Implementing canvas drawImage API for HTML Canvas elements as image source

7 files changed, 459 insertions, 75 deletions

diff --git a/components/canvas/canvas_paint_task.rs b/components/canvas/canvas_paint_task.rs
index c8781419f10..4822fd48750 100644
--- a/components/canvas/canvas_paint_task.rs
+++ b/components/canvas/canvas_paint_task.rs
@@ -16,7 +16,6 @@ use util::vec::byte_swap;
 
 use cssparser::RGBA;
 use std::borrow::ToOwned;
-use std::ops::Add;
 use std::sync::mpsc::{channel, Sender};
 
 #[derive(Clone)]
@@ -27,6 +26,8 @@ pub enum CanvasMsg {
     BeginPath,
     ClosePath,
     Fill,
+    DrawImage(Vec<u8>, Rect<i32>, Rect<i32>, bool),
+    DrawImageSelf(Size2D<i32>, Rect<i32>, Rect<i32>, bool),
     MoveTo(Point2D<f32>),
     LineTo(Point2D<f32>),
     QuadraticCurveTo(Point2D<f32>, Point2D<f32>),
@@ -38,10 +39,140 @@ pub enum CanvasMsg {
     Recreate(Size2D<i32>),
     SendPixelContents(Sender<Vec<u8>>),
     GetImageData(Rect<i32>, Size2D<i32>, Sender<Vec<u8>>),
-    PutImageData(Vec<u8>, Rect<i32>, Option<Rect<i32>>, Size2D<i32>),
+    PutImageData(Vec<u8>, Rect<i32>, Option<Rect<i32>>),
     Close,
 }
 
