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LibWeb: Avoid infinite loops in background painting

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Previously if `background-size` was 0px in any dimension we would
go into in infinite loop whilst painting.
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MacDue 2022-08-23 00:34:11 +01:00 • committed by Linus Groh
parent ae264c9143
commit 40ad8b793d
1 changed files with 8 additions and 0 deletions
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8
Userland/Libraries/LibWeb/Painting/BackgroundPainting.cpp
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@ -140,6 +140,10 @@ void paint_background(PaintContext& context, Layout::NodeWithStyleAndBoxModelMet
auto natural_image_width = image.natural_width().value_or(background_positioning_area.width()); auto natural_image_width = image.natural_width().value_or(background_positioning_area.width());
auto natural_image_height = image.natural_height().value_or(background_positioning_area.height()); auto natural_image_height = image.natural_height().value_or(background_positioning_area.height());
// If any of these are zero, the NaNs will pop up in the painting code.
if (background_positioning_area.is_empty() || natural_image_height <= 0 || natural_image_width <= 0)
continue;
// Size // Size
Gfx::FloatRect image_rect; Gfx::FloatRect image_rect;
switch (layer.size_type) { switch (layer.size_type) {
@ -181,6 +185,10 @@ void paint_background(PaintContext& context, Layout::NodeWithStyleAndBoxModelMet
} }
} }
// If after sizing we have a 0px image, we're done. Attempting to paint this would be an infinite loop.
if (image_rect.is_empty())
continue;
// If background-repeat is round for one (or both) dimensions, there is a second step. // If background-repeat is round for one (or both) dimensions, there is a second step.
// The UA must scale the image in that dimension (or both dimensions) so that it fits a // The UA must scale the image in that dimension (or both dimensions) so that it fits a
// whole number of times in the background positioning area. // whole number of times in the background positioning area.