Document how effective zoom relates to StyleImage sizing

third_party/WebKit/Source/core/style/StyleImage.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2005, 2006, 2007, 2008 Apple 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 39 matching lines @@
     {
         return data() == other.data();
     }
 
     virtual PassRefPtrWillBeRawPtr<CSSValue> cssValue() const = 0;
     virtual PassRefPtrWillBeRawPtr<CSSValue> computedCSSValue() const = 0;
 
     virtual bool canRender() const { return true; }
     virtual bool isLoaded() const { return true; }
     virtual bool errorOccurred() const { return false; }
+    // Note that the defaultObjectSize is assumed to be in the
+    // effective zoom level given by multiplier, i.e. if multiplier is
+    // the constant 1 the defaultObjectSize should be unzoomed.
     virtual LayoutSize imageSize(const LayoutObject&, float multiplier, const LayoutSize& defaultObjectSize) const = 0;
     virtual bool imageHasRelativeSize() const = 0;
     virtual bool usesImageContainerSize() const = 0;
     virtual void addClient(LayoutObject*) = 0;
     virtual void removeClient(LayoutObject*) = 0;
-    virtual PassRefPtr<Image> image(const LayoutObject&, const IntSize&, float) const = 0;
+    // Note that the containerSize is assumed to be in the effective
+    // zoom level given by multiplier, i.e if the multiplier is the
+    // constant 1 the containerSize should be unzoomed.
+    virtual PassRefPtr<Image> image(const LayoutObject&, const IntSize& containerSize, float multiplier) const = 0;
     virtual WrappedImagePtr data() const = 0;
     virtual float imageScaleFactor() const { return 1; }
     virtual bool knownToBeOpaque(const LayoutObject&) const = 0;
     virtual ImageResource* cachedImage() const { return 0; }
 
     ALWAYS_INLINE bool isImageResource() const { return m_isImageResource; }
     ALWAYS_INLINE bool isPendingImage() const { return m_isPendingImage; }
     ALWAYS_INLINE bool isGeneratedImage() const { return m_isGeneratedImage; }
     ALWAYS_INLINE bool isImageResourceSet() const { return m_isImageResourceSet; }
     ALWAYS_INLINE bool isInvalidImage() const { return m_isInvalidImage; }
@@ skipping 19 matching lines @@
     LayoutSize imageSizeForSVGImage(SVGImage*, float multiplier, const LayoutSize& defaultObjectSize) const;
 };
 
 #define DEFINE_STYLE_IMAGE_TYPE_CASTS(thisType, function) \
     DEFINE_TYPE_CASTS(thisType, StyleImage, styleImage, styleImage->function, styleImage.function); \
     inline thisType* to##thisType(const RefPtrWillBeMember<StyleImage>& styleImage) { return to##thisType(styleImage.get()); } \
     typedef int NeedsSemiColonAfterDefineStyleImageTypeCasts
 
 } // namespace blink
 #endif