Implement image-rendering:pixelated for accelerated 2D canvases.

Source/platform/graphics/Canvas2DLayerBridge.cpp

Index: Source/platform/graphics/Canvas2DLayerBridge.cpp
diff --git a/Source/platform/graphics/Canvas2DLayerBridge.cpp b/Source/platform/graphics/Canvas2DLayerBridge.cpp
index f504a01c90a916e6e191b530ea566df3ef3a893b..76242e6c9b05aa5bf2d2f63e6495e90b63706a33 100644
--- a/Source/platform/graphics/Canvas2DLayerBridge.cpp
+++ b/Source/platform/graphics/Canvas2DLayerBridge.cpp
@@ -91,10 +91,12 @@ Canvas2DLayerBridge::Canvas2DLayerBridge(PassOwnPtr<WebGraphicsContext3DProvider
     , m_framesSinceMailboxRelease(0)
     , m_destructionInProgress(false)
     , m_rateLimitingEnabled(false)
+    , m_filterLevel(SkPaint::kLow_FilterLevel)
     , m_isHidden(false)
     , m_next(0)
     , m_prev(0)
     , m_lastImageId(0)
+    , m_lastFilter(GL_LINEAR)
     , m_releasedMailboxInfoIndex(InvalidMailboxIndex)
     , m_opacityMode(opacityMode)
 {
@@ -108,6 +110,7 @@ Canvas2DLayerBridge::Canvas2DLayerBridge(PassOwnPtr<WebGraphicsContext3DProvider
     m_layer->setBlendBackgroundColor(opacityMode != Opaque);
     GraphicsLayer::registerContentsLayer(m_layer->layer());
     m_layer->setRateLimitContext(m_rateLimitingEnabled);
+    m_layer->setNearestNeighbor(m_filterLevel == SkPaint::kNone_FilterLevel);
     m_canvas->setNotificationClient(this);
 #ifndef NDEBUG
     canvas2DLayerBridgeInstanceCounter.increment();
@@ -156,6 +159,15 @@ void Canvas2DLayerBridge::beginDestruction()
     ASSERT(!m_bytesAllocated);
 }
 
+void Canvas2DLayerBridge::setFilterLevel(SkPaint::FilterLevel filterLevel)
+{
+    ASSERT(!m_destructionInProgress);
+    if (m_filterLevel != filterLevel) {
+        m_filterLevel = filterLevel;
+        m_layer->setNearestNeighbor(m_filterLevel == SkPaint::kNone_FilterLevel);
+    }
+}
+
 void Canvas2DLayerBridge::setIsHidden(bool hidden)
 {
     ASSERT(!m_destructionInProgress);
@@ -418,9 +430,11 @@ bool Canvas2DLayerBridge::prepareMailbox(WebExternalTextureMailbox* outMailbox,
     RefPtr<SkImage> image = adoptRef(m_canvas->newImageSnapshot());
 
     // Early exit if canvas was not drawn to since last prepareMailbox
-    if (image->uniqueID() == m_lastImageId)
+    GLenum filter = m_filterLevel == SkPaint::kNone_FilterLevel ? GL_NEAREST : GL_LINEAR;
+    if (image->uniqueID() == m_lastImageId && filter == m_lastFilter)
         return false;
     m_lastImageId = image->uniqueID();
+    m_lastFilter = filter;
 
     MailboxInfo* mailboxInfo = createMailboxInfo();
     mailboxInfo->m_status = MailboxInUse;
@@ -435,6 +449,8 @@ bool Canvas2DLayerBridge::prepareMailbox(WebExternalTextureMailbox* outMailbox,
     mailboxInfo->m_parentLayerBridge = this;
     *outMailbox = mailboxInfo->m_mailbox;
 
+    mailboxInfo->m_mailbox.nearestNeighbor = filter == GL_NEAREST;
+
     GrContext* grContext = m_contextProvider->grContext();
     if (!grContext)
         return true; // for testing: skip gl stuff when using a mock graphics context.
@@ -447,8 +463,8 @@ bool Canvas2DLayerBridge::prepareMailbox(WebExternalTextureMailbox* outMailbox,
     mailboxInfo->m_image->getTexture()->textureParamsModified();
 
     webContext->bindTexture(GL_TEXTURE_2D, mailboxInfo->m_image->getTexture()->getTextureHandle());
-    webContext->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-    webContext->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    webContext->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, filter);
+    webContext->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, filter);
     webContext->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     webContext->texParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
     webContext->produceTextureCHROMIUM(GL_TEXTURE_2D, mailboxInfo->m_mailbox.name);