gfx: Allow images to be shipped to the WebRender thread without shipping

over the data as well.

WebRender doesn't need the data, as it acquires it separately.

About a 50%-100% improvement in display list building time on
browser.html.

8 files changed, 152 insertions, 71 deletions

diff --git a/components/gfx/display_list/mod.rs b/components/gfx/display_list/mod.rs
index 97e2260ba99..7bba2ce0e53 100644
--- a/components/gfx/display_list/mod.rs
+++ b/components/gfx/display_list/mod.rs
@@ -24,8 +24,9 @@ use euclid::{Matrix2D, Matrix4, Point2D, Rect, SideOffsets2D, Size2D};
 use fnv::FnvHasher;
 use gfx_traits::{LayerId, ScrollPolicy};
 use heapsize::HeapSizeOf;
+use ipc_channel::ipc::IpcSharedMemory;
 use msg::constellation_msg::PipelineId;
-use net_traits::image::base::Image;
+use net_traits::image::base::{Image, PixelFormat};
 use paint_context::PaintContext;
 use range::Range;
 use serde::de::{self, Deserialize, Deserializer, MapVisitor, Visitor};
@@ -46,7 +47,7 @@ use text::TextRun;
 use text::glyph::CharIndex;
 use util::geometry::{self, MAX_RECT, ScreenPx};
 use util::print_tree::PrintTree;
-use webrender_traits::WebGLContextId;
+use webrender_traits::{self, WebGLContextId};
 
 pub use style::dom::OpaqueNode;
 
@@ -986,8 +987,11 @@ pub enum TextOrientation {
 #[derive(Clone, HeapSizeOf, Deserialize, Serialize)]
 pub struct ImageDisplayItem {
     pub base: BaseDisplayItem,
+
+    pub webrender_image: WebRenderImageInfo,
+
     #[ignore_heap_size_of = "Because it is non-owning"]
-    pub image: Arc<Image>,
+    pub image_data: Option<Arc<IpcSharedMemory>>,
 
     /// The dimensions to which the image display item should be stretched. If this is smaller than
     /// the bounds of this display item, then the image will be repeated in the appropriate
@@ -1203,10 +1207,14 @@ impl DisplayItem {
 
             DisplayItem::ImageClass(ref image_item) => {
                 debug!("Drawing image at {:?}.", image_item.base.bounds);
-                paint_context.draw_image(&image_item.base.bounds,
-                                         &image_item.stretch_size,
-                                         image_item.image.clone(),
-                                         image_item.image_rendering.clone());
+                paint_context.draw_image(
+                    &image_item.base.bounds,
+                    &image_item.stretch_size,
+                    &image_item.webrender_image,
+                    &image_item.image_data
+                               .as_ref()
+                               .expect("Non-WR painting needs image data!")[..],
+                    image_item.image_rendering.clone());
             }
 
