Submit Compositor Frame from OffscreenCanvas on main

third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcherImpl.cpp

Index: third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcherImpl.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcherImpl.cpp b/third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcherImpl.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..a94807875bf45ebc4f268d023490c4eb73021371
--- /dev/null
+++ b/third_party/WebKit/Source/platform/graphics/OffscreenCanvasFrameDispatcherImpl.cpp
@@ -0,0 +1,56 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "platform/graphics/OffscreenCanvasFrameDispatcherImpl.h"
+
+#include "cc/output/delegated_frame_data.h"
+#include "cc/quads/render_pass.h"
+#include "cc/quads/shared_quad_state.h"
+#include "cc/quads/solid_color_draw_quad.h"
+#include "public/platform/InterfaceProvider.h"
+#include "public/platform/Platform.h"
+#include "third_party/skia/include/core/SkColor.h"
+#include "third_party/skia/include/core/SkXfermode.h"
+#include "ui/gfx/geometry/rect.h"
+#include "ui/gfx/transform.h"
+
+namespace blink {
+
+OffscreenCanvasFrameDispatcherImpl::OffscreenCanvasFrameDispatcherImpl(uint32_t clientId, uint32_t localId, uint64_t nonce)
+    : m_surfaceId(cc::SurfaceId(clientId, localId, nonce))
+{
+    DCHECK(!m_service.is_bound());
+    Platform::current()->interfaceProvider()->getInterface(mojo::GetProxy(&m_service));
+}
+
+void OffscreenCanvasFrameDispatcherImpl::uploadImage(int width, int height)

[danakj, 2016/09/02 19:12:43]

I thought width and height never change, why arent these part of construction?

[Justin Novosad, 2016/09/02 19:20:08]

This is just temporary. Once we start pushing actual frames the args to this
method will probably be SkImage or some other vehicle that carries size info, so
no need to store width and height in this class IMHO.

[danakj, 2016/09/02 19:20:59]

Do sizes change? Because then we have to deal with making new surface ids and
stuff.

[xlai (Olivia), 2016/09/02 20:10:07]

Made width and height to be const member in OffscreenCanvasFrameDispatcherImpl.

+{
+    // TODO(563852): Currently this is just a simple solid-color compositor frame.
+    // We need to update this function to extract the image data from canvas.
+    cc::CompositorFrame frame;
+    frame.metadata.device_scale_factor = 1.0f;
+    frame.delegated_frame_data.reset(new cc::DelegatedFrameData());

[danakj, 2016/09/02 19:12:42]

nit: no () needed

[xlai (Olivia), 2016/09/02 20:10:07]

Done.

+    frame.delegated_frame_data->resource_list.resize(0u);

[danakj, 2016/09/02 19:12:42]

it already starts empty so i dont think u need this

[xlai (Olivia), 2016/09/02 20:10:06]

Done.

+
+    const gfx::Rect bounds(width, height);
+    const cc::RenderPassId renderPassId(1, 1);
+    std::unique_ptr<cc::RenderPass> pass = cc::RenderPass::Create();
+    pass->SetAll(renderPassId, bounds, bounds, gfx::Transform(), true);

[danakj, 2016/09/02 19:12:42]

background is normally not transparent for the root render pass, is true here
intentional? i thought canvases are opaque

[xlai (Olivia), 2016/09/02 20:10:06]

Yah you're right; I think it's more logical if canvas is opaque.

+
+    cc::SharedQuadState* sqs = pass->CreateAndAppendSharedQuadState();
+    sqs->SetAll(gfx::Transform(), bounds.size(), bounds, bounds, false, 1.f, SkXfermode::kSrc_Mode, 0);

[danakj, 2016/09/02 19:12:42]

pass an empty clip rect since is_clipped is false

SrcOver mode is more common, can you use that?

[xlai (Olivia), 2016/09/02 20:10:07]

Done.

+
+    cc::SolidColorDrawQuad* quad = pass->CreateAndAppendDrawQuad<cc::SolidColorDrawQuad>();
+    const bool forceAntialiasingOff = false;
+    const gfx::Rect opaqueRect(0, 0, 0, 0);
+    const bool needsBlending = true;
+    quad->SetAll(sqs, bounds, opaqueRect, bounds, needsBlending, SK_ColorGREEN, forceAntialiasingOff);

[danakj, 2016/09/02 19:12:42]

you can use SetNew here it's helpful and decides the opaquerect.

needsblending should be false. you don't need to force blending:
https://cs.chromium.org/chromium/src/cc/quads/draw_quad.h?rcl=1472831237&l=69

[xlai (Olivia), 2016/09/02 20:10:06]

Done. The solidcolorQuad::setNew() will set needsblending to be false by
default.

+
+    frame.delegated_frame_data->render_pass_list.push_back(std::move(pass));
+
+    m_service->SubmitCompositorFrame(m_surfaceId, std::move(frame));

[danakj, 2016/09/02 19:12:42]

The frame doesn't look totally wrong or anything to me. You could throw it in a
direct renderer and see what comes out if you want (see renderer_pixeltest.cc)

[xlai (Olivia), 2016/09/02 20:10:06]

I see. That's a useful way to debug for me. Right now I've already added a
layout test in this CL so I can see it comes out to be a green rectangle inside
the canvas.

+
+}
+
+} // namespace blink