternUnits="userSpaceOnUse">
  <path d="M0 0v30h45V0h8v30h45v8H8v30h90V0"/>
</pattern>

The second line in the above snippet — not counting the indentations — is 44 bytes. We got here from 197 bytes in six iterations. That’s a chunky 77.7% size reduction!

I’m wondering though… is this really the smallest size possible? Have we looked at all possible ways to optimize SVG patterns?

I invite you to try and further minify this code, or even experiment with alternative methods for optimizing SVG patterns. I would love to see if we could find the true global minimum with the wisdom of the crowd!

More on creating and optimizing SVG patterns

If you are interested to learn more about creating and optimizing SVG patterns, read my article about creating patterns with SVG filters. Or, if you want to check out a gallery of 60+ patterns, you can view the PetitePatterns CodePen Collection. Lastly, you’re welcome to watch my tutorials on YouTube to help you get even deeper into SVG patterns.


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SVGcode for “Live Tracing” Raster Images https://css-tricks.com/svgcode-raster-to-vector/ https://css-tricks.com/svgcode-raster-to-vector/#comments Wed, 09 Feb 2022 21:39:41 +0000 https://css-tricks.com/?p=362777 Say you have a bitmap graphic — like a JPG, PNG, or GIF — and you wish it was vector, like SVG. What do you do? You could trace it yourself in some kind of design software. Or tools within …


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Say you have a bitmap graphic — like a JPG, PNG, or GIF — and you wish it was vector, like SVG. What do you do? You could trace it yourself in some kind of design software. Or tools within design software can help.

(I don’t wanna delay the lede here, there is a free online tool for it now called SVGcode.)

I remember when Adobe Illustrator CS2 dropped in 2005 it had a feature called “Live Trace” and I totally made it my aesthetic. I used to make business cards for my folk band and they all had the look of a photograph-gone-vector. These days they apparently call it Image Trace.

Showing two images comparing a raster image to the Image Trace effect in Adobe Illustrator.

SVGcode does exactly this, for free

Adobe software costs money though, so what other options are out there? I imagine they are out there, but now there is a wonderfully single-purpose web app called SVGcode for it by Thomas Steiner! He’s written about it in a couple of places:

I think it’s so cool both in what it does (super useful!) but also in the approach (so impressive what web apps can do these days!):

It uses the File System Access API, the Async Clipboard API, the File Handling API, and Window Controls Overlay customization. […]

Credit where credit is due: I didn’t invent this. With SVGcode, I just stand on the shoulders of a command line tool called Potrace by Peter Selinger that I have converted to Web Assembly, so it can be used in a Web app.

My just-out-of-college aesthetic is gonna live on people!

Showing the Image Trace effect previewed in SVGcode.

Thomas joined me and Dave over on ShopTalk episode #497 if you’re interested in hearing straight from Thomas about not just this, but the whole world of capable web apps. That episode was sort of designed as a follow-up to an article I wrote that asks: “Why would a business push a native app over a website?”


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Using SVG in WordPress (2 Helpful Plugin Recommendations) https://css-tricks.com/using-svg-in-wordpress/ https://css-tricks.com/using-svg-in-wordpress/#comments Fri, 21 Jan 2022 19:35:31 +0000 https://css-tricks.com/?p=360346 SVG is a great image format, so it's nice to able to use it in WordPress. If you're looking to be using SVG in WordPress. , we've got you covered here with all the best options.


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There is a little legwork to do if you plan on using SVG in WordPress. For fair-enough reasons, WordPress doesn’t allow SVG out of the box. SVG is a markup syntax that has lots of power, including the ability to load other resources and run JavaScript. So, if WordPress were to blanket-ly allow SVG by default, users even with quite limited roles could upload SVG and cause problems, like XSS vulnerabilities.

But say that’s not a problem for your site and you just use SVG gosh darn it. First, let’s be clear what we mean by using SVG in WordPress: uploading SVG through the media uploader and using the SVG images within post content and as featured images.

There is nothing stopping you from, say, using SVG in your templates. Meaning inline <svg> or SVG files you link up as images in your template from your CSS or whatnot. That’s completely fine and you don’t need to do anything special for that to work in WordPress.

Example of Using SVG in WordPress. the media library is open and shows tile previews of different SVG files.

