Move common logic between BoxReflectFilterOperation and FEBoxReflect into BoxReflection.

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

+// 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.
+
+#ifndef BoxReflection_h
+#define BoxReflection_h
+
+#include "platform/PlatformExport.h"
+#include "third_party/skia/include/core/SkPicture.h"
+#include "wtf/PassRefPtr.h"
+#include "wtf/RefPtr.h"
+
+class SkImageFilter;
+class SkMatrix;
+class SkPicture;
+
+namespace blink {
+
+class FloatRect;
+
+// A reflection, as created by -webkit-box-reflect. Consists of:
+// * a direction (either vertical or horizontal)
+// * an offset to be applied to the reflection after flipping about the
+//   x- or y-axis, according to the direction
+// * a mask image, which will be applied to the reflection before the
+//   reflection matrix is applied
+class PLATFORM_EXPORT BoxReflection {
+public:
+    enum ReflectionDirection {
+        // Vertically flipped (to appear above or below).
+        VerticalReflection,
+        // Horizontally flipped (to appear to the left or right).
+        HorizontalReflection,
+    };
+
+    BoxReflection(ReflectionDirection direction, float offset, PassRefPtr<SkPicture> mask = nullptr)
+        : m_direction(direction), m_offset(offset), m_mask(mask) {}
+
+    ReflectionDirection direction() const { return m_direction; }
+    float offset() const { return m_offset; }
+    SkPicture* mask() const { return m_mask.get(); }
+
+    // Returns a matrix which maps points between the original content and its
+    // reflection. Reflections are self-inverse, so this matrix can be used to
+    // map in either direction.
+    SkMatrix reflectionMatrix() const;
+
+    // Maps a source rectangle to the destination rectangle it can affect,
+    // including this reflection. Due to the symmetry of reflections, this can
+    // also be used to map from a destination rectangle to the source rectangle
+    // which contributes to it.
+    FloatRect mapRect(const FloatRect&) const;
+
+private:
+    ReflectionDirection m_direction;
+    float m_offset;
+    RefPtr<SkPicture> m_mask;
+};
+
+inline bool operator==(const BoxReflection& a, const BoxReflection& b)
+{
+    return a.direction() == b.direction()
+        && a.offset() == b.offset()
+        && a.mask() == b.mask();
+}
+
+inline bool operator!=(const BoxReflection& a, const BoxReflection& b)
+{
+    return !(a == b);
+}
+
+} // namespace blink
+
+#endif // BoxReflection_h