Fix transformed stroke width in GrAALinearizingConvexPathRenderer.

gm/scaledstrokes.cpp

Index: gm/scaledstrokes.cpp
diff --git a/gm/scaledstrokes.cpp b/gm/scaledstrokes.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..2398113a3b29f202cf5ceb8670719d221849a6dd
--- /dev/null
+++ b/gm/scaledstrokes.cpp
@@ -0,0 +1,84 @@
+/*
+ * Copyright 2015 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 "SkCanvas.h"
+#include "SkRRect.h"
+#include "SkPath.h"
+
+class ScaledStrokesGM : public skiagm::GM {
+public:
+    ScaledStrokesGM() {}
+
+protected:
+
+    SkString onShortName() override {
+        return SkString("scaledstrokes");
+    }
+
+    SkISize onISize() override {
+        return SkISize::Make(640, 320);
+    }
+
+    void drawPath(int size, SkCanvas* canvas, SkPaint paint) {

[egdaniel, 2015/08/18 16:25:28]

make this draw_path

+        float c = 0.551915024494 * size;
+        SkPath path;
+        path.moveTo(0, size);
+        path.cubicTo(c, size, size, c, size, 0);
+        path.cubicTo(size, -c, c, -size, 0, -size);
+        path.cubicTo(-c, -size, -size, -c, -size, 0);
+        path.cubicTo(-size, c, -c, size, 0, size);
+        canvas->drawPath(path, paint);
+    }
+
+    void onDraw(SkCanvas* canvas) override {
+        SkPaint paint;
+        SkPath path;
+        paint.setStyle(SkPaint::Style::kStroke_Style);
+        canvas->translate(5, 5);
+        const SkScalar size = 60;
+        for (int i = 0; i < 2; i++) {
+            paint.setAntiAlias(i == 1);
+            canvas->save();
+            for (int j = 0; j < 4; j++) {
+                SkScalar scale = 4 - j;
+                paint.setStrokeWidth(4 / scale);
+                canvas->save();
+                canvas->translate(size / 2, size / 2);
+                canvas->scale(scale, scale);
+                drawPath(size / 2 / scale, canvas, paint);
+                canvas->restore();
+
+                canvas->save();
+                canvas->translate(size / 2, 80 + size / 2);
+                canvas->scale(scale, scale);
+                canvas->drawCircle(0, 0, size / 2 / scale, paint);
+                canvas->restore();
+
+                canvas->save();
+                canvas->translate(0, 160);
+                canvas->scale(scale, scale);
+                canvas->drawRect(SkRect::MakeXYWH(0, 0, size / scale, size / scale), paint);
+                canvas->restore();
+
+                canvas->save();
+                canvas->translate(0, 240);
+                canvas->scale(scale, scale);
+                canvas->drawLine(0, 0, size / scale, size / scale, paint);
+                canvas->restore();
+
+                canvas->translate(80, 0);
+            }
+        }
+
+    }
+
+private:
+    typedef GM INHERITED;
+};
+
+DEF_GM( return new ScaledStrokesGM; )