             DisplayItem::WebGLClass(_) => {
@@ -1390,3 +1398,25 @@ impl StackingContextId {
         StackingContextId(fragment_type, id)
     }
 }
+
+#[derive(Copy, Clone, HeapSizeOf, Deserialize, Serialize)]
+pub struct WebRenderImageInfo {
+    pub width: u32,
+    pub height: u32,
+    pub format: PixelFormat,
+    #[ignore_heap_size_of = "WebRender traits type, and tiny"]
+    pub key: Option<webrender_traits::ImageKey>,
+}
+
+impl WebRenderImageInfo {
+    #[inline]
+    pub fn from_image(image: &Image) -> WebRenderImageInfo {
+        WebRenderImageInfo {
+            width: image.width,
+            height: image.height,
+            format: image.format,
+            key: image.id,
+        }
+    }
+}
+
diff --git a/components/gfx/paint_context.rs b/components/gfx/paint_context.rs
index 9fded4e8651..7b8813d907e 100644
--- a/components/gfx/paint_context.rs
+++ b/components/gfx/paint_context.rs
@@ -17,7 +17,7 @@ use azure::{AzDrawTargetFillGlyphs, struct__AzGlyphBuffer, struct__AzPoint};
 use azure::{AzFloat, struct__AzDrawOptions, struct__AzGlyph};
 use display_list::TextOrientation::{SidewaysLeft, SidewaysRight, Upright};
 use display_list::{BLUR_INFLATION_FACTOR, BorderRadii, BoxShadowClipMode, ClippingRegion};
-use display_list::{TextDisplayItem};
+use display_list::{TextDisplayItem, WebRenderImageInfo};
 use euclid::matrix2d::Matrix2D;
 use euclid::point::Point2D;
 use euclid::rect::{Rect, TypedRect};
@@ -27,10 +27,9 @@ use euclid::size::Size2D;
 use filters;
 use font_context::FontContext;
 use gfx_traits::{color, LayerKind};
-use net_traits::image::base::{Image, PixelFormat};
+use net_traits::image::base::PixelFormat;
 use range::Range;
 use std::default::Default;
-use std::sync::Arc;
 use std::{f32, mem, ptr};
 use style::computed_values::{border_style, filter, image_rendering, mix_blend_mode};
 use text::TextRun;
@@ -181,21 +180,22 @@ impl<'a> PaintContext<'a> {
     pub fn draw_image(&self,
                       bounds: &Rect<Au>,
                       stretch_size: &Size2D<Au>,
-                      image: Arc<Image>,
+                      image_info: &WebRenderImageInfo,
+                      image_data: &[u8],
                       image_rendering: image_rendering::T) {
-        let size = Size2D::new(image.width as i32, image.height as i32);
-        let (pixel_width, source_format) = match image.format {
+        let size = Size2D::new(image_info.width as i32, image_info.height as i32);
+        let (pixel_width, source_format) = match image_info.format {
             PixelFormat::RGBA8 => (4, SurfaceFormat::B8G8R8A8),
             PixelFormat::K8 => (1, SurfaceFormat::A8),
             PixelFormat::RGB8 => panic!("RGB8 color type not supported"),
             PixelFormat::KA8 => panic!("KA8 color type not supported"),
         };
-        let stride = image.width * pixel_width;
+        let stride = image_info.width * pixel_width;
         let scale = self.screen_pixels_per_px();
 
         self.draw_target.make_current();
         let draw_target_ref = &self.draw_target;
-        let azure_surface = match draw_target_ref.create_source_surface_from_data(&image.bytes,
+        let azure_surface = match draw_target_ref.create_source_surface_from_data(image_data,
                                                                                   size,
                                                                                   stride as i32,
                                                                                   source_format) {
@@ -204,7 +204,8 @@ impl<'a> PaintContext<'a> {
         };
 
         let source_rect = Rect::new(Point2D::new(0.0, 0.0),
-                                    Size2D::new(image.width as AzFloat, image.height as AzFloat));
+                                    Size2D::new(image_info.width as AzFloat,
+                                                image_info.height as AzFloat));
         let dest_rect = bounds.to_nearest_azure_rect(scale);
 
