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LibTTF: Initial work on parsing and rasterizing composite glyphs.

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This doesn't handle every case yet.
This commit is contained in:
Srimanta Barua 2020-06-14 11:19:28 +05:30 • committed by Andreas Kling
parent bd354bc2ae
commit 1e1d2cdedf
4 changed files with 328 additions and 220 deletions
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34
Libraries/LibTTF/Font.cpp
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@ -49,6 +49,11 @@ i16 be_i16(const u8* ptr)
return (((i16) ptr[0]) << 8) | ((i16) ptr[1]);
}
float be_fword(const u8* ptr)
{
return (float) be_i16(ptr) / (float) (1 << 14);
}
u32 tag_from_str(const char *str)
{
return be_u32((const u8*) str);
@ -122,6 +127,27 @@ u16 Font::Hhea::number_of_h_metrics() const
return be_u16(m_slice.offset_pointer((u32) Offsets::NumberOfHMetrics));
}
Font::GlyphHorizontalMetrics Font::Hmtx::get_glyph_horizontal_metrics(u32 glyph_id) const
{
ASSERT(glyph_id < m_num_glyphs);
if (glyph_id < m_number_of_h_metrics) {
auto offset = glyph_id * (u32) Sizes::LongHorMetric;
u16 advance_width = be_u16(m_slice.offset_pointer(offset));
i16 left_side_bearing = be_i16(m_slice.offset_pointer(offset + 2));
return GlyphHorizontalMetrics {
.advance_width = advance_width,
.left_side_bearing = left_side_bearing,
};
}
auto offset = m_number_of_h_metrics * (u32) Sizes::LongHorMetric + (glyph_id - m_number_of_h_metrics) * (u32) Sizes::LeftSideBearing;
u16 advance_width = be_u16(m_slice.offset_pointer((m_number_of_h_metrics - 1) * (u32) Sizes::LongHorMetric));
i16 left_side_bearing = be_i16(m_slice.offset_pointer(offset));
return GlyphHorizontalMetrics {
.advance_width = advance_width,
.left_side_bearing = left_side_bearing,
};
}
u16 Font::Maxp::num_glyphs() const
{
return be_u16(m_slice.offset_pointer((u32) Offsets::NumGlyphs));
@ -287,7 +313,13 @@ RefPtr<Gfx::Bitmap> Font::raster_glyph(u32 glyph_id, float x_scale, float y_scal
}
auto glyph_offset = m_loca.get_glyph_offset(glyph_id);
auto glyph = m_glyf.glyph(glyph_offset);
return glyph.raster(x_scale, y_scale);
return glyph.raster(x_scale, y_scale, [&](u16 glyph_id) {
if (glyph_id >= m_maxp.num_glyphs()) {
glyph_id = 0;
}
auto glyph_offset = m_loca.get_glyph_offset(glyph_id);
return m_glyf.glyph(glyph_offset);
});
}
int ScaledFont::width(const StringView& string) const