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/layout/context.rs

@@ -17,7 +17,7 @@ use gfx_traits::LayerId;
 use ipc_channel::ipc::{self, IpcSender};
 use net_traits::image::base::Image;
 use net_traits::image_cache_thread::{ImageCacheChan, ImageCacheThread, ImageResponse, ImageState};
-use net_traits::image_cache_thread::{UsePlaceholder};
+use net_traits::image_cache_thread::{ImageOrMetadataAvailable, UsePlaceholder};
 use std::cell::{RefCell, RefMut};
 use std::collections::HashMap;
 use std::collections::hash_state::DefaultState;
@@ -155,7 +155,7 @@ impl<'a> LayoutContext<'a> {
                         match sync_rx.recv().unwrap().image_response {
                             ImageResponse::Loaded(image) |
                             ImageResponse::PlaceholderLoaded(image) => Some(image),
-                            ImageResponse::None => None,
+                            ImageResponse::None | ImageResponse::MetadataLoaded(_) => None,
                         }
                     }
                     // Not yet requested, async mode - request image from the cache
@@ -172,4 +172,51 @@ impl<'a> LayoutContext<'a> {
             }
         }
     }
+
+    pub fn get_or_request_image_or_meta(&self, url: Url, use_placeholder: UsePlaceholder)
+                                -> Option<ImageOrMetadataAvailable> {
+        // See if the image is already available
+        let result = self.shared.image_cache_thread.find_image_or_metadata(url.clone(),
+                                                                         use_placeholder);
+
+        match result {
+            Ok(image_or_metadata) => Some(image_or_metadata),
+            Err(state) => {
+                // If we are emitting an output file, then we need to block on
+                // image load or we risk emitting an output file missing the image.
+                let is_sync = opts::get().output_file.is_some() ||
+                              opts::get().exit_after_load;
+
+                match (state, is_sync) {
+                    // Image failed to load, so just return nothing
+                    (ImageState::LoadError, _) => None,
+                    // Not loaded, test mode - load the image synchronously
+                    (_, true) => {
+                        let (sync_tx, sync_rx) = ipc::channel().unwrap();
+                        self.shared.image_cache_thread.request_image(url,
+                                                                   ImageCacheChan(sync_tx),
+                                                                   None);
+                        match sync_rx.recv().unwrap().image_response {
+                            ImageResponse::Loaded(image) |
+                            ImageResponse::PlaceholderLoaded(image) =>
+                                Some(ImageOrMetadataAvailable::ImageAvailable(image)),
+                            ImageResponse::None | ImageResponse::MetadataLoaded(_) =>
+                                None,
+                        }
+                    }
+                    // Not yet requested, async mode - request image or metadata from the cache
+                    (ImageState::NotRequested, false) => {
+                        let sender = self.shared.image_cache_sender.lock().unwrap().clone();
+                        self.shared.image_cache_thread.request_image_and_metadata(url, sender, None);
+                        None
+                    }
+                    // Image has been requested, is still pending. Return no image
+                    // for this paint loop. When the image loads it will trigger
+                    // a reflow and/or repaint.
+                    (ImageState::Pending, false) => None,
+                }
+            }
+        }
+    }
+
 }

components/layout/fragment.rs

@@ -25,8 +25,8 @@ use ipc_channel::ipc::IpcSender;
 use layout_debug;
 use model::{self, IntrinsicISizes, IntrinsicISizesContribution, MaybeAuto, specified};
 use msg::constellation_msg::PipelineId;
-use net_traits::image::base::Image;
-use net_traits::image_cache_thread::UsePlaceholder;
+use net_traits::image::base::{Image, ImageMetadata};
+use net_traits::image_cache_thread::{ImageOrMetadataAvailable, UsePlaceholder};
 use rustc_serialize::{Encodable, Encoder};
 use script::dom::htmlcanvaselement::HTMLCanvasData;
 use std::borrow::ToOwned;
@@ -344,6 +344,7 @@ pub struct ImageFragmentInfo {
     /// The image held within this fragment.
     pub replaced_image_fragment_info: ReplacedImageFragmentInfo,
     pub image: Option<Arc<Image>>,
+    pub metadata: Option<ImageMetadata>,
 }
 
 impl ImageFragmentInfo {
@@ -361,26 +362,39 @@ impl ImageFragmentInfo {
                    .map(Au::from_px)
         }
 
-        let image = url.and_then(|url| {
-            layout_context.get_or_request_image(url, UsePlaceholder::Yes)
+        let image_or_metadata = url.and_then(|url| {
+            layout_context.get_or_request_image_or_meta(url, UsePlaceholder::Yes)
         });
 
+        let (image, metadata) = match image_or_metadata {
+            Some(ImageOrMetadataAvailable::ImageAvailable(i)) => {
+                (Some(i.clone()), Some(ImageMetadata { height: i.height, width: i.width } ))
+            }
+            Some(ImageOrMetadataAvailable::MetadataAvailable(m)) => {
+                (None, Some(m))
+            }
+            None => {
+                (None, None)
+            }
+        };
+
         ImageFragmentInfo {
             replaced_image_fragment_info: ReplacedImageFragmentInfo::new(node,
                 convert_length(node, &atom!("width")),
                 convert_length(node, &atom!("height"))),
             image: image,
+            metadata: metadata,
         }
     }
 
     /// Returns the original inline-size of the image.
     pub fn image_inline_size(&mut self) -> Au {
-        match self.image {
-            Some(ref image) => {
+        match self.metadata {
+            Some(ref metadata) => {
                 Au::from_px(if self.replaced_image_fragment_info.writing_mode_is_vertical {
-                    image.height
+                    metadata.height
                 } else {
-                    image.width
+                    metadata.width
                 } as i32)
             }
             None => Au(0)
@@ -389,12 +403,12 @@ impl ImageFragmentInfo {
 
     /// Returns the original block-size of the image.
     pub fn image_block_size(&mut self) -> Au {
-        match self.image {
-            Some(ref image) => {
+        match self.metadata {
+            Some(ref metadata) => {
                 Au::from_px(if self.replaced_image_fragment_info.writing_mode_is_vertical {
-                    image.width
+                    metadata.width
                 } else {
-                    image.height
+                    metadata.height
                 } as i32)
             }
             None => Au(0)