Taking matters into your own hands

What prevents you from using SVG in WordPress is that the Media Library Uploader rejects the file’s MIME type. To allow SVG in WordPress, you really just need this filter. This would go in your functions.php or a functionality plugin:

function cc_mime_types($mimes) {
  $mimes['svg'] = 'image/svg+xml';
  return $mimes;
}
add_filter('upload_mimes', 'cc_mime_types');

But the problem after that is that the SVG file usually won’t display correctly in the various places it needs to, like the Media Library’s image previews, the Featured Image widget, and possibly even the classic or Block Editor. I have a snippet of CSS that can be injected to fix this. But — and this is kinda why I’m writing this new post — that doesn’t seem to work for me anymore, which has got me thinking.

Plugins for using SVG in WordPress

I used to think, eh, why bother, it’s so little code to allow this might that I may as well just do it myself with the function. But WordPress, of course, has a way of shifting over time, and since supporting SVG isn’t something WordPress is going to do out of the box, this is actually a great idea for a plugin to handle. That way, the SVG plugin can evolve to handle quirks as WordPress evolves and, theoretically, if enough people use the SVG plugin, it will be maintained.

So, with that, here are a couple of plugin recommendations for using SVG in WordPress.

SVG Support

This is the one I’ve been using lately and it seems to work great for me.

Screenshot of the SVG Support plugin for WordPress in the WordPress Plugin Directory.

I just install it, activate it, and do nothing else. It does have a settings screen, but I don’t need any of those things. I really like how it asks you if it’s OK to load additional CSS on the front-end (for me, it’s not OK, so I leave it off) — although even better would be for the plugin to show you what it’s going to load so you can add it to your own CSS if you want.

The setting to restrict uploading SVG in WordPress to admins is smart, although if you want to be more serious about SVG safety, you could use this next plugin instead…

Safe SVG

This one hasn’t been updated in years, but it goes the extra mile for SVG safety in that it literally sanitizes SVG files as you upload them, and even optimizes them while it adds the SVG in WordPress.

Screenshot of the Safe SVG plugin in the WordPress Plugin Directory.

We have fairly tight editorial control over authors and such here on this site, so the security aspects of this SVG plugin aren’t a big worry to me. Plus, I like to be in charge of my own SVG optimization, so this one isn’t as perfect for me, though I’d probably recommend it to a site with less technical expertise at the site owner level.


Looks like there is Easy SVG Support as well, but it doesn’t seem to be as nice as the Support SVG plugin and hasn’t been updated recently, so I can’t recommend that.

What plugins have you successfully tried for using SVG in WordPress? Any recommendations you’d like to add?


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Flip, Invert, and Reverse https://css-tricks.com/flip-invert-and-reverse/ https://css-tricks.com/flip-invert-and-reverse/#respond Thu, 09 Dec 2021 00:27:11 +0000 https://css-tricks.com/?p=358554 The SVG <path> syntax is a beast. There are all sorts of commands that make up a mini-language all of its own — so powerful that it’s capable of drawing anything. Don’t be too scared of it, though, because some …


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The SVG <path> syntax is a beast. There are all sorts of commands that make up a mini-language all of its own — so powerful that it’s capable of drawing anything. Don’t be too scared of it, though, because some of the commands are very straightforward to understand. They read like “put pen here, draw 2 over, draw 3 down, draw 1 up, done.” Yuan Chuan starts there and demonstrates:

If you take that design and, as the title of the article suggests, flip, invert, and reverse it, you can build some really neat patterns.

That syntax you see is part of CSS Doodle and you can see the result here:


If that type of aesthetic appeals to you, it might be because you used to doodle this way as a kid, like Clive Thompson.

When I was in grade school, I used to have a very particular style of doodling.

I’d draw a pattern that was governed by five rules, rather like the ones governing an Etch-A-Sketch. They were:

1. You draw one single line. It can be as long as you like.
2. To start the line, you put your pen down.
3. You can make right-angle turns only, either 90 degrees or -90 degrees.
4. You cannot back up. You must always move forward.
5. You don’t lift your pen until you’re ready to stop. When you lift the pen, the doodle is done.

He made a Right-Angle Doodling Machine because, of course, as adults we can’t just be nostalgic — we have to throw technology and time at it to try to re-summon whatever made the thing feel special originally. But it’s never quite the same:

Does doodling with an app tickle our brains in the same way?