+impl<'a> CanvasPaintTask<'a> {
+    /// It reads image data from the canvas
+    /// canvas_size: The size of the canvas we're reading from
+    /// read_rect: The area of the canvas we want to read from
+    fn read_pixels(&self, read_rect: Rect<i32>, canvas_size: Size2D<i32>) -> Vec<u8>{
+        let canvas_rect = Rect(Point2D(0i32, 0i32), canvas_size);
+        let src_read_rect = canvas_rect.intersection(&read_rect).unwrap_or(Rect::zero());
+
+        let mut image_data = Vec::new();
+        if src_read_rect.is_empty() || canvas_size.width <= 0 && canvas_size.height <= 0 {
+          return image_data;
+        }
+
+        let data_surface = self.drawtarget.snapshot().get_data_surface();
+        let mut src_data = Vec::new();
+        data_surface.with_data(|element| { src_data = element.to_vec(); });
+        let stride = data_surface.stride();
+
+        //start offset of the copyable rectangle
+        let mut src = (src_read_rect.origin.y * stride + src_read_rect.origin.x * 4) as usize;
+        //copy the data to the destination vector
+        for _ in range(0, src_read_rect.size.height) {
+           let row = &src_data[src .. src + (4 * src_read_rect.size.width) as usize];
+           image_data.push_all(row);
+           src += stride as usize;
+        }
+
+        image_data
+    }
+
+    /// It writes image data to the canvas
+    /// source_rect: the area of the image data to be written
+    /// dest_rect: The area of the canvas where the imagedata will be copied
+    /// smoothing_enabled: if smoothing is applied to the copied pixels
+    fn write_pixels(&self, imagedata: &Vec<u8>,
+                           image_size: Size2D<i32>,
+                           source_rect: Rect<i32>,
+                           dest_rect: Rect<i32>,
+                           smoothing_enabled: bool) {
+        // From spec https://html.spec.whatwg.org/multipage/scripting.html#dom-context-2d-drawimage
+        // When scaling up, if the imageSmoothingEnabled attribute is set to true, the user agent should attempt
+        // to apply a smoothing algorithm to the image data when it is scaled.
+        // Otherwise, the image must be rendered using nearest-neighbor interpolation.
+        let filter = if smoothing_enabled {
+           Filter::Linear
+        } else {
+           Filter::Point
+        };
+
+        let source_surface = self.drawtarget.create_source_surface_from_data(imagedata.as_slice(),
+           image_size, image_size.width * 4, SurfaceFormat::B8G8R8A8);
+
+        let draw_surface_options = DrawSurfaceOptions::new(filter, true);
+        let draw_options = DrawOptions::new(1.0f64 as AzFloat, 0);
+
+        self.drawtarget.draw_surface(source_surface,
+                                    dest_rect.to_azfloat(),
+                                    source_rect.to_azfloat(),
+                                    draw_surface_options, draw_options);
+    }
+
+    /// dirty_rect: original dirty_rect provided by the putImageData call
+    /// image_data_rect: the area of the image to be copied
+    /// Result: It retuns the modified dirty_rect by the rules described in
+    /// the spec https://html.spec.whatwg.org/#dom-context-2d-putimagedata
+    fn calculate_dirty_rect(&self,
+                            mut dirty_rect: Rect<i32>,
+                            image_data_rect: Rect<i32>) -> Rect<i32>{
+        // 1) If dirtyWidth is negative,
+        // let dirtyX be dirtyX+dirtyWidth,
+        // and let dirtyWidth be equal to the absolute magnitude of dirtyWidth.
+        if dirty_rect.size.width < 0 {
+            dirty_rect.origin.x = dirty_rect.origin.x + dirty_rect.size.width;
+            dirty_rect.size.width = -dirty_rect.size.width;
+        }
+
+        // 2) If dirtyHeight is negative, let dirtyY be dirtyY+dirtyHeight,
+        // and let dirtyHeight be equal to the absolute magnitude of dirtyHeight.
+        if dirty_rect.size.height < 0 {
+            dirty_rect.origin.y = dirty_rect.origin.y + dirty_rect.size.height;
+            dirty_rect.size.height = -dirty_rect.size.height;
+        }
+
+        // 3) If dirtyX is negative, let dirtyWidth be dirtyWidth+dirtyX, and let dirtyX be zero.
+        if dirty_rect.origin.x < 0 {
+            dirty_rect.size.width += dirty_rect.origin.x;
+            dirty_rect.origin.x = 0;
+        }
+
+        // 3) If dirtyY is negative, let dirtyHeight be dirtyHeight+dirtyY, and let dirtyY be zero.
+        if dirty_rect.origin.y < 0 {
+            dirty_rect.size.height += dirty_rect.origin.y;
+            dirty_rect.origin.y = 0;
+        }
+
+        // 4) If dirtyX+dirtyWidth is greater than the width attribute of the imagedata argument,
+        // let dirtyWidth be the value of that width attribute, minus the value of dirtyX.
+        if dirty_rect.origin.x + dirty_rect.size.width > image_data_rect.size.width {
+            dirty_rect.size.width = image_data_rect.size.width - dirty_rect.origin.x;
+        }
+
+        // 4) If dirtyY+dirtyHeight is greater than the height attribute of the imagedata argument,
+        // let dirtyHeight be the value of that height attribute, minus the value of dirtyY.
+        if dirty_rect.origin.y + dirty_rect.size.height > image_data_rect.size.height {
+            dirty_rect.size.height = image_data_rect.size.height - dirty_rect.origin.y;
+        }
+
+        dirty_rect
+    }
+
+    /// It writes an image to the destination canvas
+    /// imagedata: Pixel information of the image to be written
+    /// source_rect: Area of the source image to be copied
+    /// dest_rect: Area of the destination canvas where the pixels will be copied
+    /// smoothing_enabled: It determines if smoothing is applied to the image result
+    fn write_image(&self, mut imagedata: Vec<u8>,
+                   source_rect: Rect<i32>, dest_rect: Rect<i32>, smoothing_enabled: bool) {
+        if imagedata.len() == 0 {
+            return
+        }
+        // Image data already contains the portion of the image we want to draw
+        // so the source rect corresponds to the whole area of the copied imagedata
+        let source_rect = Rect(Point2D(0i32, 0i32), source_rect.size);
+        // rgba -> bgra
+        byte_swap(imagedata.as_mut_slice());
+        self.write_pixels(&imagedata, source_rect.size, source_rect, dest_rect, smoothing_enabled);
+    }
+
+}
+
 pub struct CanvasPaintTask<'a> {
     drawtarget: DrawTarget,
     fill_style: Pattern,
@@ -80,6 +211,12 @@ impl<'a> CanvasPaintTask<'a> {
                     CanvasMsg::BeginPath => painter.begin_path(),
                     CanvasMsg::ClosePath => painter.close_path(),
                     CanvasMsg::Fill => painter.fill(),
+                    CanvasMsg::DrawImage(imagedata, dest_rect, source_rect, smoothing_enabled) => {
+                        painter.draw_image(imagedata, dest_rect, source_rect, smoothing_enabled)
+                    }
+                    CanvasMsg::DrawImageSelf(image_size, dest_rect, source_rect, smoothing_enabled) => {
+                        painter.draw_image_self(image_size, dest_rect, source_rect, smoothing_enabled)
+                    }
                     CanvasMsg::MoveTo(ref point) => painter.move_to(point),
                     CanvasMsg::LineTo(ref point) => painter.line_to(point),
                     CanvasMsg::QuadraticCurveTo(ref cp, ref pt) => {
@@ -97,8 +234,8 @@ impl<'a> CanvasPaintTask<'a> {
                     CanvasMsg::Recreate(size) => painter.recreate(size),
                     CanvasMsg::SendPixelContents(chan) => painter.send_pixel_contents(chan),
                     CanvasMsg::GetImageData(dest_rect, canvas_size, chan) => painter.get_image_data(dest_rect, canvas_size, chan),
-                    CanvasMsg::PutImageData(imagedata, image_data_rect, dirty_rect, canvas_size)
-                        => painter.put_image_data(imagedata, image_data_rect, dirty_rect, canvas_size),
+                    CanvasMsg::PutImageData(imagedata, image_data_rect, dirty_rect)
+                        => painter.put_image_data(imagedata, image_data_rect, dirty_rect),
                     CanvasMsg::Close => break,
                 }
             }
@@ -147,6 +284,21 @@ impl<'a> CanvasPaintTask<'a> {
         };
     }
 
