1 files changed, 88 insertions, 0 deletions
diff --git a/gfx/skia/skia/include/utils/SkShadowUtils.h b/gfx/skia/skia/include/utils/SkShadowUtils.h
new file mode 100644
index 0000000000..b7c43d569f
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+++ b/gfx/skia/skia/include/utils/SkShadowUtils.h
@@ -0,0 +1,88 @@
+
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#ifndef SkShadowUtils_DEFINED
+#define SkShadowUtils_DEFINED
+
+#include "include/core/SkColor.h"
+#include "include/core/SkScalar.h"
+#include "include/core/SkTypes.h"
+#include "include/private/SkShadowFlags.h"
+
+#include <cstdint>
+
+class SkCanvas;
+class SkMatrix;
+class SkPath;
+struct SkPoint3;
+struct SkRect;
+
+class SK_API SkShadowUtils {
+public:
+    /**
+     * Draw an offset spot shadow and outlining ambient shadow for the given path using a disc
+     * light. The shadow may be cached, depending on the path type and canvas matrix. If the
+     * matrix is perspective or the path is volatile, it will not be cached.
+     *
+     * @param canvas  The canvas on which to draw the shadows.
+     * @param path  The occluder used to generate the shadows.
+     * @param zPlaneParams  Values for the plane function which returns the Z offset of the
+     *  occluder from the canvas based on local x and y values (the current matrix is not applied).
+     * @param lightPos  Generally, the 3D position of the light relative to the canvas plane.
+     *                  If kDirectionalLight_ShadowFlag is set, this specifies a vector pointing
+     *                  towards the light.
+     * @param lightRadius  Generally, the radius of the disc light.
+     *                     If DirectionalLight_ShadowFlag is set, this specifies the amount of
+     *                     blur when the occluder is at Z offset == 1. The blur will grow linearly
+     *                     as the Z value increases.
+     * @param ambientColor  The color of the ambient shadow.
+     * @param spotColor  The color of the spot shadow.
+     * @param flags  Options controlling opaque occluder optimizations, shadow appearance,
+     *               and light position. See SkShadowFlags.
+     */
+    static void DrawShadow(SkCanvas* canvas, const SkPath& path, const SkPoint3& zPlaneParams,
+                           const SkPoint3& lightPos, SkScalar lightRadius,
+                           SkColor ambientColor, SkColor spotColor,
+                           uint32_t flags = SkShadowFlags::kNone_ShadowFlag);
+
+    /**
+     * Generate bounding box for shadows relative to path. Includes both the ambient and spot
+     * shadow bounds.
+     *
+     * @param ctm  Current transformation matrix to device space.
+     * @param path  The occluder used to generate the shadows.
+     * @param zPlaneParams  Values for the plane function which returns the Z offset of the
+     *  occluder from the canvas based on local x and y values (the current matrix is not applied).
+     * @param lightPos  Generally, the 3D position of the light relative to the canvas plane.
+     *                  If kDirectionalLight_ShadowFlag is set, this specifies a vector pointing
+     *                  towards the light.
+     * @param lightRadius  Generally, the radius of the disc light.
+     *                     If DirectionalLight_ShadowFlag is set, this specifies the amount of
+     *                     blur when the occluder is at Z offset == 1. The blur will grow linearly
+     *                     as the Z value increases.
+     * @param flags  Options controlling opaque occluder optimizations, shadow appearance,
+     *               and light position. See SkShadowFlags.
+     * @param bounds Return value for shadow bounding box.
+     * @return Returns true if successful, false otherwise.
+     */
+    static bool GetLocalBounds(const SkMatrix& ctm, const SkPath& path,
+                               const SkPoint3& zPlaneParams, const SkPoint3& lightPos,
+                               SkScalar lightRadius, uint32_t flags, SkRect* bounds);
+
+    /**
+     * Helper routine to compute color values for one-pass tonal alpha.
+     *
+     * @param inAmbientColor  Original ambient color
+     * @param inSpotColor  Original spot color
+     * @param outAmbientColor  Modified ambient color
+     * @param outSpotColor  Modified spot color
+     */
+    static void ComputeTonalColors(SkColor inAmbientColor, SkColor inSpotColor,
+                                   SkColor* outAmbientColor, SkColor* outSpotColor);
+};
+
+#endif