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LibWeb: Avoid painting background-images under opaque borders

Without this the background-image can be painted up to 8 extra
times, that contribute nothing to the final image.
This commit is contained in:
MacDue 2022-07-31 01:18:46 +01:00 committed by Andreas Kling
parent 6a6475673f
commit d0511ec650

View file

@ -82,6 +82,26 @@ void paint_background(PaintContext& context, Layout::NodeWithStyleAndBoxModelMet
if (!has_paintable_layers)
return;
struct {
int top { 0 };
int bottom { 0 };
int left { 0 };
int right { 0 };
} clip_shrink;
auto border_top = layout_node.computed_values().border_top();
auto border_bottom = layout_node.computed_values().border_bottom();
auto border_left = layout_node.computed_values().border_left();
auto border_right = layout_node.computed_values().border_right();
if (border_top.color.alpha() == 255 && border_bottom.color.alpha() == 255
&& border_left.color.alpha() == 255 && border_right.color.alpha() == 255) {
clip_shrink.top = border_top.width;
clip_shrink.bottom = border_bottom.width;
clip_shrink.left = border_left.width;
clip_shrink.right = border_right.width;
}
// Note: Background layers are ordered front-to-back, so we paint them in reverse
for (auto& layer : background_layers->in_reverse()) {
// TODO: Gradients!
@ -96,6 +116,12 @@ void paint_background(PaintContext& context, Layout::NodeWithStyleAndBoxModelMet
painter.add_clip_rect(clip_rect);
ScopedCornerRadiusClip corner_clip { painter, clip_rect, clip_box.radii };
if (layer.clip == CSS::BackgroundBox::BorderBox) {
// Shrink the effective clip rect if to account for the bits the borders will definitely paint over
// (if they all have alpha == 255).
clip_rect.shrink(clip_shrink.top, clip_shrink.right, clip_shrink.bottom, clip_shrink.left);
}
auto& image = *layer.background_image;
Gfx::FloatRect background_positioning_area;