+    fn draw_image(&self, imagedata: Vec<u8>, dest_rect: Rect<i32>,
+                  source_rect: Rect<i32>, smoothing_enabled: bool) {
+        self.write_image(imagedata, source_rect, dest_rect, smoothing_enabled);
+    }
+
+    fn draw_image_self(&self, image_size: Size2D<i32>,
+                       dest_rect: Rect<i32>, source_rect: Rect<i32>,
+                       smoothing_enabled: bool) {
+        // Reads pixels from source image
+        // In this case source and target are the same canvas
+        let imagedata = self.read_pixels(source_rect, image_size);
+        // Writes on target canvas
+        self.write_image(imagedata, source_rect, dest_rect, smoothing_enabled);
+    }
+
     fn move_to(&self, point: &Point2D<AzFloat>) {
         self.path_builder.move_to(*point)
     }
@@ -220,36 +372,16 @@ impl<'a> CanvasPaintTask<'a> {
             dest_rect.size.height = 1;
         }
 
-        let canvas_rect = Rect(Point2D(0i32, 0i32), canvas_size);
-        let src_read_rect = canvas_rect.intersection(&dest_rect).unwrap_or(Rect::zero());
-
-        let mut dest_data = Vec::new();
-        //load the canvas data to the source vector
-        if !src_read_rect.is_empty() && canvas_size.width != 0 && canvas_size.height != 0 {
-            let data_surface = self.drawtarget.snapshot().get_data_surface();
-            let mut src_data = Vec::new();
-            data_surface.with_data(|element| {
-                src_data = element.to_vec();
-            });
-
-            let stride = data_surface.stride();
-
-            //start offset of the copyable rectangle
-            let mut src = (src_read_rect.origin.y * stride + src_read_rect.origin.x * 4) as usize;
-            //copy the data to the destination vector
-            for _ in 0..src_read_rect.size.height {
-                let row = &src_data[src .. src + (4 * src_read_rect.size.width) as usize];
-                dest_data.push_all(row);
-                src += stride as usize;
-            }
-        }
+        let mut dest_data = self.read_pixels(dest_rect, canvas_size);
+
         // bgra -> rgba
         byte_swap(dest_data.as_mut_slice());
         chan.send(dest_data).unwrap();
     }
 
-    fn put_image_data(&mut self, mut imagedata: Vec<u8>, image_data_rect: Rect<i32>,
-                      dirty_rect: Option<Rect<i32>>, canvas_size: Size2D<i32>) {
+    fn put_image_data(&mut self, mut imagedata: Vec<u8>,
+                      image_data_rect: Rect<i32>,
+                      dirty_rect: Option<Rect<i32>>) {
 
         if image_data_rect.size.width <= 0 || image_data_rect.size.height <= 0 {
             return
@@ -259,46 +391,37 @@ impl<'a> CanvasPaintTask<'a> {
         // rgba -> bgra
         byte_swap(imagedata.as_mut_slice());
 
-        let new_image_data_rect = Rect(Point2D(0i32, 0i32),
-            Size2D(image_data_rect.size.width, image_data_rect.size.height));
-
-        let new_dirty_rect = match dirty_rect {
-            Some(mut dirty_rect) => {
-                if dirty_rect.size.width < 0 {
-                    dirty_rect.origin.x = dirty_rect.origin.x + dirty_rect.size.width;
-                    dirty_rect.size.width = -dirty_rect.size.width;
-                }
-                if dirty_rect.size.height < 0 {
-                    dirty_rect.origin.y = dirty_rect.origin.y + dirty_rect.size.height;
-                    dirty_rect.size.height = -dirty_rect.size.height;
-                }
-                new_image_data_rect.intersection(&dirty_rect)
-            },
-            None => Some(new_image_data_rect)
+        let image_rect = Rect(Point2D(0i32, 0i32),
+                               Size2D(image_data_rect.size.width, image_data_rect.size.height));
+
+        // Dirty rectangle defines the area of the source image to be copied
+        // on the destination canvas
+        let source_rect = match dirty_rect {
+            Some(dirty_rect) =>
+                self.calculate_dirty_rect(dirty_rect, image_data_rect),
+            // If no dirty area is provided we consider the whole source image
+            // as the area to be copied to the canvas
+            None => image_rect,
         };
 
