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LibGfx: Recurse TrueType composite glyphs until a simple glyph is found

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This fixes a bug in ladybird where it was crashing while rendering
characters like ščćž in the Noto Sans Regular font.

That font renders those characters as a composite where the caret
has numberOfContours = -1. When using the rasterize_impl simple path
for that, it would negatively overflow the offsets.
This commit is contained in:
Enver Balalic 2022-09-16 11:46:22 +02:00 • committed by Andreas Kling
parent e6306d459a
commit 11a44ffb69
1 changed files with 26 additions and 11 deletions
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37
Userland/Libraries/LibGfx/Font/TrueType/Glyf.h
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@ -103,6 +103,29 @@ public:
void rasterize_impl(Rasterizer&, Gfx::AffineTransform const&) const;
RefPtr<Gfx::Bitmap> rasterize_simple(i16 ascender, i16 descender, float x_scale, float y_scale) const;
template<typename GlyphCb>
void rasterize_composite_loop(Rasterizer& rasterizer, Gfx::AffineTransform& transform, GlyphCb glyph_callback) const
{
ComponentIterator component_iterator(m_slice);
while (true) {
auto opt_item = component_iterator.next();
if (!opt_item.has_value()) {
break;
}
auto item = opt_item.value();
auto affine_here = transform.multiply(item.affine);
Glyph glyph = glyph_callback(item.glyph_id);
if (glyph.m_type == Type::Simple) {
glyph.rasterize_impl(rasterizer, affine_here);
} else {
glyph.rasterize_composite_loop(rasterizer, transform, glyph_callback);
}
}
}
template<typename GlyphCb>
RefPtr<Gfx::Bitmap> rasterize_composite(i16 font_ascender, i16 font_descender, float x_scale, float y_scale, GlyphCb glyph_callback) const
{
@ -110,17 +133,9 @@ public:
u32 height = (u32)(ceilf((font_ascender - font_descender) * y_scale)) + 1;
Rasterizer rasterizer(Gfx::IntSize(width, height));
auto affine = Gfx::AffineTransform().scale(x_scale, -y_scale).translate(-m_xmin, -font_ascender);
ComponentIterator component_iterator(m_slice);
while (true) {
auto opt_item = component_iterator.next();
if (!opt_item.has_value()) {
break;
}
auto item = opt_item.value();
auto affine_here = affine.multiply(item.affine);
auto glyph = glyph_callback(item.glyph_id);
glyph.rasterize_impl(rasterizer, affine_here);
}
rasterize_composite_loop(rasterizer, affine, glyph_callback);
return rasterizer.accumulate();
}