650 lines
19 KiB
C++
650 lines
19 KiB
C++
/*
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* Copyright (c) 2022, Julian Offenhäuser <offenhaeuser@protonmail.com>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibGfx/Font/PathRasterizer.h>
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#include <LibPDF/CommonNames.h>
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#include <LibPDF/Encoding.h>
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#include <LibPDF/Fonts/PS1FontProgram.h>
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#include <LibPDF/Reader.h>
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#include <ctype.h>
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#include <math.h>
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namespace PDF {
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enum Command {
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HStem = 1,
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VStem = 3,
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VMoveTo,
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RLineTo,
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HLineTo,
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VLineTo,
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RRCurveTo,
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ClosePath,
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CallSubr,
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Return,
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Extended,
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HSbW,
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EndChar,
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RMoveTo = 21,
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HMoveTo,
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VHCurveTo = 30,
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HVCurveTo
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};
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enum ExtendedCommand {
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DotSection,
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VStem3,
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HStem3,
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Seac = 6,
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Div = 12,
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CallOtherSubr = 16,
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Pop,
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SetCurrentPoint = 33,
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};
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PDFErrorOr<void> PS1FontProgram::create(ReadonlyBytes const& bytes, RefPtr<Encoding> encoding, size_t cleartext_length, size_t encrypted_length)
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{
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Reader reader(bytes);
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if (reader.remaining() == 0)
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return error("Empty font program");
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reader.move_to(0);
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if (reader.remaining() < 2 || !reader.matches("%!"))
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return error("Not a font program");
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if (!seek_name(reader, CommonNames::Encoding))
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return error("Missing encoding array");
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if (encoding) {
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// 9.6.6.2 Encodings for Type 1 Fonts:
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// An Encoding entry may override a Type 1 font’s mapping from character codes to character names.
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m_encoding = encoding;
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} else {
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if (TRY(parse_word(reader)) == "StandardEncoding") {
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m_encoding = Encoding::standard_encoding();
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} else {
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HashMap<u16, CharDescriptor> descriptors;
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while (reader.remaining()) {
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auto word = TRY(parse_word(reader));
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if (word == "readonly") {
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break;
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} else if (word == "dup") {
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u32 char_code = TRY(parse_int(reader));
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auto name = TRY(parse_word(reader));
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descriptors.set(char_code, { name.starts_with('/') ? name.substring_view(1) : name.view(), char_code });
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}
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}
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m_encoding = TRY(Encoding::create(descriptors));
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}
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}
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bool found_font_matrix = seek_name(reader, "FontMatrix");
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if (found_font_matrix) {
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auto array = TRY(parse_number_array(reader, 6));
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m_font_matrix = { array[0], array[1], array[2], array[3], array[4], array[5] };
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} else {
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m_font_matrix = { 0.001f, 0.0f, 0.0f, 0.001f, 0.0f, 0.0f };
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}
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auto decrypted = TRY(decrypt(reader.bytes().slice(cleartext_length, encrypted_length), 55665, 4));
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return parse_encrypted_portion(decrypted);
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}
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RefPtr<Gfx::Bitmap> PS1FontProgram::rasterize_glyph(u32 char_code, float width, Gfx::GlyphSubpixelOffset subpixel_offset)
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{
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auto path = build_char(char_code, width);
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auto bounding_box = path.bounding_box().size();
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u32 w = (u32)ceilf(bounding_box.width()) + 2;
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u32 h = (u32)ceilf(bounding_box.height()) + 2;
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Gfx::PathRasterizer rasterizer(Gfx::IntSize(w, h));
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rasterizer.translate(subpixel_offset.to_float_point());
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rasterizer.draw_path(path);
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return rasterizer.accumulate();
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}
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Gfx::Path PS1FontProgram::build_char(u32 char_code, float width)
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{
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auto maybe_glyph = m_glyph_map.get(char_code);
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if (!maybe_glyph.has_value())
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return {};
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auto& glyph = maybe_glyph.value();
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auto transform = glyph_transform_to_device_space(glyph, width);
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// Translate such that the top-left point is at [0, 0].
