Addresses Issue: Support OffscreenCanvas as CanvasImageSource #24269

Added methods to canvas_data to support drawing an offscreen canvas onto another canvas
Bug fix: Swapped OffscreenCanvas width and height parameters to match Mozilla spec
Tests: Updated metadata for 866 tests

components/script/canvas_state.rs

@@ -22,6 +22,7 @@ use crate::dom::globalscope::GlobalScope;
 use crate::dom::htmlcanvaselement::{CanvasContext, HTMLCanvasElement};
 use crate::dom::imagedata::ImageData;
 use crate::dom::node::{Node, NodeDamage};
+use crate::dom::offscreencanvas::{OffscreenCanvas, OffscreenCanvasContext};
 use crate::dom::paintworkletglobalscope::PaintWorkletGlobalScope;
 use crate::dom::textmetrics::TextMetrics;
 use crate::euclidext::Size2DExt;
@@ -222,6 +223,7 @@ impl CanvasState {
     fn is_origin_clean(&self, image: CanvasImageSource) -> bool {
         match image {
             CanvasImageSource::HTMLCanvasElement(canvas) => canvas.origin_is_clean(),
+            CanvasImageSource::OffscreenCanvas(canvas) => canvas.origin_is_clean(),
             CanvasImageSource::HTMLImageElement(image) => {
                 image.same_origin(GlobalScope::entry().origin())
             },
@@ -372,6 +374,9 @@ impl CanvasState {
             CanvasImageSource::HTMLCanvasElement(ref canvas) => {
                 self.draw_html_canvas_element(&canvas, htmlcanvas, sx, sy, sw, sh, dx, dy, dw, dh)
             },
+            CanvasImageSource::OffscreenCanvas(ref canvas) => {
+                self.draw_offscreen_canvas(&canvas, htmlcanvas, sx, sy, sw, sh, dx, dy, dw, dh)
+            },
             CanvasImageSource::HTMLImageElement(ref image) => {
                 // https://html.spec.whatwg.org/multipage/#img-error
                 // If the image argument is an HTMLImageElement object that is in the broken state,
@@ -408,9 +413,9 @@ impl CanvasState {
         result
     }
 
-    fn draw_html_canvas_element(
+    fn draw_offscreen_canvas(
         &self,
-        canvas: &HTMLCanvasElement,
+        canvas: &OffscreenCanvas,
         htmlcanvas: Option<&HTMLCanvasElement>,
         sx: f64,
         sy: f64,
@@ -420,6 +425,62 @@ impl CanvasState {
         dy: f64,
         dw: Option<f64>,
         dh: Option<f64>,
+    ) -> ErrorResult {
+        let canvas_size = canvas.get_size();
+        let dw = dw.unwrap_or(canvas_size.width as f64);
+        let dh = dh.unwrap_or(canvas_size.height as f64);
+        let sw = sw.unwrap_or(canvas_size.width as f64);
+        let sh = sh.unwrap_or(canvas_size.height as f64);
+
+        let image_size = Size2D::new(canvas_size.width as f64, canvas_size.height as f64);
+        // 2. Establish the source and destination rectangles
+        let (source_rect, dest_rect) =
+            self.adjust_source_dest_rects(image_size, sx, sy, sw, sh, dx, dy, dw, dh);
+
+        if !is_rect_valid(source_rect) || !is_rect_valid(dest_rect) {
+            return Ok(());
+        }
+
+        let smoothing_enabled = self.state.borrow().image_smoothing_enabled;
+
+        if let Some(context) = canvas.context() {
+            match *context {
+                OffscreenCanvasContext::OffscreenContext2d(ref context) => {
+                    context.send_canvas_2d_msg(Canvas2dMsg::DrawImageInOther(
+                        self.get_canvas_id(),
+                        image_size,
+                        dest_rect,
+                        source_rect,
+                        smoothing_enabled,
+                    ));
+                },
+            }
+        } else {
+            self.send_canvas_2d_msg(Canvas2dMsg::DrawImage(
+                None,
+                image_size,
+                dest_rect,
+                source_rect,
+                smoothing_enabled,
+            ));
+        }
+
+        self.mark_as_dirty(htmlcanvas);
+        Ok(())
+    }
+
+    fn draw_html_canvas_element(
+        &self,
+        canvas: &HTMLCanvasElement,             // source canvas
+        htmlcanvas: Option<&HTMLCanvasElement>, // destination canvas
+        sx: f64,
+        sy: f64,
+        sw: Option<f64>,
+        sh: Option<f64>,
+        dx: f64,
+        dy: f64,
+        dw: Option<f64>,
+        dh: Option<f64>,
     ) -> ErrorResult {
         // 1. Check the usability of the image argument
         if !canvas.is_valid() {
@@ -842,6 +903,13 @@ impl CanvasState {
                     .unwrap_or_else(|| vec![0; size.area() as usize * 4]);
                 (data, size)
             },
+            CanvasImageSource::OffscreenCanvas(ref canvas) => {
+                let (data, size) = canvas.fetch_all_data().ok_or(Error::InvalidState)?;
+                let data = data
+                    .map(|data| data.to_vec())
+                    .unwrap_or_else(|| vec![0; size.area() as usize * 4]);
+                (data, size)
+            },
             CanvasImageSource::CSSStyleValue(ref value) => value
                 .get_url(self.base_url.clone())
                 .and_then(|url| self.fetch_image_data(url, None))

