michael@0: // Copyright (c) 2009 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: #include "head.h"
michael@0: 
michael@0: #include <cstring>
michael@0: 
michael@0: // head - Font Header
michael@0: // http://www.microsoft.com/typography/otspec/head.htm
michael@0: 
michael@0: #define TABLE_NAME "head"
michael@0: 
michael@0: namespace ots {
michael@0: 
michael@0: bool ots_head_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
michael@0:   Buffer table(data, length);
michael@0:   file->head = new OpenTypeHEAD;
michael@0: 
michael@0:   uint32_t version = 0;
michael@0:   if (!table.ReadU32(&version) ||
michael@0:       !table.ReadU32(&file->head->revision)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read head header");
michael@0:   }
michael@0: 
michael@0:   if (version >> 16 != 1) {
michael@0:     return OTS_FAILURE_MSG("Bad head table version of %d", version);
michael@0:   }
michael@0: 
michael@0:   // Skip the checksum adjustment
michael@0:   if (!table.Skip(4)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read checksum");
michael@0:   }
michael@0: 
michael@0:   uint32_t magic;
michael@0:   if (!table.ReadTag(&magic) ||
michael@0:       std::memcmp(&magic, "\x5F\x0F\x3C\xF5", 4)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read font magic number");
michael@0:   }
michael@0: 
michael@0:   if (!table.ReadU16(&file->head->flags)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read head flags");
michael@0:   }
michael@0: 
michael@0:   // We allow bits 0..4, 11..13
michael@0:   file->head->flags &= 0x381f;
michael@0: 
michael@0:   if (!table.ReadU16(&file->head->ppem)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read pixels per em");
michael@0:   }
michael@0: 
michael@0:   // ppem must be in range
michael@0:   if (file->head->ppem < 16 ||
michael@0:       file->head->ppem > 16384) {
michael@0:     return OTS_FAILURE_MSG("Bad ppm of %d", file->head->ppem);
michael@0:   }
michael@0: 
michael@0:   // ppem must be a power of two
michael@0: #if 0
michael@0:   // We don't call ots_failure() for now since lots of TrueType fonts are
michael@0:   // not following this rule. Putting OTS_WARNING here is too noisy.
michael@0:   if ((file->head->ppem - 1) & file->head->ppem) {
michael@0:     return OTS_FAILURE_MSG("ppm not a power of two: %d", file->head->ppem);
michael@0:   }
michael@0: #endif
michael@0: 
michael@0:   if (!table.ReadR64(&file->head->created) ||
michael@0:       !table.ReadR64(&file->head->modified)) {
michael@0:     return OTS_FAILURE_MSG("Can't read font dates");
michael@0:   }
michael@0: 
michael@0:   if (!table.ReadS16(&file->head->xmin) ||
michael@0:       !table.ReadS16(&file->head->ymin) ||
michael@0:       !table.ReadS16(&file->head->xmax) ||
michael@0:       !table.ReadS16(&file->head->ymax)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read font bounding box");
michael@0:   }
michael@0: 
michael@0:   if (file->head->xmin > file->head->xmax) {
michael@0:     return OTS_FAILURE_MSG("Bad x dimension in the font bounding box (%d, %d)", file->head->xmin, file->head->xmax);
michael@0:   }
michael@0:   if (file->head->ymin > file->head->ymax) {
michael@0:     return OTS_FAILURE_MSG("Bad y dimension in the font bounding box (%d, %d)", file->head->ymin, file->head->ymax);
michael@0:   }
michael@0: 
michael@0:   if (!table.ReadU16(&file->head->mac_style)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read font style");
michael@0:   }
michael@0: 
michael@0:   // We allow bits 0..6
michael@0:   file->head->mac_style &= 0x7f;
michael@0: 
michael@0:   if (!table.ReadU16(&file->head->min_ppem)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read font minimum ppm");
michael@0:   }
michael@0: 
michael@0:   // We don't care about the font direction hint
michael@0:   if (!table.Skip(2)) {
michael@0:     return OTS_FAILURE_MSG("Failed to skip font direction hint");
michael@0:   }
michael@0: 
michael@0:   if (!table.ReadS16(&file->head->index_to_loc_format)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read index to loc format");
michael@0:   }
michael@0:   if (file->head->index_to_loc_format < 0 ||
michael@0:       file->head->index_to_loc_format > 1) {
michael@0:     return OTS_FAILURE_MSG("Bad index to loc format %d", file->head->index_to_loc_format);
michael@0:   }
michael@0: 
michael@0:   int16_t glyph_data_format;
michael@0:   if (!table.ReadS16(&glyph_data_format) ||
michael@0:       glyph_data_format) {
michael@0:     return OTS_FAILURE_MSG("Failed to read glyph data format");
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool ots_head_should_serialise(OpenTypeFile *file) {
michael@0:   return file->head != NULL;
michael@0: }
michael@0: 
michael@0: bool ots_head_serialise(OTSStream *out, OpenTypeFile *file) {
michael@0:   if (!out->WriteU32(0x00010000) ||
michael@0:       !out->WriteU32(file->head->revision) ||
michael@0:       !out->WriteU32(0) ||  // check sum not filled in yet
michael@0:       !out->WriteU32(0x5F0F3CF5) ||
michael@0:       !out->WriteU16(file->head->flags) ||
michael@0:       !out->WriteU16(file->head->ppem) ||
michael@0:       !out->WriteR64(file->head->created) ||
michael@0:       !out->WriteR64(file->head->modified) ||
michael@0:       !out->WriteS16(file->head->xmin) ||
michael@0:       !out->WriteS16(file->head->ymin) ||
michael@0:       !out->WriteS16(file->head->xmax) ||
michael@0:       !out->WriteS16(file->head->ymax) ||
michael@0:       !out->WriteU16(file->head->mac_style) ||
michael@0:       !out->WriteU16(file->head->min_ppem) ||
michael@0:       !out->WriteS16(2) ||
michael@0:       !out->WriteS16(file->head->index_to_loc_format) ||
michael@0:       !out->WriteS16(0)) {
michael@0:     return OTS_FAILURE_MSG("Failed to write head table");
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: void ots_head_free(OpenTypeFile *file) {
michael@0:   delete file->head;
michael@0: }
michael@0: 
michael@0: }  // namespace