Refactor BlendMode into a separate class.

Source/core/rendering/RenderLayerBlendInfo.cpp

+/*
+ * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
+ *
+ * Portions are Copyright (C) 1998 Netscape Communications Corporation.
+ *
+ * Other contributors:
+ *   Robert O'Callahan <roc+@cs.cmu.edu>
+ *   David Baron <dbaron@fas.harvard.edu>
+ *   Christian Biesinger <cbiesinger@web.de>
+ *   Randall Jesup <rjesup@wgate.com>
+ *   Roland Mainz <roland.mainz@informatik.med.uni-giessen.de>
+ *   Josh Soref <timeless@mac.com>
+ *   Boris Zbarsky <bzbarsky@mit.edu>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Alternatively, the contents of this file may be used under the terms
+ * of either the Mozilla Public License Version 1.1, found at
+ * http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public
+ * License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html
+ * (the "GPL"), in which case the provisions of the MPL or the GPL are
+ * applicable instead of those above.  If you wish to allow use of your
+ * version of this file only under the terms of one of those two
+ * licenses (the MPL or the GPL) and not to allow others to use your
+ * version of this file under the LGPL, indicate your decision by
+ * deletingthe provisions above and replace them with the notice and
+ * other provisions required by the MPL or the GPL, as the case may be.
+ * If you do not delete the provisions above, a recipient may use your
+ * version of this file under any of the LGPL, the MPL or the GPL.
+ */
+
+#include "config.h"
+#include "core/rendering/RenderLayerBlendInfo.h"
+
+#include "core/rendering/CompositedLayerMapping.h"
+#include "core/rendering/RenderLayer.h"
+#include "core/rendering/RenderLayerModelObject.h"
+
+namespace WebCore {
+
+RenderLayerBlendInfo::RenderLayerBlendInfo(RenderLayerModelObject* renderer)
+    : m_renderer(renderer)
+    , m_blendMode(blink::WebBlendModeNormal)
+    , m_childLayerHasBlendMode(false)
+    , m_childLayerHasBlendModeStatusDirty(false)
+{
+}
+
+bool RenderLayerBlendInfo::hasBlendMode() const
+{
+    return RuntimeEnabledFeatures::cssCompositingEnabled() && m_renderer->hasBlendMode();
+}
+
+void RenderLayerBlendInfo::updateBlendMode()
+{
+    if (!RuntimeEnabledFeatures::cssCompositingEnabled())
+        return;
+
+    blink::WebBlendMode newBlendMode = m_renderer->style()->blendMode();
+    if (newBlendMode == m_blendMode)
+        return;
+
+    bool hadBlendMode = m_blendMode != blink::WebBlendModeNormal;
+    m_blendMode = newBlendMode;
+
+    RenderLayer* layer = m_renderer->layer();
+    // Only update the flag if a blend mode is set or unset.
+    if (layer->parent() && (!hadBlendMode || !hasBlendMode()))
+        layer->parent()->blendInfo().dirtyAncestorChainBlendedDescendantStatus();
+
+    if (layer->hasCompositedLayerMapping())
+        layer->compositedLayerMapping()->setBlendMode(newBlendMode);
+}
+
+void RenderLayerBlendInfo::dirtyAncestorChainBlendedDescendantStatus()
+{
+    for (RenderLayer* layer = m_renderer->layer(); layer; layer = layer->parent()) {
+        if (layer->blendInfo().childLayerHasBlendModeStatusDirty())
+            break;
+
+        layer->blendInfo().setChildLayerHasBlendModeStatusDirty(true);
+
+        if (layer->stackingNode()->isStackingContext())
+            break;
+    }
+}
+
+void RenderLayerBlendInfo::setAncestorChainBlendedDescendant()
+{
+    for (RenderLayer* layer = m_renderer->layer(); layer; layer = layer->parent()) {
+        if (!layer->blendInfo().childLayerHasBlendModeStatusDirty() && layer->blendInfo().childLayerHasBlendMode())
+            break;
+
+        layer->blendInfo().setChildLayerHasBlendMode(true);
+        layer->blendInfo().setChildLayerHasBlendModeStatusDirty(false);
+
+        if (layer->stackingNode()->isStackingContext())
+            break;
+    }
+}
+
+} // namespace WebCore