Mask/background-repeat: round should round the number of tiles of an image to the nearest natural n…

Source/core/rendering/RenderBoxModelObject.cpp

Index: Source/core/rendering/RenderBoxModelObject.cpp
diff --git a/Source/core/rendering/RenderBoxModelObject.cpp b/Source/core/rendering/RenderBoxModelObject.cpp
index aada21668d2aeabe3d149fa3e8ad5fe5988748ad..f978c7a4ffd12272bd05d5d0e7921ffc3b84b580 100644
--- a/Source/core/rendering/RenderBoxModelObject.cpp
+++ b/Source/core/rendering/RenderBoxModelObject.cpp
@@ -1062,8 +1062,7 @@ void RenderBoxModelObject::calculateBackgroundImageGeometry(const FillLayer* fil
 
     LayoutUnit computedXPosition = minimumValueForLength(fillLayer->xPosition(), availableWidth, renderView, true);
     if (backgroundRepeatX == RoundFill && positioningAreaSize.width() > 0 && fillTileSize.width() > 0) {
-        int nrTiles = ceil((double)positioningAreaSize.width() /
-            fillTileSize.width());
+        long nrTiles = lroundf((float)positioningAreaSize.width() / fillTileSize.width());

[eseidel, 2013/09/17 18:07:00]

So this is intentionally causing whitespace when the author doesn't match the
background tile size precisely to the size of the div?  I'm confused.  Why
wouldn't we want to ceil here?

[eseidel, 2013/09/17 18:08:32]

I see.  The author has *specifically* requested that we round instead of ceil
and that's the problem.  They want this whitespace for whatever reason. :)

[Julien - ping for review, 2013/09/17 18:37:48]

This mandated by the specification.

Thanks for making the change to long even if it turns out I got confused and
it's not needed as we are taking the result of the division of 2 integers. The
new code is more future proof though.

 
         if (fillLayer->size().size.height().isAuto() && backgroundRepeatY != RoundFill) {
             fillTileSize.setHeight(fillTileSize.height() * positioningAreaSize.width() / (nrTiles * fillTileSize.width()));
@@ -1076,8 +1075,7 @@ void RenderBoxModelObject::calculateBackgroundImageGeometry(const FillLayer* fil
 
     LayoutUnit computedYPosition = minimumValueForLength(fillLayer->yPosition(), availableHeight, renderView, true);
     if (backgroundRepeatY == RoundFill && positioningAreaSize.height() > 0 && fillTileSize.height() > 0) {
-        int nrTiles = ceil((double)positioningAreaSize.height() /
-            fillTileSize.height());
+        long nrTiles = lroundf((float)positioningAreaSize.height() / fillTileSize.height());
 
         if (fillLayer->size().size.width().isAuto() && backgroundRepeatX != RoundFill) {
             fillTileSize.setWidth(fillTileSize.width() * positioningAreaSize.height() / (nrTiles * fillTileSize.height()));