Implement a computeFastBounds() traversal for SkImageFilter.

This allows for correct culling of primitives which have image filters applied.

R=reed@google.com
BUG=skia:

Review URL: https://codereview.chromium.org/137423005

git-svn-id: http://skia.googlecode.com/svn/trunk@13207 2bbb7eff-a529-9590-31e7-b0007b416f81

6 files changed, 56 insertions, 0 deletions

diff --git a/src/effects/SkBitmapSource.cpp b/src/effects/SkBitmapSource.cpp
index daf4fb08b3..4aab92fc66 100644
--- a/src/effects/SkBitmapSource.cpp
+++ b/src/effects/SkBitmapSource.cpp
@@ -78,3 +78,7 @@ bool SkBitmapSource::onFilterImage(Proxy* proxy, const SkBitmap&, const SkMatrix
     offset->fY = dstIRect.fTop;
     return true;
 }
+
+void SkBitmapSource::computeFastBounds(const SkRect&, SkRect* dst) const {
+    *dst = fDstRect;
+}
diff --git a/src/effects/SkBlurImageFilter.cpp b/src/effects/SkBlurImageFilter.cpp
index 3e60c9bb87..5d9a077d43 100644
--- a/src/effects/SkBlurImageFilter.cpp
+++ b/src/effects/SkBlurImageFilter.cpp
@@ -224,6 +224,17 @@ bool SkBlurImageFilter::onFilterImage(Proxy* proxy,
     return true;
 }
 
+
+void SkBlurImageFilter::computeFastBounds(const SkRect& src, SkRect* dst) const {
+    if (getInput(0)) {
+        getInput(0)->computeFastBounds(src, dst);
+    } else {
+        *dst = src;
+    }
+
+    dst->outset(SkScalarMul(fSigma.width(), SkIntToScalar(3)),
+                SkScalarMul(fSigma.height(), SkIntToScalar(3)));
+}
 bool SkBlurImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
                                        SkBitmap* result, SkIPoint* offset) {
 #if SK_SUPPORT_GPU
diff --git a/src/effects/SkDisplacementMapEffect.cpp b/src/effects/SkDisplacementMapEffect.cpp
index 6ad46badb9..fc8d3dda72 100644
--- a/src/effects/SkDisplacementMapEffect.cpp
+++ b/src/effects/SkDisplacementMapEffect.cpp
@@ -246,6 +246,14 @@ bool SkDisplacementMapEffect::onFilterImage(Proxy* proxy,
     return true;
 }
 
+void SkDisplacementMapEffect::computeFastBounds(const SkRect& src, SkRect* dst) const {
+    if (getColorInput()) {
+        getColorInput()->computeFastBounds(src, dst);
+    } else {
+        *dst = src;
+    }
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 #if SK_SUPPORT_GPU
diff --git a/src/effects/SkDropShadowImageFilter.cpp b/src/effects/SkDropShadowImageFilter.cpp
index 61093784fa..87dfa92f9b 100644
--- a/src/effects/SkDropShadowImageFilter.cpp
+++ b/src/effects/SkDropShadowImageFilter.cpp
@@ -95,3 +95,18 @@ bool SkDropShadowImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& source
     offset->fY = bounds.fTop;
     return true;
 }
+
+void SkDropShadowImageFilter::computeFastBounds(const SkRect& src, SkRect* dst) const {
+    if (getInput(0)) {
+        getInput(0)->computeFastBounds(src, dst);
+    } else {
+        *dst = src;
+    }
+
+    SkRect shadowBounds = *dst;
+    shadowBounds.offset(fDx, fDy);
+    shadowBounds.outset(SkScalarMul(fSigmaX, SkIntToScalar(3)),
+                        SkScalarMul(fSigmaY, SkIntToScalar(3)));
+    dst->join(shadowBounds);
+}
+
diff --git a/src/effects/SkMorphologyImageFilter.cpp b/src/effects/SkMorphologyImageFilter.cpp
index af45c0d3a1..5008ad1814 100644
--- a/src/effects/SkMorphologyImageFilter.cpp
+++ b/src/effects/SkMorphologyImageFilter.cpp
@@ -239,6 +239,15 @@ bool SkDilateImageFilter::onFilterImage(Proxy* proxy,
     return this->filterImageGeneric(dilateXProc, dilateYProc, proxy, source, ctm, dst, offset);
 }
 
+void SkMorphologyImageFilter::computeFastBounds(const SkRect& src, SkRect* dst) const {
+    if (getInput(0)) {
+        getInput(0)->computeFastBounds(src, dst);
+    } else {
+        *dst = src;
+    }
+    dst->outset(SkIntToScalar(fRadius.width()), SkIntToScalar(fRadius.height()));
+}
+
 #if SK_SUPPORT_GPU
 
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/src/effects/SkOffsetImageFilter.cpp b/src/effects/SkOffsetImageFilter.cpp
index 61f68f7afe..e69cf411e3 100644
--- a/src/effects/SkOffsetImageFilter.cpp
+++ b/src/effects/SkOffsetImageFilter.cpp
@@ -65,6 +65,15 @@ bool SkOffsetImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& source,
     return true;
 }
 
+void SkOffsetImageFilter::computeFastBounds(const SkRect& src, SkRect* dst) const {
+    if (getInput(0)) {
+        getInput(0)->computeFastBounds(src, dst);
+    } else {
+        *dst = src;
+    }
+    dst->offset(fOffset.fX, fOffset.fY);
+}
+
 bool SkOffsetImageFilter::onFilterBounds(const SkIRect& src, const SkMatrix& ctm,
                                          SkIRect* dst) {
     SkVector vec;