Improving canvas 2D performance by switching graphics rendering pipeline.

third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp

 /*
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 130 matching lines @@
 inline HTMLCanvasElement::HTMLCanvasElement(Document& document)
     : HTMLElement(canvasTag, document)
     , ContextLifecycleObserver(&document)
     , PageVisibilityObserver(document.page())
     , m_size(DefaultWidth, DefaultHeight)
     , m_ignoreReset(false)
     , m_externallyAllocatedMemory(0)
     , m_originClean(true)
     , m_didFailToCreateImageBuffer(false)
     , m_imageBufferIsClear(false)
+    , m_numFramesSinceLastRenderingModeSwitch(0)
 {
     CanvasMetrics::countCanvasContextUsage(CanvasMetrics::CanvasCreated);
 }
 
 DEFINE_NODE_FACTORY(HTMLCanvasElement)
 
 HTMLCanvasElement::~HTMLCanvasElement()
 {
     v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(-m_externallyAllocatedMemory);
 }
@@ skipping 148 matching lines @@
     // paint invalidations if the canvas is accelerated, since
     // the canvas contents are sent separately through a texture layer.
     if (ro && (!m_context || !m_context->isAccelerated())) {
         LayoutRect mappedDirtyRect(enclosingIntRect(mapRect(m_dirtyRect, srcRect, FloatRect(ro->contentBoxRect()))));
         // For querying PaintLayer::compositingState()
         // FIXME: is this invalidation using the correct compositing state?
         DisableCompositingQueryAsserts disabler;
         ro->invalidatePaintRectangle(mappedDirtyRect);
     }
     m_dirtyRect = FloatRect();
+
+    m_numFramesSinceLastRenderingModeSwitch++;
+    if (m_context->is2d() && buffer()->isAccelerated()
+        && m_numFramesSinceLastRenderingModeSwitch >= ExpensiveCanvasHeuristicParameters::MinFramesBeforeSwitch) {
+        if (RuntimeEnabledFeatures::enableCanvas2dDynamicRenderingModeSwitchingEnabled()) {

[Stephen White, 2016/07/19 15:47:41]

Nit: perhaps this check should be outside of all of this code (ie., above line
321 above). Would that make sense?

[sebastienlc, 2016/07/19 18:59:24]

Done.

+            if (!m_context->isAccelerationOptimalForCanvasContent()) {
+                // The switch must be done asynchronously in order to avoid switching during the paint invalidation step.
+                Platform::current()->currentThread()->getWebTaskRunner()->postTask(
+                    BLINK_FROM_HERE,
+                    WTF::bind([](WeakPtr<ImageBuffer> buffer) {

[Stephen White, 2016/07/19 15:47:41]

Do you still need WTF::bind() here, or could you just use the lambda directly?
The type conversion *should* just work without the bind(), although I'm
half-speculating here. Maybe give it a try?

[sebastienlc, 2016/07/19 18:59:24]

I tried but the type conversion doesn't seem to work.

+                        if (buffer) {
+                            buffer->disableAcceleration();
+                        }
+                    },
+                    m_imageBuffer->m_weakPtrFactory.createWeakPtr()));
+                m_numFramesSinceLastRenderingModeSwitch = 0;
+            }
+        }
+    }
 }
 
 void HTMLCanvasElement::didDisableAcceleration()
 {
     // We must force a paint invalidation on the canvas even if it's
     // content did not change because it layer was destroyed.
     didDraw(FloatRect(0, 0, size().width(), size().height()));
 }
 
 void HTMLCanvasElement::restoreCanvasMatrixClipStack(SkCanvas* canvas) const
@@ skipping 866 matching lines @@
 
 bool HTMLCanvasElement::createSurfaceLayer()
 {
     DCHECK(!m_surfaceLayerBridge);
     std::unique_ptr<CanvasSurfaceLayerBridgeClient> bridgeClient = wrapUnique(new CanvasSurfaceLayerBridgeClientImpl());
     m_surfaceLayerBridge = wrapUnique(new CanvasSurfaceLayerBridge(std::move(bridgeClient)));
     return m_surfaceLayerBridge->createSurfaceLayer(this->width(), this->height());
 }
 
 } // namespace blink