Added classes SkPatch and SkPatchMesh which help encapsulate and generalize this new primitive. The functionality and responsability of each class is better explained in the comments of the files.

Each patch defines a method genMesh that produces the geometry to draw. To do this they receive a SkPatchMesh object which they need to initialize in order to set up how the data is going to be formatted. Later they call function like setColor or pointAt to set the values at a specific index, the SkMeshPatch object handles the indices based on the format and makes it transparent to the client.

Added a slide to sample app to show how to set up this classes and how they interact.

BUG=skia:
R=jvanverth@google.com, egdaniel@google.com, bsalomon@google.com

Author: dandov@google.com

Review URL: https://codereview.chromium.org/405163003

1 files changed, 114 insertions, 0 deletions

diff --git a/gm/patch.cpp b/gm/patch.cpp
new file mode 100644
index 0000000000..eb99944c0b
--- /dev/null
+++ b/gm/patch.cpp
@@ -0,0 +1,114 @@
+
+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+// This test only works with the GPU backend.
+
+#include "gm.h"
+
+#if SK_SUPPORT_GPU
+
+#include "GrContext.h"
+#include "GrTest.h"
+
+#include "SkPatch.h"
+
+namespace skiagm {
+/**
+ * This GM draws a SkPatch.
+ */
+class SkPatchGM : public GM {
+public:
+    SkPatchGM() {
+        this->setBGColor(0xFFFFFFFF);
+    }
+
+protected:
+    virtual SkString onShortName() SK_OVERRIDE {
+        return SkString("patch_primitive");
+    }
+
+    virtual SkISize onISize() SK_OVERRIDE {
+        return SkISize::Make(800, 800);
+    }
+
+    virtual uint32_t onGetFlags() const SK_OVERRIDE {
+        return kGPUOnly_Flag;
+    }
+
+
+    virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+
+        SkPaint paint;
+        SkColor colors[4] = {
+            SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE, SK_ColorCYAN
+        };
+        SkPoint points[] = {
+            {100,100},{130,50},{500,70}, {650,60},
+            {350,125},{490,555},{600,700},
+            {515,595},{140,550},{110,590},
+            {125,400},{70,150}
+            
+        };
+
+        SkPatch coons(points, colors);
+        
+        SkPatch::VertexData data;
+        coons.getVertexData(&data, 10);
+
+        canvas->drawVertices(SkCanvas::kTriangles_VertexMode,data.fVertexCount,
+            data.fPoints, data.fTexCoords, data.fColors, NULL, data.fIndices,
+            data.fIndexCount, paint);
+
+        //draw control points
+        SkPoint bottom[4];
+        coons.getBottomPoints(bottom);
+        SkPoint top[4];
+        coons.getTopPoints(top);
+        SkPoint left[4];
+        coons.getLeftPoints(left);
+        SkPoint right[4];
+        coons.getRightPoints(right);
+
+        SkPoint corners[4] = { bottom[0], bottom[3], top[0], top[3] };
+        canvas->drawPoints(SkCanvas::kLines_PointMode, 4, bottom, paint);
+        canvas->drawPoints(SkCanvas::kLines_PointMode, 2, bottom+1, paint);
+        canvas->drawPoints(SkCanvas::kLines_PointMode, 4, top, paint);
+        canvas->drawPoints(SkCanvas::kLines_PointMode, 4, left, paint);
+        canvas->drawPoints(SkCanvas::kLines_PointMode, 4, right, paint);
+
+        canvas->drawPoints(SkCanvas::kLines_PointMode, 2, top+1, paint);
+        canvas->drawPoints(SkCanvas::kLines_PointMode, 2, left+1, paint);
+        canvas->drawPoints(SkCanvas::kLines_PointMode, 2, right+1, paint);
+
+        paint.setStrokeWidth(10);
+
+        paint.setColor(SK_ColorRED);
+        canvas->drawPoints(SkCanvas::kPoints_PointMode, 4, corners, paint);
+
+        paint.setColor(SK_ColorBLUE);
+        canvas->drawPoints(SkCanvas::kPoints_PointMode, 2, bottom+1, paint);
+
+        paint.setColor(SK_ColorCYAN);
+        canvas->drawPoints(SkCanvas::kPoints_PointMode, 2, top+1, paint);
+
+        paint.setColor(SK_ColorYELLOW);
+        canvas->drawPoints(SkCanvas::kPoints_PointMode, 2, left+1, paint);
+
+        paint.setColor(SK_ColorGREEN);
+        canvas->drawPoints(SkCanvas::kPoints_PointMode, 2, right+1, paint);
+    }
+
+private:
+    typedef GM INHERITED;
+};
+
+DEF_GM( return SkNEW(SkPatchGM); )
+
+}
+
+#endif