detach blur result texture when it is the same texture used to render path mask

gm/skbug1719.cpp

Index: gm/skbug1719.cpp
diff --git a/gm/skbug1719.cpp b/gm/skbug1719.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..01bb844a872383e3e5393be3416fbac980d1398d
--- /dev/null
+++ b/gm/skbug1719.cpp
@@ -0,0 +1,102 @@
+/*
+ * Copyright 2013 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 "SkColorFilter.h"
+#include "SkBlurMaskFilter.h"
+
+namespace skiagm {
+
+/**
+ * This test exercises bug 1719. An anti-aliased blurred path is rendered through a soft clip. On
+ * the GPU a scratch texture was used to hold the original path mask as well as the blurred path
+ * result. The same texture is then incorrectly used to generate the soft clip mask for the draw.
+ * Thus the same texture is used for both the blur mask and soft mask in a single draw.
+ *
+ * The correct image should look like a thin stroked round rect.
+ */
+class SkBug1719GM : public GM {
+public:
+    SkBug1719GM() {}
+
+protected:
+    virtual SkString onShortName() SK_OVERRIDE {
+        return SkString("skbug1719");
+    }
+
+    virtual SkISize onISize() SK_OVERRIDE {
+        return make_isize(300, 100);
+    }
+
+    virtual void onDrawBackground(SkCanvas* canvas) SK_OVERRIDE {
+        SkPaint bgPaint;
+        bgPaint.setColor(0xFF303030);
+        canvas->drawPaint(bgPaint);
+    }
+
+    virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+        canvas->translate(SkIntToScalar(-800), SkIntToScalar(-650));
+
+        // The data is lifted from an SKP that exhibited the bug.
+
+        // This is a round rect.
+        SkPath clipPath;
+        clipPath.moveTo(832.f, 654.f);
+        clipPath.lineTo(1034.f, 654.f);
+        clipPath.cubicTo(1038.4183f, 654.f, 1042.f, 657.58173f, 1042.f, 662.f);
+        clipPath.lineTo(1042.f, 724.f);
+        clipPath.cubicTo(1042.f, 728.41827f, 1038.4183f, 732.f, 1034.f, 732.f);
+        clipPath.lineTo(832.f, 732.f);
+        clipPath.cubicTo(827.58173f, 732.f, 824.f, 728.41827f, 824.f, 724.f);
+        clipPath.lineTo(824.f, 662.f);
+        clipPath.cubicTo(824.f, 657.58173f, 827.58173f, 654.f, 832.f, 654.f);
+        clipPath.close();
+
+        // This is a round rect nested inside a rect.
+        SkPath drawPath;
+        drawPath.moveTo(823.f, 653.f);
+        drawPath.lineTo(1043.f, 653.f);
+        drawPath.lineTo(1043.f, 733.f);
+        drawPath.lineTo(823.f, 733.f);
+        drawPath.lineTo(823.f, 653.f);
+        drawPath.close();
+        drawPath.moveTo(832.f, 654.f);
+        drawPath.lineTo(1034.f, 654.f);
+        drawPath.cubicTo(1038.4183f, 654.f, 1042.f, 657.58173f, 1042.f, 662.f);
+        drawPath.lineTo(1042.f, 724.f);
+        drawPath.cubicTo(1042.f, 728.41827f, 1038.4183f, 732.f, 1034.f, 732.f);
+        drawPath.lineTo(832.f, 732.f);
+        drawPath.cubicTo(827.58173f, 732.f, 824.f, 728.41827f, 824.f, 724.f);
+        drawPath.lineTo(824.f, 662.f);
+        drawPath.cubicTo(824.f, 657.58173f, 827.58173f, 654.f, 832.f, 654.f);
+        drawPath.close();
+        drawPath.setFillType(SkPath::kEvenOdd_FillType);
+
+        SkPaint paint;
+        paint.setAntiAlias(true);
+        paint.setColor(0xFF000000);
+        paint.setMaskFilter(
+            SkBlurMaskFilter::Create(SkBlurMaskFilter::kNormal_BlurStyle,
+                                     0.78867501f,
+                                     SkBlurMaskFilter::kHighQuality_BlurFlag))->unref();
+        paint.setColorFilter(
+            SkColorFilter::CreateModeFilter(0xBFFFFFFF, SkXfermode::kSrcIn_Mode))->unref();
+
+        canvas->clipPath(clipPath, SkRegion::kIntersect_Op, true);
+        canvas->drawPath(drawPath, paint);
+    }
+
+private:
+
+    typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_GM(return new SkBug1719GM;)
+
+}