Move common logic between BoxReflectFilterOperation and FEBoxReflect into BoxReflection.

third_party/WebKit/Source/platform/graphics/BoxReflection.cpp

+// Copyright 2016 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/BoxReflection.h"
+
+#include "platform/geometry/FloatRect.h"
+#include "platform/graphics/skia/SkiaUtils.h"
+#include "third_party/skia/include/core/SkImageFilter.h"
+#include "third_party/skia/include/core/SkMatrix.h"
+#include "third_party/skia/include/core/SkPicture.h"
+#include "third_party/skia/include/core/SkRefCnt.h"
+#include "third_party/skia/include/core/SkXfermode.h"
+#include "third_party/skia/include/effects/SkPictureImageFilter.h"
+#include "third_party/skia/include/effects/SkXfermodeImageFilter.h"
+
+#include <utility>
+
+namespace blink {
+
+SkMatrix BoxReflection::reflectionMatrix() const
+{
+    SkMatrix flipMatrix;
+    switch (m_direction) {
+    case VerticalReflection:
+        flipMatrix.setScale(1, -1);
+        flipMatrix.postTranslate(0, m_offset);
+        break;
+    case HorizontalReflection:
+        flipMatrix.setScale(-1, 1);
+        flipMatrix.postTranslate(m_offset, 0);
+        break;
+    default:
+        // MSVC requires that SkMatrix be initialized in this unreachable case.
+        NOTREACHED();
+        flipMatrix.reset();
+        break;
+    }
+    return flipMatrix;
+}
+
+FloatRect BoxReflection::mapRect(const FloatRect& rect) const
+{
+    SkRect reflection(rect);
+    reflectionMatrix().mapRect(&reflection);
+    FloatRect result = rect;
+    result.unite(reflection);
+    return result;
+}
+
+} // namespace blink