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LibPDF+LibGfx: Do not try to read "hmtx" table for PDFs

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It is sometimes truncated in fonts embedded in PDFs, and the data
is not needed to render PDFs. 26 of my 1000 test files complained
"Could not load Hmtx: Not enough data" before.

Increases number of PDFs that render without diagnostics from
743 to 764.
This commit is contained in:
Nico Weber 2024-02-20 11:42:59 -05:00 • committed by Andreas Kling
parent 5efe80af7f
commit 0dee94ef40
Notes: sideshowbarker 2024-07-17 09:49:33 +09:00
3 changed files with 14 additions and 8 deletions
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9
Userland/Libraries/LibGfx/Font/OpenType/Font.cpp
View file

@ -271,9 +271,12 @@ ErrorOr<NonnullRefPtr<Font>> Font::try_load_from_offset(ReadonlyBytes buffer, u3
return Error::from_string_literal("Font is missing Maxp"); return Error::from_string_literal("Font is missing Maxp");
auto maxp = TRY(Maxp::from_slice(opt_maxp_slice.value())); auto maxp = TRY(Maxp::from_slice(opt_maxp_slice.value()));
Optional<Hmtx> hmtx;
if (!(options.skip_tables & Options::SkipTables::Hmtx)) {
if (!opt_hmtx_slice.has_value()) if (!opt_hmtx_slice.has_value())
return Error::from_string_literal("Font is missing Hmtx"); return Error::from_string_literal("Font is missing Hmtx");
auto hmtx = TRY(Hmtx::from_slice(opt_hmtx_slice.value(), maxp.num_glyphs(), hhea.number_of_h_metrics())); hmtx = TRY(Hmtx::from_slice(opt_hmtx_slice.value(), maxp.num_glyphs(), hhea.number_of_h_metrics()));
}
NonnullOwnPtr<CharCodeToGlyphIndex> cmap = options.external_cmap ? options.external_cmap.release_nonnull() : TRY(CmapCharCodeToGlyphIndex::from_slice(opt_cmap_slice.value())); NonnullOwnPtr<CharCodeToGlyphIndex> cmap = options.external_cmap ? options.external_cmap.release_nonnull() : TRY(CmapCharCodeToGlyphIndex::from_slice(opt_cmap_slice.value()));
@ -412,14 +415,14 @@ Gfx::ScaledGlyphMetrics Font::glyph_metrics(u32 glyph_id, float x_scale, float y
return embedded_bitmap_metrics.release_value(); return embedded_bitmap_metrics.release_value();
} }
if (!m_loca.has_value() || !m_glyf.has_value()) { if (!m_loca.has_value() || !m_glyf.has_value() || !m_hmtx.has_value()) {
return Gfx::ScaledGlyphMetrics {}; return Gfx::ScaledGlyphMetrics {};
} }
if (glyph_id >= glyph_count()) { if (glyph_id >= glyph_count()) {
glyph_id = 0; glyph_id = 0;
} }
auto horizontal_metrics = m_hmtx.get_glyph_horizontal_metrics(glyph_id); auto horizontal_metrics = m_hmtx->get_glyph_horizontal_metrics(glyph_id);
auto glyph_offset = m_loca->get_glyph_offset(glyph_id); auto glyph_offset = m_loca->get_glyph_offset(glyph_id);
auto glyph = m_glyf->glyph(glyph_offset); auto glyph = m_glyf->glyph(glyph_offset);
return Gfx::ScaledGlyphMetrics { return Gfx::ScaledGlyphMetrics {

7
Userland/Libraries/LibGfx/Font/OpenType/Font.h
View file

@ -34,6 +34,9 @@ struct FontOptions {
enum SkipTables { enum SkipTables {
// If set, do not try to read the 'name' table. family() and variant() will return empty strings. // If set, do not try to read the 'name' table. family() and variant() will return empty strings.
Name = 1 << 0, Name = 1 << 0,
// If set, do not try to read the 'hmtx' table. This will make glyph_metrics() return 0 for everyting and is_fixed_width() return true.
Hmtx = 1 << 1,
}; };
u32 skip_tables { 0 }; u32 skip_tables { 0 };
}; };
@ -94,7 +97,7 @@ private:
Optional<Name>&& name, Optional<Name>&& name,
Hhea&& hhea, Hhea&& hhea,
Maxp&& maxp, Maxp&& maxp,
Hmtx&& hmtx, Optional<Hmtx>&& hmtx,
NonnullOwnPtr<CharCodeToGlyphIndex> cmap, NonnullOwnPtr<CharCodeToGlyphIndex> cmap,
Optional<Loca>&& loca, Optional<Loca>&& loca,
Optional<Glyf>&& glyf, Optional<Glyf>&& glyf,
@ -130,7 +133,7 @@ private:
Optional<Name> m_name; Optional<Name> m_name;
Hhea m_hhea; Hhea m_hhea;
Maxp m_maxp; Maxp m_maxp;
Hmtx m_hmtx; Optional<Hmtx> m_hmtx;
Optional<Loca> m_loca; Optional<Loca> m_loca;
Optional<Glyf> m_glyf; Optional<Glyf> m_glyf;
NonnullOwnPtr<CharCodeToGlyphIndex> m_cmap; NonnullOwnPtr<CharCodeToGlyphIndex> m_cmap;

2
Userland/Libraries/LibPDF/Fonts/PDFFont.h
View file

@ -19,7 +19,7 @@ class Renderer;
// PDF files don't need most of the data in OpenType fonts, and even contain invalid data for // PDF files don't need most of the data in OpenType fonts, and even contain invalid data for
// these tables in some cases. Skip reading these tables. // these tables in some cases. Skip reading these tables.
constexpr u32 pdf_skipped_opentype_tables = OpenType::FontOptions::SkipTables::Name; constexpr u32 pdf_skipped_opentype_tables = OpenType::FontOptions::SkipTables::Name | OpenType::FontOptions::SkipTables::Hmtx;
class PDFFont : public RefCounted<PDFFont> { class PDFFont : public RefCounted<PDFFont> {
public: public: