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LibWeb: When painting, reduce computation cost by using the reciprocal

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Rather than dividing the rect width and high by the border lengths,
this change multiples those lengths by the reciprocal of the width
and height because this is a faster operation. When mousing around on
the html spec website, the profile showed that inline painting
went from ~15% to ~3%
This commit is contained in:
James Bellamy 2022-03-21 19:15:01 +00:00 • committed by Andreas Kling
parent 4f786a7f66
commit 7ab62ecd16
1 changed files with 8 additions and 4 deletions
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12
Userland/Libraries/LibWeb/Painting/BorderPainting.cpp
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@ -24,10 +24,14 @@ BorderRadiusData normalized_border_radius_data(Layout::Node const& node, Gfx::Fl
// Scale overlapping curves according to https://www.w3.org/TR/css-backgrounds-3/#corner-overlap
auto f = 1.0f;
f = min(f, rect.width() / (float)(top_left_radius_px + top_right_radius_px));
f = min(f, rect.height() / (float)(top_right_radius_px + bottom_right_radius_px));
f = min(f, rect.width() / (float)(bottom_left_radius_px + bottom_right_radius_px));
f = min(f, rect.height() / (float)(top_left_radius_px + bottom_left_radius_px));
auto width_reciprocal = 1.0f / rect.width();
auto height_reciprocal = 1.0f / rect.height();
f = max(f, width_reciprocal * (top_left_radius_px + top_right_radius_px));
f = max(f, height_reciprocal * (top_right_radius_px + bottom_right_radius_px));
f = max(f, width_reciprocal * (bottom_left_radius_px + bottom_right_radius_px));
f = max(f, height_reciprocal * (top_left_radius_px + bottom_left_radius_px));
f = 1.0f / f;
top_left_radius_px = (int)(top_left_radius_px * f);
top_right_radius_px = (int)(top_right_radius_px * f);