Implementing ACCELERATED_COMPOSITING via Skia

WebCore/platform/graphics/skia/LayerRendererSkia.cpp

+/*
+ * Copyright (c) 2010, Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+
+#include "config.h"
+
+#if USE(ACCELERATED_COMPOSITING)
+#include "LayerRendererSkia.h"
+#include "LayerSkia.h"
+#include "PlatformContextSkia.h"
+
+#include "skia/ext/platform_canvas.h"
+
+namespace WebCore {
+
+PassOwnPtr<LayerRendererSkia> LayerRendererSkia::create()
+{
+    return new LayerRendererSkia();
+}
+
+LayerRendererSkia::LayerRendererSkia()
+    : m_rootLayer(0)
+    , m_needsDisplay(false)
+{
+}
+
+LayerRendererSkia::~LayerRendererSkia()
+{
+}
+
+void LayerRendererSkia::drawLayersInCanvas(skia::PlatformCanvas* canvas, SkRect clipRect)
+{
+    if (!m_rootLayer)
+        return;
+
+    canvas->save();
+    canvas->clipRect(clipRect);
+
+    // First composite the root layer into the canvas.
+    canvas->drawBitmap(m_rootLayer->platformCanvas()->getDevice()->accessBitmap(false), 0, 0, NULL);
+
+    // Account for the scroll offset before compositing the remaining layers.
+    // Note that the root layer's painting takes into account the scroll offset already.
+    canvas->translate(-m_scrollFrame.fLeft, -m_scrollFrame.fTop);
+
+    float opacity = 1.0f;
+    const Vector<RefPtr<LayerSkia>>& sublayers = m_rootLayer->getSublayers();
+    for (size_t ii = 0; ii < sublayers.size(); ii++) {
+        drawLayerInCanvasRecursive(canvas, sublayers[ii].get(), opacity);
+    }
+
+    canvas->restore();
+
+    m_needsDisplay = false;
+}
+
+void LayerRendererSkia::updateLayerContents()
+{
+    if (m_rootLayer) {
+        updateLayerContentsRecursive(m_rootLayer.get());
+    }
+}
+
+void LayerRendererSkia::drawLayerInCanvasRecursive(skia::PlatformCanvas* canvas, LayerSkia* layer, float opacity)
+{
+    // Guarantees that the canvas is restored to a known state on destruction.
+    SkAutoCanvasRestore autoRestoreCanvas(canvas, true);
+
+    SkPoint position = layer->position();
+    SkPoint anchorPoint = layer->anchorPoint();
+    SkMatrix transform = layer->transform();
+    SkIRect bounds = layer->bounds();
+
+    canvas->translate(position.fX, position.fY);
+
+    SkScalar tx = SkScalarMul(anchorPoint.fX, bounds.width());
+    SkScalar ty = SkScalarMul(anchorPoint.fY, bounds.height());
+    canvas->translate(tx, ty);
+    canvas->concat(transform);
+    canvas->translate(-tx, -ty);
+
+    // The position we get is for the center of the layer but
+    // drawBitmap starts at the upper-left corner and therefore
+    // we need to adjust our transform.
+    canvas->translate(-0.5f * bounds.width(), -0.5f * bounds.height());
+
+    SkPaint opacityPaint;
+    opacity = opacity * layer->opacity();
+    opacityPaint.setAlpha(opacity * 255);
+
+    canvas->drawBitmap(layer->platformCanvas()->getDevice()->accessBitmap(false), 0, 0, &opacityPaint);
+
+    const Vector<RefPtr<LayerSkia>>& sublayers = layer->getSublayers();
+    for (size_t ii = 0; ii < sublayers.size(); ii++) {
+        drawLayerInCanvasRecursive(canvas, sublayers[ii].get(), opacity);
+    }
+}
+
+void LayerRendererSkia::updateLayerContentsRecursive(LayerSkia* layer)
+{
+    layer->updateContents();
+
+    const Vector<RefPtr<LayerSkia>>& sublayers = layer->getSublayers();
+    for (size_t ii = 0; ii < sublayers.size(); ii++) {
+        updateLayerContentsRecursive(sublayers[ii].get());
+    }
+}
+
+} // namespace WebCore
+
+#endif // USE(ACCELERATED_COMPOSITING)