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LibPDF: Add spec comments and FIXMEs to Type0Font::draw_string()

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Nico Weber 2023-08-14 08:50:30 -04:00 • committed by Andreas Kling
parent a18500c78c
commit 1c263eee61
1 changed files with 19 additions and 0 deletions
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19
Userland/Libraries/LibPDF/Fonts/Type0Font.cpp
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@ -155,6 +155,25 @@ void Type0Font::set_font_size(float)
PDFErrorOr<Gfx::FloatPoint> Type0Font::draw_string(Gfx::Painter& painter, Gfx::FloatPoint glyph_position, DeprecatedString const& string, Color const& paint_color, float font_size, float character_spacing, float word_spacing, float horizontal_scaling)
{
// Type0 fonts map bytes to character IDs ("CIDs"), and then CIDs to glyphs.
// ISO 32000 (PDF 2.0) 9.7.6.2 CMap mapping describes how to map bytes to CIDs:
// "The Encoding entry of a Type 0 font dictionary specifies a CMap [...]
// A sequence of one or more bytes shall be extracted from the string and matched against
// the codespace ranges in the CMap. That is, the first byte shall be matched against 1-byte codespace ranges;
// if no match is found, a second byte shall be extracted, and the 2-byte code shall be matched against 2-byte
// codespace ranges [...]"
// 9.7.5.2 Predefined CMaps:
// "When the current font is a Type 0 font whose Encoding entry is Identity-H or Identity-V,
// the string to be shown shall contain pairs of bytes representing CIDs, high-order byte first."
// Type0Font::initialize() currently rejects everything except Identity-H.
// FIXME: Support more.
if (string.length() % 2 != 0)
return Error::malformed_error("Identity-H but length not multiple of 2");
// FIXME: Map string data to CIDs, then call m_cid_font_type with CIDs.
return m_cid_font_type->draw_string(painter, glyph_position, string, paint_color, font_size, character_spacing, word_spacing, horizontal_scaling);
}