mirror of
https://github.com/gnif/LookingGlass.git
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120 lines
3.3 KiB
C
120 lines
3.3 KiB
C
/**
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* Looking Glass
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* Copyright © 2017-2026 The Looking Glass Authors
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* https://looking-glass.io
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc., 59
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* Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "font.h"
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#include <limits.h>
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#include <stdint.h>
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#if defined(__GNUC__)
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wunused-function"
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#endif
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#define STBTT_STATIC
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#define STB_TRUETYPE_IMPLEMENTATION
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#include "repos/gui/cimgui/imgui/imstb_truetype.h"
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#if defined(__GNUC__)
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#pragma GCC diagnostic pop
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#endif
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static uint16_t font_readU16(const unsigned char * data)
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{
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return (uint16_t)(((uint16_t)data[0] << 8) | data[1]);
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}
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static uint32_t font_readU32(const unsigned char * data)
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{
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return
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((uint32_t)data[0] << 24) |
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((uint32_t)data[1] << 16) |
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((uint32_t)data[2] << 8) |
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(uint32_t)data[3];
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}
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static bool font_getSfntOffset(const unsigned char * data, size_t size,
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int fontIndex, size_t * offset)
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{
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if (!data || size < 12 || size > INT_MAX || fontIndex < 0)
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return false;
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size_t fontOffset = 0;
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const uint32_t signature = font_readU32(data);
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switch (signature)
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{
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case 0x00010000: // TrueType 1.0
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case 0x74727565: // true
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case 0x74797031: // typ1
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case 0x4F54544F: // OTTO
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if (fontIndex != 0)
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return false;
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break;
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case 0x74746366: // ttcf
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{
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const uint32_t version = font_readU32(data + 4);
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const uint32_t fontCount = font_readU32(data + 8);
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if ((version != 0x00010000 && version != 0x00020000) ||
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(uint32_t)fontIndex >= fontCount ||
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fontCount > (size - 12) / 4)
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return false;
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fontOffset = font_readU32(data + 12 + (size_t)fontIndex * 4);
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if (fontOffset > size - 12 || fontOffset > INT_MAX)
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return false;
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break;
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}
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default:
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return false;
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}
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const uint16_t tableCount = font_readU16(data + fontOffset + 4);
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if (tableCount > (size - fontOffset - 12) / 16)
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return false;
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const unsigned char * table = data + fontOffset + 12;
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for (uint16_t i = 0; i < tableCount; ++i, table += 16)
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{
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const size_t tableOffset = font_readU32(table + 8);
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const size_t tableSize = font_readU32(table + 12);
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if (tableOffset > size || tableSize > size - tableOffset)
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return false;
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}
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*offset = fontOffset;
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return true;
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}
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bool font_isStbTruetypeCompatible(
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const void * data, size_t size, int fontIndex)
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{
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size_t checkedOffset;
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if (!font_getSfntOffset(data, size, fontIndex, &checkedOffset))
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return false;
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const int stbOffset =
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stbtt_GetFontOffsetForIndex((const unsigned char *)data, fontIndex);
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if (stbOffset < 0 || (size_t)stbOffset != checkedOffset)
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return false;
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stbtt_fontinfo info;
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return stbtt_InitFont(&info, data, stbOffset);
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}
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