Share some code between 2D canvas and WebGL

components/canvas/webgl_thread.rs

@@ -6,7 +6,6 @@ use canvas_traits::webgl::*;
 use euclid::Size2D;
 use fnv::FnvHashMap;
 use gleam::gl;
-use ipc_channel::ipc::IpcBytesSender;
 use offscreen_gl_context::{GLContext, GLContextAttributes, GLLimits, NativeGLContextMethods};
 use pixels;
 use std::thread;
@@ -791,8 +790,16 @@ impl WebGLImpl {
                 ctx.gl().pixel_store_i(name, val),
             WebGLCommand::PolygonOffset(factor, units) =>
                 ctx.gl().polygon_offset(factor, units),
-            WebGLCommand::ReadPixels(x, y, width, height, format, pixel_type, ref chan) => {
-                Self::read_pixels(ctx.gl(), x, y, width, height, format, pixel_type, chan)
+            WebGLCommand::ReadPixels(rect, format, pixel_type, ref sender) => {
+                let pixels = ctx.gl().read_pixels(
+                    rect.origin.x as i32,
+                    rect.origin.y as i32,
+                    rect.size.width as i32,
+                    rect.size.height as i32,
+                    format,
+                    pixel_type,
+                );
+                sender.send(&pixels).unwrap();
             }
             WebGLCommand::RenderbufferStorage(target, format, width, height) =>
                 ctx.gl().renderbuffer_storage(target, format, width, height),
@@ -1335,20 +1342,6 @@ impl WebGLImpl {
         }
     }
 
-    fn read_pixels(
-        gl: &gl::Gl,
-        x: i32,
-        y: i32,
-        width: i32,
-        height: i32,
-        format: u32,
-        pixel_type: u32,
-        chan: &IpcBytesSender,
-    ) {
-      let result = gl.read_pixels(x, y, width, height, format, pixel_type);
-      chan.send(&result).unwrap()
-    }
-
     fn finish(gl: &gl::Gl, chan: &WebGLSender<()>) {
         gl.finish();
         chan.send(()).unwrap();

components/canvas_traits/webgl.rs

@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use euclid::Size2D;
+use euclid::{Rect, Size2D};
 use gleam::gl;
 use ipc_channel::ipc::{IpcBytesReceiver, IpcBytesSender};
 use offscreen_gl_context::{GLContextAttributes, GLLimits};
@@ -227,7 +227,7 @@ pub enum WebGLCommand {
     GetRenderbufferParameter(u32, u32, WebGLSender<i32>),
     PolygonOffset(f32, f32),
     RenderbufferStorage(u32, u32, i32, i32),
-    ReadPixels(i32, i32, i32, i32, u32, u32, IpcBytesSender),
+    ReadPixels(Rect<u32>, u32, u32, IpcBytesSender),
     SampleCoverage(f32, bool),
     Scissor(i32, i32, u32, u32),
     StencilFunc(u32, i32, u32),

components/pixels/lib.rs

@@ -4,7 +4,7 @@
 
 extern crate euclid;
 
-use euclid::{Rect, Size2D};
+use euclid::{Point2D, Rect, Size2D};
 use std::borrow::Cow;
 
 pub fn get_rect(pixels: &[u8], size: Size2D<u32>, rect: Rect<u32>) -> Cow<[u8]> {
@@ -63,3 +63,21 @@ pub fn premultiply_inplace(pixels: &mut [u8]) -> bool {
 pub fn multiply_u8_color(a: u8, b: u8) -> u8 {
     return (a as u32 * b as u32 / 255) as u8;
 }
+
+pub fn clip(
+    mut origin: Point2D<i32>,
+    mut size: Size2D<u32>,
+    surface: Size2D<u32>,
+) -> Option<Rect<u32>> {
+    if origin.x < 0 {
+        size.width = size.width.saturating_sub(-origin.x as u32);
+        origin.x = 0;
+    }
+    if origin.y < 0 {
+        size.height = size.height.saturating_sub(-origin.y as u32);
+        origin.y = 0;
+    }
+    Rect::new(origin.to_u32(), size)
+        .intersection(&Rect::from_size(surface))
+        .filter(|rect| !rect.is_empty())
+}

components/script/dom/canvasrenderingcontext2d.rs

@@ -1168,7 +1168,7 @@ impl CanvasRenderingContext2DMethods for CanvasRenderingContext2D {
         // FIXME(nox): This is probably wrong when this is a context for an
         // offscreen canvas.
         let canvas_size = self.canvas.as_ref().map_or(Size2D::zero(), |c| c.get_size());
-        let read_rect = match clip(origin, size, canvas_size) {
+        let read_rect = match pixels::clip(origin, size, canvas_size) {
             Some(rect) => rect,
             None => {
                 // All the pixels are outside the canvas surface.
@@ -1220,7 +1220,7 @@ impl CanvasRenderingContext2DMethods for CanvasRenderingContext2D {
             Point2D::new(dirty_x, dirty_y),
             Size2D::new(dirty_width, dirty_height),
         );
-        let src_rect = match clip(src_origin, src_size, imagedata_size) {
+        let src_rect = match pixels::clip(src_origin, src_size, imagedata_size) {
             Some(rect) => rect,
             None => return,
         };
@@ -1230,7 +1230,7 @@ impl CanvasRenderingContext2DMethods for CanvasRenderingContext2D {
         );
         // By clipping to the canvas surface, we avoid sending any pixel
         // that would fall outside it.
-        let dst_rect = match clip(dst_origin, src_rect.size, canvas_size) {
+        let dst_rect = match pixels::clip(dst_origin, src_rect.size, canvas_size) {
             Some(rect) => rect,
             None => return,
         };
@@ -1537,21 +1537,3 @@ fn adjust_size_sign(
     }
     (origin, size.to_u32())
 }
-
-fn clip(
-    mut origin: Point2D<i32>,
-    mut size: Size2D<u32>,
-    surface: Size2D<u32>,
-) -> Option<Rect<u32>> {
-    if origin.x < 0 {
-        size.width = size.width.saturating_sub(-origin.x as u32);
-        origin.x = 0;
-    }
-    if origin.y < 0 {
-        size.height = size.height.saturating_sub(-origin.y as u32);
-        origin.y = 0;
-    }
-    Rect::new(origin.to_u32(), size)
-        .intersection(&Rect::from_size(surface))
-        .filter(|rect| !rect.is_empty())
-}

