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

If the dest isn't pixel aligned, or if a non 90 degree rotation is
present, we need to use drawRect() for drawing anti-aliased bitmaps on
non-msaa targets or the edges won't be anti-aliased as intended.

Note: If the bitmap size is bigger than max texture size we fall back to drawBitmapCommon.

Original-Author: Henry Song <henrysong@samsung.com>

Review URL: https://codereview.chromium.org/649313003

1 files changed, 34 insertions, 1 deletions

diff --git a/src/gpu/SkGpuDevice.cpp b/src/gpu/SkGpuDevice.cpp
index e6c8343943..3a0d6f4e3a 100644
--- a/src/gpu/SkGpuDevice.cpp
+++ b/src/gpu/SkGpuDevice.cpp
@@ -1063,7 +1063,40 @@ void SkGpuDevice::drawBitmapCommon(const SkDraw& draw,
         }
     }
 
-    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