components/script/dom/offscreencanvas.rs

@@ -16,9 +16,12 @@ use crate::dom::globalscope::GlobalScope;
 use crate::dom::htmlcanvaselement::HTMLCanvasElement;
 use crate::dom::offscreencanvasrenderingcontext2d::OffscreenCanvasRenderingContext2D;
 use crate::script_runtime::JSContext;
+use canvas_traits::canvas::{CanvasMsg, FromScriptMsg};
 use dom_struct::dom_struct;
 use euclid::default::Size2D;
+use ipc_channel::ipc::IpcSharedMemory;
 use js::rust::HandleValue;
+use profile_traits::ipc;
 use ref_filter_map;
 use std::cell::Cell;
 use std::cell::Ref;
@@ -34,57 +37,91 @@ pub enum OffscreenCanvasContext {
 #[dom_struct]
 pub struct OffscreenCanvas {
     eventtarget: EventTarget,
-    height: Cell<u64>,
     width: Cell<u64>,
+    height: Cell<u64>,
     context: DomRefCell<Option<OffscreenCanvasContext>>,
     placeholder: Option<Dom<HTMLCanvasElement>>,
 }
 
 impl OffscreenCanvas {
     pub fn new_inherited(
-        height: u64,
         width: u64,
+        height: u64,
         placeholder: Option<&HTMLCanvasElement>,
     ) -> OffscreenCanvas {
         OffscreenCanvas {
             eventtarget: EventTarget::new_inherited(),
-            height: Cell::new(height),
             width: Cell::new(width),
+            height: Cell::new(height),
             context: DomRefCell::new(None),
             placeholder: placeholder.map(Dom::from_ref),
         }
     }
 
     pub fn new(
         global: &GlobalScope,
-        height: u64,
         width: u64,
+        height: u64,
         placeholder: Option<&HTMLCanvasElement>,
     ) -> DomRoot<OffscreenCanvas> {
         reflect_dom_object(
-            Box::new(OffscreenCanvas::new_inherited(height, width, placeholder)),
+            Box::new(OffscreenCanvas::new_inherited(width, height, placeholder)),
             global,
             OffscreenCanvasWrap,
         )
     }
 
     pub fn Constructor(
         global: &GlobalScope,
-        height: u64,
         width: u64,
+        height: u64,
     ) -> Fallible<DomRoot<OffscreenCanvas>> {
-        let offscreencanvas = OffscreenCanvas::new(global, height, width, None);
+        let offscreencanvas = OffscreenCanvas::new(global, width, height, None);
         Ok(offscreencanvas)
     }
 
     pub fn get_size(&self) -> Size2D<u64> {
         Size2D::new(self.Width(), self.Height())
     }
 
