/* * Copyright (C) 2015 Frederic Wang (fred.wang@free.fr). All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include "config.h" #include "OpenTypeCG.h" #include "OpenTypeTypes.h" namespace WebCore { namespace OpenType { #if PLATFORM(WIN) static const unsigned long kCTFontTableOS2 = 'OS/2'; #endif static inline short readShortFromTable(const UInt8* os2Data, CFIndex offset) { return *(reinterpret_cast<const OpenType::Int16*>(os2Data + offset)); } bool tryGetTypoMetrics(CTFontRef font, short& ascent, short& descent, short& lineGap) { bool result = false; if (auto os2Table = adoptCF(CTFontCopyTable(font, kCTFontTableOS2, kCTFontTableOptionNoOptions))) { // For the structure of the OS/2 table, see // https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6OS2.html const CFIndex fsSelectionOffset = 16 * 2 + 10 + 4 * 4 + 4 * 1; const CFIndex sTypoAscenderOffset = fsSelectionOffset + 3 * 2; const CFIndex sTypoDescenderOffset = sTypoAscenderOffset + 2; const CFIndex sTypoLineGapOffset = sTypoDescenderOffset + 2; if (CFDataGetLength(os2Table.get()) >= sTypoLineGapOffset + 2) { const UInt8* os2Data = CFDataGetBytePtr(os2Table.get()); // We test the use typo bit on the least significant byte of fsSelection. const UInt8 useTypoMetricsMask = 1 << 7; if (*(os2Data + fsSelectionOffset + 1) & useTypoMetricsMask) { ascent = readShortFromTable(os2Data, sTypoAscenderOffset); descent = readShortFromTable(os2Data, sTypoDescenderOffset); lineGap = readShortFromTable(os2Data, sTypoLineGapOffset); result = true; } } } return result; } } // namespace OpenType } // namespace WebCore