third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.cpp

// Copyright 2014 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/paint/DrawingRecorder.h"

#include "platform/RuntimeEnabledFeatures.h"
#include "platform/graphics/GraphicsContext.h"
#include "platform/graphics/GraphicsLayer.h"
#include "platform/graphics/paint/PaintController.h"
#include "third_party/skia/include/core/SkPicture.h"

namespace blink {

DrawingRecorder::DrawingRecorder(GraphicsContext& context, const DisplayItemClient& displayItemClient, DisplayItem::Type displayItemType, const FloatRect& floatCullRect)
    : m_context(context)
    , m_displayItemClient(displayItemClient)
    , m_displayItemType(displayItemType)
    , m_knownToBeOpaque(false)
#if DCHECK_IS_ON()
    , m_displayItemPosition(m_context.getPaintController().newDisplayItemList().size())
#endif
{
    if (context.getPaintController().displayItemConstructionIsDisabled())
        return;

    // Must check DrawingRecorder::useCachedDrawingIfPossible before creating the DrawingRecorder.
    DCHECK(RuntimeEnabledFeatures::paintUnderInvalidationCheckingEnabled()
        || !useCachedDrawingIfPossible(m_context, m_displayItemClient, m_displayItemType));

    DCHECK(DisplayItem::isDrawingType(displayItemType));

#if DCHECK_IS_ON()
    context.setInDrawingRecorder(true);
#endif

    // Use the enclosing int rect, since pixel-snapping may be applied to the bounds of the object during painting. Potentially expanding
    // the cull rect by a pixel or two also does not affect correctness, and is very unlikely to matter for performance.
    IntRect cullRect = enclosingIntRect(floatCullRect);
    context.beginRecording(cullRect);

#if DCHECK_IS_ON()
    if (RuntimeEnabledFeatures::slimmingPaintStrictCullRectClippingEnabled()) {
        // Skia depends on the cull rect containing all of the display item commands. When strict
        // cull rect clipping is enabled, make this explicit. This allows us to identify potential
        // incorrect cull rects that might otherwise be masked due to Skia internal optimizations.
        context.save();
        // Expand the verification clip by one pixel to account for Skia's SkCanvas::getClipBounds()
        // expansion, used in testing cull rects.
        // TODO(schenney) This is not the best place to do this. Ideally, we would expand by one pixel
        // in device (pixel) space, but to do that we would need to add the verification mode to Skia.
        cullRect.inflate(1);
        context.clipRect(cullRect, NotAntiAliased, SkRegion::kIntersect_Op);
    }
#endif
}

DrawingRecorder::~DrawingRecorder()
{
    if (m_context.getPaintController().displayItemConstructionIsDisabled())
        return;

#if DCHECK_IS_ON()
    if (RuntimeEnabledFeatures::slimmingPaintStrictCullRectClippingEnabled())
        m_context.restore();

    m_context.setInDrawingRecorder(false);
    DCHECK(m_displayItemPosition == m_context.getPaintController().newDisplayItemList().size());
#endif

    m_context.getPaintController().createAndAppend<DrawingDisplayItem>(m_displayItemClient, m_displayItemType, m_context.endRecording(), m_knownToBeOpaque);
}

} // namespace blink