Add optional sw generated path coverage mask caching

gm/pathmaskcache.cpp

Index: gm/pathmaskcache.cpp
diff --git a/gm/pathmaskcache.cpp b/gm/pathmaskcache.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..21397f077d9cc970003592cbcbf0207becedfa32
--- /dev/null
+++ b/gm/pathmaskcache.cpp
@@ -0,0 +1,117 @@
+/*
+ * 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"
+
+#if SK_SUPPORT_GPU
+
+#include "GrContext.h"
+#include "GrContextOptions.h"
+#include "SkPath.h"
+
+/** This tests the GPU backend's caching of path coverage masks */
+class PathMaskCache : public skiagm::GM {
+public:
+    PathMaskCache() {}
+
+protected:
+    SkString onShortName() override { return SkString("path_mask_cache"); }
+
+    SkISize onISize() override {
+        return SkISize::Make(650, 950);
+    }
+
+    void onDraw(SkCanvas* canvas) override {
+        static constexpr SkScalar kPad = 5.f;
+
+        SkPaint paint;
+        paint.setAntiAlias(true);
+        auto drawPathSet = [canvas] (const SkPath& path, const SkMatrix& m) {
+            SkPaint paint;
+            paint.setAntiAlias(true);
+            SkRect bounds = path.getBounds();
+            m.mapRect(&bounds);
+            bounds.roundOut();
+            canvas->save();
+                canvas->translate(-bounds.fLeft, -bounds.fTop);
+
+                canvas->save();
+                    canvas->concat(m);
+                    canvas->drawPath(path, paint);
+                canvas->restore();
+
+                // translate by integer
+                canvas->translate(bounds.width() + kPad, 0.f);
+                canvas->save();
+                    canvas->concat(m);
+                    canvas->drawPath(path, paint);
+                canvas->restore();
+
+                // translate by non-integer
+                canvas->translate(bounds.width() + kPad + 0.15f, 0.f);
+                canvas->save();
+                    canvas->concat(m);
+                    canvas->drawPath(path, paint);
+                canvas->restore();
+
+                // translate again so total translate fraction is almost identical to previous.
+                canvas->translate(bounds.width() + kPad + 0.002f, 0.f);
+                canvas->save();
+                    canvas->concat(m);
+                    canvas->drawPath(path, paint);
+                canvas->restore();
+            canvas->restore();
+            return bounds.fBottom + kPad;
+        };
+
+
+        SkTArray<SkPath> paths;
+        paths.push_back();
+        paths.back().moveTo(0.f, 0.f);
+        paths.back().lineTo(98.f, 100.f);
+        paths.back().lineTo(100.f, 100.f);
+        paths.back().conicTo(150.f, 50.f, 100.f, 0.f, 0.6f);
+        paths.back().conicTo(148.f, 50.f, 100.f, 100.f, 0.6f);
+        paths.back().conicTo(50.f, 30.f, 0.f, 100.f, 0.9f);
+
+        paths.push_back();
+        paths.back().addCircle(30.f, 30.f, 30.f);
+        paths.back().addRect(SkRect::MakeXYWH(45.f, 45.f, 50.f, 60.f));
+        paths.back().setFillType(SkPath::kEvenOdd_FillType);
+
+        canvas->translate(kPad, kPad);
+
+        for (const SkPath& path : paths) {
+            SkScalar ty = drawPathSet(path, SkMatrix::I());
+            canvas->translate(0, ty);
+
+            // Non-uniform scale.
+            SkMatrix s;
+            s.setScale(0.5f, 2.f);
+            ty = drawPathSet(path, s);
+            canvas->translate(0.f, ty);
+
+            // Rotation
+            SkMatrix r;
+            r.setRotate(60.f, path.getBounds().centerX(), path.getBounds().centerY());
+            ty = drawPathSet(path, r);
+            canvas->translate(0.f, ty);
+        }
+    }
+
+    void modifyGrContextOptions(GrContextOptions* options) override {
+        options->fForceSWPathMasks = true;
+        options->fAllowPathMaskCaching = true;
+    }
+
+private:
+    typedef GM INHERITED;
+};
+
+DEF_GM( return new PathMaskCache(); )
+
+#endif