Avoid unneeded paint copies in SkDraw::drawBitmap

src/core/SkDraw.cpp

Index: src/core/SkDraw.cpp
diff --git a/src/core/SkDraw.cpp b/src/core/SkDraw.cpp
index 34c7d73b3ed1852342ad7a924ccc7a8a698b04fb..53c8e5f0e886a7f93a217213cb5b36ee4571ab52 100644
--- a/src/core/SkDraw.cpp
+++ b/src/core/SkDraw.cpp
@@ -1302,8 +1302,10 @@ void SkDraw::drawBitmap(const SkBitmap& bitmap, const SkMatrix& prematrix,
         return;
     }
 
-    SkPaint paint(origPaint);
-    paint.setStyle(SkPaint::kFill_Style);
+    SkTCopyOnFirstWrite<SkPaint> paint(origPaint);
+    if (origPaint.getStyle() != SkPaint::kFill_Style) {
+        paint.writable()->setStyle(SkPaint::kFill_Style);
+    }
 
     SkMatrix matrix;
     matrix.setConcat(*fMatrix, prematrix);
@@ -1313,7 +1315,7 @@ void SkDraw::drawBitmap(const SkBitmap& bitmap, const SkMatrix& prematrix,
     }
 
     if (bitmap.colorType() != kAlpha_8_SkColorType
-        && SkTreatAsSprite(matrix, bitmap.dimensions(), paint)) {
+        && SkTreatAsSprite(matrix, bitmap.dimensions(), *paint)) {
         //
         // It is safe to call lock pixels now, since we know the matrix is
         // (more or less) identity.
@@ -1328,7 +1330,7 @@ void SkDraw::drawBitmap(const SkBitmap& bitmap, const SkMatrix& prematrix,
         if (clipHandlesSprite(*fRC, ix, iy, pmap)) {
             SkTBlitterAllocator allocator;
             // blitter will be owned by the allocator.
-            SkBlitter* blitter = SkBlitter::ChooseSprite(fDst, paint, pmap, ix, iy, &allocator);
+            SkBlitter* blitter = SkBlitter::ChooseSprite(fDst, *paint, pmap, ix, iy, &allocator);
             if (blitter) {
                 SkScan::FillIRect(SkIRect::MakeXYWH(ix, iy, pmap.width(), pmap.height()),
                                   *fRC, blitter);
@@ -1344,9 +1346,9 @@ void SkDraw::drawBitmap(const SkBitmap& bitmap, const SkMatrix& prematrix,
     draw.fMatrix = &matrix;
 
     if (bitmap.colorType() == kAlpha_8_SkColorType) {
-        draw.drawBitmapAsMask(bitmap, paint);
+        draw.drawBitmapAsMask(bitmap, *paint);
     } else {
-        SkAutoBitmapShaderInstall install(bitmap, paint);
+        SkAutoBitmapShaderInstall install(bitmap, *paint);
         const SkPaint& paintWithShader = install.paintWithShader();
         const SkRect srcBounds = SkRect::MakeIWH(bitmap.width(), bitmap.height());
         if (dstBounds) {