-        if let Some(new_dirty_rect) = new_dirty_rect {
-            let moved_dirty_rect = Rect(new_dirty_rect.origin.add(image_data_rect.origin),
-                                        new_dirty_rect.size).intersection(&Rect(Point2D(0i32, 0i32),
-                                        canvas_size)).unwrap_or(Rect::zero());
-            if moved_dirty_rect.is_empty() {
-                return
-            }
-
-            let source_surface = self.drawtarget.create_source_surface_from_data(&imagedata,
-                image_data_rect.size, image_data_rect.size.width * 4, SurfaceFormat::B8G8R8A8);
-
-            let draw_surface_options = DrawSurfaceOptions::new(Filter::Linear, true);
-            let draw_options = DrawOptions::new(1.0f64 as AzFloat, 0);
-
-            self.drawtarget.draw_surface(source_surface,
-                Rect(Point2D(moved_dirty_rect.origin.x as AzFloat, moved_dirty_rect.origin.y as AzFloat),
-                     Size2D(moved_dirty_rect.size.width as AzFloat, moved_dirty_rect.size.height as AzFloat)),
-                Rect(Point2D((moved_dirty_rect.origin.x - image_data_rect.origin.x) as AzFloat,
-                             (moved_dirty_rect.origin.y - image_data_rect.origin.y) as AzFloat),
-                     Size2D(moved_dirty_rect.size.width as AzFloat, moved_dirty_rect.size.height as AzFloat)),
-                draw_surface_options, draw_options);
+        // 5) If either dirtyWidth or dirtyHeight is negative or zero,
+        // stop without affecting any bitmaps
+        if source_rect.size.width <= 0 || source_rect.size.height <= 0 {
+            return
         }
+
+        // 6) For all integer values of x and y where dirtyX ≤ x < dirty
+        // X+dirtyWidth and dirtyY ≤ y < dirtyY+dirtyHeight, copy the
+        // four channels of the pixel with coordinate (x, y) in the imagedata
+        // data structure's Canvas Pixel ArrayBuffer to the pixel with coordinate
+        // (dx+x, dy+y) in the rendering context's scratch bitmap.
+        // It also clips the destination rectangle to the canvas area
+        let dest_rect = Rect(
+            Point2D(image_data_rect.origin.x + source_rect.origin.x,
+                    image_data_rect.origin.y + source_rect.origin.y),
+            Size2D(source_rect.size.width, source_rect.size.height));
+
+        self.write_pixels(&imagedata, image_data_rect.size, source_rect, dest_rect, true)
     }
 }
 
