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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 19:33:14 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 19:33:14 +0000 |
commit | 36d22d82aa202bb199967e9512281e9a53db42c9 (patch) | |
tree | 105e8c98ddea1c1e4784a60a5a6410fa416be2de /modules/woff2/src/transform.cc | |
parent | Initial commit. (diff) | |
download | firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.tar.xz firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.zip |
Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'modules/woff2/src/transform.cc')
-rw-r--r-- | modules/woff2/src/transform.cc | 430 |
1 files changed, 430 insertions, 0 deletions
diff --git a/modules/woff2/src/transform.cc b/modules/woff2/src/transform.cc new file mode 100644 index 0000000000..1016efcd2b --- /dev/null +++ b/modules/woff2/src/transform.cc @@ -0,0 +1,430 @@ +/* Copyright 2013 Google Inc. All Rights Reserved. + + Distributed under MIT license. + See file LICENSE for detail or copy at https://opensource.org/licenses/MIT +*/ + +/* Library for preprocessing fonts as part of the WOFF 2.0 conversion. */ + +#include "./transform.h" + +#include <complex> // for std::abs + +#include "./buffer.h" +#include "./font.h" +#include "./glyph.h" +#include "./table_tags.h" +#include "./variable_length.h" + +namespace woff2 { + +namespace { + +const int FLAG_ARG_1_AND_2_ARE_WORDS = 1 << 0; +const int FLAG_WE_HAVE_INSTRUCTIONS = 1 << 8; +const int FLAG_OVERLAP_SIMPLE_BITMAP = 1 << 0; + +void WriteBytes(std::vector<uint8_t>* out, const uint8_t* data, size_t len) { + if (len == 0) return; + size_t offset = out->size(); + out->resize(offset + len); + memcpy(&(*out)[offset], data, len); +} + +void WriteBytes(std::vector<uint8_t>* out, const std::vector<uint8_t>& in) { + for (size_t i = 0; i < in.size(); ++i) { + out->push_back(in[i]); + } +} + +void WriteUShort(std::vector<uint8_t>* out, int value) { + out->push_back(value >> 8); + out->push_back(value & 255); +} + +void WriteLong(std::vector<uint8_t>* out, int value) { + out->push_back((value >> 24) & 255); + out->push_back((value >> 16) & 255); + out->push_back((value >> 8) & 255); + out->push_back(value & 255); +} + +// Glyf table preprocessing, based on +// GlyfEncoder.java +class GlyfEncoder { + public: + explicit GlyfEncoder(int num_glyphs) + : n_glyphs_(num_glyphs) { + bbox_bitmap_.resize(((num_glyphs + 31) >> 5) << 2); + } + + bool Encode(int glyph_id, const Glyph& glyph) { + if (glyph.composite_data_size > 0) { + WriteCompositeGlyph(glyph_id, glyph); + } else if (glyph.contours.size() > 0) { + WriteSimpleGlyph(glyph_id, glyph); + } else { + WriteUShort(&n_contour_stream_, 0); + } + return true; + } + + void GetTransformedGlyfBytes(std::vector<uint8_t>* result) { + WriteUShort(result, 0); // Version + WriteUShort(result, overlap_bitmap_.empty() + ? 0x00 + : FLAG_OVERLAP_SIMPLE_BITMAP); // Flags + WriteUShort(result, n_glyphs_); + WriteUShort(result, 0); // index_format, will be set later + WriteLong(result, n_contour_stream_.size()); + WriteLong(result, n_points_stream_.size()); + WriteLong(result, flag_byte_stream_.size()); + WriteLong(result, glyph_stream_.size()); + WriteLong(result, composite_stream_.size()); + WriteLong(result, bbox_bitmap_.size() + bbox_stream_.size()); + WriteLong(result, instruction_stream_.size()); + WriteBytes(result, n_contour_stream_); + WriteBytes(result, n_points_stream_); + WriteBytes(result, flag_byte_stream_); + WriteBytes(result, glyph_stream_); + WriteBytes(result, composite_stream_); + WriteBytes(result, bbox_bitmap_); + WriteBytes(result, bbox_stream_); + WriteBytes(result, instruction_stream_); + if (!overlap_bitmap_.empty()) { + WriteBytes(result, overlap_bitmap_); + } + } + + private: + void WriteInstructions(const Glyph& glyph) { + Write255UShort(&glyph_stream_, glyph.instructions_size); + WriteBytes(&instruction_stream_, + glyph.instructions_data, glyph.instructions_size); + } + + bool ShouldWriteSimpleGlyphBbox(const Glyph& glyph) { + if (glyph.contours.empty() || glyph.contours[0].empty()) { + return glyph.x_min || glyph.y_min || glyph.x_max || glyph.y_max; + } + + int16_t x_min = glyph.contours[0][0].x; + int16_t y_min = glyph.contours[0][0].y; + int16_t x_max = x_min; + int16_t y_max = y_min; + for (const auto& contour : glyph.contours) { + for (const auto& point : contour) { + if (point.x < x_min) x_min = point.x; + if (point.x > x_max) x_max = point.x; + if (point.y < y_min) y_min = point.y; + if (point.y > y_max) y_max = point.y; + } + } + + if (glyph.x_min != x_min) + return true; + if (glyph.y_min != y_min) + return true; + if (glyph.x_max != x_max) + return true; + if (glyph.y_max != y_max) + return true; + + return false; + } + + void WriteSimpleGlyph(int glyph_id, const Glyph& glyph) { + if (glyph.overlap_simple_flag_set) { + EnsureOverlapBitmap(); + overlap_bitmap_[glyph_id >> 3] |= 0x80 >> (glyph_id & 7); + } + int num_contours = glyph.contours.size(); + WriteUShort(&n_contour_stream_, num_contours); + if (ShouldWriteSimpleGlyphBbox(glyph)) { + WriteBbox(glyph_id, glyph); + } + for (int i = 0; i < num_contours; i++) { + Write255UShort(&n_points_stream_, glyph.contours[i].size()); + } + int lastX = 0; + int lastY = 0; + for (int i = 0; i < num_contours; i++) { + int num_points = glyph.contours[i].size(); + for (int j = 0; j < num_points; j++) { + int x = glyph.contours[i][j].x; + int y = glyph.contours[i][j].y; + int dx = x - lastX; + int dy = y - lastY; + WriteTriplet(glyph.contours[i][j].on_curve, dx, dy); + lastX = x; + lastY = y; + } + } + if (num_contours > 0) { + WriteInstructions(glyph); + } + } + + void WriteCompositeGlyph(int glyph_id, const Glyph& glyph) { + WriteUShort(&n_contour_stream_, -1); + WriteBbox(glyph_id, glyph); + WriteBytes(&composite_stream_, + glyph.composite_data, + glyph.composite_data_size); + if (glyph.have_instructions) { + WriteInstructions(glyph); + } + } + + void WriteBbox(int glyph_id, const Glyph& glyph) { + bbox_bitmap_[glyph_id >> 3] |= 0x80 >> (glyph_id & 7); + WriteUShort(&bbox_stream_, glyph.x_min); + WriteUShort(&bbox_stream_, glyph.y_min); + WriteUShort(&bbox_stream_, glyph.x_max); + WriteUShort(&bbox_stream_, glyph.y_max); + } + + void WriteTriplet(bool on_curve, int x, int y) { + int abs_x = std::abs(x); + int abs_y = std::abs(y); + int on_curve_bit = on_curve ? 0 : 128; + int x_sign_bit = (x < 0) ? 0 : 1; + int y_sign_bit = (y < 0) ? 