Refactor shadow rendering logic.

Source/core/platform/graphics/DrawLooper.h

 /*
  * Copyright (C) 2013 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
@@ skipping 10 matching lines @@
  * 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.
  */
 
-#ifndef TransformBuilder_h
-#define TransformBuilder_h
+#ifndef DrawLooper_h
+#define DrawLooper_h
 
-#include "core/platform/graphics/transforms/TransformOperations.h"
+#include "third_party/skia/include/core/SkDrawLooper.h"
+
+// SkPaint and SkPoint are needed before SkLayerDrawLooper.h; they should be #included there.
+// Can be removed once https://codereview.chromium.org/14607015/ is submitted.
+#include "third_party/skia/include/core/SkPaint.h"
+#include "third_party/skia/include/core/SkPoint.h"
+
+#include "third_party/skia/include/core/SkRefCnt.h"
+#include "third_party/skia/include/effects/SkLayerDrawLooper.h"
 #include "wtf/Noncopyable.h"
 
 namespace WebCore {
 
-class RenderStyle;
-class CSSValue;
+class Color;
+class FloatSize;
 
-class TransformBuilder {
-    WTF_MAKE_NONCOPYABLE(TransformBuilder); WTF_MAKE_FAST_ALLOCATED;
+class DrawLooper {
+    // Implementing the copy constructor properly would require writing code to
+    // copy the underlying SkDrawLooper.
+    WTF_MAKE_NONCOPYABLE(DrawLooper);
+
 public:
-    TransformBuilder();
-    ~TransformBuilder();
+    enum ShadowTransformMode {
+        ShadowRespectsTransforms,
+        ShadowIgnoresTransforms
+    };
+    enum ShadowAlphaMode {
+        ShadowRespectsAlpha,
+        ShadowIgnoresAlpha
+    };
 
-    static bool createTransformOperations(CSSValue* inValue, RenderStyle* inStyle, RenderStyle* rootStyle, TransformOperations& outOperations);
+    DrawLooper();
+    ~DrawLooper() { }
+    SkLayerDrawLooper* skDrawLooper() { return m_skDrawLooper.get(); }
+
+    void addUnmodifiedContent();
+    void addShadow(const FloatSize& offset, float blur, const Color&,
+        ShadowTransformMode = ShadowRespectsTransforms,
+        ShadowAlphaMode = ShadowRespectsAlpha);
+
+private:
+    SkAutoTUnref<SkLayerDrawLooper> m_skDrawLooper;
 };
 
 } // namespace WebCore
 
-#endif // TransformBuilder_h
+#endif // DrawLooper_h