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auto bounding_box = glyph.path.bounding_box();
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Gfx::FloatPoint translation(-bounding_box.x(), -(bounding_box.y() + bounding_box.height()));
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transform.translate(translation);
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return glyph.path.copy_transformed(transform);
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}
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Gfx::FloatPoint PS1FontProgram::glyph_translation(u32 char_code, float width) const
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{
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auto maybe_glyph = m_glyph_map.get(char_code);
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if (!maybe_glyph.has_value())
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return {};
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auto& glyph = maybe_glyph.value();
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auto transform = glyph_transform_to_device_space(glyph, width);
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// Undo the translation we applied earlier.
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auto bounding_box = glyph.path.bounding_box();
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Gfx::FloatPoint translation(bounding_box.x(), bounding_box.y() + bounding_box.height());
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return transform.map(translation);
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}
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Gfx::AffineTransform PS1FontProgram::glyph_transform_to_device_space(Glyph const& glyph, float width) const
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{
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auto scale = width / (m_font_matrix.a() * glyph.width + m_font_matrix.e());
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auto transform = m_font_matrix;
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// Convert character space to device space.
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transform.scale(scale, -scale);
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return transform;
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}
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PDFErrorOr<PS1FontProgram::Glyph> PS1FontProgram::parse_glyph(ReadonlyBytes const& data, GlyphParserState& state)
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{
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auto push = [&](float value) -> PDFErrorOr<void> {
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if (state.sp >= state.stack.size())
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return error("Operand stack overflow");
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state.stack[state.sp++] = value;
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return {};
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};
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auto pop = [&]() -> float {
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return state.sp ? state.stack[--state.sp] : 0.0f;
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};
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auto& path = state.glyph.path;
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// Parse the stream of parameters and commands that make up a glyph outline.
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for (size_t i = 0; i < data.size(); ++i) {
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auto require = [&](unsigned num) -> PDFErrorOr<void> {
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if (i + num >= data.size())
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return error("Malformed glyph outline definition");
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return {};
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};
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int v = data[i];
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if (v == 255) {
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TRY(require(4));
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int a = data[++i];
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int b = data[++i];
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int c = data[++i];
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int d = data[++i];
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TRY(push((a << 24) + (b << 16) + (c << 8) + d));
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} else if (v >= 251) {
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TRY(require(1));
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auto w = data[++i];
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TRY(push(-((v - 251) * 256) - w - 108));
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} else if (v >= 247) {
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TRY(require(1));
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auto w = data[++i];
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TRY(push(((v - 247) * 256) + w + 108));
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} else if (v >= 32) {
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TRY(push(v - 139));
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} else {
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// Not a parameter but a command byte.
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switch (v) {
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case HStem:
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case VStem:
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state.sp = 0;
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break;
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case VMoveTo: {
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auto dy = pop();
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state.point.translate_by(0.0f, dy);
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if (state.flex_feature) {
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state.flex_sequence[state.flex_index++] = state.point.x();
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state.flex_sequence[state.flex_index++] = state.point.y();
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} else {
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path.move_to(state.point);
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}
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state.sp = 0;
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break;
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}
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case RLineTo: {
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auto dy = pop();
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auto dx = pop();
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state.point.translate_by(dx, dy);
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path.line_to(state.point);
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state.sp = 0;
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break;
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}
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case HLineTo: {
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auto dx = pop();
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state.point.translate_by(dx, 0.0f);
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path.line_to(state.point);
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state.sp = 0;
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break;
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}
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case VLineTo: {
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auto dy = pop();
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state.point.translate_by(0.0f, dy);
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path.line_to(state.point);
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state.sp = 0;
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break;
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}
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case RRCurveTo: {
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auto dy3 = pop();
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auto dx3 = pop();
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auto dy2 = pop();
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auto dx2 = pop();
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auto dy1 = pop();
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auto dx1 = pop();
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auto& point = state.point;
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path.cubic_bezier_curve_to(
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point + Gfx::FloatPoint(dx1, dy1),
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point + Gfx::FloatPoint(dx1 + dx2, dy1 + dy2),
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point + Gfx::FloatPoint(dx1 + dx2 + dx3, dy1 + dy2 + dy3));
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point.translate_by(dx1 + dx2 + dx3, dy1 + dy2 + dy3);
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state.sp = 0;
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break;
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}
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case ClosePath:
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path.close();
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state.sp = 0;
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break;
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case CallSubr: {
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auto subr_number = pop();
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if (static_cast<size_t>(subr_number) >= m_subroutines.size())
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return error("Subroutine index out of range");
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// Subroutines 0-2 handle the flex feature.