+    pub fn origin_is_clean(&self) -> bool {
+        match *self.context.borrow() {
+            Some(OffscreenCanvasContext::OffscreenContext2d(ref context)) => {
+                context.origin_is_clean()
+            },
+            _ => true,
+        }
+    }
+
     pub fn context(&self) -> Option<Ref<OffscreenCanvasContext>> {
         ref_filter_map::ref_filter_map(self.context.borrow(), |ctx| ctx.as_ref())
     }
 
+    pub fn fetch_all_data(&self) -> Option<(Option<IpcSharedMemory>, Size2D<u32>)> {
+        let size = self.get_size();
+
+        if size.width == 0 || size.height == 0 {
+            return None;
+        }
+
+        let data = match self.context.borrow().as_ref() {
+            Some(&OffscreenCanvasContext::OffscreenContext2d(ref context)) => {
+                let (sender, receiver) =
+                    ipc::channel(self.global().time_profiler_chan().clone()).unwrap();
+                let msg = CanvasMsg::FromScript(
+                    FromScriptMsg::SendPixels(sender),
+                    context.get_canvas_id(),
+                );
+                context.get_ipc_renderer().send(msg).unwrap();
+
+                Some(receiver.recv().unwrap())
+            },
+            None => None,
+        };
+
+        Some((data, size.to_u32()))
+    }
+
     #[allow(unsafe_code)]
     fn get_or_init_2d_context(&self) -> Option<DomRoot<OffscreenCanvasRenderingContext2D>> {
         if let Some(ctx) = self.context() {

components/script/dom/offscreencanvasrenderingcontext2d.rs

@@ -24,8 +24,10 @@ use crate::dom::htmlcanvaselement::HTMLCanvasElement;
 use crate::dom::imagedata::ImageData;
 use crate::dom::offscreencanvas::OffscreenCanvas;
 use crate::dom::textmetrics::TextMetrics;
+use canvas_traits::canvas::{Canvas2dMsg, CanvasId, CanvasMsg};
 use dom_struct::dom_struct;
 use euclid::default::Size2D;
+use ipc_channel::ipc::IpcSender;
 
 #[dom_struct]
 pub struct OffscreenCanvasRenderingContext2D {
@@ -72,6 +74,22 @@ impl OffscreenCanvasRenderingContext2D {
     pub fn set_canvas_bitmap_dimensions(&self, size: Size2D<u64>) {
         self.canvas_state.borrow().set_bitmap_dimensions(size);
     }
+
+    pub fn send_canvas_2d_msg(&self, msg: Canvas2dMsg) {
+        self.canvas_state.borrow().send_canvas_2d_msg(msg)
+    }
+
+    pub fn origin_is_clean(&self) -> bool {
+        self.canvas_state.borrow().origin_is_clean()
+    }
+
+    pub fn get_canvas_id(&self) -> CanvasId {
+        self.canvas_state.borrow().get_canvas_id()
+    }
+
+    pub fn get_ipc_renderer(&self) -> IpcSender<CanvasMsg> {
+        self.canvas_state.borrow().get_ipc_renderer().clone()
+    }
 }
 
 impl OffscreenCanvasRenderingContext2DMethods for OffscreenCanvasRenderingContext2D {

components/script/dom/webidls/CanvasRenderingContext2D.webidl

@@ -12,7 +12,7 @@ typedef (HTMLOrSVGImageElement or
          /*HTMLVideoElement or*/
          HTMLCanvasElement or
          /*ImageBitmap or*/
-         /*OffscreenCanvas or*/
+         OffscreenCanvas or
          /*CSSImageValue*/ CSSStyleValue) CanvasImageSource;
 
 enum CanvasFillRule { "nonzero", "evenodd" };