Fix the rendering error of SkDraw::drawVertices in gpu path for solid color

src/core/SkVertState.cpp

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkVertState.h"
+
+bool VertState::Triangles(VertState* state) {
+    int index = state->fCurrIndex;
+    if (index + 3 > state->fCount) {
+        return false;
+    }
+    state->f0 = index + 0;
+    state->f1 = index + 1;
+    state->f2 = index + 2;
+    state->fCurrIndex = index + 3;
+    return true;
+}
+
+bool VertState::TrianglesX(VertState* state) {
+    const uint16_t* indices = state->fIndices;
+    int index = state->fCurrIndex;
+    if (index + 3 > state->fCount) {
+        return false;
+    }
+    state->f0 = indices[index + 0];
+    state->f1 = indices[index + 1];
+    state->f2 = indices[index + 2];
+    state->fCurrIndex = index + 3;
+    return true;
+}
+
+bool VertState::TriangleStrip(VertState* state) {
+    int index = state->fCurrIndex;
+    if (index + 3 > state->fCount) {
+        return false;
+    }
+    state->f2 = index + 2;
+    if (index & 1) {
+        state->f0 = index + 1;
+        state->f1 = index + 0;
+    } else {
+        state->f0 = index + 0;
+        state->f1 = index + 1;
+    }
+    state->fCurrIndex = index + 1;
+    return true;
+}
+
+bool VertState::TriangleStripX(VertState* state) {
+    const uint16_t* indices = state->fIndices;
+    int index = state->fCurrIndex;
+    if (index + 3 > state->fCount) {
+        return false;
+    }
+    state->f2 = indices[index + 2];
+    if (index & 1) {
+        state->f0 = indices[index + 1];
+        state->f1 = indices[index + 0];
+    } else {
+        state->f0 = indices[index + 0];
+        state->f1 = indices[index + 1];
+    }
+    state->fCurrIndex = index + 1;
+    return true;
+}
+
+bool VertState::TriangleFan(VertState* state) {
+    int index = state->fCurrIndex;
+    if (index + 3 > state->fCount) {
+        return false;
+    }
+    state->f0 = 0;
+    state->f1 = index + 1;
+    state->f2 = index + 2;
+    state->fCurrIndex = index + 1;
+    return true;
+}
+
+bool VertState::TriangleFanX(VertState* state) {
+    const uint16_t* indices = state->fIndices;
+    int index = state->fCurrIndex;
+    if (index + 3 > state->fCount) {
+        return false;
+    }
+    state->f0 = indices[0];
+    state->f1 = indices[index + 1];
+    state->f2 = indices[index + 2];
+    state->fCurrIndex = index + 1;
+    return true;
+}
+
+VertState::Proc VertState::chooseProc(SkCanvas::VertexMode mode) {
+    switch (mode) {
+        case SkCanvas::kTriangles_VertexMode:
+            return fIndices ? TrianglesX : Triangles;
+        case SkCanvas::kTriangleStrip_VertexMode:
+            return fIndices ? TriangleStripX : TriangleStrip;
+        case SkCanvas::kTriangleFan_VertexMode:
+            return fIndices ? TriangleFanX : TriangleFan;
+        default:
+            return NULL;
+    }
+}