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LibWeb: Remove implicit conversion from float and double to CSSPixels

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In general it is not safe to convert any arbitrary floating-point value
to CSSPixels. CSSPixels has a resolution of 0.015625, which for small
values (e.g. scale factors between 0 and 1), can produce bad results
if converted to CSSPixels then scaled back up. In the worst case values
can underflow to zero and produce incorrect results.
This commit is contained in:
MacDue 2023-08-26 15:03:04 +01:00 • committed by Alexander Kalenik
parent 0f9c088302
commit 360c0eb509
43 changed files with 248 additions and 221 deletions
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6
Userland/Libraries/LibWeb/Painting/StackingContext.cpp
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@ -448,12 +448,12 @@ void StackingContext::paint(PaintContext& context) const
// to the size of the source (which could add some artefacts, though just scaling the bitmap already does that).
// We need to copy the background at the destination because a bunch of our rendering effects now rely on
// being able to sample the painter (see border radii, shadows, filters, etc).
CSSPixelPoint destination_clipped_fixup {};
Gfx::FloatPoint destination_clipped_fixup {};
auto try_get_scaled_destination_bitmap = [&]() -> ErrorOr<NonnullRefPtr<Gfx::Bitmap>> {
Gfx::IntRect actual_destination_rect;
auto bitmap = TRY(context.painter().get_region_bitmap(destination_rect, Gfx::BitmapFormat::BGRA8888, actual_destination_rect));
// get_region_bitmap() may clip to a smaller region if the requested rect goes outside the painter, so we need to account for that.
destination_clipped_fixup = CSSPixelPoint { destination_rect.location() - actual_destination_rect.location() };
destination_clipped_fixup = Gfx::FloatPoint { destination_rect.location() - actual_destination_rect.location() };
destination_rect = actual_destination_rect;
if (source_rect.size() != transformed_destination_rect.size()) {
auto sx = static_cast<float>(source_rect.width()) / transformed_destination_rect.width();
@ -469,7 +469,7 @@ void StackingContext::paint(PaintContext& context) const
return;
auto bitmap = bitmap_or_error.release_value_but_fixme_should_propagate_errors();
Gfx::Painter painter(bitmap);
painter.translate(context.rounded_device_point(-paintable_box().absolute_paint_rect().location() + destination_clipped_fixup).to_type<int>());
painter.translate(context.rounded_device_point(-paintable_box().absolute_paint_rect().location() + destination_clipped_fixup.to_type<CSSPixels>()).to_type<int>());
auto paint_context = context.clone(painter);
paint_internal(paint_context);