layout: Add support for <object> with image data URLs (#32069)

This is enough support for `<object>` to get Acid2 working.

Co-authored-by: Oriol Brufau <obrufau@igalia.com>

Cargo.lock

@@ -3091,6 +3091,7 @@ dependencies = [
  "bitflags 2.5.0",
  "canvas_traits",
  "cssparser",
+ "data-url",
  "embedder_traits",
  "euclid",
  "fnv",
@@ -3119,6 +3120,7 @@ dependencies = [
  "style_traits",
  "unicode-script",
  "unicode-segmentation",
+ "url",
  "webrender_api",
  "xi-unicode",
 ]

components/layout_2020/Cargo.toml

@@ -44,6 +44,8 @@ style = { workspace = true }
 style_traits = { workspace = true }
 unicode-script = { workspace = true }
 unicode-segmentation = { workspace = true }
+url = { workspace = true }
+data-url = { workspace = true }
 webrender_api = { workspace = true }
 xi-unicode = { workspace = true }
 

components/layout_2020/dom.rs

@@ -6,10 +6,15 @@ use std::marker::PhantomData;
 use std::sync::{Arc, Mutex};
 
 use atomic_refcell::{AtomicRef, AtomicRefCell, AtomicRefMut};
+use html5ever::{local_name, namespace_url, ns};
 use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::image::base::Image as NetImage;
-use script_layout_interface::wrapper_traits::{LayoutDataTrait, LayoutNode, ThreadSafeLayoutNode};
-use script_layout_interface::HTMLCanvasDataSource;
+use script_layout_interface::wrapper_traits::{
+    LayoutDataTrait, LayoutNode, ThreadSafeLayoutElement, ThreadSafeLayoutNode,
+};
+use script_layout_interface::{
+    HTMLCanvasDataSource, LayoutElementType, LayoutNodeType as ScriptLayoutNodeType,
+};
 use servo_arc::Arc as ServoArc;
 use style::properties::ComputedValues;
 
@@ -95,6 +100,7 @@ pub(crate) trait NodeExt<'dom>: 'dom + LayoutNode<'dom> {
     fn as_canvas(self) -> Option<(CanvasInfo, PhysicalSize<f64>)>;
     fn as_iframe(self) -> Option<(PipelineId, BrowsingContextId)>;
     fn as_video(self) -> Option<(webrender_api::ImageKey, PhysicalSize<f64>)>;
+    fn as_typeless_object_with_data_attribute(self) -> Option<String>;
     fn style(self, context: &LayoutContext) -> ServoArc<ComputedValues>;
 
     fn layout_data_mut(self) -> AtomicRefMut<'dom, InnerDOMLayoutData>;
@@ -163,6 +169,25 @@ where
         }
     }
 
+    fn as_typeless_object_with_data_attribute(self) -> Option<String> {
+        if self.type_id() != ScriptLayoutNodeType::Element(LayoutElementType::HTMLObjectElement) {
+            return None;
+        }
+        let Some(element) = self.to_threadsafe().as_element() else {
+            return None;
+        };
+
+        // TODO: This is the what the legacy layout system does, but really if Servo
+        // supports any `<object>` that's an image, it should support those with URLs
+        // and `type` attributes with image mime types.
+        if element.get_attr(&ns!(), &local_name!("type")).is_some() {
+            return None;
+        }
+        element
+            .get_attr(&ns!(), &local_name!("data"))
+            .map(|string| string.to_owned())
+    }
+
     fn style(self, context: &LayoutContext) -> ServoArc<ComputedValues> {
         self.to_threadsafe().style(context.shared_context())
     }

components/layout_2020/dom_traversal.rs

@@ -175,7 +175,7 @@ fn traverse_element<'dom, Node>(
 ) where
     Node: NodeExt<'dom>,
 {
-    let replaced = ReplacedContent::for_element(element);
+    let replaced = ReplacedContent::for_element(element, context);
     let style = element.style(context);
     match Display::from(style.get_box().display) {
         Display::None => element.unset_all_boxes(),

