Add fast path in arcTo and addArc for 0==sweep && 0|360==sweepAngle

http://codereview.appspot.com/6463071/



git-svn-id: http://skia.googlecode.com/svn/trunk@5190 2bbb7eff-a529-9590-31e7-b0007b416f81

2 files changed, 65 insertions, 0 deletions

diff --git a/bench/PathBench.cpp b/bench/PathBench.cpp
index a8b31e2777..61014e832e 100644
--- a/bench/PathBench.cpp
+++ b/bench/PathBench.cpp
@@ -617,6 +617,57 @@ private:
     typedef RandomPathBench INHERITED;
 };
 
+
+class CirclesBench : public SkBenchmark {
+protected:
+    SkString            fName;
+
+    enum {
+        N = SkBENCHLOOP(100)
+    };
+public:
+    CirclesBench(void* param) : INHERITED(param) {
+        fName.printf("circles");
+    }
+
+protected:
+    virtual const char* onGetName() SK_OVERRIDE {
+        return fName.c_str();
+    }
+
+    virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+        SkPaint paint;
+
+        paint.setColor(SK_ColorBLACK);
+        paint.setAntiAlias(true);
+
+        SkRandom rand;
+
+        SkRect r;
+
+        for (int i = 0; i < 5000; ++i) {
+            SkScalar radius = rand.nextUScalar1() * 3;
+            r.fLeft = rand.nextUScalar1() * 300;
+            r.fTop =  rand.nextUScalar1() * 300;
+            r.fRight =  r.fLeft + 2 * radius;
+            r.fBottom = r.fTop + 2 * radius;
+
+            SkPath temp;
+
+            // mimic how Chrome does circles
+            temp.arcTo(r, 0, 0, false);
+            temp.addOval(r, SkPath::kCCW_Direction);
+            temp.arcTo(r, 360, 0, true);
+            temp.close();
+        
+            canvas->drawPath(temp, paint);
+        }
+    }
+
+private:
+    typedef SkBenchmark INHERITED;
+};
+
 static SkBenchmark* FactT00(void* p) { return new TrianglePathBench(p, FLAGS00); }
 static SkBenchmark* FactT01(void* p) { return new TrianglePathBench(p, FLAGS01); }
 static SkBenchmark* FactT10(void* p) { return new TrianglePathBench(p, FLAGS10); }
@@ -712,3 +763,7 @@ static BenchRegistry gRegAddMatrix(FactAddMatrix);
 static BenchRegistry gRegPathTo(FactPathTo);
 static BenchRegistry gRegReverseAdd(FactReverseAdd);
 static BenchRegistry gRegReverseTo(FactReverseTo);
+
+static SkBenchmark* CirclesTest(void* p) { return new CirclesBench(p); }
+static BenchRegistry gRegCirclesTest(CirclesTest);
+
diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp
index 674ba980f6..8184345a5b 100644
--- a/src/core/SkPath.cpp
+++ b/src/core/SkPath.cpp
@@ -933,6 +933,16 @@ void SkPath::addCircle(SkScalar x, SkScalar y, SkScalar r, Direction dir) {
 static int build_arc_points(const SkRect& oval, SkScalar startAngle,
                             SkScalar sweepAngle,
                             SkPoint pts[kSkBuildQuadArcStorage]) {
+
+    if (0 == sweepAngle && 
+        (0 == startAngle || SkIntToScalar(360) == startAngle)) {
+        // Chrome uses this path to move into and out of ovals. If not
+        // treated as a special case the moves can distort the oval's
+        // bounding box (and break the circle special case).
+        pts[0].set(oval.fRight, oval.centerY());
+        return 1;
+    }
+
     SkVector start, stop;
 
     start.fY = SkScalarSinCos(SkDegreesToRadians(startAngle), &start.fX);