Draw thin slices of an image w/ anti-aliasing for 2D <canvas>

Source/platform/graphics/GraphicsContext.h

 /*
  * Copyright (C) 2003, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008-2009 Torch Mobile, Inc.
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 118 matching lines @@
 
     SkDrawLooper* drawLooper() const { return immutableState()->drawLooper(); }
 
     FloatRect getClipBounds() const;
     bool getTransformedClipBounds(FloatRect* bounds) const;
     SkMatrix getTotalMatrix() const;
 
     void setShouldAntialias(bool antialias) { mutableState()->setShouldAntialias(antialias); }
     bool shouldAntialias() const { return immutableState()->shouldAntialias(); }
 
+    // Enables the use of the shouldAntialias flag for images. Note that this
+    // only affects the (rasterized) image geometry, and not the quality of the
+    // interpolation (for that, see setImageInterpolationQuality.)
+    void enableDefaultAntialiasingForImages() { m_antialiasImages = true; }
+    bool shouldAntialiasImages() const { return m_antialiasImages && shouldAntialias(); }

[Justin Novosad, 2014/03/28 18:20:38]

I think the name is a bit misleading. Perhaps: shouldAntialiasHairline Images?
or thin images? something like that.  The fact is that rotated/skewed images
will still be draw anti-aliased even if this bit is not set.

[fs, 2014/03/31 08:21:11]

Makes sense. Renamed accordingly.

It also occurred to me that it might make sense to reverse the logic (and hence
settings) to always enable AA, but then selectively disable it for the
rectilinear cases (except the "hairline" case, which would then still have a
flag I suppose - so no major improvement in cleanliness.) If that sounds
reasonable, I'd be happy to do that change here or as a follow up CL.

+
     void setShouldClampToSourceRect(bool clampToSourceRect) { mutableState()->setShouldClampToSourceRect(clampToSourceRect); }
     bool shouldClampToSourceRect() const { return immutableState()->shouldClampToSourceRect(); }
 
     void setShouldSmoothFonts(bool smoothFonts) { mutableState()->setShouldSmoothFonts(smoothFonts); }
     bool shouldSmoothFonts() const { return immutableState()->shouldSmoothFonts(); }
 
     // Turn off LCD text for the paint if not supported on this context.
     void adjustTextRenderMode(SkPaint*);
     bool couldUseLCDRenderedText();
 
@@ skipping 348 matching lines @@
     bool m_trackTextRegion : 1;
     SkRect m_textRegion;
 
     // Are we on a high DPI display? If so, spelling and grammar markers are larger.
     bool m_useHighResMarker : 1;
     // FIXME: Make this go away: crbug.com/236892
     bool m_updatingControlTints : 1;
     bool m_accelerated : 1;
     bool m_isCertainlyOpaque : 1;
     bool m_printing : 1;
+    bool m_antialiasImages : 1;
 };
 
 } // namespace WebCore
 
 #endif // GraphicsContext_h