Add support for static SVG images using resvg crate (#36721)

This change adds support for rendering static SVG images using the
`resvg` crate, allowing svg sources in the `img` tag and in CSS
`background` and `content` properties. There are some limitations in
using resvg:

1. There is no support for animations or interactivity as these would
require implementing the full DOM layer of SVG specification.
2. Only system fonts can be used for text rendering. There is some
mechanism to provide a custom font resolver to usvg, but that is not
explored in this change.
3. resvg's handling of certain edge cases involving lack of explicit
`width` and `height` on the root svg element deviates from what the
specification expects from browsers. For example, resvg uses the values
in `viewBox` to derive the missing width or height dimension, but
without scaling that dimension to preserve the aspect ratio. It also
doesn't allow overriding this behavior.

Demo screenshot:
![servo - resvg
img](https://github.com/user-attachments/assets/8ecb2de2-ab7c-48e2-9f08-2d09d2cb8791)

<details>
<summary>Source</summary>

```
<style>
 #svg1 {
   border: 1px solid red;
 }

 #svg2 {
   border: 1px solid red;
   width: 300px;
 }
 #svg3 {
   border: 1px solid red;
   width: 300px;
   height: 200px;
   object-fit: contain;
 }
 #svg4 {
   border: 1px solid red;
   width: 300px;
   height: 200px;
   object-fit: cover;
 }
 #svg5 {
   border: 1px solid red;
   width: 300px;
   height: 200px;
   object-fit: fill;
 }
 #svg6 {
   border: 1px solid red;
   width: 300px;
   height: 200px;
   object-fit: none;
 }
</style>
</head>
<body>
        <div>
          <img id="svg1" src="https://raw.githubusercontent.com/servo/servo/refs/heads/main/resources/servo.svg" alt="Servo logo">
        </div>
        <div>
          <img id="svg2" src="https://raw.githubusercontent.com/servo/servo/refs/heads/main/resources/servo.svg" alt="Servo logo">
          <img id="svg3" src="https://raw.githubusercontent.com/servo/servo/refs/heads/main/resources/servo.svg" alt="Servo logo">
          <img id="svg4" src="https://raw.githubusercontent.com/servo/servo/refs/heads/main/resources/servo.svg" alt="Servo logo">
        </div>
        <div>
          <img id="svg5" src="https://raw.githubusercontent.com/servo/servo/refs/heads/main/resources/servo.svg" alt="Servo logo">
          <img id="svg6" src="https://raw.githubusercontent.com/servo/servo/refs/heads/main/resources/servo.svg" alt="Servo logo">
        </div>
</body>
```

</details>

---------

Signed-off-by: Mukilan Thiyagarajan <mukilan@igalia.com>
Signed-off-by: Martin Robinson <mrobinson@igalia.com>
Co-authored-by: Martin Robinson <mrobinson@igalia.com>
This commit is contained in:
Mukilan Thiyagarajan 2025-05-27 16:32:40 +05:30 committed by GitHub
parent 324196351e
commit 8a20e42de4
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
267 changed files with 2374 additions and 544 deletions

View file

@ -4,13 +4,12 @@
use std::any::Any;
use std::marker::PhantomData;
use std::sync::Arc;
use atomic_refcell::{AtomicRef, AtomicRefCell, AtomicRefMut};
use base::id::{BrowsingContextId, PipelineId};
use html5ever::{local_name, ns};
use malloc_size_of_derive::MallocSizeOf;
use pixels::Image;
use net_traits::image_cache::Image;
use script::layout_dom::ServoLayoutNode;
use script_layout_interface::wrapper_traits::{
LayoutDataTrait, LayoutNode, ThreadSafeLayoutElement, ThreadSafeLayoutNode,
@ -197,7 +196,7 @@ impl Drop for BoxSlot<'_> {
pub(crate) trait NodeExt<'dom> {
/// Returns the image if its loaded, and its size in image pixels
/// adjusted for `image_density`.
fn as_image(&self) -> Option<(Option<Arc<Image>>, PhysicalSize<f64>)>;
fn as_image(&self) -> Option<(Option<Image>, PhysicalSize<f64>)>;
fn as_canvas(&self) -> Option<(CanvasInfo, PhysicalSize<f64>)>;
fn as_iframe(&self) -> Option<(PipelineId, BrowsingContextId)>;
fn as_video(&self) -> Option<(Option<webrender_api::ImageKey>, Option<PhysicalSize<f64>>)>;
@ -220,12 +219,15 @@ pub(crate) trait NodeExt<'dom> {
}
impl<'dom> NodeExt<'dom> for ServoLayoutNode<'dom> {
fn as_image(&self) -> Option<(Option<Arc<Image>>, PhysicalSize<f64>)> {
fn as_image(&self) -> Option<(Option<Image>, PhysicalSize<f64>)> {
let node = self.to_threadsafe();
let (resource, metadata) = node.image_data()?;
let (width, height) = resource
.as_ref()
.map(|image| (image.width, image.height))
.map(|image| {
let image_metadata = image.metadata();
(image_metadata.width, image_metadata.height)
})
.or_else(|| metadata.map(|metadata| (metadata.width, metadata.height)))
.unwrap_or((0, 0));
let (mut width, mut height) = (width as f64, height as f64);