I don’t think so. When I mess around with this right-angle drawing-machine, my brain doesn’t feel quite as activated, nor as rested, as when I make the same drawings by hand.

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Fractional SVG stars with CSS https://css-tricks.com/fractional-svg-stars-with-css/ https://css-tricks.com/fractional-svg-stars-with-css/#comments Thu, 02 Dec 2021 15:42:37 +0000 https://css-tricks.com/?p=358210 Some ⭐️⭐️⭐️⭐️⭐️ star rating systems aren’t always exactly even stars. Say you want to support rating something 2.25 stars. To do that you could “fill” the shape of the stars partially. I like this idea by Samuel Kraft. The tricky …


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Some ⭐️⭐️⭐️⭐️⭐️ star rating systems aren’t always exactly even stars. Say you want to support rating something 2.25 stars. To do that you could “fill” the shape of the stars partially. I like this idea by Samuel Kraft. The tricky part is:

The final step is making the overlay div only affect the star SVGs beneath, not the background. We can do this by using the CSS mix-blend-mode property with the color value.

Check out Samuel’s post for an interactive demo and deeper information, but I thought I’d give it a crack myself to get a feel for the idea:

The idea is that this is an overlay on top of the stars. You can’t see it and it doesn’t affect the stars because it’s either black or white and mix-blend-mode: color; means that overlay will only effect elements that do have color.

There are loads of ways to do rating stars, for the record. We covered five of them a little while back. One rather clever method in there is using unicode stars (like, as text), then filling their background with -webkit-background-clip: text; which means you can partially fill them (like with a hard-stop linear-gradient()). Solid trickery, that.

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Which SVG technique performs best for way too many icons? https://css-tricks.com/which-svg-technique-performs-best-for-way-too-many-icons/ https://css-tricks.com/which-svg-technique-performs-best-for-way-too-many-icons/#respond Tue, 23 Nov 2021 19:21:28 +0000 https://css-tricks.com/?p=357412 Tyler Sticka digs in here in the best possible way: by making a test page and literally measuring performance. Maybe 1,000 icons is a little bit of an edge case, but hey, 250 rows of data with four icons in …


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Tyler Sticka digs in here in the best possible way: by making a test page and literally measuring performance. Maybe 1,000 icons is a little bit of an edge case, but hey, 250 rows of data with four icons in each gets you there. Tyler covers the nuances carefully in the post. The different techniques tested: inline <svg>, same-document sprite <symbol>s, external-document sprite <symbol>s, <img> with an external source, <img> with a data URL, <img> with a filter, <div> with a background-image of an external source, <div> with a background-image of a data URL, and a <div> with a mask. Phew! That’s a lot — and they are all useful techniques in their own right.

Which technique won? Inline <svg>, unless the SVGs are rather complex, then <img> is better. That’s what I would have put my money on. I’ve been on that train for a while now.

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Favicons: How to Make Sure Browsers Only Download the SVG Version https://css-tricks.com/favicons-how-to-make-sure-browsers-only-download-the-svg-version/ https://css-tricks.com/favicons-how-to-make-sure-browsers-only-download-the-svg-version/#comments Fri, 05 Nov 2021 20:47:32 +0000 https://css-tricks.com/?p=355780 Šime Vidas DM’d me the other day about this thread from subzey on Twitter. My HTML for favicons was like this:

<!-- Warning! Typo! --<link rel="icon" href="/favicon.ico" size="any"<link rel="icon" href="/favicon.svg" type="image/svg+xml"

The attribute size is a typo there, …


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Šime Vidas DM’d me the other day about this thread from subzey on Twitter. My HTML for favicons was like this:

<!-- Warning! Typo! -->
<link rel="icon" href="/favicon.ico" size="any">
<link rel="icon" href="/favicon.svg" type="image/svg+xml">

The attribute size is a typo there, and should be sizes. Like this:

<!-- Correct -->
<link rel="icon" href="/favicon.ico" sizes="any">
<link rel="icon" href="/favicon.svg" type="image/svg+xml">

And with that, Chrome no longer double downloaded both icons, and instead uses the SVG alone (as it should). Just something to watch out for. My ICO file is 5.8kb, so now that’s 5.8kb saved on every single uncached page load, which feels non-trivial to me.

Šime noted this in Web Platform News #42:

SVG favicons are supported in all modern browsers except Safari. If your website declares both an ICO (fallback) and SVG icon, make sure to add the sizes=any attribute to the ICO <link> to prevent Chrome from downloading and using the ICO icon instead of the SVG icon (see Chrome bug 1162276 for more info). CSS-Tricks is an example of a website that has the optimal icon markup in its <head> (three <link> elements, one each for favicon.ico, favicon.svg, and apple-touch-icon.png).

That note about CSS-Tricks is a bit generous in that it’s only correct because my incorrectness was pointed out ahead of time. I think the root of my typo was Andrey’s article, but that’s been fixed. Andrey’s article is still likely the best reference for the most practical favicon markup.


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How I Made a Generator for SVG Loaders With Sass and SMIL Options https://css-tricks.com/how-i-made-a-generator-for-svg-loaders-with-sass-and-smil-options/ https://css-tricks.com/how-i-made-a-generator-for-svg-loaders-with-sass-and-smil-options/#comments Thu, 26 Aug 2021 14:35:03 +0000 https://css-tricks.com/?p=350223 While learning Vue.js, I started building free web tools that involved the exploration of SVG, with the goal of learning something about both! Let’s take a look at one of those tools: a generator that makes SVG loaders and …


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While learning Vue.js, I started building free web tools that involved the exploration of SVG, with the goal of learning something about both! Let’s take a look at one of those tools: a generator that makes SVG loaders and lets you choose between SMIL or Sass animation, different styles, colors, shapes, and effects. It even lets you paste in a custom path or text, and then download the final SVG, copy the code, or open a demo over at CodePen.

How it started

Three coincidences led me to build a generator for SVG loaders.

Coincidence 1: Sarah Drasner’s book

The first time I read about Sass loops was in Sarah Drasner’s SVG Animations. She shows how to stagger animations with a Sass function (like the does in Chapter 6, “Animating Data Visualizations”).

I was inspired by that chapter and the possibilities of Sass loops.

Coincidence 2: A GIF

At that same point in life, I was asked to replicate a “loader” element, similar to Apple’s old classic.

A round segmented spinner where each segment fades in and out in succession to create a circling effect.
This is a mockup of the loader I was asked to make.

I referenced Sarah’s example to make it happen. This is the Sass loop code I landed on:

@for $i from 1 to 12 {
  .loader:nth-of-type(#{$i}) {
    animation: 1s $i * 0.08s opacityLoader infinite;
  }
}
@keyframes opacityLoader {
 to { opacity: 0; }
}

This defines a variable for a number (i) from 1 to 12 that increases the delay of the animation with every :nth-child element. It was the perfect use case to animate as many elements as I wanted with only two lines of Sass, saving me CSS declarations for each of the delays I needed. This is the same animation, but written in vanilla CSS to show the difference:

.loader:nth-of-type(1) {
  animation: 1s 0.08s opacityLoader infinite;
}
.loader:nth-of-type(2) {
  animation: 1s 0.16s opacityLoader infinite;
}

/* ... */

.loader:nth-of-type(12) {
  animation: 1s 0.96s opacityLoader infinite;
}
@keyframes opacityLoader {
  to { opacity: 0; }
}

Coincidence 3: An idea

With these things going on in my head, I had an idea for a gallery of loaders, where each loader is made from the same Sass loop. I always struggle to find these kinds of things online, so I thought it might be useful for others, not to mention myself.

I had already built this kind of thing before as a personal project, so I ended up building a loader generator. Let me know if you find bugs in it!

One loader, two outputs

I was blocked by my own developer skills while creating a generator that produces the right Sass output. I decided to try another animation approach with SMIL animations, and that’s what I wound up deciding to use.

But then I received some help (thanks, ekrof!) and got Sass to work after all.

So, I ended up adding both options to the generator. I found it was a challenge to make both languages return the same result. In fact, they sometimes produce different results.

