New function SkBlitter::blitAntiRect(); specifically accelerated for

supersampled antialiased clips.



git-svn-id: http://skia.googlecode.com/svn/trunk@2783 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 16 insertions, 4 deletions

diff --git a/src/core/SkBlitter.cpp b/src/core/SkBlitter.cpp
index 307d51b340..17cba4776d 100644
--- a/src/core/SkBlitter.cpp
+++ b/src/core/SkBlitter.cpp
@@ -52,6 +52,16 @@ void SkBlitter::blitRect(int x, int y, int width, int height) {
     }
 }
 
+/// Default implementation doesn't check for any easy optimizations
+/// such as alpha == 0 or 255; also uses blitV(), which some subclasses
+/// may not support.
+void SkBlitter::blitAntiRect(int x, int y, int width, int height,
+                             SkAlpha leftAlpha, SkAlpha rightAlpha) {
+    this->blitV(x, y, height, leftAlpha);
+    this->blitRect(x + 1, y, width, height);
+    this->blitV(x + width - 1, y, height, rightAlpha);
+}
+
 //////////////////////////////////////////////////////////////////////////////
 
 static inline void bits_to_runs(SkBlitter* blitter, int x, int y,
@@ -118,7 +128,8 @@ void SkBlitter::blitMask(const SkMask& mask, const SkIRect& clip) {
             int rite_mask = 0xFF << (8 - (rite_edge & 7));
             int full_runs = (rite_edge >> 3) - ((left_edge + 7) >> 3);
 
-            // check for empty right mask, so we don't read off the end (or go slower than we need to)
+            // check for empty right mask, so we don't read off the end
+            // (or go slower than we need to)
             if (rite_mask == 0) {
                 SkASSERT(full_runs >= 0);
                 full_runs -= 1;
@@ -128,8 +139,8 @@ void SkBlitter::blitMask(const SkMask& mask, const SkIRect& clip) {
                 full_runs -= 1;
             }
 
-            // back up manually so we can keep in sync with our byte-aligned src
-            // have cx reflect our actual starting x-coord
+            // Back up manually so we can keep in sync with our byte-aligned
+            // src; have cx reflect our actual starting x-coord.
             cx -= left_edge & 7;
 
             if (full_runs < 0) {
@@ -141,7 +152,8 @@ void SkBlitter::blitMask(const SkMask& mask, const SkIRect& clip) {
                 }
             } else {
                 while (--height >= 0) {
-                    bits_to_runs(this, cx, cy, bits, left_mask, full_runs + 2, rite_mask);
+                    bits_to_runs(this, cx, cy, bits, left_mask, full_runs + 2,
+                                 rite_mask);
                     bits += mask_rowBytes;
                     cy += 1;
                 }