jamesmartin / Inline_svg
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Inline SVG
Styling a SVG document with CSS for use on the web is most reliably achieved by adding classes to the document and embedding it inline in the HTML.
This gem adds Rails helper methods (inline_svg_tag and inline_svg_pack_tag) that read an SVG document (via Sprockets or Webpacker, so works with the Rails Asset Pipeline), applies a CSS class attribute to the root of the document and
then embeds it into a view.
Inline SVG supports:
- Rails 3 (from v0.12.0)
- Rails 4
- Rails 5 (from v0.10.0)
- Rails 6 with Sprockets or Webpacker (from v1.5.2).
Changelog
This project adheres to Semantic Versioning. All notable changes are documented in the CHANGELOG.
Installation
Add this line to your application's Gemfile:
gem 'inline_svg'
And then execute:
$ bundle
Or install it yourself as:
$ gem install inline_svg
Usage
# Sprockets
inline_svg_tag(file_name, options={})
# Webpacker
inline_svg_pack_tag(file_name, options={})
Note: The remainder of this README uses inline_svg_tag for examples, but the exact same principles work for inline_svg_pack_tag.
The file_name can be a full path to a file, the file's basename or an IO
object. The
actual path of the file on disk is resolved using
Sprockets (when available), a naive file finder (/public/assets/...) or in the case of IO objects the SVG data is read from the object.
This means you can pre-process and fingerprint your SVG files like other Rails assets, or choose to find SVG data yourself.
Here's an example of embedding an SVG document and applying a 'class' attribute:
<html>
<head>
<title>Embedded SVG Documents<title>
</head>
<body>
<h1>Embedded SVG Documents</h1>
<div>
<%= inline_svg_tag "some-document.svg", class: 'some-class' %>
</div>
</body>
</html>
Here's some CSS to target the SVG, resize it and turn it an attractive shade of blue:
.some-class {
display: block;
margin: 0 auto;
fill: #3498db;
width: 5em;
height: 5em;
}
Options
| key | description |
|---|---|
id |
set a ID attribute on the SVG |
class |
set a CSS class attribute on the SVG |
style |
set a CSS style attribute on the SVG |
data |
add data attributes to the SVG (supply as a hash) |
size |
set width and height attributes on the SVG Can also be set using height and/or width attributes, which take precedence over size Supplied as "{Width} * {Height}" or "{Number}", so "30px*45px" becomes width="30px" and height="45px", and "50%" becomes width="50%" and height="50%"
|
title |
add a <title> node inside the top level of the SVG document |
desc |
add a <desc> node inside the top level of the SVG document |
nocomment |
remove comment tags from the SVG document |
preserve_aspect_ratio |
adds a preserveAspectRatio attribute to the SVG |
aria |
adds common accessibility attributes to the SVG (see PR #34 for details) |
aria_hidden |
adds the aria-hidden=true attribute to the SVG |
fallback |
set fallback SVG document |
Example:
inline_svg_tag(
"some-document.svg",
id: 'some-id',
class: 'some-class',
data: {some: "value"},
size: '30% * 20%',
title: 'Some Title',
desc: 'Some description',
nocomment: true,
preserve_aspect_ratio: 'xMaxYMax meet',
aria: true,
aria_hidden: true,
fallback: 'fallback-document.svg'
)
Accessibility
Use the aria: true option to make inline_svg_tag add the following
accessibility (a11y) attributes to your embedded SVG:
- Adds a
role="img"attribute to the root SVG element - Adds a
aria-labelled-by="title-id desc-id"attribute to the root SVG element, if the document contains<title>or<desc>elements
Here's an example:
<%=
inline_svg_tag('iconmonstr-glasses-12-icon.svg',
aria: true, title: 'An SVG',
desc: 'This is my SVG. There are many like it. You get the picture')
%>
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" \
role="img" aria-labelledby="bx6wix4t9pxpwxnohrhrmms3wexsw2o m439lk7mopdzmouktv2o689pl59wmd2">
<title id="bx6wix4t9pxpwxnohrhrmms3wexsw2o">An SVG</title>
<desc id="m439lk7mopdzmouktv2o689pl59wmd2">This is my SVG. There are many like it. You get the picture</desc>
</svg>
Note: The title and desc id attributes generated for, and referenced by, aria-labelled-by are one-way digests based on the value of the title and desc elements and an optional "salt" value using the SHA1 algorithm. This reduces the chance of inline_svg_tag embedding elements inside the SVG with id attributes that clash with other elements elsewhere on the page.
