Auto merge of #14075 - MortimerGoro:webgl-resize, r=MortimerGoro

Implement WebGLContext resize

<!-- Please describe your changes on the following line: -->

Related PR: https://github.com/servo/webrender/pull/519

Implement WebGLContext resize (canvas.width & canvas.height). I have tested:

- Fixes WebGL apps that initialize canvas size after calling canvas.getContext("webgl")
- Support WebGL apps that change the canvas size & viewport on window.onresize

---
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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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- [x] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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Cargo.lock

@@ -243,7 +243,7 @@ dependencies = [
  "ipc-channel 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.1.35 (registry+https://github.com/rust-lang/crates.io-index)",
- "offscreen_gl_context 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "offscreen_gl_context 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "plugins 0.0.1",
  "util 0.0.1",
  "webrender_traits 0.11.0 (git+https://github.com/servo/webrender)",
@@ -388,7 +388,7 @@ dependencies = [
  "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "msg 0.0.1",
  "net_traits 0.0.1",
- "offscreen_gl_context 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "offscreen_gl_context 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "plugins 0.0.1",
  "profile_traits 0.0.1",
  "rand 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1801,7 +1801,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "offscreen_gl_context"
-version = "0.5.0"
+version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cgl 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2191,7 +2191,7 @@ dependencies = [
  "msg 0.0.1",
  "net_traits 0.0.1",
  "num-traits 0.1.35 (registry+https://github.com/rust-lang/crates.io-index)",
- "offscreen_gl_context 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "offscreen_gl_context 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "open 1.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "phf 0.7.20 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2279,7 +2279,7 @@ dependencies = [
  "libc 0.2.17 (registry+https://github.com/rust-lang/crates.io-index)",
  "msg 0.0.1",
  "net_traits 0.0.1",
- "offscreen_gl_context 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "offscreen_gl_context 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "plugins 0.0.1",
  "profile_traits 0.0.1",
  "rustc-serialize 0.3.19 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3065,7 +3065,7 @@ dependencies = [
  "lazy_static 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.1.35 (registry+https://github.com/rust-lang/crates.io-index)",
- "offscreen_gl_context 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "offscreen_gl_context 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rayon 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "time 0.1.35 (registry+https://github.com/rust-lang/crates.io-index)",
  "webrender_traits 0.11.0 (git+https://github.com/servo/webrender)",
@@ -3084,7 +3084,7 @@ dependencies = [
  "gleam 0.2.24 (registry+https://github.com/rust-lang/crates.io-index)",
  "heapsize 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "ipc-channel 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "offscreen_gl_context 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "offscreen_gl_context 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 0.8.18 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_derive 0.8.18 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -3329,7 +3329,7 @@ dependencies = [
 "checksum num_cpus 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "8890e6084723d57d0df8d2720b0d60c6ee67d6c93e7169630e4371e88765dcad"
 "checksum objc 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7c9311aa5acd7bee14476afa0f0557f564e9d0d61218a8b833d9b1f871fa5fba"
 "checksum odds 0.2.16 (registry+https://github.com/rust-lang/crates.io-index)" = "f3701cfdec1676e319ad37ff96c31de39df8c92006032976153366f52693bf40"
-"checksum offscreen_gl_context 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "9da33a538d9c8fc81102e5d5c1ed844568b400d86c22413550a9b8474be62ba3"
+"checksum offscreen_gl_context 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "2fe2fe54ba2b6ea8f43a17b16c13168c5bbf008e0fc91b34122a11f637e2728a"
 "checksum ogg 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "426d8dc59cdd206be1925461087350385c0a02f291d87625829c6d08e72b457b"
 "checksum ogg_metadata 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e755cc735fa6faa709cb23048433d9201d6caa85fa96215386ccdd5e9b40ad01"
 "checksum open 1.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "c228597177bc4a6876e278f7c7948ac033bfcb4d163ccdd5a009557c8fe5fa1e"

components/canvas/webgl_paint_thread.rs

@@ -251,8 +251,8 @@ impl WebGLPaintThread {
                     unsafe { gl::Scissor(0, 0, size.width, size.height); }
                 }
             }
-            WebGLPaintTaskData::WebRender(_, _) => {
+            WebGLPaintTaskData::WebRender(ref api, id) => {
-                // TODO
+                api.resize_webgl_context(id, &size);
             }
         }
 

components/script/dom/webglrenderingcontext.rs

@@ -133,6 +133,10 @@ pub struct WebGLRenderingContext {
     current_program: MutNullableHeap<JS<WebGLProgram>>,
     #[ignore_heap_size_of = "Because it's small"]
     current_vertex_attrib_0: Cell<(f32, f32, f32, f32)>,
+    #[ignore_heap_size_of = "Because it's small"]
+    current_scissor: Cell<(i32, i32, i32, i32)>,
+    #[ignore_heap_size_of = "Because it's small"]
+    current_clear_color: Cell<(f32, f32, f32, f32)>,
 }
 
 impl WebGLRenderingContext {
@@ -163,6 +167,8 @@ impl WebGLRenderingContext {
                 bound_renderbuffer: MutNullableHeap::new(None),
                 current_program: MutNullableHeap::new(None),
                 current_vertex_attrib_0: Cell::new((0f32, 0f32, 0f32, 1f32)),
+                current_scissor: Cell::new((0, 0, size.width, size.height)),
+                current_clear_color: Cell::new((0.0, 0.0, 0.0, 0.0))
             }
         })
     }
@@ -203,6 +209,22 @@ impl WebGLRenderingContext {
 
     pub fn recreate(&self, size: Size2D<i32>) {
         self.ipc_renderer.send(CanvasMsg::Common(CanvasCommonMsg::Recreate(size))).unwrap();
+
+        // ClearColor needs to be restored because after a resize the GLContext is recreated
+        // and the framebuffer is cleared using the default black transparent color.
+        let color = self.current_clear_color.get();
+        self.ipc_renderer
+            .send(CanvasMsg::WebGL(WebGLCommand::ClearColor(color.0, color.1, color.2, color.3)))
+            .unwrap();
+
+        // WebGL Spec: Scissor rect must not change if the canvas is resized.
+        // See: webgl/conformance-1.0.3/conformance/rendering/gl-scissor-canvas-dimensions.html
+        // NativeContext handling library changes the scissor after a resize, so we need to reset the
+        // default scissor when the canvas was created or the last scissor that the user set.
+        let rect = self.current_scissor.get();
+        self.ipc_renderer
+            .send(CanvasMsg::WebGL(WebGLCommand::Scissor(rect.0, rect.1, rect.2, rect.3)))
+            .unwrap()
     }
 
     pub fn ipc_renderer(&self) -> IpcSender<CanvasMsg> {
@@ -1136,6 +1158,7 @@ impl WebGLRenderingContextMethods for WebGLRenderingContext {
 
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.3
     fn ClearColor(&self, red: f32, green: f32, blue: f32, alpha: f32) {
+        self.current_clear_color.set((red, green, blue, alpha));
         self.ipc_renderer
             .send(CanvasMsg::WebGL(WebGLCommand::ClearColor(red, green, blue, alpha)))
             .unwrap()
@@ -1903,6 +1926,7 @@ impl WebGLRenderingContextMethods for WebGLRenderingContext {
             return self.webgl_error(InvalidValue)
         }
 
+        self.current_scissor.set((x, y, width, height));
         self.ipc_renderer
             .send(CanvasMsg::WebGL(WebGLCommand::Scissor(x, y, width, height)))
             .unwrap()