components/layout_2020/flow/root.rs

@@ -204,7 +204,7 @@ impl BoxTree {
 
         loop {
             if let Some((primary_style, display_inside, update_point)) = update_point(dirty_node) {
-                let contents = ReplacedContent::for_element(dirty_node)
+                let contents = ReplacedContent::for_element(dirty_node, context)
                     .map_or(Contents::OfElement, Contents::Replaced);
                 let info = NodeAndStyleInfo::new(dirty_node, Arc::clone(&primary_style));
                 let out_of_flow_absolutely_positioned_box = ArcRefCell::new(
@@ -262,8 +262,8 @@ fn construct_for_root_element<'dom>(
         Display::GeneratingBox(display_generating_box) => display_generating_box.display_inside(),
     };
 
-    let contents =
-        ReplacedContent::for_element(root_element).map_or(Contents::OfElement, Contents::Replaced);
+    let contents = ReplacedContent::for_element(root_element, context)
+        .map_or(Contents::OfElement, Contents::Replaced);
     let root_box = if box_style.position.is_absolutely_positioned() {
         BlockLevelBox::OutOfFlowAbsolutelyPositionedBox(ArcRefCell::new(
             AbsolutelyPositionedBox::construct(context, &info, display_inside, contents),

components/layout_2020/replaced.rs

@@ -7,6 +7,7 @@ use std::sync::{Arc, Mutex};
 
 use app_units::Au;
 use canvas_traits::canvas::{CanvasId, CanvasMsg, FromLayoutMsg};
+use data_url::DataUrl;
 use ipc_channel::ipc::{self, IpcSender};
 use msg::constellation_msg::{BrowsingContextId, PipelineId};
 use net_traits::image::base::Image;
@@ -19,6 +20,7 @@ use style::values::computed::image::Image as ComputedImage;
 use style::values::computed::{Length, LengthOrAuto};
 use style::values::CSSFloat;
 use style::Zero;
+use url::Url;
 use webrender_api::ImageKey;
 
 use crate::context::LayoutContext;
@@ -131,7 +133,17 @@ pub(crate) enum ReplacedContentKind {
 }
 
 impl ReplacedContent {
-    pub fn for_element<'dom>(element: impl NodeExt<'dom>) -> Option<Self> {
+    pub fn for_element<'dom>(element: impl NodeExt<'dom>, context: &LayoutContext) -> Option<Self> {
+        if let Some(ref data_attribute_string) = element.as_typeless_object_with_data_attribute() {
+            if let Some(url) = try_to_parse_image_data_url(data_attribute_string) {
+                return Self::from_image_url(
+                    element,
+                    context,
+                    &ComputedUrl::Valid(ServoArc::new(url)),
+                );
+            }
+        }
+
         let (kind, intrinsic_size_in_dots) = {
             if let Some((image, intrinsic_size_in_dots)) = element.as_image() {
                 (
@@ -558,3 +570,28 @@ impl ReplacedContent {
         }
     }
 }
+
+fn try_to_parse_image_data_url(string: &str) -> Option<Url> {
+    if !string.starts_with("data:") {
+        return None;
+    }
+    let Some(data_url) = DataUrl::process(string).ok() else {
+        return None;
+    };
+
+    let mime_type = data_url.mime_type();
+    if mime_type.type_ != "image" {
+        return None;
+    }
+
+    // TODO: Find a better way to test for supported image formats. Currently this type of check is
+    // repeated several places in Servo, but should be centralized somehow.
+    if !matches!(
+        mime_type.subtype.as_str(),
+        "png" | "jpeg" | "gif" | "webp" | "bmp" | "ico"
+    ) {
+        return None;
+    }
+
+    Url::parse(string).ok()
+}

tests/wpt/meta/quirks/table-cell-width-calculation.html.ini

@@ -34,3 +34,6 @@
 
   [The table cell width calculation quirk, non-auto width on cell]
     expected: FAIL
+
+  [The table cell width calculation quirk, the quirk shouldn't apply for <object>]
+    expected: FAIL

tests/wpt/mozilla/meta/css/object_element_a.html.ini

@@ -1,2 +0,0 @@
-[object_element_a.html]
-  expected: FAIL