Fix quickReject computation for blurs
https://codereview.chromium.org/17035007/
git-svn-id: http://skia.googlecode.com/svn/trunk@10428 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/blurquickreject.cpp b/gm/blurquickreject.cpp
new file mode 100644
index 0000000..b1406f3
--- /dev/null
+++ b/gm/blurquickreject.cpp
@@ -0,0 +1,82 @@
+/*
+ * 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 "SkCanvas.h"
+#include "SkBlurMaskFilter.h"
+
+// This GM tests out the quick reject bounds of the blur mask filter. It draws
+// four blurred rects around a central clip. The blurred rect geometry outset
+// by the blur radius does not overlap the clip rect so, if the blur clipping
+// just uses the radius, they will be clipped out (and the result will differ
+// from the result if quick reject were disabled. If the blur clipping uses
+// the correct 3 sigma bound then the images with and without quick rejecting
+// will be the same.
+class BlurQuickRejectGM : public skiagm::GM {
+public:
+ BlurQuickRejectGM() {}
+
+protected:
+ virtual SkString onShortName() SK_OVERRIDE {
+ return SkString("blurquickreject");
+ }
+
+ virtual SkISize onISize() SK_OVERRIDE {
+ return SkISize::Make(kWidth, kHeight);
+ }
+
+ virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+ static const SkScalar kBlurRadius = SkIntToScalar(20);
+ static const SkScalar kBoxSize = SkIntToScalar(100);
+
+ SkRect clipRect = SkRect::MakeXYWH(0, 0, kBoxSize, kBoxSize);
+ SkRect blurRects[] = {
+ { -kBoxSize - (kBlurRadius+1), 0, -(kBlurRadius+1), kBoxSize },
+ { 0, -kBoxSize - (kBlurRadius+1), kBoxSize, -(kBlurRadius+1) },
+ { kBoxSize+kBlurRadius+1, 0, 2*kBoxSize+kBlurRadius+1, kBoxSize },
+ { 0, kBoxSize+kBlurRadius+1, kBoxSize, 2*kBoxSize+kBlurRadius+1 }
+ };
+ SkColor colors[] = {
+ SK_ColorRED,
+ SK_ColorGREEN,
+ SK_ColorBLUE,
+ SK_ColorYELLOW,
+ };
+ SkASSERT(SK_ARRAY_COUNT(colors) == SK_ARRAY_COUNT(blurRects));
+
+ SkPaint hairlinePaint;
+ hairlinePaint.setStyle(SkPaint::kStroke_Style);
+ hairlinePaint.setColor(SK_ColorWHITE);
+ hairlinePaint.setStrokeWidth(0);
+
+ SkPaint blurPaint;
+ blurPaint.setFilterBitmap(true);
+ SkMaskFilter* mf = SkBlurMaskFilter::Create(kBlurRadius,
+ SkBlurMaskFilter::kNormal_BlurStyle);
+ blurPaint.setMaskFilter(mf)->unref();
+
+ canvas->clear(SK_ColorBLACK);
+ canvas->save();
+ canvas->translate(kBoxSize, kBoxSize);
+ canvas->drawRect(clipRect, hairlinePaint);
+ canvas->clipRect(clipRect);
+ for (int i = 0; i < SK_ARRAY_COUNT(blurRects); ++i) {
+ blurPaint.setColor(colors[i]);
+ canvas->drawRect(blurRects[i], blurPaint);
+ canvas->drawRect(blurRects[i], hairlinePaint);
+ }
+ canvas->restore();
+ }
+
+private:
+ static const int kWidth = 300;
+ static const int kHeight = 300;
+
+ typedef GM INHERITED;
+};
+
+DEF_GM( return new BlurQuickRejectGM(); )