| // Copyright 2013 Google Inc. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| // |
| // Glyph normalization |
| |
| #include "./normalize.h" |
| |
| #include <inttypes.h> |
| #include <stddef.h> |
| |
| #include "./buffer.h" |
| #include "./port.h" |
| #include "./font.h" |
| #include "./glyph.h" |
| #include "./round.h" |
| #include "./store_bytes.h" |
| #include "./table_tags.h" |
| |
| namespace woff2 { |
| |
| namespace { |
| |
| void StoreLoca(int index_fmt, uint32_t value, size_t* offset, uint8_t* dst) { |
| if (index_fmt == 0) { |
| Store16(value >> 1, offset, dst); |
| } else { |
| StoreU32(value, offset, dst); |
| } |
| } |
| |
| void NormalizeSimpleGlyphBoundingBox(Glyph* glyph) { |
| if (glyph->contours.empty() || glyph->contours[0].empty()) { |
| return; |
| } |
| 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; |
| } |
| } |
| glyph->x_min = x_min; |
| glyph->y_min = y_min; |
| glyph->x_max = x_max; |
| glyph->y_max = y_max; |
| } |
| |
| } // namespace |
| |
| bool NormalizeGlyphs(Font* font) { |
| Font::Table* head_table = font->FindTable(kHeadTableTag); |
| Font::Table* glyf_table = font->FindTable(kGlyfTableTag); |
| Font::Table* loca_table = font->FindTable(kLocaTableTag); |
| if (head_table == NULL || loca_table == NULL || glyf_table == NULL) { |
| return FONT_COMPRESSION_FAILURE(); |
| } |
| int index_fmt = head_table->data[51]; |
| int num_glyphs = NumGlyphs(*font); |
| |
| // We need to allocate a bit more than its original length for the normalized |
| // glyf table, since it can happen that the glyphs in the original table are |
| // 2-byte aligned, while in the normalized table they are 4-byte aligned. |
| // That gives a maximum of 2 bytes increase per glyph. However, there is no |
| // theoretical guarantee that the total size of the flags plus the coordinates |
| // is the smallest possible in the normalized version, so we have to allow |
| // some general overhead. |
| // TODO(user) Figure out some more precise upper bound on the size of |
| // the overhead. |
| size_t max_normalized_glyf_size = 1.1 * glyf_table->length + 2 * num_glyphs; |
| |
| glyf_table->buffer.resize(max_normalized_glyf_size); |
| loca_table->buffer.resize(Round4(loca_table->length)); |
| uint8_t* glyf_dst = &glyf_table->buffer[0]; |
| uint8_t* loca_dst = &loca_table->buffer[0]; |
| uint32_t glyf_offset = 0; |
| size_t loca_offset = 0; |
| |
| for (int i = 0; i < num_glyphs; ++i) { |
| StoreLoca(index_fmt, glyf_offset, &loca_offset, loca_dst); |
| 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(); |
| } |
| NormalizeSimpleGlyphBoundingBox(&glyph); |
| size_t glyf_dst_size = glyf_table->buffer.size() - glyf_offset; |
| if (!StoreGlyph(glyph, glyf_dst + glyf_offset, &glyf_dst_size)) { |
| return FONT_COMPRESSION_FAILURE(); |
| } |
| glyf_dst_size = Round4(glyf_dst_size); |
| if (glyf_dst_size > std::numeric_limits<uint32_t>::max() || |
| glyf_offset + static_cast<uint32_t>(glyf_dst_size) < glyf_offset || |
| (index_fmt == 0 && glyf_offset + glyf_dst_size >= (1UL << 17))) { |
| return FONT_COMPRESSION_FAILURE(); |
| } |
| glyf_offset += glyf_dst_size; |
| } |
| StoreLoca(index_fmt, glyf_offset, &loca_offset, loca_dst); |
| |
| glyf_table->buffer.resize(glyf_offset); |
| glyf_table->data = &glyf_table->buffer[0]; |
| glyf_table->length = glyf_offset; |
| loca_table->data = &loca_table->buffer[0]; |
| |
| return true; |
| } |
| |
| bool NormalizeOffsets(Font* font) { |
| uint32_t offset = 12 + 16 * font->num_tables; |
| for (auto& i : font->tables) { |
| i.second.offset = offset; |
| offset += Round4(i.second.length); |
| } |
| return true; |
| } |
| |
| namespace { |
| |
| uint32_t ComputeChecksum(const uint8_t* buf, size_t size) { |
| uint32_t checksum = 0; |
| for (size_t i = 0; i < size; i += 4) { |
| checksum += ((buf[i] << 24) | |
| (buf[i + 1] << 16) | |
| (buf[i + 2] << 8) | |
| buf[i + 3]); |
| } |
| return checksum; |
| } |
| |
| uint32_t ComputeHeaderChecksum(const Font& font) { |
| uint32_t checksum = font.flavor; |
| uint16_t max_pow2 = font.num_tables ? Log2Floor(font.num_tables) : 0; |
| uint16_t search_range = max_pow2 ? 1 << (max_pow2 + 4) : 0; |
| uint16_t range_shift = (font.num_tables << 4) - search_range; |
| checksum += (font.num_tables << 16 | search_range); |
| checksum += (max_pow2 << 16 | range_shift); |
| for (const auto& i : font.tables) { |
| checksum += i.second.tag; |
| checksum += i.second.checksum; |
| checksum += i.second.offset; |
| checksum += i.second.length; |
| } |
| return checksum; |
| } |
| |
| } // namespace |
| |
| bool FixChecksums(Font* font) { |
| Font::Table* head_table = font->FindTable(kHeadTableTag); |
| if (head_table == NULL || head_table->length < 12) { |
| return FONT_COMPRESSION_FAILURE(); |
| } |
| head_table->buffer.resize(Round4(head_table->length)); |
| uint8_t* head_buf = &head_table->buffer[0]; |
| memcpy(head_buf, head_table->data, Round4(head_table->length)); |
| head_table->data = head_buf; |
| size_t offset = 8; |
| StoreU32(0, &offset, head_buf); |
| uint32_t file_checksum = 0; |
| for (auto& i : font->tables) { |
| Font::Table* table = &i.second; |
| table->checksum = ComputeChecksum(table->data, table->length); |
| file_checksum += table->checksum; |
| } |
| file_checksum += ComputeHeaderChecksum(*font); |
| offset = 8; |
| StoreU32(0xb1b0afba - file_checksum, &offset, head_buf); |
| return true; |
| } |
| |
| bool NormalizeFont(Font* font) { |
| return (RemoveDigitalSignature(font) && |
| NormalizeGlyphs(font) && |
| NormalizeOffsets(font) && |
| FixChecksums(font)); |
| } |
| |
| } // namespace woff2 |