         // TODO(pcwalton): According to CSS-IMAGES-3 § 5.3, nearest-neighbor interpolation is a
diff --git a/components/layout/context.rs b/components/layout/context.rs
index 49dc10cb457..143e78f810e 100644
--- a/components/layout/context.rs
+++ b/components/layout/context.rs
@@ -11,11 +11,12 @@ use app_units::Au;
 use canvas_traits::CanvasMsg;
 use euclid::Rect;
 use fnv::FnvHasher;
+use gfx::display_list::WebRenderImageInfo;
 use gfx::font_cache_thread::FontCacheThread;
 use gfx::font_context::FontContext;
 use gfx_traits::LayerId;
 use heapsize::HeapSizeOf;
-use ipc_channel::ipc::{self, IpcSender};
+use ipc_channel::ipc::{self, IpcSender, IpcSharedMemory};
 use net_traits::image::base::Image;
 use net_traits::image_cache_thread::{ImageCacheChan, ImageCacheThread, ImageResponse, ImageState};
 use net_traits::image_cache_thread::{ImageOrMetadataAvailable, UsePlaceholder};
@@ -24,7 +25,7 @@ use std::collections::HashMap;
 use std::hash::BuildHasherDefault;
 use std::rc::Rc;
 use std::sync::mpsc::Sender;
-use std::sync::{Arc, Mutex};
+use std::sync::{Arc, Mutex, RwLock};
 use style::context::{LocalStyleContext, StyleContext};
 use style::matching::{ApplicableDeclarationsCache, StyleSharingCandidateCache};
 use style::selector_impl::ServoSelectorImpl;
@@ -99,6 +100,11 @@ pub struct SharedLayoutContext {
 
     /// The visible rects for each layer, as reported to us by the compositor.
     pub visible_rects: Arc<HashMap<LayerId, Rect<Au>, BuildHasherDefault<FnvHasher>>>,
+
+    /// A cache of WebRender image info.
+    pub webrender_image_cache: Arc<RwLock<HashMap<(Url, UsePlaceholder),
+                                                  WebRenderImageInfo,
+                                                  BuildHasherDefault<FnvHasher>>>>,
 }
 
 pub struct LayoutContext<'a> {
@@ -132,45 +138,36 @@ impl<'a> LayoutContext<'a> {
         self.cached_local_layout_context.font_context.borrow_mut()
     }
 
-    pub fn get_or_request_image(&self, url: Url, use_placeholder: UsePlaceholder)
-                                -> Option<Arc<Image>> {
+    fn get_or_request_image_synchronously(&self, url: Url, use_placeholder: UsePlaceholder)
+                                          -> Option<Arc<Image>> {
+        debug_assert!(opts::get().output_file.is_some() || opts::get().exit_after_load);
+
         // See if the image is already available
-        let result = self.shared.image_cache_thread.find_image(url.clone(),
-                                                             use_placeholder);
+        let result = self.shared.image_cache_thread.find_image(url.clone(), use_placeholder);
 
         match result {
-            Ok(image) => Some(image),
-            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(image),
-                            ImageResponse::None | ImageResponse::MetadataLoaded(_) => None,
+            Ok(image) => return Some(image),
+            Err(ImageState::LoadError) => {
+                // Image failed to load, so just return nothing
+                return None
+            }
+            Err(_) => {}
+        }
+
+        // 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 (sync_tx, sync_rx) = ipc::channel().unwrap();
+        self.shared.image_cache_thread.request_image(url, ImageCacheChan(sync_tx), None);
+        loop {
+            match sync_rx.recv() {
+                Err(_) => return None,
+                Ok(response) => {
+                    match response.image_response {
+                        ImageResponse::Loaded(image) | ImageResponse::PlaceholderLoaded(image) => {
+                            return Some(image)
                         }
+                        ImageResponse::None | ImageResponse::MetadataLoaded(_) => {}
                     }
-                    // Not yet requested, async mode - request image from the cache
-                    (ImageState::NotRequested, false) => {
-                        let sender = self.shared.image_cache_sender.lock().unwrap().clone();
-                        self.shared.image_cache_thread.request_image(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,
                 }
             }
         }
@@ -180,7 +177,7 @@ impl<'a> LayoutContext<'a> {
                                 -> Option<ImageOrMetadataAvailable> {
         // If we are emitting an output file, load the image synchronously.
         if opts::get().output_file.is_some() || opts::get().exit_after_load {
-            return self.get_or_request_image(url, use_placeholder)
+            return self.get_or_request_image_synchronously(url, use_placeholder)
                        .map(|img| ImageOrMetadataAvailable::ImageAvailable(img));
         }
         // See if the image is already available
@@ -202,4 +199,43 @@ impl<'a> LayoutContext<'a> {
         }
     }
 