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if (subr_number == 0) {
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if (state.flex_index != 14)
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break;
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auto& flex = state.flex_sequence;
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path.cubic_bezier_curve_to(
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{ flex[2], flex[3] },
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{ flex[4], flex[5] },
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{ flex[6], flex[7] });
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path.cubic_bezier_curve_to(
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{ flex[8], flex[9] },
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{ flex[10], flex[11] },
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{ flex[12], flex[13] });
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state.flex_feature = false;
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state.sp = 0;
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} else if (subr_number == 1) {
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state.flex_feature = true;
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state.flex_index = 0;
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state.sp = 0;
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} else if (subr_number == 2) {
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state.sp = 0;
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} else {
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auto subr = m_subroutines[subr_number];
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if (subr.is_empty())
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return error("Empty subroutine");
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TRY(parse_glyph(subr, state));
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}
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break;
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}
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case Return:
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break;
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case Extended: {
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TRY(require(1));
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switch (data[++i]) {
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case DotSection:
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case VStem3:
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case HStem3:
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case Seac:
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// FIXME: Do something with these?
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state.sp = 0;
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break;
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case Div: {
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auto num2 = pop();
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auto num1 = pop();
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TRY(push(num2 ? num1 / num2 : 0.0f));
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break;
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}
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case CallOtherSubr: {
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auto othersubr_number = pop();
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auto n = static_cast<int>(pop());
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if (othersubr_number == 0) {
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state.postscript_stack[state.postscript_sp++] = pop();
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state.postscript_stack[state.postscript_sp++] = pop();
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pop();
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} else if (othersubr_number == 3) {
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state.postscript_stack[state.postscript_sp++] = 3;
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} else {
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for (int i = 0; i < n; ++i)
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state.postscript_stack[state.postscript_sp++] = pop();
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}
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(void)othersubr_number;
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break;
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}
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case Pop:
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TRY(push(state.postscript_stack[--state.postscript_sp]));
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break;
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case SetCurrentPoint: {
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auto y = pop();
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auto x = pop();
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state.point = { x, y };
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path.move_to(state.point);
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state.sp = 0;
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break;
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}
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default:
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return error(DeprecatedString::formatted("Unhandled command: 12 {}", data[i]));
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}
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break;
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}
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case HSbW: {
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auto wx = pop();
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auto sbx = pop();
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state.glyph.width = wx;
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state.point = { sbx, 0.0f };
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state.sp = 0;
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break;
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}
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case EndChar:
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break;
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case RMoveTo: {
