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

R=robertphillips@google.com

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/26968006

git-svn-id: http://skia.googlecode.com/svn/trunk@11805 2bbb7eff-a529-9590-31e7-b0007b416f81

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;)
+
+}

gyp/gmslides.gypi

@@ -115,6 +115,7 @@
     '../gm/shadows.cpp',
     '../gm/shallowgradient.cpp',
     '../gm/simpleaaclip.cpp',
+    '../gm/skbug1719.cpp',
     '../gm/stringart.cpp',
     '../gm/spritebitmap.cpp',
     '../gm/srcmode.cpp',

src/gpu/SkGpuDevice.cpp

@@ -951,8 +951,17 @@ void SkGpuDevice::drawPath(const SkDraw& draw, const SkPath& origSrcPath,
                 GrTexture* filtered;
 
                 if (paint.getMaskFilter()->filterMaskGPU(mask.texture(), maskRect, &filtered, true)) {
+                    // filterMaskGPU gives us ownership of a ref to the result
                     SkAutoTUnref<GrTexture> atu(filtered);
 
+                    // If the scratch texture that we used as the filter src also holds the filter
+                    // result then we must detach so that this texture isn't recycled for a later
+                    // draw.
+                    if (filtered == mask.texture()) {
+                        mask.detach();
+                        filtered->unref(); // detach transfers GrAutoScratchTexture's ref to us.
+                    }
+
                     if (draw_mask(fContext, maskRect, &grPaint, filtered)) {
                         // This path is completely drawn
                         return;