+    pub fn get_webrender_image_for_url(&self,
+                                       url: &Url,
+                                       use_placeholder: UsePlaceholder,
+                                       fetch_image_data_as_well: bool)
+                                       -> Option<(WebRenderImageInfo, Option<IpcSharedMemory>)> {
+        if !fetch_image_data_as_well {
+            let webrender_image_cache = self.shared.webrender_image_cache.read().unwrap();
+            if let Some(existing_webrender_image) =
+                    webrender_image_cache.get(&((*url).clone(), use_placeholder)) {
+                return Some(((*existing_webrender_image).clone(), None))
+            }
+        }
+
+        match self.get_or_request_image_or_meta((*url).clone(), use_placeholder) {
+            Some(ImageOrMetadataAvailable::ImageAvailable(image)) => {
+                let image_info = WebRenderImageInfo::from_image(&*image);
+                if image_info.key.is_none() {
+                    let bytes = if !fetch_image_data_as_well {
+                        None
+                    } else {
+                        Some(image.bytes.clone())
+                    };
+                    Some((image_info, bytes))
+                } else if !fetch_image_data_as_well {
+                    let mut webrender_image_cache = self.shared
+                                                        .webrender_image_cache
+                                                        .write()
+                                                        .unwrap();
+                    webrender_image_cache.insert(((*url).clone(), use_placeholder),
+                                                 image_info);
+                    Some((image_info, None))
+                } else {
+                    Some((image_info, Some(image.bytes.clone())))
+                }
+            }
+            None | Some(ImageOrMetadataAvailable::MetadataAvailable(_)) => None,
+        }
+    }
 }
+
diff --git a/components/layout/display_list_builder.rs b/components/layout/display_list_builder.rs
index f498d83c389..407d4d19a05 100644
--- a/components/layout/display_list_builder.rs
+++ b/components/layout/display_list_builder.rs
@@ -29,7 +29,7 @@ use gfx::display_list::{GradientDisplayItem};
 use gfx::display_list::{GradientStop, IframeDisplayItem, ImageDisplayItem, WebGLDisplayItem, LayeredItem, LayerInfo};
 use gfx::display_list::{LineDisplayItem, OpaqueNode, SolidColorDisplayItem};
 use gfx::display_list::{StackingContext, StackingContextId, StackingContextType};
-use gfx::display_list::{TextDisplayItem, TextOrientation, DisplayListEntry};
+use gfx::display_list::{TextDisplayItem, TextOrientation, DisplayListEntry, WebRenderImageInfo};
 use gfx::paint_thread::THREAD_TINT_COLORS;
 use gfx::text::glyph::CharIndex;
 use gfx_traits::{color, ScrollPolicy};
@@ -37,7 +37,7 @@ use inline::{FIRST_FRAGMENT_OF_ELEMENT, InlineFlow, LAST_FRAGMENT_OF_ELEMENT};
 use ipc_channel::ipc::{self, IpcSharedMemory};
 use list_item::ListItemFlow;
 use model::{self, MaybeAuto, ToGfxMatrix};
-use net_traits::image::base::{Image, PixelFormat};
+use net_traits::image::base::PixelFormat;
 use net_traits::image_cache_thread::UsePlaceholder;
 use range::Range;
 use std::default::Default;
@@ -136,7 +136,7 @@ pub trait FragmentDisplayListBuilding {
     fn compute_background_image_size(&self,
                                      style: &ComputedValues,
                                      bounds: &Rect<Au>,
-                                     image: &Image)
+                                     image: &WebRenderImageInfo)
                                      -> Size2D<Au>;
 
