Use IpcSharedMemory for Canvas2dMsg::DrawImage (servo#30544)

* Use `IpcSharedMemory` for `Canvas2DMsg::DrawImage`

* Fix `Canvas2dMsg::DrawEmptyImage` crashes

* Do not premultiply canvas image data

* Move `image_data` back to its original position

components/canvas/canvas_data.rs

@@ -446,11 +446,12 @@ impl<'a> CanvasData<'a> {
 
     pub fn draw_image(
         &mut self,
-        image_data: Vec<u8>,
+        image_data: &[u8],
         image_size: Size2D<f64>,
         dest_rect: Rect<f64>,
         source_rect: Rect<f64>,
         smoothing_enabled: bool,
+        premultiply: bool,
     ) {
         // We round up the floating pixel values to draw the pixels
         let source_rect = source_rect.ceil();
@@ -469,6 +470,7 @@ impl<'a> CanvasData<'a> {
                 source_rect.size,
                 dest_rect,
                 smoothing_enabled,
+                premultiply,
                 &draw_options,
             );
         };
@@ -1306,17 +1308,24 @@ pub struct CanvasPaintState<'a> {
 /// image_size: The size of the image to be written
 /// dest_rect: Area of the destination target where the pixels will be copied
 /// smoothing_enabled: It determines if smoothing is applied to the image result
+/// premultiply: Determines whenever the image data should be premultiplied or not
 fn write_image(
     draw_target: &mut dyn GenericDrawTarget,
-    image_data: Vec<u8>,
+    mut image_data: Vec<u8>,
     image_size: Size2D<f64>,
     dest_rect: Rect<f64>,
     smoothing_enabled: bool,
+    premultiply: bool,
     draw_options: &DrawOptions,
 ) {
     if image_data.is_empty() {
         return;
     }
+
+    if premultiply {
+        pixels::rgba8_premultiply_inplace(&mut image_data);
+    }
+
     let image_rect = Rect::new(Point2D::zero(), image_size);
 
     // From spec https://html.spec.whatwg.org/multipage/#dom-context-2d-drawimage

components/canvas/canvas_paint_thread.rs

@@ -175,22 +175,27 @@ impl<'a> CanvasPaintThread<'a> {
                 .canvas(canvas_id)
                 .is_point_in_path(x, y, fill_rule, chan),
             Canvas2dMsg::DrawImage(
-                imagedata,
+                ref image_data,
                 image_size,
                 dest_rect,
                 source_rect,
                 smoothing_enabled,
-            ) => {
-                let data = imagedata.map_or_else(
-                    || vec![0; image_size.width as usize * image_size.height as usize * 4],
-                    |bytes| bytes.into_vec(),
-                );
+            ) => self.canvas(canvas_id).draw_image(
+                &*image_data,
+                image_size,
+                dest_rect,
+                source_rect,
+                smoothing_enabled,
+                true,
+            ),
+            Canvas2dMsg::DrawEmptyImage(image_size, dest_rect, source_rect) => {
                 self.canvas(canvas_id).draw_image(
-                    data,
+                    &vec![0; image_size.area() as usize * 4],
                     image_size,
                     dest_rect,
                     source_rect,
-                    smoothing_enabled,
+                    false,
+                    false,
                 )
             },
             Canvas2dMsg::DrawImageInOther(
@@ -204,11 +209,12 @@ impl<'a> CanvasPaintThread<'a> {
                     .canvas(canvas_id)
                     .read_pixels(source_rect.to_u64(), image_size.to_u64());
                 self.canvas(other_canvas_id).draw_image(
-                    image_data.into(),
+                    &image_data,
                     source_rect.size,
                     dest_rect,
                     source_rect,
                     smoothing,
+                    false,
                 );
             },
             Canvas2dMsg::MoveTo(ref point) => self.canvas(canvas_id).move_to(point),

components/canvas_traits/canvas.rs

@@ -41,7 +41,8 @@ pub struct CanvasImageData {
 pub enum Canvas2dMsg {
     Arc(Point2D<f32>, f32, f32, f32, bool),
     ArcTo(Point2D<f32>, Point2D<f32>, f32),
-    DrawImage(Option<ByteBuf>, Size2D<f64>, Rect<f64>, Rect<f64>, bool),
+    DrawImage(IpcSharedMemory, Size2D<f64>, Rect<f64>, Rect<f64>, bool),
+    DrawEmptyImage(Size2D<f64>, Rect<f64>, Rect<f64>),
     DrawImageInOther(CanvasId, Size2D<f64>, Rect<f64>, Rect<f64>, bool),
     BeginPath,
     BezierCurveTo(Point2D<f32>, Point2D<f32>, Point2D<f32>),

