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

If both textures and vertex-colors are NULL, drawVertices should stroke hairlines with the paint's color.
This behavior is a useful debugging mode to visualize the mesh.

BUG=skia:2266
R=bsalomon@google.com, reed@google.com

Author: yunchao.he@intel.com

Review URL: https://codereview.chromium.org/189963004

git-svn-id: http://skia.googlecode.com/svn/trunk@14985 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 106 insertions, 0 deletions

diff --git a/src/core/SkVertState.cpp b/src/core/SkVertState.cpp
new file mode 100644
index 0000000000..f23b1083fe
--- /dev/null
+++ b/src/core/SkVertState.cpp
@@ -0,0 +1,106 @@
+/*
+ * 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;
+    }
+}