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auto dy = pop();
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auto dx = pop();
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state.point.translate_by(dx, dy);
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if (state.flex_feature) {
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state.flex_sequence[state.flex_index++] = state.point.x();
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state.flex_sequence[state.flex_index++] = state.point.y();
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} else {
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path.move_to(state.point);
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}
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state.sp = 0;
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break;
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}
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case HMoveTo: {
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auto dx = pop();
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state.point.translate_by(dx, 0.0f);
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if (state.flex_feature) {
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state.flex_sequence[state.flex_index++] = state.point.x();
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state.flex_sequence[state.flex_index++] = state.point.y();
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} else {
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path.move_to(state.point);
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}
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state.sp = 0;
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break;
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}
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case VHCurveTo: {
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auto dx3 = pop();
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auto dy2 = pop();
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auto dx2 = pop();
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auto dy1 = pop();
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auto& point = state.point;
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path.cubic_bezier_curve_to(
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point + Gfx::FloatPoint(0.0f, dy1),
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point + Gfx::FloatPoint(dx2, dy1 + dy2),
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point + Gfx::FloatPoint(dx2 + dx3, dy1 + dy2));
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point.translate_by(dx2 + dx3, dy1 + dy2);
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state.sp = 0;
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break;
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}
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case HVCurveTo: {
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auto dy3 = pop();
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auto dy2 = pop();
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auto dx2 = pop();
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auto dx1 = pop();
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auto& point = state.point;
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path.cubic_bezier_curve_to(
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point + Gfx::FloatPoint(dx1, 0.0f),
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point + Gfx::FloatPoint(dx1 + dx2, dy2),
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point + Gfx::FloatPoint(dx1 + dx2, dy2 + dy3));
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point.translate_by(dx1 + dx2, dy2 + dy3);
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state.sp = 0;
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break;
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}
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default:
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return error(DeprecatedString::formatted("Unhandled command: {}", v));
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}
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}
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}
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return state.glyph;
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}
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PDFErrorOr<void> PS1FontProgram::parse_encrypted_portion(ByteBuffer const& buffer)
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{
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Reader reader(buffer);
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if (seek_name(reader, "lenIV"))
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m_lenIV = TRY(parse_int(reader));
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if (!seek_name(reader, "Subrs"))
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return error("Missing subroutine array");
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m_subroutines = TRY(parse_subroutines(reader));
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if (!seek_name(reader, "CharStrings"))
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return error("Missing char strings array");
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while (reader.remaining()) {
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auto word = TRY(parse_word(reader));
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VERIFY(!word.is_empty());
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if (word == "end")
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break;
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if (word[0] == '/') {
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auto encrypted_size = TRY(parse_int(reader));
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auto rd = TRY(parse_word(reader));
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if (rd == "-|" || rd == "RD") {
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auto line = TRY(decrypt(reader.bytes().slice(reader.offset(), encrypted_size), m_encryption_key, m_lenIV));
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reader.move_by(encrypted_size);
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auto name_mapping = m_encoding->name_mapping();
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auto char_code = name_mapping.ensure(word.substring_view(1));