     /// Adds the display items necessary to paint the background image of this fragment to the
@@ -404,7 +404,7 @@ impl FragmentDisplayListBuilding for Fragment {
     fn compute_background_image_size(&self,
                                      style: &ComputedValues,
                                      bounds: &Rect<Au>,
-                                     image: &Image)
+                                     image: &WebRenderImageInfo)
                                      -> Size2D<Au> {
         // If `image_aspect_ratio` < `bounds_aspect_ratio`, the image is tall; otherwise, it is
         // wide.
@@ -462,14 +462,17 @@ impl FragmentDisplayListBuilding for Fragment {
                                                clip: &ClippingRegion,
                                                image_url: &Url) {
         let background = style.get_background();
-        let image =
-            state.layout_context.get_or_request_image(image_url.clone(), UsePlaceholder::No);
-        if let Some(image) = image {
+        let fetch_image_data_as_well = !opts::get().use_webrender;
+        let webrender_image =
+            state.layout_context.get_webrender_image_for_url(image_url,
+                                                             UsePlaceholder::No,
+                                                             fetch_image_data_as_well);
+        if let Some((webrender_image, image_data)) = webrender_image {
             debug!("(building display list) building background image");
 
             // Use `background-size` to get the size.
             let mut bounds = *absolute_bounds;
-            let image_size = self.compute_background_image_size(style, &bounds, &*image);
+            let image_size = self.compute_background_image_size(style, &bounds, &webrender_image);
 
             // Clip.
             //
@@ -560,7 +563,8 @@ impl FragmentDisplayListBuilding for Fragment {
                                                                     style,
                                                                     Cursor::DefaultCursor),
                                            &clip),
-                image: image.clone(),
+                webrender_image: webrender_image,
+                image_data: image_data.map(Arc::new),
                 stretch_size: Size2D::new(image_size.width, image_size.height),
                 image_rendering: style.get_effects().image_rendering.clone(),
             }), display_list_section);
@@ -1173,7 +1177,8 @@ impl FragmentDisplayListBuilding for Fragment {
                                                                             &*self.style,
                                                                             Cursor::DefaultCursor),
                                                    clip),
-                        image: image.clone(),
+                        webrender_image: WebRenderImageInfo::from_image(image),
+                        image_data: Some(Arc::new(image.bytes.clone())),
                         stretch_size: stacking_relative_content_box.size,
                         image_rendering: self.style.get_effects().image_rendering.clone(),
                     }), DisplayListSection::Content);
@@ -1214,13 +1219,13 @@ impl FragmentDisplayListBuilding for Fragment {
                                                                                     &*self.style,
                                                                                     Cursor::DefaultCursor),
                                                            clip),
-                                image: Arc::new(Image {
+                                image_data: Some(Arc::new(canvas_data.image_data)),
+                                webrender_image: WebRenderImageInfo {
                                     width: width as u32,
                                     height: height as u32,
                                     format: PixelFormat::RGBA8,
-                                    bytes: canvas_data.image_data,
-                                    id: canvas_data.image_key,
-                                }),
+                                    key: canvas_data.image_key,
+                                },
                                 stretch_size: stacking_relative_content_box.size,
                                 image_rendering: image_rendering::T::Auto,
                             })
diff --git a/components/layout/layout_thread.rs b/components/layout/layout_thread.rs
index 603fa35472c..041eab87168 100644
--- a/components/layout/layout_thread.rs
+++ b/components/layout/layout_thread.rs
@@ -24,6 +24,7 @@ use flow_ref::{self, FlowRef};
 use fnv::FnvHasher;
 use gfx::display_list::{ClippingRegion, DisplayItemMetadata, DisplayList, LayerInfo};
 use gfx::display_list::{OpaqueNode, StackingContext, StackingContextId, StackingContextType};
+use gfx::display_list::{WebRenderImageInfo};
 use gfx::font;
 use gfx::font_cache_thread::FontCacheThread;
 use gfx::font_context;
@@ -39,6 +40,7 @@ use layout_traits::LayoutThreadFactory;
 use log;
 use msg::constellation_msg::{ConstellationChan, ConvertPipelineIdToWebRender, Failure, PipelineId};
 use net_traits::image_cache_thread::{ImageCacheChan, ImageCacheResult, ImageCacheThread};
+use net_traits::image_cache_thread::{UsePlaceholder};
 use parallel;
 use profile_traits::mem::{self, Report, ReportKind, ReportsChan};
 use profile_traits::time::{TimerMetadataFrameType, TimerMetadataReflowType};
@@ -84,7 +86,7 @@ use util::thread;
 use util::thread_state;
 use util::workqueue::WorkQueue;
 use webrender_helpers::{WebRenderDisplayListConverter, WebRenderFrameBuilder};
-use webrender_traits::{self, AuxiliaryListsBuilder};
+use webrender_traits;
 use wrapper::{LayoutNode, NonOpaqueStyleAndLayoutData, ServoLayoutNode, ThreadSafeLayoutNode};
 
