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LibPDF: Implement initial support for Type0 truetype fonts

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Disclaimers, similar to what's on #23202 (and most of the
prerequisites mentioned there are needed for this too):

* Only supports the `Identity-H` type0 cmap at the moment
* Doesn't support vertical text yet
* Only supports the `Identity` CIDToGIDMap at the moment
  (this one is a truetype-only thing)
This commit is contained in:
Nico Weber 2024-02-16 19:51:13 -05:00 • committed by Andreas Kling
parent 76a439124d
commit f4a59246f5
1 changed files with 44 additions and 10 deletions
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54
Userland/Libraries/LibPDF/Fonts/Type0Font.cpp
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@ -4,6 +4,7 @@
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibGfx/Font/OpenType/Font.h>
#include <LibGfx/Font/ScaledFont.h>
#include <LibPDF/CommonNames.h>
#include <LibPDF/Fonts/CFF.h>
@ -113,6 +114,14 @@ public:
static PDFErrorOr<NonnullOwnPtr<CIDFontType2>> create(Document*, NonnullRefPtr<DictObject> const& descendant, float font_size);
virtual PDFErrorOr<void> draw_glyph(Gfx::Painter&, Gfx::FloatPoint, float width, u32 cid, Renderer const&) override;
private:
CIDFontType2(RefPtr<Gfx::Font> font)
: m_font(move(font))
{
}
RefPtr<Gfx::Font> m_font;
};
PDFErrorOr<NonnullOwnPtr<CIDFontType2>> CIDFontType2::create(Document* document, NonnullRefPtr<DictObject> const& descendant, float font_size)
@ -128,22 +137,31 @@ PDFErrorOr<NonnullOwnPtr<CIDFontType2>> CIDFontType2::create(Document* document,
}
}
class IdentityCIDToGIDMap : public OpenType::CharCodeToGlyphIndex {
public:
virtual u32 glyph_id_for_code_point(u32 char_code) const override
{
return char_code;
}
};
RefPtr<Gfx::Font> font;
if (descriptor->contains(CommonNames::FontFile2)) {
auto font_file_stream = TRY(descriptor->get_stream(document, CommonNames::FontFile2));
float point_size = (font_size * POINTS_PER_INCH) / DEFAULT_DPI;
// FIXME: Load font_file_stream->bytes() as TTF data, similar to TrueTypeFont::initialize().
// Unfortunately, TTF data in Type0 CIDFontType2 fonts don't contain the "cmap" table
// that's mandatory per TTF spec and the PDF stores that mapping in CIDToGIDMap instead.
// OpenType::Font::try_load currently rejects TTF data without "cmap" data.
(void)font_file_stream;
(void)point_size;
auto ttf_font = TRY(OpenType::Font::try_load_from_externally_owned_memory(font_file_stream->bytes(), 0, make<IdentityCIDToGIDMap>()));
font = adopt_ref(*new Gfx::ScaledFont(*ttf_font, point_size, point_size));
}
return TRY(adopt_nonnull_own_or_enomem(new (nothrow) CIDFontType2()));
if (!font) {
// FIXME: Should we use a fallback font? How common is this for type 0 fonts?
return Error::malformed_error("CIDFontType2: missing FontFile2");
}
return TRY(adopt_nonnull_own_or_enomem(new (nothrow) CIDFontType2(move(font))));
}
PDFErrorOr<void> CIDFontType2::draw_glyph(Gfx::Painter&, Gfx::FloatPoint, float, u32, Renderer const&)
PDFErrorOr<void> CIDFontType2::draw_glyph(Gfx::Painter& painter, Gfx::FloatPoint point, float width, u32 char_code, Renderer const& renderer)
{
// ISO 32000 (PDF 2.0) 9.7.4.2 Glyph selection in CIDFonts
// "For Type 2, the CIDFont program is actually a TrueType font program, which has no native notion of CIDs.
@ -157,8 +175,24 @@ PDFErrorOr<void> CIDFontType2::draw_glyph(Gfx::Painter&, Gfx::FloatPoint, float,
// that maps CIDs to the glyph indices for the appropriate glyph descriptions in that font program.
// * If the TrueType font program is not embedded but is referenced by name, and the Type 2 CIDFont dictionary
// contains a CIDToGIDMap entry, the CIDToGIDMap entry shall be ignored, since it is not meaningful
/// to refer to glyph indices in an external font program."
return Error::rendering_unsupported_error("Type0 font CIDFontType2 not implemented yet");
// to refer to glyph indices in an external font program."
// FIXME: We don't support non-embedded type0 truetype fonts yet.
auto style = renderer.state().paint_style;
// Undo shift in Glyf::Glyph::append_simple_path() via OpenType::Font::rasterize_glyph().
auto position = point.translated(0, -m_font->pixel_metrics().ascent);
if (style.has<Color>()) {
painter.draw_glyph(position, char_code, *m_font, style.get<Color>());
} else {
// FIXME: Bounding box and sample point look to be pretty wrong
style.get<NonnullRefPtr<Gfx::PaintStyle>>()->paint(Gfx::IntRect(position.x(), position.y(), width, 0), [&](auto sample) {
painter.draw_glyph(position, char_code, *m_font, sample(Gfx::IntPoint(position.x(), position.y())));
});
}
return {};
}
Type0Font::Type0Font() = default;