Custom Transformations
The transformation behavior of inline_svg_tag can be customized by creating custom transformation classes.
For example, inherit from InlineSvg::CustomTransformation and implement the #transform method:
# Sets the `custom` attribute on the root SVG element to supplied value
# Remember to return a document, as this will be passed along the transformation chain
class MyCustomTransform < InlineSvg::CustomTransformation
def transform(doc)
with_svg(doc) do |svg|
svg["custom"] = value
end
end
end
Add the custom configuration in an initializer (E.g. ./config/initializers/inline_svg.rb):
# Note that the named `attribute` will be used to pass a value to your custom transform
InlineSvg.configure do |config|
config.add_custom_transformation(attribute: :my_custom_attribute, transform: MyCustomTransform)
end
The custom transformation can then be called like so:
%div
= inline_svg_tag "some-document.svg", my_custom_attribute: 'some value'
In this example, the following transformation would be applied to a SVG document:
<svg custom="some value">...</svg>
You can also provide a default_value to the custom transformation, so even if you don't pass a value it will be triggered
# Note that the named `attribute` will be used to pass a value to your custom transform
InlineSvg.configure do |config|
config.add_custom_transformation(attribute: :my_custom_attribute, transform: MyCustomTransform, default_value: 'default value')
end
The custom transformation will be triggered even if you don't pass any attribute value
%div
= inline_svg_tag "some-document.svg"
= inline_svg_tag "some-document.svg", my_custom_attribute: 'some value'
In this example, the following transformation would be applied to a SVG document:
<svg custom="default value">...</svg>
And
<svg custom="some value">...</svg>
Passing a priority option with your custom transformation allows you to
control the order that transformations are applied to the SVG document:
InlineSvg.configure do |config|
config.add_custom_transformation(attribute: :custom_one, transform: MyCustomTransform, priority: 1)
config.add_custom_transformation(attribute: :custom_two, transform: MyOtherCustomTransform, priority: 2)
end
Transforms are applied in ascending order (lowest number first).
Note: Custom transformations are always applied after all built-in transformations, regardless of priority.
Custom asset file loader
An asset file loader returns a String representing a SVG document given a
filename. Custom asset loaders should be a Ruby object that responds to a
method called named, that takes one argument (a string representing the
filename of the SVG document).
A simple example might look like this:
class MyAssetFileLoader
def self.named(filename)
# ... load SVG document however you like
return "<svg>some document</svg>"
end
end
Configure your custom asset file loader in an initializer like so:
InlineSvg.configure do |config|
config.asset_file = MyAssetFileLoader
end
Caching all assets at boot time
When your deployment strategy prevents dynamic asset file loading from disk it
can be helpful to cache all possible SVG assets in memory at application boot
time. In this case, you can configure the InlineSvg::CachedAssetFile to scan
any number of paths on disks and load all the assets it finds into memory.
For example, in this configuration we load every *.svg file found beneath the
configured paths into memory:
InlineSvg.configure do |config|
config.asset_file = InlineSvg::CachedAssetFile.new(
paths: [
"#{Rails.root}/public/path/to/assets",
"#{Rails.root}/public/other/path/to/assets"
],
filters: /\.svg/
)
end
Note: Paths are read recursively, so think about keeping your SVG assets
restricted to as few paths as possible, and using the filter option to further
restrict assets to only those likely to be used by inline_svg_tag.
Missing SVG Files
If the specified SVG file cannot be found a helpful, empty SVG document is embedded into the page instead. The embedded document contains a single comment displaying the filename of the SVG image the helper tried to render:
<svg><!-- SVG file not found: 'some-missing-file.svg' --></svg>
You may apply a class to this empty SVG document by specifying the following configuration:
InlineSvg.configure do |config|
config.svg_not_found_css_class = 'svg-not-found'
end
Which would instead render:
<svg class='svg-not-found'><!-- SVG file not found: 'some-missing-file.svg' --></svg>
Alternatively, inline_svg_tag can be configured to raise an exception when a file
is not found:
InlineSvg.configure do |config|
config.raise_on_file_not_found = true
end
Contributing
- Fork it ( http://github.com/jamesmartin/inline_svg/fork )
- Create your feature branch (
git checkout -b my-new-feature) - Commit your changes (
git commit -am 'Add some feature') - Push to the branch (
git push origin my-new-feature) - Create new Pull Request
Please write tests for anything you change, add or fix. There is a basic Rails app that demonstrates the gem's functionality in use.