@@ -404,3 +527,14 @@ impl FillOrStrokeStyle {
         }
     }
 }
+
+pub trait ToAzFloat {
+    fn to_azfloat(&self) -> Rect<AzFloat>;
+}
+
+impl ToAzFloat for Rect<i32> {
+    fn to_azfloat(&self) -> Rect<AzFloat> {
+        Rect(Point2D(self.origin.x as AzFloat, self.origin.y as AzFloat),
+             Size2D(self.size.width as AzFloat, self.size.height as AzFloat))
+    }
+}
diff --git a/components/script/dom/canvasrenderingcontext2d.rs b/components/script/dom/canvasrenderingcontext2d.rs
index 4c2e05b4b9e..58f3b51ab05 100644
--- a/components/script/dom/canvasrenderingcontext2d.rs
+++ b/components/script/dom/canvasrenderingcontext2d.rs
@@ -6,6 +6,7 @@ use dom::bindings::codegen::Bindings::CanvasRenderingContext2DBinding;
 use dom::bindings::codegen::Bindings::CanvasRenderingContext2DBinding::CanvasRenderingContext2DMethods;
 use dom::bindings::codegen::Bindings::CanvasRenderingContext2DBinding::CanvasWindingRule;
 use dom::bindings::codegen::Bindings::ImageDataBinding::ImageDataMethods;
+use dom::bindings::codegen::UnionTypes::HTMLCanvasElementOrCanvasRenderingContext2D;
 use dom::bindings::codegen::UnionTypes::StringOrCanvasGradientOrCanvasPattern;
 use dom::bindings::error::Error::{IndexSize, TypeError};
 use dom::bindings::error::Fallible;
@@ -37,6 +38,7 @@ pub struct CanvasRenderingContext2D {
     global: GlobalField,
     renderer: Sender<CanvasMsg>,
     canvas: JS<HTMLCanvasElement>,
+    image_smoothing_enabled: Cell<bool>,
     stroke_color: Cell<RGBA>,
     fill_color: Cell<RGBA>,
     transform: Cell<Matrix2D<f32>>,
@@ -56,6 +58,7 @@ impl CanvasRenderingContext2D {
             global: GlobalField::from_rooted(&global),
             renderer: CanvasPaintTask::start(size),
             canvas: JS::from_rooted(canvas),
+            image_smoothing_enabled: Cell::new(true),
             stroke_color: Cell::new(black),
             fill_color: Cell::new(black),
             transform: Cell::new(Matrix2D::identity()),
@@ -75,6 +78,120 @@ impl CanvasRenderingContext2D {
     fn update_transform(&self) {
         self.renderer.send(CanvasMsg::SetTransform(self.transform.get())).unwrap()
     }
+
+    // It is used by DrawImage to calculate the size of the source and destination rectangles based
+    // on the drawImage call arguments
+    // source rectangle = area of the original image to be copied
+    // destination rectangle = area of the destination canvas where the source image is going to be drawn
+    fn adjust_source_dest_rects(&self,
+                  canvas: JSRef<HTMLCanvasElement>,
+                  sx: f64, sy: f64, sw: f64, sh: f64,
+                  dx: f64, dy: f64, dw: f64, dh: f64) -> (Rect<i32>, Rect<i32>) {
+        let image_size = canvas.get_size();
+        let image_rect = Rect(Point2D(0f64, 0f64),
+                              Size2D(image_size.width as f64, image_size.height as f64));
+
+        // The source rectangle is the rectangle whose corners are the four points (sx, sy),
+        // (sx+sw, sy), (sx+sw, sy+sh), (sx, sy+sh).
+        let source_rect = Rect(Point2D(sx, sy),
+                               Size2D(sw, sh));
+
+        // When the source rectangle is outside the source image,
+        // the source rectangle must be clipped to the source image
+        let source_rect_clipped = source_rect.intersection(&image_rect).unwrap_or(Rect::zero());
+
+        // Width and height ratios between the non clipped and clipped source rectangles
+        let width_ratio: f64 = source_rect_clipped.size.width / source_rect.size.width;
+        let height_ratio: f64 = source_rect_clipped.size.height / source_rect.size.height;
+
+        // When the source rectangle is outside the source image,
+        // the destination rectangle must be clipped in the same proportion.
+        let dest_rect_width_scaled: f64 = dw * width_ratio;
+        let dest_rect_height_scaled: f64 = dh * height_ratio;
+
+        // The destination rectangle is the rectangle whose corners are the four points (dx, dy),
+        // (dx+dw, dy), (dx+dw, dy+dh), (dx, dy+dh).
+        let dest_rect = Rect(Point2D(dx.to_i32().unwrap(),
+                                     dy.to_i32().unwrap()),
+                             Size2D(dest_rect_width_scaled.to_i32().unwrap(),
+                                    dest_rect_height_scaled.to_i32().unwrap()));
+
+        let source_rect = Rect(Point2D(source_rect_clipped.origin.x.to_i32().unwrap(),
+                                     source_rect_clipped.origin.y.to_i32().unwrap()),
+                             Size2D(source_rect_clipped.size.width.to_i32().unwrap(),
+                                    source_rect_clipped.size.height.to_i32().unwrap()));
+
+        return (source_rect, dest_rect)
+    }
+
+    //
+    // drawImage coordinates explained
+    //
+    //  Source Image      Destination Canvas
+    // +-------------+     +-------------+
+    // |             |     |             |
+    // |(sx,sy)      |     |(dx,dy)      |
+    // |   +----+    |     |   +----+    |
+    // |   |    |    |     |   |    |    |
+    // |   |    |sh  |---->|   |    |dh  |
+    // |   |    |    |     |   |    |    |
+    // |   +----+    |     |   +----+    |
+    // |     sw      |     |     dw      |
+    // |             |     |             |
+    // +-------------+     +-------------+
+    //
+    //
+    // The rectangle (sx, sy, sw, sh) from the source image
+    // is copied on the rectangle (dx, dy, dh, dw) of the destination canvas
+    //
+    // https://html.spec.whatwg.org/multipage/scripting.html#dom-context-2d-drawimage
+    fn draw_html_canvas_element(&self,
+                  canvas: JSRef<HTMLCanvasElement>,
+                  sx: f64, sy: f64, sw: f64, sh: f64,
+                  dx: f64, dy: f64, dw: f64, dh: f64) -> Fallible<()> {
+
+        // 1. Check the usability of the image argument
+        if !canvas.is_valid() {
+            return Ok(())
+        }
+
+        // 2. Establish the source and destination rectangles
+        let (source_rect, dest_rect) = self.adjust_source_dest_rects(canvas, sx, sy, sw, sh, dx, dy, dw, dh);
+
+        if !is_rect_valid(source_rect) || !is_rect_valid(dest_rect) {
+            return Err(IndexSize)
+        }
+
+        let smoothing_enabled = self.image_smoothing_enabled.get();
+        let canvas_size = canvas.get_size();
+
+        // If the source and target canvas are the same
+        let msg = if self.canvas.root().r() == canvas {
+            CanvasMsg::DrawImageSelf(canvas_size, dest_rect, source_rect, smoothing_enabled)
+        } else { // Source and target canvases are different
+            let context = canvas.get_2d_context().root();
+            let renderer = context.r().get_renderer();
+            let (sender, receiver) = channel::<Vec<u8>>();
+            // Reads pixels from source image
+            renderer.send(CanvasMsg::GetImageData(source_rect, canvas_size, sender)).unwrap();
+            let imagedata = receiver.recv().unwrap();
+            // Writes pixels to destination canvas
+            CanvasMsg::DrawImage(imagedata, dest_rect, source_rect, smoothing_enabled)
+        };
+
+        self.renderer.send(msg).unwrap();
+        Ok(())
+    }
+}
+
+pub trait CanvasRenderingContext2DHelpers {
+    fn get_renderer(&self) -> Sender<CanvasMsg>;
+}
+
+impl CanvasRenderingContext2DHelpers for CanvasRenderingContext2D {
+    fn get_renderer(&self) -> Sender<CanvasMsg> {
+        self.renderer.clone()
+    }
 }
 