0 : 1; + int xy_sign_bits = x_sign_bit + 2 * y_sign_bit; + if (x == 0 && abs_y < 1280) { + flag_byte_stream_.push_back(on_curve_bit + + ((abs_y & 0xf00) >> 7) + y_sign_bit); + glyph_stream_.push_back(abs_y & 0xff); + } else if (y == 0 && abs_x < 1280) { + flag_byte_stream_.push_back(on_curve_bit + 10 + + ((abs_x & 0xf00) >> 7) + x_sign_bit); + glyph_stream_.push_back(abs_x & 0xff); + } else if (abs_x < 65 && abs_y < 65) { + flag_byte_stream_.push_back(on_curve_bit + 20 + + ((abs_x - 1) & 0x30) + + (((abs_y - 1) & 0x30) >> 2) + + xy_sign_bits); + glyph_stream_.push_back((((abs_x - 1) & 0xf) << 4) | ((abs_y - 1) & 0xf)); + } else if (abs_x < 769 && abs_y < 769) { + flag_byte_stream_.push_back(on_curve_bit + 84 + + 12 * (((abs_x - 1) & 0x300) >> 8) + + (((abs_y - 1) & 0x300) >> 6) + xy_sign_bits); + glyph_stream_.push_back((abs_x - 1) & 0xff); + glyph_stream_.push_back((abs_y - 1) & 0xff); + } else if (abs_x < 4096 && abs_y < 4096) { + flag_byte_stream_.push_back(on_curve_bit + 120 + xy_sign_bits); + glyph_stream_.push_back(abs_x >> 4); + glyph_stream_.push_back(((abs_x & 0xf) << 4) | (abs_y >> 8)); + glyph_stream_.push_back(abs_y & 0xff); + } else { + flag_byte_stream_.push_back(on_curve_bit + 124 + xy_sign_bits); + glyph_stream_.push_back(abs_x >> 8); + glyph_stream_.push_back(abs_x & 0xff); + glyph_stream_.push_back(abs_y >> 8); + glyph_stream_.push_back(abs_y & 0xff); + } + } + + void EnsureOverlapBitmap() { + if (overlap_bitmap_.empty()) { + overlap_bitmap_.resize((n_glyphs_ + 7) >> 3); + } + } + + std::vector<uint8_t> n_contour_stream_; + std::vector<uint8_t> n_points_stream_; + std::vector<uint8_t> flag_byte_stream_; + std::vector<uint8_t> composite_stream_; + std::vector<uint8_t> bbox_bitmap_; + std::vector<uint8_t> bbox_stream_; + std::vector<uint8_t> glyph_stream_; + std::vector<uint8_t> instruction_stream_; + std::vector<uint8_t> overlap_bitmap_; + int n_glyphs_; +}; + +} // namespace + +bool TransformGlyfAndLocaTables(Font* font) { + // no transform for CFF + const Font::Table* glyf_table = font->FindTable(kGlyfTableTag); + const Font::Table* loca_table = font->FindTable(kLocaTableTag); + + // If you don't have glyf/loca this transform isn't very interesting + if (loca_table == NULL && glyf_table == NULL) { + return true; + } + // It would be best if you didn't have just one of glyf/loca + if ((glyf_table == NULL) != (loca_table == NULL)) { + return FONT_COMPRESSION_FAILURE(); + } + // Must share neither or both loca & glyf + if (loca_table->IsReused() != glyf_table->IsReused()) { + return FONT_COMPRESSION_FAILURE(); + } + if (loca_table->IsReused()) { + return true; + } + + Font::Table* transformed_glyf = &font->tables[kGlyfTableTag ^ 0x80808080]; + Font::Table* transformed_loca = &font->tables[kLocaTableTag ^ 0x80808080]; + + int num_glyphs = NumGlyphs(*font); + GlyfEncoder encoder(num_glyphs); + for (int i = 0; i < num_glyphs; ++i) { + Glyph glyph; + const uint8_t* glyph_data; + size_t glyph_size; + if (!GetGlyphData(*font, i, &glyph_data, &glyph_size) || + (glyph_size > 0 && !ReadGlyph(glyph_data, glyph_size, &glyph))) { + return FONT_COMPRESSION_FAILURE(); + } + encoder.Encode(i, glyph); + } + encoder.GetTransformedGlyfBytes(&transformed_glyf->buffer); + + const Font::Table* head_table = font->FindTable(kHeadTableTag); + if (head_table == NULL || head_table->length < 52) { + return FONT_COMPRESSION_FAILURE(); + } + transformed_glyf->buffer[7] = head_table->data[51]; // index_format + + transformed_glyf->tag = kGlyfTableTag ^ 0x80808080; + transformed_glyf->length = transformed_glyf->buffer.size(); + transformed_glyf->data = transformed_glyf->buffer.data(); + + transformed_loca->tag = kLocaTableTag ^ 0x80808080; + transformed_loca->length = 0; + transformed_loca->data = NULL; + + return true; +} + +// See https://www.microsoft.com/typography/otspec/hmtx.htm +// See WOFF2 spec, 5.4. Transformed hmtx table format +bool