Straighten out zoom and border-image

third_party/WebKit/Source/core/paint/NinePieceImagePainter.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/NinePieceImagePainter.h"
 
 #include "core/frame/Deprecation.h"
 #include "core/layout/ImageQualityController.h"
 #include "core/layout/LayoutBoxModelObject.h"
 #include "core/paint/BoxPainter.h"
@@ skipping 31 matching lines @@
         || (style.borderTopWidth() && (style.borderTop().style() == BorderStyleNone || style.borderTop().style() == BorderStyleHidden))
         || (style.borderBottomWidth() && (style.borderBottom().style() == BorderStyleNone || style.borderBottom().style() == BorderStyleHidden)))
         Deprecation::countDeprecation(m_layoutObject.document(), UseCounter::BorderImageWithBorderStyleNone);
 
     // FIXME: border-image is broken with full page zooming when tiling has to happen, since the tiling function
     // doesn't have any understanding of the zoom that is in effect on the tile.
     LayoutRect rectWithOutsets = rect;
     rectWithOutsets.expand(style.imageOutsets(ninePieceImage));
     LayoutRect borderImageRect = rectWithOutsets;
 
-    IntSize imageSize = roundedIntSize(styleImage->imageSize(m_layoutObject, 1, borderImageRect.size()));
+    LayoutSize defaultObjectSize = borderImageRect.size();
+    defaultObjectSize.scale(1 / style.effectiveZoom());
+    IntSize imageSize = roundedIntSize(styleImage->imageSize(m_layoutObject, 1, defaultObjectSize));
 
     IntRectOutsets borderWidths(style.borderTopWidth(), style.borderRightWidth(),
         style.borderBottomWidth(), style.borderLeftWidth());
     NinePieceImageGrid grid(ninePieceImage, imageSize, pixelSnappedIntRect(borderImageRect), borderWidths);
 
-    RefPtr<Image> image = styleImage->image(m_layoutObject, imageSize, style.effectiveZoom());
+    RefPtr<Image> image = styleImage->image(m_layoutObject, imageSize, 1);

[fs, 2016/03/22 14:07:23]

Maybe add a comment (or two) about why the zoom/scale factors are chosen this
way (i.e a boiled down version of the commit message or so.)

[davve, 2016/03/22 14:29:00]

I added two lines to the follow-up documentation patch I was scribbling at
anyway.

https://codereview.chromium.org/1824003002

Would that do?

 
     InterpolationQuality interpolationQuality = BoxPainter::chooseInterpolationQuality(m_layoutObject, image.get(), 0, rectWithOutsets.size());
     InterpolationQuality previousInterpolationQuality = graphicsContext.imageInterpolationQuality();
     graphicsContext.setImageInterpolationQuality(interpolationQuality);
 
     TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("devtools.timeline"), "PaintImage", "data",
         InspectorPaintImageEvent::data(m_layoutObject, *styleImage));
 
     for (NinePiece piece = MinPiece; piece < MaxPiece; ++piece) {
         NinePieceImageGrid::NinePieceDrawInfo drawInfo = grid.getNinePieceDrawInfo(piece);
@@ skipping 11 matching lines @@
                     drawInfo.tileRule.vertical, op);
             }
         }
     }
 
     graphicsContext.setImageInterpolationQuality(previousInterpolationQuality);
     return true;
 }
 
 } // namespace blink