 pub trait LayoutCanvasRenderingContext2DHelpers {
@@ -151,6 +268,102 @@ impl<'a> CanvasRenderingContext2DMethods for JSRef<'a, CanvasRenderingContext2D>
         self.renderer.send(CanvasMsg::Fill).unwrap();
     }
 
+    // https://html.spec.whatwg.org/multipage/scripting.html#dom-context-2d-drawimage
+    fn DrawImage(self, image: HTMLCanvasElementOrCanvasRenderingContext2D,
+                 dx: f64, dy: f64) -> Fallible<()> {
+
+        // From rules described in the spec:
+        // If the sx, sy, sw, and sh arguments are omitted, they must default to 0, 0,
+        // the image's intrinsic width in image pixels,
+        // and the image's intrinsic height in image pixels, respectively
+        let sx: f64 = 0f64;
+        let sy: f64 = 0f64;
+
+        match image {
+            HTMLCanvasElementOrCanvasRenderingContext2D::eHTMLCanvasElement(image) => {
+                let canvas = image.root();
+                let canvas_size = canvas.r().get_size();
+                let dw: f64 = canvas_size.width as f64;
+                let dh: f64 = canvas_size.height as f64;
+                let sw: f64 = dw;
+                let sh: f64 = dh;
+                return self.draw_html_canvas_element(canvas.r(),
+                                                     sx, sy, sw, sh,
+                                                     dx, dy, dw, dh)
+            }
+            HTMLCanvasElementOrCanvasRenderingContext2D::eCanvasRenderingContext2D(image) => {
+                let image = image.root();
+                let context = image.r();
+                let canvas = context.Canvas().root();
+                let canvas_size = canvas.r().get_size();
+                let dw: f64 = canvas_size.width as f64;
+                let dh: f64 = canvas_size.height as f64;
+                let sw: f64 = dw;
+                let sh: f64 = dh;
+                return self.draw_html_canvas_element(canvas.r(),
+                                                     sx, sy, sw, sh,
+                                                     dx, dy, dw, dh)
+            }
+        }
+    }
+
+    // https://html.spec.whatwg.org/multipage/scripting.html#dom-context-2d-drawimage
+    fn DrawImage_(self, image: HTMLCanvasElementOrCanvasRenderingContext2D,
+                  dx: f64, dy: f64, dw: f64, dh: f64) -> Fallible<()> {
+
+        // From rules described in the spec:
+        // If the sx, sy, sw, and sh arguments are omitted, they must default to 0, 0,
+        // the image's intrinsic width in image pixels,
+        // and the image's intrinsic height in image pixels, respectively
+        let sx: f64 = 0f64;
+        let sy: f64 = 0f64;
+
+        match image {
+            HTMLCanvasElementOrCanvasRenderingContext2D::eHTMLCanvasElement(image) => {
+                let canvas = image.root();
+                let canvas_size = canvas.r().get_size();
+                let sw: f64 = canvas_size.width as f64;
+                let sh: f64 = canvas_size.height as f64;
+                return self.draw_html_canvas_element(canvas.r(),
+                                                     sx, sy, sw, sh,
+                                                     dx, dy, dw, dh)
+            }
+            HTMLCanvasElementOrCanvasRenderingContext2D::eCanvasRenderingContext2D(image) => {
+                let image = image.root();
+                let context = image.r();
+                let canvas = context.Canvas().root();
+                let canvas_size = canvas.r().get_size();
+                let sw: f64 = canvas_size.width as f64;
+                let sh: f64 = canvas_size.height as f64;
+                return self.draw_html_canvas_element(canvas.r(),
+                                                     sx, sy, sw, sh,
+                                                     dx, dy, dw, dh)
+            }
+        }
+    }
+
+    // https://html.spec.whatwg.org/multipage/scripting.html#dom-context-2d-drawimage
+    fn DrawImage__(self, image: HTMLCanvasElementOrCanvasRenderingContext2D,
+                         sx: f64, sy: f64, sw: f64, sh: f64,
+                         dx: f64, dy: f64, dw: f64, dh: f64) -> Fallible<()> {
+        match image {
+            HTMLCanvasElementOrCanvasRenderingContext2D::eHTMLCanvasElement(image) => {
+                let canvas = image.root();
+                return self.draw_html_canvas_element(canvas.r(),
+                                                     sx, sy, sw, sh,
+                                                     dx, dy, dw, dh)
+            }
+            HTMLCanvasElementOrCanvasRenderingContext2D::eCanvasRenderingContext2D(image) => {
+                let image = image.root();
+                let context = image.r();
+                let canvas = context.Canvas().root();
+                return self.draw_html_canvas_element(canvas.r(),
+                                                     sx, sy, sw, sh,
+                                                     dx, dy, dw, dh)
+            }
+        }
+    }
+
     fn MoveTo(self, x: f64, y: f64) {
         self.renderer.send(CanvasMsg::MoveTo(Point2D(x as f32, y as f32))).unwrap();
     }
@@ -175,6 +388,16 @@ impl<'a> CanvasRenderingContext2DMethods for JSRef<'a, CanvasRenderingContext2D>
                                           start as f32, end as f32, ccw)).unwrap();
     }
 
