Avoid recomputing two consecutive identical 1D filters.

If the arguments to the X and Y filter computation are identical,
the results will be identical; copying is much faster than recomputing.

With a change like https://codereview.chromium.org/183763047/ applied
this speeds up BitmapScaleBench on Linux by around 10%.

BUG=skia:2236
R=humper@google.com, tomhudson@google.com

Author: tomhudson@chromium.org

Review URL: https://codereview.chromium.org/188743002

git-svn-id: http://skia.googlecode.com/svn/trunk@13687 2bbb7eff-a529-9590-31e7-b0007b416f81

diff --git a/src/core/SkBitmapScaler.cpp b/src/core/SkBitmapScaler.cpp
index a90be05..9e8c5fe 100644 (file)
--- a/src/core/SkBitmapScaler.cpp
+++ b/src/core/SkBitmapScaler.cpp
@@ -89,8 +89,15 @@ SkResizeFilter::SkResizeFilter(SkBitmapScaler::ResizeMethod method,
 
     this->computeFilters(srcFullWidth, destSubset.fLeft, destSubset.width(),
                          scaleX, &fXFilter, convolveProcs);
-    this->computeFilters(srcFullHeight, destSubset.fTop, destSubset.height(),
-                         scaleY, &fYFilter, convolveProcs);
+    if (srcFullWidth == srcFullHeight &&
+        destSubset.fLeft == destSubset.fTop &&
+        destSubset.width() == destSubset.height()&&
+        scaleX == scaleY) {
+        fYFilter = fXFilter;
+    } else {
+        this->computeFilters(srcFullHeight, destSubset.fTop, destSubset.height(),
+                          scaleY, &fYFilter, convolveProcs);
+    }
 }
 
 // TODO(egouriou): Take advantage of periods in the convolution.