components/script/dom/htmlcanvaselement.rs

@@ -368,13 +368,13 @@ impl HTMLCanvasElementMethods for HTMLCanvasElement {
                 context.get_rect(Rect::from_size(self.get_size()))
             },
             Some(CanvasContext::WebGL(ref context)) => {
-                match context.get_image_data(self.Width(), self.Height()) {
+                match context.get_image_data(self.get_size()) {
                     Some(data) => data,
                     None => return Ok(USVString("data:,".into())),
                 }
             },
             Some(CanvasContext::WebGL2(ref context)) => {
-                match context.base_context().get_image_data(self.Width(), self.Height()) {
+                match context.base_context().get_image_data(self.get_size()) {
                     Some(data) => data,
                     None => return Ok(USVString("data:,".into())),
                 }

components/script/dom/webglrenderingcontext.rs

@@ -52,7 +52,7 @@ use dom::webgluniformlocation::WebGLUniformLocation;
 use dom::webglvertexarrayobjectoes::WebGLVertexArrayObjectOES;
 use dom::window::Window;
 use dom_struct::dom_struct;
-use euclid::Size2D;
+use euclid::{Point2D, Rect, Size2D};
 use half::f16;
 use ipc_channel::ipc;
 use js::jsapi::{JSContext, JSObject, Type};
@@ -1070,23 +1070,20 @@ impl WebGLRenderingContext {
     // can fail and that it is UB what happens in that case.
     //
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#2.2
-    pub fn get_image_data(&self, width: u32, height: u32) -> Option<Vec<u8>> {
+    pub fn get_image_data(&self, mut size: Size2D<u32>) -> Option<Vec<u8>> {
         handle_potential_webgl_error!(self, self.validate_framebuffer(), return None);
 
         let (fb_width, fb_height) = handle_potential_webgl_error!(
             self,
             self.get_current_framebuffer_size().ok_or(InvalidOperation),
             return None
         );
-        let width = cmp::min(width, fb_width as u32);
-        let height = cmp::min(height, fb_height as u32);
+        size.width = cmp::min(size.width, fb_width as u32);
+        size.height = cmp::min(size.height, fb_height as u32);
 
         let (sender, receiver) = ipc::bytes_channel().unwrap();
         self.send_command(WebGLCommand::ReadPixels(
-            0,
-            0,
-            width as i32,
-            height as i32,
+            Rect::from_size(size),
             constants::RGBA,
             constants::UNSIGNED_BYTE,
             sender,
@@ -2879,45 +2876,29 @@ impl WebGLRenderingContextMethods for WebGLRenderingContext {
             return self.webgl_error(InvalidOperation);
         }
 
-        let mut src_x = x;
-        let mut src_y = y;
-        let mut src_width = width;
-        let mut src_height = height;
-        let mut dest_offset = 0;
-
-        if src_x < 0 {
-            if src_width <= -src_x {
-                return;
-            }
-            dest_offset += bytes_per_pixel * -src_x;
-            src_width += src_x;
-            src_x = 0;
-        }
-        if src_y < 0 {
-            if src_height <= -src_y {
-                return;
-            }
-            dest_offset += row_len * -src_y;
-            src_height += src_y;
-            src_y = 0;
-        }
+        let src_origin = Point2D::new(x, y);
+        let src_size = Size2D::new(width as u32, height as u32);
+        let fb_size = Size2D::new(fb_width as u32, fb_height as u32);
+        let src_rect = match pixels::clip(src_origin, src_size, fb_size) {
+            Some(rect) => rect,
+            None => return,
+        };
 
-        if src_x + src_width > fb_width {
-            src_width = fb_width - src_x;
+        let mut dest_offset = 0;
+        if x < 0 {
+            dest_offset += -x * bytes_per_pixel;
         }
-        if src_y + src_height > fb_height {
-            src_height = fb_height - src_y;
+        if y < 0 {
+            dest_offset += -y * row_len;
         }
 
         let (sender, receiver) = ipc::bytes_channel().unwrap();
-        self.send_command(WebGLCommand::ReadPixels(
-            src_x, src_y, src_width, src_height, format, pixel_type, sender,
-        ));
-
+        self.send_command(WebGLCommand::ReadPixels(src_rect, format, pixel_type, sender));
         let src = receiver.recv().unwrap();
-        let src_row_len = (src_width * bytes_per_pixel) as usize;
-        for i in 0..src_height {
-            let dest_start = (dest_offset + i * dest_stride) as usize;
+
+        let src_row_len = src_rect.size.width as usize * bytes_per_pixel as usize;
+        for i in 0..src_rect.size.height {
+            let dest_start = dest_offset as usize + i as usize * dest_stride as usize;
             let dest_end = dest_start + src_row_len;
             let src_start = i as usize * src_row_len;
             let src_end = src_start + src_row_len;