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LibPDF: Add very basic support for Adobe Type 1 font rendering

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Previously we would draw all text, no matter what font type, as
Liberation Serif, which results in things like ugly character spacing.

We now have partial support for drawing Type 1 glyphs, which are part of
a PostScript font program. We completely ignore hinting for now, which
results in ugly looking characters at low resolutions, but gain support
for a large number of typefaces, including most of the default fonts
used in TeX.
This commit is contained in:
Julian Offenhäuser 2022-08-25 11:06:21 +02:00 • committed by Andreas Kling
parent e6f29302a7
commit b14f0950a5
9 changed files with 752 additions and 16 deletions
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30
Userland/Libraries/LibPDF/Renderer.cpp
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@ -643,25 +643,37 @@ void Renderer::show_text(String const& string)
{
auto& text_rendering_matrix = calculate_text_rendering_matrix();
auto font_type = text_state().font->type();
auto font_size = text_rendering_matrix.x_scale() * text_state().font_size;
auto font_size_int = static_cast<int>(text_rendering_matrix.x_scale() * text_state().font_size);
auto font = Gfx::FontDatabase::the().get(text_state().font_family, text_state().font_variant, font_size_int);
VERIFY(font);
auto glyph_position = text_rendering_matrix.map(Gfx::FloatPoint { 0.0f, 0.0f });
// Account for the reversed font baseline
glyph_position.set_y(glyph_position.y() - static_cast<float>(font->baseline()));
RefPtr<Gfx::Font> font;
// For types other than Type 1 and the standard 14 fonts, use Liberation Serif for now
if (font_type != PDFFont::Type::Type1 || text_state().font->is_standard_font()) {
font = Gfx::FontDatabase::the().get(text_state().font_family, text_state().font_variant, font_size);
VERIFY(font);
// Account for the reversed font baseline
glyph_position.set_y(glyph_position.y() - static_cast<float>(font->baseline()));
}
auto original_position = glyph_position;
for (auto char_code : string.bytes()) {
auto code_point = text_state().font->char_code_to_code_point(char_code);
auto char_width = text_state().font->get_char_width(char_code, font_size);
if (code_point != 0x20)
m_painter.draw_glyph(glyph_position.to_type<int>(), code_point, *font, state().paint_color);
auto glyph_width = char_width * font_size;
if (code_point != 0x20) {
if (font.is_null()) {
text_state().font->draw_glyph(m_painter, glyph_position.to_type<int>(), glyph_width, code_point, state().paint_color);
} else {
m_painter.draw_glyph(glyph_position.to_type<int>(), code_point, *font, state().paint_color);
}
}
auto tx = glyph_width;
tx += text_state().character_spacing;