+    // https://html.spec.whatwg.org/#dom-context-2d-imagesmoothingenabled
+    fn ImageSmoothingEnabled(self) -> bool {
+        self.image_smoothing_enabled.get()
+    }
+
+    // https://html.spec.whatwg.org/#dom-context-2d-imagesmoothingenabled
+    fn SetImageSmoothingEnabled(self, value: bool) -> () {
+        self.image_smoothing_enabled.set(value);
+    }
+
     fn StrokeStyle(self) -> StringOrCanvasGradientOrCanvasPattern {
         // FIXME(pcwalton, #4761): This is not spec-compliant. See:
         //
@@ -261,8 +484,7 @@ impl<'a> CanvasRenderingContext2DMethods for JSRef<'a, CanvasRenderingContext2D>
         let data = imagedata.get_data_array(&self.global.root().r());
         let image_data_rect = Rect(Point2D(dx.to_i32().unwrap(), dy.to_i32().unwrap()), imagedata.get_size());
         let dirty_rect = None;
-        let canvas_size = self.canvas.root().r().get_size();
-        self.renderer.send(CanvasMsg::PutImageData(data, image_data_rect, dirty_rect, canvas_size)).unwrap()
+        self.renderer.send(CanvasMsg::PutImageData(data, image_data_rect, dirty_rect)).unwrap()
     }
 
     fn PutImageData_(self, imagedata: JSRef<ImageData>, dx: f64, dy: f64,
@@ -274,8 +496,7 @@ impl<'a> CanvasRenderingContext2DMethods for JSRef<'a, CanvasRenderingContext2D>
         let dirty_rect = Some(Rect(Point2D(dirtyX.to_i32().unwrap(), dirtyY.to_i32().unwrap()),
                                    Size2D(dirtyWidth.to_i32().unwrap(),
                                           dirtyHeight.to_i32().unwrap())));
-        let canvas_size = self.canvas.root().r().get_size();
-        self.renderer.send(CanvasMsg::PutImageData(data, image_data_rect, dirty_rect, canvas_size)).unwrap()
+        self.renderer.send(CanvasMsg::PutImageData(data, image_data_rect, dirty_rect)).unwrap()
     }
 
     fn CreateLinearGradient(self, x0: f64, y0: f64, x1: f64, y1: f64) -> Fallible<Temporary<CanvasGradient>> {
@@ -309,3 +530,8 @@ pub fn parse_color(string: &str) -> Result<RGBA,()> {
     }
 }
 
+// Used by drawImage to determine if a source or destination rectangle is valid
+// Origin coordinates and size cannot be negative. Size has to be greater than zero
+fn is_rect_valid(rect: Rect<i32>) -> bool {
+    rect.origin.x >= 0 && rect.origin.y >= 0 && rect.size.width > 0 && rect.size.height > 0
+}
diff --git a/components/script/dom/htmlcanvaselement.rs b/components/script/dom/htmlcanvaselement.rs
index 9c3c11d5dbc..e4fc68565a3 100644
--- a/components/script/dom/htmlcanvaselement.rs
+++ b/components/script/dom/htmlcanvaselement.rs
@@ -91,12 +91,22 @@ impl LayoutHTMLCanvasElementHelpers for LayoutJS<HTMLCanvasElement> {
 
 pub trait HTMLCanvasElementHelpers {
     fn get_size(&self) -> Size2D<i32>;
+    fn get_2d_context(self) -> Temporary<CanvasRenderingContext2D>;
+    fn is_valid(self) -> bool;
 }
 
 impl<'a> HTMLCanvasElementHelpers for JSRef<'a, HTMLCanvasElement> {
     fn get_size(&self) -> Size2D<i32> {
         Size2D(self.Width() as i32, self.Height() as i32)
     }
+
+    fn get_2d_context(self) -> Temporary<CanvasRenderingContext2D> {
+        self.GetContext(String::from_str("2d")).unwrap()
+    }
+
+    fn is_valid(self) -> bool {
+        self.height.get() != 0 && self.width.get() != 0
+    }
 }
 
 impl<'a> HTMLCanvasElementMethods for JSRef<'a, HTMLCanvasElement> {
diff --git a/components/script/dom/webidls/CanvasRenderingContext2D.webidl b/components/script/dom/webidls/CanvasRenderingContext2D.webidl
index 1cc40eb0f3f..0218600bba1 100644
--- a/components/script/dom/webidls/CanvasRenderingContext2D.webidl
+++ b/components/script/dom/webidls/CanvasRenderingContext2D.webidl
@@ -6,6 +6,12 @@
 enum CanvasWindingRule { "nonzero", "evenodd" };
 