SMIL vs. CSS/Sass

I learned quite a bit about SMIL and CSS/Sass animations along the way. These are a few of the key takeaways that helped me on my way to making the generator:

  • SMIL doesn’t rely on any external resources. It animates SVG via presentation attributes directly in the SVG markup. That’s something that neither CSS nor Sass can do.
  • SMIL animations are preserved when an SVG is embedded as an image or as a background image. It is possible to add a CSS <style> block directly inside the SVG, but not so much with Sass, of course. That’s why there is an option to download the actual SVG file when selecting the SMIL option in the generator.
  • SMIL animations look a bit more fluid. I couldn’t find the reason for this (if anyone has any deeper information here, please share!). I though it was related to GPU acceleration, but it seems they both use the same animation engine.
Two spinners, one left and one right. They are both red and consist of circles that fade in and out in succession as an animated GIF.
SMIL (left) and Sass (right)

You might notice a difference in the chaining of the animations between both languages:

  • I used additive="sum" in SMIL to add animations one after the other. This makes sure each new animation effect avoids overriding the previous animation.
  • That said, in CSS/Sass, the W3C points out that [when] multiple animations are attempting to modify the same property, then the animation closest to the end of the list of names wins.

That’s why the order in which animations are applied might change the Sass output.

Working with transforms

Working with transformations in the loader’s styling was a big issue. I had applied transform: rotate inline to each shape because it’s a simple way to place them next to each other in a circle and with a face pointing toward the center.

<svg>
  <!-- etc. -->
  <use class="loader" xlink:href="#loader" transform="rotate(0 50 50)" />
  <use class="loader" xlink:href="#loader" transform="rotate(30 50 50)" />
  <use class="loader" xlink:href="#loader" transform="rotate(60 50 50)" />
  <!-- etc. -->
</svg>

I could declare a type in SMIL with <animateTransform> (e.g. scale or translate) to add that specific transform to the original transformation of each shape:

<animateTransform
  attributeName="transform"
  type="translate"
  additive="sum"
  dur="1s"
  :begin="`${i * 0.08}s`"
  repeatCount="indefinite"
  from="0 0"
  to="10"
/>

But instead, transform in CSS was overriding any previous transform applied to the inline SVG. In other words, the original position reset to 0 and showed a very different result from what SMIL produced. That meant the animations wound up looking identical no matter what.

The same two red spinners as before but with different results. The SMIL version on the left seems to work as expected but the Sass one on the right doesn't animate in a circle like it should.

The (not very pretty) solution to make the Sass similar to SMIL was to place each shape inside a group (<g>) element, and apply the inline rotation to the groups, and the animation to the shapes. This way, the inline transform isn’t affected by the animation.

<svg>
  <!-- etc. -->
  <g class="loader" transform="rotate(0 50 50)">
    <use xlink:href="#loader" />
  </g>
  <g class="loader" transform="rotate(30 50 50)">
    <use xlink:href="#loader" />
  </g>
  <!-- etc. -->
</svg>

Now both languages have a very similar result.

The technology I used

I used Vue.js and Nuxt.js. Both have great documentation, but there are more specific reasons why I choose them.

I like Vue for lots of reasons:

  • Vue encapsulates HTML, CSS, and JavaScript as a “single file component” where all the code lives in a single file that’s easier to work with.
  • The way Vue binds and dynamically updates HTML or SVG attributes is very intuitive.
  • HTML and SVG don’t require any extra transformations (like making the code JSX-compatible).

As far as Nuxt goes:

  • It has a quick boilerplate that helps you focus on development instead of configuration.
  • There’s automatic routing and it supports auto-importing components.
  • It’s a good project structure with pages, components, and layouts.
  • It’s easier to optimize for SEO, thanks to meta tags.

Let’s look at a few example loaders

What I like about the end result is that the generator isn’t a one-trick pony. There’s no one way to use it. Because it outputs both SMIL and CSS/Sass, there are several ways to integrate a loader into your own project.

Download the SMIL SVG and use it as a background image in CSS

Like I mentioned earlier, SMIL features are preserved when an SVG is used as a background image file. So, simply download the SVG from the generator, upload it to your server, and reference it in CSS as a background image.

Similarly, we could use the SVG as a background image of a pseudo-element:

Drop the SVG right into the HTML markup

The SVG doesn’t have to be a background image. It’s just code, after all. That means we can simply drop the code from the generator into our own markup and let SMIL do its thing.