components/script/canvas_state.rs

@@ -15,13 +15,12 @@ use canvas_traits::canvas::{
 use cssparser::{Color as CSSColor, Parser, ParserInput, RGBA};
 use euclid::default::{Point2D, Rect, Size2D, Transform2D};
 use euclid::vec2;
-use ipc_channel::ipc::{self, IpcSender};
+use ipc_channel::ipc::{self, IpcSender, IpcSharedMemory};
 use net_traits::image_cache::{ImageCache, ImageResponse};
 use net_traits::request::CorsSettings;
 use pixels::PixelFormat;
 use profile_traits::ipc as profiled_ipc;
 use script_traits::ScriptMsg;
-use serde_bytes::ByteBuf;
 use servo_url::{ImmutableOrigin, ServoUrl};
 use style::properties::longhands::font_variant_caps::computed_value::T as FontVariantCaps;
 use style::properties::style_structs::Font;
@@ -260,7 +259,7 @@ impl CanvasState {
         &self,
         url: ServoUrl,
         cors_setting: Option<CorsSettings>,
-    ) -> Option<(Vec<u8>, Size2D<u32>)> {
+    ) -> Option<(IpcSharedMemory, Size2D<u32>)> {
         let img = match self.request_image_from_cache(url, cors_setting) {
             ImageResponse::Loaded(img, _) => img,
             ImageResponse::PlaceholderLoaded(_, _) |
@@ -272,7 +271,7 @@ impl CanvasState {
 
         let image_size = Size2D::new(img.width, img.height);
         let image_data = match img.format {
-            PixelFormat::BGRA8 => img.bytes.to_vec(),
+            PixelFormat::BGRA8 => img.bytes.clone(),
             pixel_format => unimplemented!("unsupported pixel format ({:?})", pixel_format),
         };
 
@@ -492,12 +491,10 @@ impl CanvasState {
                 },
             }
         } else {
-            self.send_canvas_2d_msg(Canvas2dMsg::DrawImage(
-                None,
+            self.send_canvas_2d_msg(Canvas2dMsg::DrawEmptyImage(
                 image_size,
                 dest_rect,
                 source_rect,
-                smoothing_enabled,
             ));
         }
 
@@ -554,12 +551,10 @@ impl CanvasState {
                 _ => return Err(Error::InvalidState),
             }
         } else {
-            self.send_canvas_2d_msg(Canvas2dMsg::DrawImage(
-                None,
+            self.send_canvas_2d_msg(Canvas2dMsg::DrawEmptyImage(
                 image_size,
                 dest_rect,
                 source_rect,
-                smoothing_enabled,
             ));
         }
 
@@ -582,10 +577,9 @@ impl CanvasState {
         dh: Option<f64>,
     ) -> ErrorResult {
         debug!("Fetching image {}.", url);
-        let (mut image_data, image_size) = self
+        let (image_data, image_size) = self
             .fetch_image_data(url, cors_setting)
             .ok_or(Error::InvalidState)?;
-        pixels::rgba8_premultiply_inplace(&mut image_data);
         let image_size = image_size.to_f64();
 
         let dw = dw.unwrap_or(image_size.width);
@@ -603,7 +597,7 @@ impl CanvasState {
 
         let smoothing_enabled = self.state.borrow().image_smoothing_enabled;
         self.send_canvas_2d_msg(Canvas2dMsg::DrawImage(
-            Some(ByteBuf::from(image_data)),
+            image_data,
             image_size,
             dest_rect,
             source_rect,
@@ -916,6 +910,7 @@ impl CanvasState {
                     .and_then(|url| {
                         self.fetch_image_data(url, cors_setting_for_element(image.upcast()))
                     })
+                    .map(|data| (data.0.to_vec(), data.1))
                     .ok_or(Error::InvalidState)?
             },
             CanvasImageSource::HTMLCanvasElement(ref canvas) => {
@@ -935,6 +930,7 @@ impl CanvasState {
             CanvasImageSource::CSSStyleValue(ref value) => value
                 .get_url(self.base_url.clone())
                 .and_then(|url| self.fetch_image_data(url, None))
+                .map(|data| (data.0.to_vec(), data.1))
                 .ok_or(Error::InvalidState)?,
         };