 // http://www.whatwg.org/html/#2dcontext
+typedef (/* HTMLImageElement or
+         HTMLVideoElement or */
+         HTMLCanvasElement or
+         CanvasRenderingContext2D /* or
+         ImageBitmap */) CanvasImageSource;
+
 //[Constructor(optional unsigned long width, unsigned long height), Exposed=Window,Worker]
 interface CanvasRenderingContext2D {
 
@@ -47,7 +53,7 @@ interface CanvasRenderingContext2D {
   //         attribute DOMString globalCompositeOperation; // (default source-over)
 
   // image smoothing
-  //         attribute boolean imageSmoothingEnabled; // (default true)
+           attribute boolean imageSmoothingEnabled; // (default true)
 
   // colours and styles (see also the CanvasDrawingStyles interface)
            attribute (DOMString or CanvasGradient or CanvasPattern) strokeStyle; // (default black)
@@ -101,9 +107,12 @@ interface CanvasRenderingContext2D {
   //TextMetrics measureText(DOMString text);
 
   // drawing images
-  //void drawImage(CanvasImageSource image, unrestricted double dx, unrestricted double dy);
-  //void drawImage(CanvasImageSource image, unrestricted double dx, unrestricted double dy, unrestricted double dw, unrestricted double dh);
-  //void drawImage(CanvasImageSource image, unrestricted double sx, unrestricted double sy, unrestricted double sw, unrestricted double sh, unrestricted double dx, unrestricted double dy, unrestricted double dw, unrestricted double dh);
+  [Throws]
+  void drawImage(CanvasImageSource image, /* unrestricted */ double dx, /* unrestricted */ double dy);
+  [Throws]
+  void drawImage(CanvasImageSource image, /* unrestricted */ double dx, /* unrestricted */ double dy, /* unrestricted */ double dw, /* unrestricted */ double dh);
+  [Throws]
+  void drawImage(CanvasImageSource image, /* unrestricted */ double sx, /* unrestricted */ double sy, /* unrestricted */ double sw, /* unrestricted */ double sh, /* unrestricted */ double dx, /* unrestricted */ double dy, /* unrestricted */ double dw, /* unrestricted */ double dh);
 
   // hit regions
   //void addHitRegion(optional HitRegionOptions options);
@@ -135,7 +144,7 @@ interface CanvasPathMethods {
                      /*unrestricted*/ double x,
                      /*unrestricted*/ double y);
 
-  //void arcTo(double x1, double y1, double x2, double y2, double radius); 
+  //void arcTo(double x1, double y1, double x2, double y2, double radius);
 // NOT IMPLEMENTED  [LenientFloat] void arcTo(double x1, double y1, double x2, double y2, double radiusX, double radiusY, double rotation);
 
   //void rect(double x, double y, double w, double h);
diff --git a/components/servo/Cargo.lock b/components/servo/Cargo.lock
index bc520d62f3e..750871127ad 100644
--- a/components/servo/Cargo.lock
+++ b/components/servo/Cargo.lock
@@ -898,6 +898,7 @@ dependencies = [
 name = "util"
 version = "0.0.1"
 dependencies = [
+ "azure 0.1.0 (git+https://github.com/servo/rust-azure)",
  "bitflags 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "cssparser 0.2.0 (git+https://github.com/servo/rust-cssparser)",
  "geom 0.1.0 (git+https://github.com/servo/rust-geom)",
diff --git a/components/util/Cargo.toml b/components/util/Cargo.toml
index 1fc0ac21f61..706ca02e9b6 100644
--- a/components/util/Cargo.toml
+++ b/components/util/Cargo.toml
@@ -24,6 +24,9 @@ git = "https://github.com/servo/rust-cssparser"
 [dependencies.selectors]
 git = "https://github.com/servo/rust-selectors"
 
+[dependencies.azure]
+git = "https://github.com/servo/rust-azure"
+
 [dependencies.geom]
 git = "https://github.com/servo/rust-geom"
 
diff --git a/components/util/lib.rs b/components/util/lib.rs
index 62068621467..c9b1c5bb76a 100644
--- a/components/util/lib.rs
+++ b/components/util/lib.rs
@@ -24,6 +24,7 @@
 
 #[macro_use] extern crate log;
 
+extern crate azure;
 extern crate alloc;
 #[macro_use] extern crate bitflags;
 extern crate cssparser;