Convert drawPaint to drawRRect in simple cases

gm/rrectclipdrawpaint.cpp

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gm.h"
+#include "SkPath.h"
+#include "SkGradientShader.h"
+
+// Exercises code in GrDrawContext that attempts to replace a rrect clip/draw paint with draw rrect.
+DEF_SIMPLE_GM(rrect_clip_draw_paint, canvas, 256, 256) {
+    SkRRect rrect = SkRRect::MakeRectXY(SkRect::MakeXYWH(10.f, 10.f, 236.f, 236.f), 30.f, 40.f);
+
+    SkPaint p;
+    p.setColor(SK_ColorRED);
+
+    SkMatrix zoomOut;
+    zoomOut.setScale(0.7f, 0.7f, 128.f, 128.f);
+
+    const SkRect layerRect = SkRect::MakeWH(256.f, 256.f);
+    canvas->saveLayer(layerRect, nullptr);
+    canvas->clipRRect(rrect, SkRegion::kIntersect_Op, true);
+    canvas->drawPaint(p);
+    canvas->restore();
+
+    canvas->concat(zoomOut);
+    p.setColor(SK_ColorBLUE);
+    canvas->saveLayer(layerRect, nullptr);
+    canvas->clipRRect(rrect, SkRegion::kIntersect_Op, false);
+    canvas->drawPaint(p);
+    canvas->restore();
+
+    static constexpr SkPoint kPts[] = {{0.f, 0.f}, {256.f, 256.f}};
+    static constexpr SkColor kColors1[] = {SK_ColorCYAN, SK_ColorGREEN};
+    p.setShader(SkGradientShader::MakeLinear(kPts, kColors1, nullptr, 2,
+                                             SkShader::kClamp_TileMode));
+    canvas->concat(zoomOut);
+    canvas->saveLayer(layerRect, nullptr);
+    canvas->clipRRect(rrect, SkRegion::kIntersect_Op, true);
+    canvas->drawPaint(p);
+    canvas->restore();
+
+    static constexpr SkColor kColors2[] = {SK_ColorMAGENTA, SK_ColorGRAY};
+    p.setShader(SkGradientShader::MakeRadial({128.f, 128.f}, 128.f, kColors2, nullptr, 2,
+                                             SkShader::kClamp_TileMode));
+    canvas->concat(zoomOut);
+    canvas->saveLayer(layerRect, nullptr);
+    canvas->clipRRect(rrect, SkRegion::kIntersect_Op, false);
+    canvas->drawPaint(p);
+    canvas->restore();
+}