Change shadow tessellators to use SkColor and move to util.

BUG=skia:6119

Change-Id: I4c4a8933c663ccc057596318a06c538175b9f16b
Reviewed-on: https://skia-review.googlesource.com/7726
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>

1 files changed, 133 insertions, 0 deletions

diff --git a/src/utils/SkShadowTessellator.h b/src/utils/SkShadowTessellator.h
new file mode 100755
index 0000000000..ababba74dd
--- /dev/null
+++ b/src/utils/SkShadowTessellator.h
@@ -0,0 +1,133 @@
+/*
+ * 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 SkShadowTessellator_DEFINED
+#define SkShadowTessellator_DEFINED
+
+#include "SkTDArray.h"
+#include "SkPoint.h"
+
+#include "SkColor.h"
+
+class SkMatrix;
+class SkPath;
+
+// TODO: derive these two classes from a base class containing common elements
+
+/**
+ * This class generates an ambient shadow for a path by walking the path, outsetting by the
+ * radius, and setting inner and outer colors to umbraColor and penumbraColor, respectively.
+ * If transparent is true, then the center of the ambient shadow will be filled in.
+ */
+class SkAmbientShadowTessellator {
+public:
+    SkAmbientShadowTessellator(const SkPath& path, SkScalar radius, SkColor umbraColor,
+                               SkColor penumbraColor, bool transparent);
+
+    int      vertexCount() { return fPositions.count(); }
+    SkPoint* positions() { return fPositions.begin(); }
+    SkColor* colors() { return fColors.begin(); }
+    int      indexCount() { return fIndices.count(); }
+    uint16_t* indices() { return fIndices.begin(); }
+
+private:
+    void handleLine(const SkPoint& p);
+
+    void handleQuad(const SkPoint pts[3]);
+
+    void handleCubic(SkPoint pts[4]);
+
+    void handleConic(SkPoint pts[3], SkScalar w);
+
+    void addArc(const SkVector& nextNormal);
+    void finishArcAndAddEdge(const SkVector& nextPoint, const SkVector& nextNormal);
+    void addEdge(const SkVector& nextPoint, const SkVector& nextNormal);
+
+    SkScalar            fRadius;
+    SkColor             fUmbraColor;
+    SkColor             fPenumbraColor;
+    bool                fTransparent;
+
+    SkTDArray<SkPoint>  fPositions;
+    SkTDArray<SkColor>  fColors;
+    SkTDArray<uint16_t> fIndices;
+
+    int                 fPrevInnerIndex;
+    SkVector            fPrevNormal;
+    int                 fFirstVertex;
+    SkVector            fFirstNormal;
+    SkScalar            fDirection;
+    int                 fCentroidCount;
+
+    // first three points
+    SkTDArray<SkPoint>  fInitPoints;
+    // temporary buffer
+    SkTDArray<SkPoint>  fPointBuffer;
+};
+
+/**
+ * This class generates an spot shadow for a path by walking the transformed path, further 
+ * transforming by the scale and translation, and outsetting and insetting by a radius.
+ * The center will be clipped against the original path unless transparent is true.
+ */
+class SkSpotShadowTessellator {
+public:
+    SkSpotShadowTessellator(const SkPath& path, SkScalar scale, const SkVector& translate,
+                            SkScalar radius, SkColor umbraColor, SkColor penumbraColor,
+                            bool transparent);
+
+    int      vertexCount() { return fPositions.count(); }
+    SkPoint* positions() { return fPositions.begin(); }
+    SkColor* colors() { return fColors.begin(); }
+    int      indexCount() { return fIndices.count(); }
+    uint16_t* indices() { return fIndices.begin(); }
+
+private:
+    void computeClipBounds(const SkPath& path);
+
+    void handleLine(const SkPoint& p);
+    void handleLine(SkScalar scale, const SkVector& xlate, SkPoint p);
+
+    void handleQuad(const SkPoint pts[3]);
+    void handleQuad(SkScalar scale, const SkVector& xlate, SkPoint pts[3]);
+
+    void handleCubic(SkScalar scale, const SkVector& xlate, SkPoint pts[4]);
+
+    void handleConic(SkScalar scale, const SkVector& xlate, SkPoint pts[3], SkScalar w);
+
+    void mapPoints(SkScalar scale, const SkVector& xlate, SkPoint* pts, int count);
+    void addInnerPoint(const SkPoint& pathPoint, SkColor umbraColor, SkScalar radiusSqd);
+    void addArc(const SkVector& nextNormal);
+    void finishArcAndAddEdge(const SkVector& nextPoint, const SkVector& nextNormal);
+    void addEdge(const SkVector& nextPoint, const SkVector& nextNormal);
+
+    SkScalar            fRadius;
+    SkColor             fUmbraColor;
+    SkColor             fPenumbraColor;
+
+    SkTDArray<SkPoint>  fPositions;
+    SkTDArray<SkColor>  fColors;
+    SkTDArray<uint16_t> fIndices;
+
+    int                 fPrevInnerIndex;
+    SkPoint             fPrevPoint;
+    SkVector            fPrevNormal;
+    int                 fFirstVertex;
+    SkPoint             fFirstPoint;
+    SkVector            fFirstNormal;
+    SkScalar            fDirection;
+
+    SkPoint             fCentroid;
+    SkTDArray<SkPoint>  fClipPolygon;
+
+    // first three points
+    SkTDArray<SkPoint>  fInitPoints;
+    // temporary buffer
+    SkTDArray<SkPoint>  fPointBuffer;
+};
+
+#endif