Use a Sass loop on the inline SVG

This is what I was originally inspired to do, but ran into some roadblocks. Instead of writing CSS declarations for each animation, we can use the Sass loop produced by the generator. The loop targets a .loader class that’s already applied to the outputted SVG. So, once Sass is compiled to CSS, we get a nice spinning animation.

I’m still working on this

My favorite part of the generator is the custom shape option where you can add text, emojis, or any SVG element to the mix:

The same circle spinner but using custom SVG shapes: one a word, one a poop emoji, and bright pink and orange asterisk.
Custom text, emoji, and SVG

What I would like to do is add a third option for styles to have just one element where you get to work with your own SVG element. That way, there’s less to work with, while allowing for simpler outputs.

The challenge with this project is working with custom values for so many things, like duration, direction, distance, and degrees. Another challenge for me personally is becoming more familiar with Vue because I want to go back and clean up that messy code. That said, the project is open source, and pull requests are welcome! Feel free to send suggestions, feedback, or even Vue course recommendations, especially ones related to SVG or making generators.

This all started with a Sass loop that I read in a book. It isn’t the cleanest code in the world, but I’m left blown away by the power of SMIL animations. I highly recommend Sarah Soueidan’s guide for a deeper dive into what SMIL is capable of doing.

If you’re curious about the safety of SMIL, that is for good reason. There was a time when Chrome was going to entirely deprecated SMIL (see the opening note in MDN). But that deprecation has been suspended and hasn’t (seemingly) been talked about in a while.

Can I use SMIL?

This browser support data is from Caniuse, which has more detail. A number indicates that browser supports the feature at that version and up.

Desktop

ChromeFirefoxIEEdgeSafari
54No796

Mobile / Tablet

Android ChromeAndroid FirefoxAndroidiOS Safari
12612736.0-6.1

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Cutouts https://css-tricks.com/cutouts/ https://css-tricks.com/cutouts/#respond Mon, 16 Aug 2021 20:49:09 +0000 https://css-tricks.com/?p=346686 Ahmad Shadeed dug into shape “cutouts” the other day. Imagine a shape with another smaller shape carved out of it. In his typical comprehensive way, Ahmad laid out the situation well—looking at tricky situations that complicate things.

The first thing …


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Ahmad Shadeed dug into shape “cutouts” the other day. Imagine a shape with another smaller shape carved out of it. In his typical comprehensive way, Ahmad laid out the situation well—looking at tricky situations that complicate things.

The first thing I’d think of is CSS’ clip-path, since it has that circle() syntax that seems like it a good fit, but no!, we need the opposite of what clip-path: circle() does, as we aren’t drawing a circle to be the clipping path here, but drawing all the way around the shape and then up into that second smaller circle and back out, like a bite out of a cookie. That puts us in clip-path: path() territory, which mercifully exists, and yet!, doesn’t quite get there because the path() syntax in CSS only works with fixed-pixel units which is often too limiting in fluid width layouts.

So that puts us at clip-path: url("#my-path"); (referencing an <svg> path), which is exactly where Ahmad starts this journey. But then he explores other options like a clever use of mask-image and a direct use of SVG <mask> and <image>, which turns out to be the winner.

Ideas like this have a weird way of entering the collective front-end developer consciousness somehow. Jay wrote up a very similar journey of wanting to do a shape cutout. Again, the problem:

clip-path defines a visible region, meaning that if you want all but a tiny chunk of the button to be visible, you need to define a path or polygon which is the inverse of the original. Here’s a demo of what I mean, using Clippy:

Jay Freestone, “Cutouts with CSS Masks”

In this case, polygon() has potential because it supports % units for flexibility (also, don’t miss Ana’s idea where the unit types are mixed within the polygon for a some-fixed-some-fluid concept).

Jay’s conclusion is that SVG has the most benefits of all the options:

[…] my overall impression is that mask-composite remains the more flexible solution, since it becomes trivial to use any SVG shape as the mask, not just a triangle or a simple polygon. The likelihood is that you’ll want to simply export an SVG and drop it in. Engineering the inverse result as clip-path is likely to get pretty hairy quickly.

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SVG Gobbler https://css-tricks.com/svg-gobbler/ https://css-tricks.com/svg-gobbler/#comments Fri, 06 Aug 2021 19:32:54 +0000 https://css-tricks.com/?p=346259 Great little project from Ross Moody:

SVG Gobbler is a browser extension that finds the vector content on the page you’re viewing and gives you the option to download, optimize, copy, view the code, or export it as an image.


