Make layout use available image data before querying the image cache.

components/layout/fragment.rs

@@ -401,6 +401,11 @@ pub struct ImageFragmentInfo {
     pub metadata: Option<ImageMetadata>,
 }
 
+enum ImageOrMetadata {
+    Image(Arc<Image>),
+    Metadata(ImageMetadata),
+}
+
 impl ImageFragmentInfo {
     /// Creates a new image fragment from the given URL and local image cache.
     ///
@@ -412,14 +417,29 @@ impl ImageFragmentInfo {
         node: &N,
         layout_context: &LayoutContext,
     ) -> ImageFragmentInfo {
-        let image_or_metadata = url.and_then(|url| {
-            layout_context.get_or_request_image_or_meta(node.opaque(), url, UsePlaceholder::Yes)
-        });
+        // First use any image data present in the element...
+        let image_or_metadata = node.image_data().and_then(|(image, metadata)| {
+            match (image, metadata) {
+                (Some(image), _) => Some(ImageOrMetadata::Image(image)),
+                (None, Some(metadata)) => Some(ImageOrMetadata::Metadata(metadata)),
+                _ => None,
+            }
+        }).or_else(|| url.and_then(|url| {
+            // Otherwise query the image cache for anything known about the associated source URL.
+            layout_context.get_or_request_image_or_meta(
+                node.opaque(),
+                url,
+                UsePlaceholder::Yes
+            ).map(|result| match result {
+                ImageOrMetadataAvailable::ImageAvailable(i, _) => ImageOrMetadata::Image(i),
+                ImageOrMetadataAvailable::MetadataAvailable(m) => ImageOrMetadata::Metadata(m),
+            })
+        }));
 
         let current_pixel_density = density.unwrap_or(1f64);
 
         let (image, metadata) = match image_or_metadata {
-            Some(ImageOrMetadataAvailable::ImageAvailable(i, _)) => {
+            Some(ImageOrMetadata::Image(i)) => {
                 let height = (i.height as f64 / current_pixel_density) as u32;
                 let width = (i.width as f64 / current_pixel_density) as u32;
                 (
@@ -434,7 +454,7 @@ impl ImageFragmentInfo {
                     }),
                 )
             },
-            Some(ImageOrMetadataAvailable::MetadataAvailable(m)) => {
+            Some(ImageOrMetadata::Metadata(m)) => {
                 (
                     None,
                     Some(ImageMetadata {

components/layout_thread/dom_wrapper.rs

@@ -36,6 +36,7 @@ use html5ever::{LocalName, Namespace};
 use layout::data::StyleAndLayoutData;
 use layout::wrapper::GetRawData;
 use msg::constellation_msg::{BrowsingContextId, PipelineId};
+use net_traits::image::base::{Image, ImageMetadata};
 use range::Range;
 use script::layout_exports::{CharacterDataTypeId, ElementTypeId, HTMLElementTypeId, NodeTypeId};
 use script::layout_exports::{Document, Element, Node, Text};
@@ -59,6 +60,7 @@ use std::fmt::Debug;
 use std::hash::{Hash, Hasher};
 use std::marker::PhantomData;
 use std::ptr::NonNull;
+use std::sync::Arc as StdArc;
 use std::sync::atomic::Ordering;
 use style::CaseSensitivityExt;
 use style::applicable_declarations::ApplicableDeclarationBlock;
@@ -1048,6 +1050,11 @@ impl<'ln> ThreadSafeLayoutNode for ServoThreadSafeLayoutNode<'ln> {
         this.image_density()
     }
 
+    fn image_data(&self) -> Option<(Option<StdArc<Image>>, Option<ImageMetadata>)> {
+        let this = unsafe { self.get_jsmanaged() };
+        this.image_data()
+    }
+
     fn canvas_data(&self) -> Option<HTMLCanvasData> {
         let this = unsafe { self.get_jsmanaged() };
         this.canvas_data()

components/script/dom/htmlimageelement.rs

@@ -1328,6 +1328,9 @@ pub trait LayoutHTMLImageElementHelpers {
     #[allow(unsafe_code)]
     unsafe fn image_density(&self) -> Option<f64>;
 
