Auto merge of #5635 - mmatyas:canvas_linecapjoin, r=jdm

This patch adds support for setting the line cap and join. However, it seems there's a problem on the azure-side, as the line cap setting doesn't work. Changing either the default values or using the new function has no effect. Line join works fine though.

<!-- Reviewable:start -->
[<img src="https://reviewable.io/review_button.png" height=40 alt="Review on Reviewable"/>](https://reviewable.io/reviews/servo/servo/5635)
<!-- Reviewable:end -->

3 files changed, 40 insertions, 2 deletions

diff --git a/components/script/dom/bindings/trace.rs b/components/script/dom/bindings/trace.rs
index 9d4e548e161..1695f16ead7 100644
--- a/components/script/dom/bindings/trace.rs
+++ b/components/script/dom/bindings/trace.rs
@@ -35,6 +35,7 @@ use dom::bindings::utils::{Reflectable, Reflector, WindowProxyHandler};
 use script_task::ScriptChan;
 
 use canvas::canvas_paint_task::{CanvasGradientStop, LinearGradientStyle, RadialGradientStyle};
+use canvas::canvas_paint_task::{LineCapStyle, LineJoinStyle};
 use cssparser::RGBA;
 use encoding::types::EncodingRef;
 use geom::matrix2d::Matrix2D;
@@ -259,6 +260,7 @@ no_jsmanaged_fields!(RGBA);
 no_jsmanaged_fields!(Matrix2D<T>);
 no_jsmanaged_fields!(StorageType);
 no_jsmanaged_fields!(CanvasGradientStop, LinearGradientStyle, RadialGradientStyle);
+no_jsmanaged_fields!(LineCapStyle, LineJoinStyle);
 
 impl JSTraceable for Box<ScriptChan+Send> {
     #[inline]
diff --git a/components/script/dom/canvasrenderingcontext2d.rs b/components/script/dom/canvasrenderingcontext2d.rs
index 32db448af01..891c2d49b87 100644
--- a/components/script/dom/canvasrenderingcontext2d.rs
+++ b/components/script/dom/canvasrenderingcontext2d.rs
@@ -29,6 +29,7 @@ use geom::size::Size2D;
 
 use canvas::canvas_paint_task::{CanvasMsg, CanvasPaintTask, FillOrStrokeStyle};
 use canvas::canvas_paint_task::{LinearGradientStyle, RadialGradientStyle};
+use canvas::canvas_paint_task::{LineCapStyle, LineJoinStyle};
 
 use net_traits::image::base::Image;
 use net_traits::image_cache_task::{ImageResponseMsg, Msg};
@@ -40,6 +41,7 @@ use std::num::{Float, ToPrimitive};
 use std::sync::{Arc};
 use std::sync::mpsc::{channel, Sender};
 
+use util::str::DOMString;
 use url::Url;
 use util::vec::byte_swap;
 
@@ -53,6 +55,8 @@ pub struct CanvasRenderingContext2D {
     image_smoothing_enabled: Cell<bool>,
     stroke_color: Cell<RGBA>,
     line_width: Cell<f64>,
+    line_cap: Cell<LineCapStyle>,
+    line_join: Cell<LineJoinStyle>,
     miter_limit: Cell<f64>,
     fill_color: Cell<RGBA>,
     transform: Cell<Matrix2D<f32>>,
@@ -76,6 +80,8 @@ impl CanvasRenderingContext2D {
             image_smoothing_enabled: Cell::new(true),
             stroke_color: Cell::new(black),
             line_width: Cell::new(1.0),
+            line_cap: Cell::new(LineCapStyle::Butt),
+            line_join: Cell::new(LineJoinStyle::Miter),
             miter_limit: Cell::new(10.0),
             fill_color: Cell::new(black),
             transform: Cell::new(Matrix2D::identity()),
@@ -819,6 +825,36 @@ impl<'a> CanvasRenderingContext2DMethods for JSRef<'a, CanvasRenderingContext2D>
         self.renderer.send(CanvasMsg::SetLineWidth(width as f32)).unwrap()
     }
 
+    fn LineCap(self) -> DOMString {
+        match self.line_cap.get() {
+            LineCapStyle::Butt => "butt".to_owned(),
+            LineCapStyle::Round => "round".to_owned(),
+            LineCapStyle::Square => "square".to_owned(),
+        }
+    }
+
+    fn SetLineCap(self, cap_str: DOMString) {
+        if let Some(cap) = LineCapStyle::from_str(&cap_str) {
+            self.line_cap.set(cap);
+            self.renderer.send(CanvasMsg::SetLineCap(cap)).unwrap()
+        }
+    }
+
+    fn LineJoin(self) -> DOMString {
+        match self.line_join.get() {
+            LineJoinStyle::Round => "round".to_owned(),
+            LineJoinStyle::Bevel => "bevel".to_owned(),
+            LineJoinStyle::Miter => "miter".to_owned(),
+        }
+    }
+
+    fn SetLineJoin(self, join_str: DOMString) {
+        if let Some(join) = LineJoinStyle::from_str(&join_str) {
+            self.line_join.set(join);
+            self.renderer.send(CanvasMsg::SetLineJoin(join)).unwrap()
+        }
+    }
+
     fn MiterLimit(self) -> f64 {
         self.miter_limit.get()
     }
diff --git a/components/script/dom/webidls/CanvasRenderingContext2D.webidl b/components/script/dom/webidls/CanvasRenderingContext2D.webidl
index 8b3070c6f64..2805a273550 100644
--- a/components/script/dom/webidls/CanvasRenderingContext2D.webidl
+++ b/components/script/dom/webidls/CanvasRenderingContext2D.webidl
@@ -134,8 +134,8 @@ interface CanvasRenderingContext2D {
 interface CanvasDrawingStyles {
   // line caps/joins
   attribute unrestricted double lineWidth; // (default 1)
-  //attribute DOMString lineCap; // "butt", "round", "square" (default "butt")
-  //attribute DOMString lineJoin; // "round", "bevel", "miter" (default "miter")
+  attribute DOMString lineCap; // "butt", "round", "square" (default "butt")
+  attribute DOMString lineJoin; // "round", "bevel", "miter" (default "miter")
   attribute unrestricted double miterLimit; // (default 10)
 
   // dashed lines