Fix quickReject computation for blurs

src/effects/SkBlurMaskFilter.cpp

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBlurMaskFilter.h"
 #include "SkBlurMask.h"
@@ skipping 42 matching lines @@
                                            const SkIRect& clipBounds,
                                            NinePatch*) const SK_OVERRIDE;
 
     bool filterRectMask(SkMask* dstM, const SkRect& r, const SkMatrix& matrix,
                         SkIPoint* margin, SkMask::CreateMode createMode) const;
 
 private:
     // To avoid unseemly allocation requests (esp. for finite platforms like
     // handset) we limit the radius so something manageable. (as opposed to
     // a request like 10,000)
-    static const SkScalar kMAX_RADIUS;
+    static const SkScalar kMAX_BLUR_RADIUS;
     // This constant approximates the scaling done in the software path's
     // "high quality" mode, in SkBlurMask::Blur() (1 / sqrt(3)).
     // IMHO, it actually should be 1:  we blur "less" than we should do
     // according to the CSS and canvas specs, simply because Safari does the same.
     // Firefox used to do the same too, until 4.0 where they fixed it.  So at some
     // point we should probably get rid of these scaling constants and rebaseline
     // all the blur tests.
     static const SkScalar kBLUR_SIGMA_SCALE;
 
     SkScalar                    fRadius;
     SkBlurMaskFilter::BlurStyle fBlurStyle;
     uint32_t                    fBlurFlags;
 
     SkBlurMaskFilterImpl(SkFlattenableReadBuffer&);
     virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
 #if SK_SUPPORT_GPU
     SkScalar computeXformedRadius(const SkMatrix& ctm) const {
         bool ignoreTransform = SkToBool(fBlurFlags & SkBlurMaskFilter::kIgnoreTransform_BlurFlag);
 
         SkScalar xformedRadius = ignoreTransform ? fRadius
                                                  : ctm.mapRadius(fRadius);
-        return SkMinScalar(xformedRadius, kMAX_RADIUS);
+        return SkMinScalar(xformedRadius, kMAX_BLUR_RADIUS);
     }
 #endif
 
     typedef SkMaskFilter INHERITED;
 };
 
-const SkScalar SkBlurMaskFilterImpl::kMAX_RADIUS = SkIntToScalar(128);
-const SkScalar SkBlurMaskFilterImpl::kBLUR_SIGMA_SCALE = 0.6f;
+const SkScalar SkBlurMaskFilterImpl::kMAX_BLUR_RADIUS = SkIntToScalar(128);
+const SkScalar SkBlurMaskFilterImpl::kBLUR_SIGMA_SCALE = SkFloatToScalar(0.6f);
 
 SkMaskFilter* SkBlurMaskFilter::Create(SkScalar radius,
                                        SkBlurMaskFilter::BlurStyle style,
                                        uint32_t flags) {
     // use !(radius > 0) instead of radius <= 0 to reject NaN values
     if (!(radius > 0) || (unsigned)style >= SkBlurMaskFilter::kBlurStyleCount
         || flags > SkBlurMaskFilter::kAll_BlurFlag) {
         return NULL;
     }
 
@@ skipping 28 matching lines @@
 bool SkBlurMaskFilterImpl::filterMask(SkMask* dst, const SkMask& src,
                                       const SkMatrix& matrix,
                                       SkIPoint* margin) const{
     SkScalar radius;
     if (fBlurFlags & SkBlurMaskFilter::kIgnoreTransform_BlurFlag) {
         radius = fRadius;
     } else {
         radius = matrix.mapRadius(fRadius);
     }
 
-    radius = SkMinScalar(radius, kMAX_RADIUS);
+    radius = SkMinScalar(radius, kMAX_BLUR_RADIUS);
     SkBlurMask::Quality blurQuality =
         (fBlurFlags & SkBlurMaskFilter::kHighQuality_BlurFlag) ?
             SkBlurMask::kHigh_Quality : SkBlurMask::kLow_Quality;
 
     return SkBlurMask::Blur(dst, src, radius, (SkBlurMask::Style)fBlurStyle,
                             blurQuality, margin);
 }
 
 bool SkBlurMaskFilterImpl::filterRectMask(SkMask* dst, const SkRect& r,
                                           const SkMatrix& matrix,
                                           SkIPoint* margin, SkMask::CreateMode createMode) const{
     SkScalar radius;
     if (fBlurFlags & SkBlurMaskFilter::kIgnoreTransform_BlurFlag) {
         radius = fRadius;
     } else {
         radius = matrix.mapRadius(fRadius);
     }
 
-    radius = SkMinScalar(radius, kMAX_RADIUS);
+    radius = SkMinScalar(radius, kMAX_BLUR_RADIUS);
 
     return SkBlurMask::BlurRect(dst, r, radius, (SkBlurMask::Style)fBlurStyle,
                                 margin, createMode);
 }
 
 #include "SkCanvas.h"
 
 static bool drawRectsIntoMask(const SkRect rects[], int count, SkMask* mask) {
     rects[0].roundOut(&mask->fBounds);
     mask->fRowBytes = SkAlign4(mask->fBounds.width());
@@ skipping 155 matching lines @@
         }
     }
     patch->fMask.fBounds.offsetTo(0, 0);
     patch->fOuterRect = dstM.fBounds;
     patch->fCenter = center;
     return kTrue_FilterReturn;
 }
 
 void SkBlurMaskFilterImpl::computeFastBounds(const SkRect& src,
                                              SkRect* dst) const {
-    dst->set(src.fLeft - fRadius, src.fTop - fRadius,
-             src.fRight + fRadius, src.fBottom + fRadius);
+    SkScalar gpuPad, rasterPad;
+
+    {
+        // GPU path
+        SkScalar sigma = SkScalarMul(fRadius, kBLUR_SIGMA_SCALE);
+        gpuPad = sigma * 3.0f;
+    }
+
+    {
+        // raster path
+        SkScalar radius = SkScalarMul(fRadius, SkBlurMask::kBlurRadiusFudgeFactor);
+ 
+        radius = (radius + .5f) * 2.f;
+
+        rasterPad = SkIntToScalar(SkScalarRoundToInt(radius * 3)/2);
+    }
+
+    SkScalar pad = SkMaxScalar(gpuPad, rasterPad);
+
+    dst->set(src.fLeft  - pad, src.fTop    - pad,
+             src.fRight + pad, src.fBottom + pad);
 }
 
 SkBlurMaskFilterImpl::SkBlurMaskFilterImpl(SkFlattenableReadBuffer& buffer)
         : SkMaskFilter(buffer) {
     fRadius = buffer.readScalar();
     fBlurStyle = (SkBlurMaskFilter::BlurStyle)buffer.readInt();
     fBlurFlags = buffer.readUInt() & SkBlurMaskFilter::kAll_BlurFlag;
     SkASSERT(fRadius >= 0);
     SkASSERT((unsigned)fBlurStyle < SkBlurMaskFilter::kBlurStyleCount);
 }
@@ skipping 122 matching lines @@
     } else {
         str->append("None");
     }
     str->append("))");
 }
 #endif
 
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkBlurMaskFilter)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkBlurMaskFilterImpl)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END