use drawRect when drawing a bitmap with anti-aliasing on a non-msaa target

src/gpu/SkGpuDevice.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGpuDevice.h"
 
 #include "effects/GrBicubicEffect.h"
@@ skipping 1044 matching lines @@
     } else {
         SkASSERT(dstSizePtr);
         srcRect = *srcRectPtr;
         dstSize = *dstSizePtr;
         if (srcRect.fLeft <= 0 && srcRect.fTop <= 0 &&
             srcRect.fRight >= bitmap.width() && srcRect.fBottom >= bitmap.height()) {
             flags = (SkCanvas::DrawBitmapRectFlags) (flags | SkCanvas::kBleed_DrawBitmapRectFlag);
         }
     }
 
-    if (paint.getMaskFilter()){
+    // If the render target is not msaa and draw is antialiased, we call
+    // drawRect instead of drawing on the render target directly.
+    // FIXME: the tiled bitmap code path doesn't currently support
+    // anti-aliased edges, we work around that for now by drawing directly
+    // if the image size exceeds maximum texture size.
+    int maxTextureSize = fContext->getMaxTextureSize();
+    bool directDraw = fRenderTarget->isMultisampled() ||
+                      !paint.isAntiAlias() ||
+                      bitmap.width() > maxTextureSize ||
+                      bitmap.height() > maxTextureSize;
+
+    // we check whether dst rect are pixel aligned
+    if (!directDraw) {
+        bool staysRect = fContext->getMatrix().rectStaysRect();
+
+        if (staysRect) {
+            SkRect rect;
+            SkRect dstRect = SkRect::MakeXYWH(0, 0, dstSize.fWidth, dstSize.fHeight);
+            fContext->getMatrix().mapRect(&rect, dstRect);
+            const SkScalar *scalars = rect.asScalars();
+            bool isDstPixelAligned = true;
+            for (int i = 0; i < 4; i++) {
+                if (!SkScalarIsInt(scalars[i])) {
+                    isDstPixelAligned = false;
+                    break;
+                }
+            }
+
+            if (isDstPixelAligned)
+                directDraw = true;
+        }
+    }
+
+    if (paint.getMaskFilter() || !directDraw) {
         // Convert the bitmap to a shader so that the rect can be drawn
         // through drawRect, which supports mask filters.
         SkBitmap        tmp;    // subset of bitmap, if necessary
         const SkBitmap* bitmapPtr = &bitmap;
         SkMatrix localM;
         if (srcRectPtr) {
             localM.setTranslate(-srcRectPtr->fLeft, -srcRectPtr->fTop);
             localM.postScale(dstSize.fWidth / srcRectPtr->width(),
                              dstSize.fHeight / srcRectPtr->height());
             // In bleed mode we position and trim the bitmap based on the src rect which is
@@ skipping 770 matching lines @@
     return true;
 }
 
 SkImageFilter::Cache* SkGpuDevice::getImageFilterCache() {
     // We always return a transient cache, so it is freed after each
     // filter traversal.
     return SkImageFilter::Cache::Create(kDefaultImageFilterCacheSize);
 }
 
 #endif