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GlyphParserState state;
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m_glyph_map.set(char_code, TRY(parse_glyph(line, state)));
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}
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}
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}
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return {};
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}
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PDFErrorOr<Vector<ByteBuffer>> PS1FontProgram::parse_subroutines(Reader& reader)
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{
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if (!reader.matches_number())
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return error("Expected array length");
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auto length = TRY(parse_int(reader));
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VERIFY(length <= 1024);
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Vector<ByteBuffer> array;
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TRY(array.try_resize(length));
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while (reader.remaining()) {
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auto word = TRY(parse_word(reader));
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if (word.is_empty())
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VERIFY(0);
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if (word == "dup") {
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auto index = TRY(parse_int(reader));
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auto entry = TRY(parse_word(reader));
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if (entry.is_empty())
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return error("Empty array entry");
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if (index >= length)
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return error("Array index out of bounds");
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if (isdigit(entry[0])) {
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auto maybe_encrypted_size = entry.to_int();
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if (!maybe_encrypted_size.has_value())
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return error("Malformed array");
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auto rd = TRY(parse_word(reader));
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if (rd == "-|" || rd == "RD") {
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array[index] = TRY(decrypt(reader.bytes().slice(reader.offset(), maybe_encrypted_size.value()), m_encryption_key, m_lenIV));
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reader.move_by(maybe_encrypted_size.value());
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}
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} else {
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array[index] = TRY(ByteBuffer::copy(entry.bytes()));
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}
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} else if (word == "index") {
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break;
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}
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}
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return array;
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}
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PDFErrorOr<Vector<float>> PS1FontProgram::parse_number_array(Reader& reader, size_t length)
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{
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Vector<float> array;
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||
TRY(array.try_resize(length));
|
||
|
||
reader.consume_whitespace();
|
||
|
||
if (!reader.consume('['))
|
||
return error("Expected array to start with '['");
|
||
|
||
reader.consume_whitespace();
|
||
|
||
for (size_t i = 0; i < length; ++i)
|
||
array.at(i) = TRY(parse_float(reader));
|
||
|
||
if (!reader.consume(']'))
|
||
return error("Expected array to end with ']'");
|
||
|
||
return array;
|
||
}
|
||
|
||
PDFErrorOr<DeprecatedString> PS1FontProgram::parse_word(Reader& reader)
|
||
{
|
||
reader.consume_whitespace();
|
||
|
||
auto start = reader.offset();
|
||
reader.move_while([&](char c) {
|
||
return !reader.matches_whitespace() && c != '[' && c != ']';
|
||
});
|
||
auto end = reader.offset();
|
||
|
||
if (reader.matches_whitespace())
|
||
reader.consume();
|
||
|
||
return StringView(reader.bytes().data() + start, end - start);
|
||
}
|
||
|
||
PDFErrorOr<float> PS1FontProgram::parse_float(Reader& reader)
|
||
{
|
||
auto word = TRY(parse_word(reader));
|
||
return strtof(DeprecatedString(word).characters(), nullptr);
|
||
}
|
||
|
||
PDFErrorOr<int> PS1FontProgram::parse_int(Reader& reader)
|
||
{
|
||
auto maybe_int = TRY(parse_word(reader)).to_int();
|
||
if (!maybe_int.has_value())
|
||
return error("Invalid int");
|
||
return maybe_int.value();
|
||
}
|
||
|
||
PDFErrorOr<ByteBuffer> PS1FontProgram::decrypt(ReadonlyBytes const& encrypted, u16 key, size_t skip)
|
||
{
|
||
auto decrypted = TRY(ByteBuffer::create_uninitialized(encrypted.size() - skip));
|
||
|
||
u16 R = key;
|
||
u16 c1 = 52845;
|
||
u16 c2 = 22719;
|
||
|
||
for (size_t i = 0; i < encrypted.size(); ++i) {
|
||
u8 C = encrypted[i];
|
||
u8 P = C ^ (R >> 8);
|
||
R = (C + R) * c1 + c2;
|
||
if (i >= skip)
|
||
decrypted[i - skip] = P;
|
||
}
|
||
|
||
return decrypted;
|
||
}
|
||
|
||
bool PS1FontProgram::seek_name(Reader& reader, DeprecatedString const& name)
|
||
{
|
||
auto start = reader.offset();
|
||
|
||
reader.move_to(0);
|
||
while (reader.remaining()) {
|
||
if (reader.consume('/') && reader.matches(name.characters())) {
|
||
// Skip name
|
||
reader.move_while([&](char) {
|
||
return reader.matches_regular_character();
|
||
});
|
||
reader.consume_whitespace();
|
||
return true;
|
||
}
|
||
}
|
||
|
||
// Jump back to where we started
|
||
reader.move_to(start);
|
||
return false;
|
||
}
|
||
|
||
Error PS1FontProgram::error(
|
||
DeprecatedString const& message
|
||
#ifdef PDF_DEBUG
|
||
,
|
||
SourceLocation loc
|
||
#endif
|
||
)
|
||
{
|
||
#ifdef PDF_DEBUG
|
||
dbgln("\033[31m{} Type 1 font error: {}\033[0m", loc, message);
|
||
#endif
|
||
|
||
return Error { Error::Type::MalformedPDF, message };
|
||
}
|
||
}
|