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Great little project from Ross Moody:

SVG Gobbler is a browser extension that finds the vector content on the page you’re viewing and gives you the option to download, optimize, copy, view the code, or export it as an image.

When a site uses SVG as an <img>, you can right-click/save-as like any other image. But when SVG is inline as <svg> (which often makes sense for styling reasons), it’s harder to snag a copy of it. I usually end up opening DevTools, finding the <svg>, right clicking that, using Copy > Copy outerHTML, pasting into a text file, and saving out as whatever.svg. A little more toil than I’d like.

Show an open DevTools window with a contextual MacOS menu open on top of it with the option Copy highlighted, which opens to a second panel in the contextual menu where an option to copy the HTML is highlighted in bright blue.

With SVG Gobbler, I click the browser extension and it presents me a nice grid of options:

A browser window open with a black header that has the red SVG Gobbler logo flashed left and white buttons to send feedback and toggle dark mode flashed right. Below that is a grid of SVG icons, including the CSS-Tricks logo, a magnifying glass, a close icon, a downward chevron, the Jetpack logo, and an orange downward arrow.

I can quickly download them from here, but notice it will even optimize them for me if I like, or export as a PNG instead. Neat! I’ve made use of this today already, and I’ve only just installed it today.

By way of feedback, I’d say it would be nice to:

  1. Have a way to size the PNG export (might as well allow me to make it huge if I need to).
  2. Export in next-gen formats that might even be better than PNG as far as file size, like WebP or AVIF.
  3. SVG that has a fill of white should be shown on a non-white background so you can see what they are.
  4. Offer, optionally, to let me name the file as I download it rather than always naming it gobbler-original.svg

A stretch goal would be to somehow extract the CSS used on the site into the <svg>. I notice some SVGs it finds look very different when exported, because the page was making use of outside-the-SVG styles to style it, which are lost when exported.

I wonder if the changes to Safari extensions will allow Ross to easily port this to Safari (even Mobile Safari?!).


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My Struggle to Use and Animate a Conic Gradient in SVG https://css-tricks.com/my-struggle-to-use-and-animate-a-conic-gradient-in-svg/ https://css-tricks.com/my-struggle-to-use-and-animate-a-conic-gradient-in-svg/#comments Thu, 08 Jul 2021 14:35:38 +0000 https://css-tricks.com/?p=343623 The wonderful company I work for, Payoneer, has a new logo, and my job was to recreate it and animate it for a loader component in our app. I’ll explain exactly how I did it, share the problems I …


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The wonderful company I work for, Payoneer, has a new logo, and my job was to recreate it and animate it for a loader component in our app. I’ll explain exactly how I did it, share the problems I had, and walk you through the solution I came up with. And, as a bonus, we’ll look at animating it!

But first, I guess some of you are asking yourselves… Recreate it? Why?

The branding agency that designed our logo sent us a full set of assets categorized by themes. They came in all sizes and in every available format. We had everything, including SVGs, for the logo and the loader animation. But we couldn’t use them.

Here’s why. Let’s take a look at the logo:

We call the new logo “The Halo.”

The logo is a ring with a conic gradient that consists of five colors, and… that’s it. The problem is that SVG doesn’t support angled gradients (for now, at least), so when we export a design that has a conic gradient as an SVG, we need some sort of hack to get the desired result.

Now, I’m no expert when it comes to working with vector graphic software, so there might be a different (and perhaps better) way to do this, but I know that the most common way to export conic gradients to SVG is to convert the gradient element to an image and insert that image into the SVG as a base64 string. That’s also what we got from the branding agency, and I trust them to know the best way to export an SVG.

But, since the final SVG file now contains a PNG base64 string, the file size jumped to nearly 1MB, which might not be a total disaster, but it’s much higher than the 2KB that it should be. Multiply that difference by three themes (no text, light text, and dark text variations), and we’re looking at 3MB worth of images instead of 3KB worth of code. That’s a big difference, so we’ve decided to recreate the logo with SVG.

But how?!

