Revamp filter primitive region calculations for Filter Effects

third_party/WebKit/Source/platform/graphics/filters/FETile.cpp

 /*
  * Copyright (C) 2008 Alex Mathews <possessedpenguinbob@gmail.com>
  * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 28 matching lines @@
 }
 
 FloatRect FETile::mapPaintRect(const FloatRect& rect, bool forward) const
 {
     return forward ? maxEffectRect() : inputEffect(0)->maxEffectRect();
 }
 
 sk_sp<SkImageFilter> FETile::createImageFilter()
 {
     sk_sp<SkImageFilter> input(SkiaImageFilterBuilder::build(inputEffect(0), operatingColorSpace()));
-    FloatRect srcRect = inputEffect(0)->filterPrimitiveSubregion();
-    FloatRect dstRect = applyEffectBoundaries(getFilter()->filterRegion());
+    FloatRect srcRect;
+    if (inputEffect(0)->getFilterEffectType() == FilterEffectTypeSourceInput)

[Stephen White, 2016/09/13 15:48:02]

Would it not be possible to have make filterPrimitiveSubregion() virtual, and
have SourceGraphic return filterRegion() as its filterPrimitiveSubregion()? It
would allow us to eliminate the special case here. Or is that a bad idea for
other reasons?

[fs, 2016/09/13 16:11:52]

I think that more general here would be to check clipsToBounds() (== has filter
primitive region), so specializing to SourceGraphic probably isn't necessarily
the right thing. (Also the filter [and hence region] of the source may differ
from the filter of the feTile in some cases.)

+        srcRect = getFilter()->filterRegion();
+    else
+        srcRect = inputEffect(0)->filterPrimitiveSubregion();
+    FloatRect dstRect = filterPrimitiveSubregion();
     return SkTileImageFilter::Make(srcRect, dstRect, std::move(input));
 }
 
 TextStream& FETile::externalRepresentation(TextStream& ts, int indent) const
 {
     writeIndent(ts, indent);
     ts << "[feTile";
     FilterEffect::externalRepresentation(ts);
     ts << "]\n";
     inputEffect(0)->externalRepresentation(ts, indent + 1);
 
     return ts;
 }
 
 } // namespace blink