first attempt to plumb fast blur code into skia mask filter

src/effects/SkBlurMask.cpp

Index: src/effects/SkBlurMask.cpp
diff --git a/src/effects/SkBlurMask.cpp b/src/effects/SkBlurMask.cpp
index 413e8c0690311238dbc17b02f6568b1a0c732c61..5afda47a16e2f24c0c8f9e81ac72192c6b0b2391 100644
--- a/src/effects/SkBlurMask.cpp
+++ b/src/effects/SkBlurMask.cpp
@@ -1185,6 +1185,15 @@ static float gaussianIntegral(float x) {
     return 0.4375f + (-x3 / 6.0f - 3.0f * x2 * 0.25f - 1.125f * x);
 }
 
+/*  Compute the size of the array allocated for the
+    profile.

[bungeman-skia, 2013/03/11 20:03:36]

Nit: this was wrapped before, but doesn't need to be now. Nice to have it all on
one line.

+*/
+
+static int compute_profile_size(SkScalar radius) {
+    return SkScalarRoundToInt(radius * 3);
+    
+} 
+
 /*
     compute_profile allocates and fills in an array of floating
     point values between 0 and 255 for the profile signature of
@@ -1193,15 +1202,14 @@ static float gaussianIntegral(float x) {
     all the time, we actually fill in the profile pre-inverted
     (already done 255-x).
 
-    The function returns the size of the array allocated for the
-    profile.  It's the responsibility of the caller to delete the
+    It's the responsibility of the caller to delete the
     memory returned in profile_out.
 */
 
-static int compute_profile(SkScalar radius, unsigned int **profile_out) {
-    int size = SkScalarRoundToInt(radius * 3);
+static void compute_profile(SkScalar radius, unsigned int **profile_out) {
+    int size = compute_profile_size(radius);
+    
     int center = size >> 1;
-
     unsigned int *profile = SkNEW_ARRAY(unsigned int, size);
 
     float invr = 1.f/radius;
@@ -1214,7 +1222,6 @@ static int compute_profile(SkScalar radius, unsigned int **profile_out) {
     }
 
     *profile_out = profile;
-    return size;
 }
 
 // TODO MAYBE: Maintain a profile cache to avoid recomputing this for
@@ -1236,19 +1243,16 @@ static inline unsigned int profile_lookup( unsigned int *profile, int loc, int b
 
 bool SkBlurMask::BlurRect(SkMask *dst, const SkRect &src,
                           SkScalar provided_radius, Style style,
-                          SkIPoint *margin) {
+                          SkIPoint *margin, bool perform_blur) {

[bungeman-skia, 2013/03/11 20:03:36]

Maybe use SkMask::CreateMode to avoid awkward 'do what I want' and 'what do I
name this' debates?

     int profile_size;
-    unsigned int *profile;
 
-    float radius = SkScalarToFloat( SkScalarMul( provided_radius, kBlurRadiusFudgeFactor ) );
+    float radius = SkScalarToFloat(SkScalarMul(provided_radius, kBlurRadiusFudgeFactor));
 
     // adjust blur radius to match interpretation from boxfilter code
-    radius = (radius + .5f) *2.f;
-
-    profile_size = compute_profile( radius, &profile );
-
-    SkAutoTDeleteArray<unsigned int> ada(profile);
+    radius = (radius + .5f) * 2.f;
 
+    profile_size = compute_profile_size(radius);
+    
     int pad = profile_size/2;
     if (margin) {
         margin->set( pad, pad );
@@ -1259,20 +1263,32 @@ bool SkBlurMask::BlurRect(SkMask *dst, const SkRect &src,
     int shadow_right = (int)(src.width()) + pad;
     int shadow_bottom = (int)(src.height()) + pad;
 
-    dst->fBounds.set(shadow_left, shadow_top, shadow_right, shadow_bottom);
+    dst->fBounds.set(shadow_left + src.fLeft, shadow_top + src.fTop, shadow_right + src.fRight, shadow_bottom + src.fBottom);

[bungeman-skia, 2013/03/11 20:03:36]

This line is long.

 
     dst->fRowBytes = dst->fBounds.width();
     dst->fFormat = SkMask::kA8_Format;
     dst->fImage = NULL;
-
+    
+    int             sw = SkScalarFloorToInt(src.width());

[bungeman-skia, 2013/03/11 20:03:36]

I know this used to have this crazy spacing, but I think the reason for it has
been lost to the sands of time.

+    int             sh = SkScalarFloorToInt(src.height());
+    
+    if (!perform_blur) {
+        if (style == kInner_Style) {
+            dst->fBounds.set(0, 0, sw, sh); // restore trimmed bounds
+            dst->fRowBytes = sw;
+        }
+        return true;
+    }
+    unsigned int *profile = NULL;

[bungeman-skia, 2013/03/11 20:03:36]

Probably want a blank line above, since this is part of the next block of code
and not associated with the above block.

+    
+    compute_profile(radius, &profile);
+    SkAutoTDeleteArray<unsigned int> ada(profile);
+    
     size_t dstSize = dst->computeImageSize();
     if (0 == dstSize) {
         return false;   // too big to allocate, abort
     }
 
-    int             sw = SkScalarFloorToInt(src.width());
-    int             sh = SkScalarFloorToInt(src.height());
-
     uint8_t*        dp = SkMask::AllocImage(dstSize);
 
     dst->fImage = dp;