Even though CSS fully supports conic gradients, SVG does not. So the first question I asked myself was how to create a conic gradient in SVG. Actually, I asked Google. And what I found was a lot of cool, unique, creative ways to add a conic gradients to SVG, most of them relying on some sort of clip-path implementation. I first created a short <path> that represents the shape of the ring and used it as a clip-path on a simple <rect> element.

Next, I needed to fill the <rect> with conic gradients, but first, I had to find all the correct color stops to recreate the look. That took a while, but after a lot of fine tuning, I got a result I’m happy with:

div.gradient {
  background-image: conic-gradient(from 270deg, #ff4800 10%, #dfd902 35%, #20dc68, #0092f4, #da54d8 72% 75%, #ff4800 95%);
}

The last step was to replace the <rect> with something else that supports conic gradients, and the simplest way I’ve found is to use an SVG <foreignObject> element with a regular <div> inside it, and a conic-gradient as a background-image. Then all I needed to do was to set the clip-path on the <foreignObject> element, and that’s it.

So, that’s how I used a conic gradient in an SVG to keep the design fully vector and scalable with less than 20 lines of code, and less than 2KB in file size.

But that was the easy part. Now let’s talk animation.

The loader

Our app shows a loading animation every time a user logs in. We had been using a GIF file for it, but I had been meaning to update it to a pure CSS/SVG animation for months. The benefits are obvious: faster render means a more seamless loading experience, and a smaller file size means even faster loading. We simply get more for less, which is especially ideal for a loading animation.

Here’s the animation I was aiming for:

This type of animation is actually fairly easy with SVG. All we really need is a trick using stroke-dasharray and stroke-dashoffset. That was my starting point. I created a new <path> in the center of the ring, removed the fill, added a stroke with the right stroke-width, and then worked on the animation.

It took me some playing around to get the movement just like the designers wanted it. I ended up using two animations, actually: one controls the stroke-dashoffset, and the second rotates the entire <path> a full turn.

But, since the clip-path property refers to the fill of the shape, animating the stroke meant I had to solve one of two problems: I could either find a different way to animate the movement, or find a different way to add the colors to the stroke.

So I went back to Google and all of the creative ideas I found before, but most of them were pretty much un-animatable, so I started looking for a good non-clip-path way to add colors to the stroke. I looked at a few “out-of-the-box” solutions, checked out masking, and ended up with the simplest perfect solution:

.logoBlend {
  mix-blend-mode: lighten;
}

A lighten blend mode looks at the RGB colors of each pixel of the rendered element, compares it to the RGB value of the background pixel that’s behind it, and keeps whichever is highest. That means that the parts of the element that are white will remain white, and the dark parts will get the values of the background pixel.

By adding a white <rect> to the black path, I essentially blocked anything that’s behind it. Meanwhile, everything that’s behind the animated black stroke is visible. That meant I could bring back the <foreignObject> with the conic-gradient, put it behind the mix-blend-mode layer, and give it a simple rotate animation to match the design.

Note that the end result of this method will have a white background, not transparent like the static logo, but I was fine with that. If you need to, you can flip it around, use black background, and hide the light parts of your element by setting the blend mode to darken.

Final touches

I was pretty much done at this point, and quite happy with the end result. But a couple of days later, I got a Lottie-based JSON file from the branding agency with the exact same animation. In retrospect, maybe I could spare my work and use their file, it would have worked just fine. Even the file size was surprisingly small, but it was still 8✕ bigger than the SVG, so we ended up using my animation anyway.

But, that meant I had one last thing to do. The Lottie animation had a “start animation” where the small orange dot grows into view, and I had to add it to my animation as well. I added a short 0.5s delay to all three animations as well as a scaling animation in the beginning.

Click on “Rerun” on the Pen to see the animation again from the initial dot.

That’s it! Now my company has a new logo and a set of lightweight, fully scalable assets to use across our web platforms.

And for those of you wondering, yes, I did end up creating a nice little Logo component in React since we’re using it. It even renders the SVG according to a theme passed to it as a prop, making the implementation easier, and keeping all future changes in a single location.

What about you?

Do you think there’s a better way to get the same result? Share your thoughts in the comments! And thank you for reading.


My Struggle to Use and Animate a Conic Gradient in SVG originally published on CSS-Tricks, which is part of the DigitalOcean family. You should get the newsletter.

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