 /// The number of screens of data we're allowed to generate display lists for in each direction.
@@ -235,6 +237,10 @@ pub struct LayoutThread {
     /// The CSS error reporter for all CSS loaded in this layout thread
     error_reporter: CSSErrorReporter,
 
+    webrender_image_cache: Arc<RwLock<HashMap<(Url, UsePlaceholder),
+                                              WebRenderImageInfo,
+                                              BuildHasherDefault<FnvHasher>>>>,
+
     // Webrender interface, if enabled.
     webrender_api: Option<webrender_traits::RenderApi>,
 }
@@ -475,6 +481,8 @@ impl LayoutThread {
                   pipelineid: id,
                   script_chan: Arc::new(Mutex::new(script_chan)),
               },
+              webrender_image_cache:
+                  Arc::new(RwLock::new(HashMap::with_hasher(Default::default()))),
         }
     }
 
@@ -516,6 +524,7 @@ impl LayoutThread {
             canvas_layers_sender: Mutex::new(self.canvas_layers_sender.clone()),
             url: (*url).clone(),
             visible_rects: self.visible_rects.clone(),
+            webrender_image_cache: self.webrender_image_cache.clone(),
         }
     }
 
diff --git a/components/layout/webrender_helpers.rs b/components/layout/webrender_helpers.rs
index 1f5f9671821..fcf0e204a0d 100644
--- a/components/layout/webrender_helpers.rs
+++ b/components/layout/webrender_helpers.rs
@@ -436,7 +436,7 @@ impl WebRenderDisplayItemConverter for DisplayItem {
                 }
             }
             DisplayItem::ImageClass(ref item) => {
-                if let Some(id) = item.image.id {
+                if let Some(id) = item.webrender_image.key {
                     if item.stretch_size.width > Au(0) &&
                        item.stretch_size.height > Au(0) {
                         builder.push_image(level,
diff --git a/components/msg/constellation_msg.rs b/components/msg/constellation_msg.rs
index 83f308b26fd..34512fedf8b 100644
--- a/components/msg/constellation_msg.rs
+++ b/components/msg/constellation_msg.rs
@@ -222,7 +222,7 @@ pub struct ImageMetadata {
     pub height: u32,
 }
 
-#[derive(Deserialize, Serialize, HeapSizeOf)]
+#[derive(Clone, Deserialize, Serialize, HeapSizeOf)]
 pub struct Image {
     pub width: u32,
     pub height: u32,
diff --git a/components/net_traits/image_cache_thread.rs b/components/net_traits/image_cache_thread.rs
index 8324bae8b23..0011cab8e9f 100644
--- a/components/net_traits/image_cache_thread.rs
+++ b/components/net_traits/image_cache_thread.rs
@@ -96,7 +96,7 @@ pub enum ImageCacheCommand {
     Exit(IpcSender<()>),
 }
 
-#[derive(Copy, Clone, PartialEq, Deserialize, Serialize)]
+#[derive(Copy, Clone, PartialEq, Hash, Eq, Deserialize, Serialize)]
 pub enum UsePlaceholder {
     No,
     Yes,