Auto merge of #9208 - jmr0:master-img, r=asajeffrey

Use image metadata to lay out images

Fixes #7047.

cc: @jdm

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components/script/dom/bindings/trace.rs

@@ -58,7 +58,7 @@ use libc;
 use msg::constellation_msg::ConstellationChan;
 use msg::constellation_msg::{PipelineId, SubpageId, WindowSizeData};
 use net_traits::Metadata;
-use net_traits::image::base::Image;
+use net_traits::image::base::{Image, ImageMetadata};
 use net_traits::image_cache_thread::{ImageCacheChan, ImageCacheThread};
 use net_traits::storage_thread::StorageType;
 use profile_traits::mem::ProfilerChan as MemProfilerChan;
@@ -265,7 +265,7 @@ no_jsmanaged_fields!(Receiver<T>);
 no_jsmanaged_fields!(Rect<T>);
 no_jsmanaged_fields!(Size2D<T>);
 no_jsmanaged_fields!(Arc<T>);
-no_jsmanaged_fields!(Image, ImageCacheChan, ImageCacheThread);
+no_jsmanaged_fields!(Image, ImageMetadata, ImageCacheChan, ImageCacheThread);
 no_jsmanaged_fields!(Metadata);
 no_jsmanaged_fields!(Atom, Namespace, QualName);
 no_jsmanaged_fields!(Trusted<T: Reflectable>);

components/script/dom/canvasrenderingcontext2d.rs

@@ -444,7 +444,7 @@ impl CanvasRenderingContext2D {
 
         let img = match self.request_image_from_cache(url) {
             ImageResponse::Loaded(img) => img,
-            ImageResponse::PlaceholderLoaded(_) | ImageResponse::None => {
+            ImageResponse::PlaceholderLoaded(_) | ImageResponse::None | ImageResponse::MetadataLoaded(_) => {
                 return None;
             }
         };

components/script/dom/htmlimageelement.rs

@@ -21,7 +21,7 @@ use dom::node::{Node, NodeDamage, document_from_node, window_from_node};
 use dom::virtualmethods::VirtualMethods;
 use ipc_channel::ipc;
 use ipc_channel::router::ROUTER;
-use net_traits::image::base::Image;
+use net_traits::image::base::{Image, ImageMetadata};
 use net_traits::image_cache_thread::{ImageResponder, ImageResponse};
 use script_thread::ScriptThreadEventCategory::UpdateReplacedElement;
 use script_thread::{CommonScriptMsg, Runnable, ScriptChan};
@@ -35,6 +35,7 @@ pub struct HTMLImageElement {
     htmlelement: HTMLElement,
     url: DOMRefCell<Option<Url>>,
     image: DOMRefCell<Option<Arc<Image>>>,
+    metadata: DOMRefCell<Option<ImageMetadata>>,
 }
 
 impl HTMLImageElement {
@@ -64,12 +65,17 @@ impl Runnable for ImageResponseHandlerRunnable {
         // Update the image field
         let element = self.element.root();
         let element_ref = element.r();
-        *element_ref.image.borrow_mut() = match self.image {
+        let (image, metadata, trigger_image_load) = match self.image {
             ImageResponse::Loaded(image) | ImageResponse::PlaceholderLoaded(image) => {
-                Some(image)
+                (Some(image.clone()), Some(ImageMetadata { height: image.height, width: image.width } ), true)
             }
-            ImageResponse::None => None,
+            ImageResponse::MetadataLoaded(meta) => {
+                (None, Some(meta), false)
+            }
+            ImageResponse::None => (None, None, true)
         };
+        *element_ref.image.borrow_mut() = image;
+        *element_ref.metadata.borrow_mut() = metadata;
 
         // Mark the node dirty
         let document = document_from_node(&*element);
@@ -77,7 +83,9 @@ impl Runnable for ImageResponseHandlerRunnable {
 
         // Fire image.onload
         let window = window_from_node(document.r());
-        element.upcast::<EventTarget>().fire_simple_event("load", GlobalRef::Window(window.r()));
+        if trigger_image_load {
+            element.upcast::<EventTarget>().fire_simple_event("load", GlobalRef::Window(window.r()));
+        }
         // Trigger reflow
         window.add_pending_reflow();
     }
@@ -116,7 +124,7 @@ impl HTMLImageElement {
                         UpdateReplacedElement, runnable));
                 });
 
-                image_cache.request_image(img_url,
+                image_cache.request_image_and_metadata(img_url,
                                           window.image_cache_chan(),
                                           Some(ImageResponder::new(responder_sender)));
             }
@@ -128,6 +136,7 @@ impl HTMLImageElement {
             htmlelement: HTMLElement::new_inherited(localName, prefix, document),
             url: DOMRefCell::new(None),
             image: DOMRefCell::new(None),
+            metadata: DOMRefCell::new(None),
         }
     }
 
@@ -218,20 +227,20 @@ impl HTMLImageElementMethods for HTMLImageElement {
 
     // https://html.spec.whatwg.org/multipage/#dom-img-naturalwidth
     fn NaturalWidth(&self) -> u32 {
-        let image = self.image.borrow();
+        let metadata = self.metadata.borrow();
 
-        match *image {
-            Some(ref image) => image.width,
+        match *metadata {
+            Some(ref metadata) => metadata.width,
             None => 0,
         }
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-img-naturalheight
     fn NaturalHeight(&self) -> u32 {
-        let image = self.image.borrow();
+        let metadata = self.metadata.borrow();
 
-        match *image {
-            Some(ref image) => image.height,
+        match *metadata {
+            Some(ref metadata) => metadata.height,
             None => 0,
         }
     }

components/script/dom/webglrenderingcontext.rs

@@ -1138,7 +1138,8 @@ impl WebGLRenderingContextMethods for WebGLRenderingContext {
 
                 let img = match canvas_utils::request_image_from_cache(window.r(), img_url) {
                     ImageResponse::Loaded(img) => img,
-                    ImageResponse::PlaceholderLoaded(_) | ImageResponse::None
+                    ImageResponse::PlaceholderLoaded(_) | ImageResponse::None |
+                    ImageResponse::MetadataLoaded(_)
                         => return,
                 };