+    #[allow(unsafe_code)]
+    unsafe fn image_data(&self) -> (Option<Arc<Image>>, Option<ImageMetadata>);
+
     fn get_width(&self) -> LengthOrPercentageOrAuto;
     fn get_height(&self) -> LengthOrPercentageOrAuto;
 }
@@ -1351,6 +1354,14 @@ impl LayoutHTMLImageElementHelpers for LayoutDom<HTMLImageElement> {
             .clone()
     }
 
+    #[allow(unsafe_code)]
+    unsafe fn image_data(&self) -> (Option<Arc<Image>>, Option<ImageMetadata>) {
+        let current_request = (*self.unsafe_get())
+            .current_request
+            .borrow_for_layout();
+        (current_request.image.clone(), current_request.metadata.clone())
+    }
+
     #[allow(unsafe_code)]
     unsafe fn image_density(&self) -> Option<f64> {
         (*self.unsafe_get())

components/script/dom/node.rs

@@ -62,6 +62,7 @@ use js::jsapi::{JSContext, JSObject, JSRuntime};
 use libc::{self, c_void, uintptr_t};
 use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
 use msg::constellation_msg::{BrowsingContextId, PipelineId};
+use net_traits::image::base::{Image, ImageMetadata};
 use ref_slice::ref_slice;
 use script_layout_interface::{HTMLCanvasData, HTMLMediaData, LayoutElementType, LayoutNodeType};
 use script_layout_interface::{OpaqueStyleAndLayoutData, SVGSVGData, TrustedNodeAddress};
@@ -81,6 +82,7 @@ use std::default::Default;
 use std::iter;
 use std::mem;
 use std::ops::Range;
+use std::sync::Arc as StdArc;
 use style::context::QuirksMode;
 use style::dom::OpaqueNode;
 use style::selector_parser::{SelectorImpl, SelectorParser};
@@ -1086,6 +1088,7 @@ pub trait LayoutNodeHelpers {
     fn selection(&self) -> Option<Range<usize>>;
     fn image_url(&self) -> Option<ServoUrl>;
     fn image_density(&self) -> Option<f64>;
+    fn image_data(&self) -> Option<(Option<StdArc<Image>>, Option<ImageMetadata>)>;
     fn canvas_data(&self) -> Option<HTMLCanvasData>;
     fn media_data(&self) -> Option<HTMLMediaData>;
     fn svg_data(&self) -> Option<SVGSVGData>;
@@ -1233,6 +1236,13 @@ impl LayoutNodeHelpers for LayoutDom<Node> {
         }
     }
 
+    #[allow(unsafe_code)]
+    fn image_data(&self) -> Option<(Option<StdArc<Image>>, Option<ImageMetadata>)> {
+        unsafe {
+            self.downcast::<HTMLImageElement>().map(|e| e.image_data())
+        }
+    }
+
     #[allow(unsafe_code)]
     fn image_density(&self) -> Option<f64> {
         unsafe {

components/script_layout_interface/wrapper_traits.rs

@@ -13,10 +13,12 @@ use atomic_refcell::AtomicRef;
 use gfx_traits::{ByteIndex, FragmentType, combine_id_with_fragment_type};
 use html5ever::{Namespace, LocalName};
 use msg::constellation_msg::{BrowsingContextId, PipelineId};
+use net_traits::image::base::{Image, ImageMetadata};
 use range::Range;
 use servo_arc::Arc;
 use servo_url::ServoUrl;
 use std::fmt::Debug;
+use std::sync::Arc as StdArc;
 use style::attr::AttrValue;
 use style::context::SharedStyleContext;
 use style::data::ElementData;
@@ -276,6 +278,9 @@ pub trait ThreadSafeLayoutNode:
     /// If this is an image element, returns its current-pixel-density. If this is not an image element, fails.
     fn image_density(&self) -> Option<f64>;
 
+    /// If this is an image element, returns its image data. Otherwise, returns `None`.
+    fn image_data(&self) -> Option<(Option<StdArc<Image>>, Option<ImageMetadata>)>;
+
     fn canvas_data(&self) -> Option<HTMLCanvasData>;
 
     fn svg_data(&self) -> Option<SVGSVGData>;