TransformHmtxTable(Font* font) { + const Font::Table* glyf_table = font->FindTable(kGlyfTableTag); + const Font::Table* hmtx_table = font->FindTable(kHmtxTableTag); + const Font::Table* hhea_table = font->FindTable(kHheaTableTag); + + // If you don't have hmtx or a glyf not much is going to happen here + if (hmtx_table == NULL || glyf_table == NULL) { + return true; + } + + // hmtx without hhea doesn't make sense + if (hhea_table == NULL) { + return FONT_COMPRESSION_FAILURE(); + } + + // Skip 34 to reach 'hhea' numberOfHMetrics + Buffer hhea_buf(hhea_table->data, hhea_table->length); + uint16_t num_hmetrics; + if (!hhea_buf.Skip(34) || !hhea_buf.ReadU16(&num_hmetrics)) { + return FONT_COMPRESSION_FAILURE(); + } + + // Must have at least one hMetric + if (num_hmetrics < 1) { + return FONT_COMPRESSION_FAILURE(); + } + + int num_glyphs = NumGlyphs(*font); + + // Most fonts can be transformed; assume it's a go until proven otherwise + std::vector<uint16_t> advance_widths; + std::vector<int16_t> proportional_lsbs; + std::vector<int16_t> monospace_lsbs; + + bool remove_proportional_lsb = true; + bool remove_monospace_lsb = (num_glyphs - num_hmetrics) > 0; + + Buffer hmtx_buf(hmtx_table->data, hmtx_table->length); + for (int i = 0; i < num_glyphs; i++) { + Glyph glyph; + const uint8_t* glyph_data; + size_t glyph_size; + if (!GetGlyphData(*font, i, &glyph_data, &glyph_size) || + (glyph_size > 0 && !ReadGlyph(glyph_data, glyph_size, &glyph))) { + return FONT_COMPRESSION_FAILURE(); + } + + uint16_t advance_width = 0; + int16_t lsb = 0; + + if (i < num_hmetrics) { + // [0, num_hmetrics) are proportional hMetrics + if (!hmtx_buf.ReadU16(&advance_width)) { + return FONT_COMPRESSION_FAILURE(); + } + + if (!hmtx_buf.ReadS16(&lsb)) { + return FONT_COMPRESSION_FAILURE(); + } + + if (glyph_size > 0 && glyph.x_min != lsb) { + remove_proportional_lsb = false; + } + + advance_widths.push_back(advance_width); + proportional_lsbs.push_back(lsb); + } else { + // [num_hmetrics, num_glyphs) are monospace leftSideBearing's + if (!hmtx_buf.ReadS16(&lsb)) { + return FONT_COMPRESSION_FAILURE(); + } + if (glyph_size > 0 && glyph.x_min != lsb) { + remove_monospace_lsb = false; + } + monospace_lsbs.push_back(lsb); + } + + // If we know we can't optimize, bail out completely + if (!remove_proportional_lsb && !remove_monospace_lsb) { + return true; + } + } + + Font::Table* transformed_hmtx = &font->tables[kHmtxTableTag ^ 0x80808080]; + + uint8_t flags = 0; + size_t transformed_size = 1 + 2 * advance_widths.size(); + if (remove_proportional_lsb) { + flags |= 1; + } else { + transformed_size += 2 * proportional_lsbs.size(); + } + if (remove_monospace_lsb) { + flags |= 1 << 1; + } else { + transformed_size += 2 * monospace_lsbs.size(); + } + + transformed_hmtx->buffer.reserve(transformed_size); + std::vector<uint8_t>* out = &transformed_hmtx->buffer; + WriteBytes(out, &flags, 1); + for (uint16_t advance_width : advance_widths) { + WriteUShort(out, advance_width); + } + + if (!remove_proportional_lsb) { + for (int16_t lsb : proportional_lsbs) { + WriteUShort(out, lsb); + } + } + if (!remove_monospace_lsb) { + for (int16_t lsb : monospace_lsbs) { + WriteUShort(out, lsb); + } + } + + transformed_hmtx->tag = kHmtxTableTag ^ 0x80808080; + transformed_hmtx->flag_byte = 1 << 6; + transformed_hmtx->length = transformed_hmtx->buffer.size(); + transformed_hmtx->data = transformed_hmtx->buffer.data(); + + + return true; +} + +} // namespace woff2 |