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 "loca.h"
michael@0: 
michael@0: #include "head.h"
michael@0: #include "maxp.h"
michael@0: 
michael@0: // loca - Index to Location
michael@0: // http://www.microsoft.com/typography/otspec/loca.htm
michael@0: 
michael@0: #define TABLE_NAME "loca"
michael@0: 
michael@0: namespace ots {
michael@0: 
michael@0: bool ots_loca_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
michael@0:   Buffer table(data, length);
michael@0: 
michael@0:   // We can't do anything useful in validating this data except to ensure that
michael@0:   // the values are monotonically increasing.
michael@0: 
michael@0:   OpenTypeLOCA *loca = new OpenTypeLOCA;
michael@0:   file->loca = loca;
michael@0: 
michael@0:   if (!file->maxp || !file->head) {
michael@0:     return OTS_FAILURE_MSG("maxp or head tables missing from font, needed by loca");
michael@0:   }
michael@0: 
michael@0:   const unsigned num_glyphs = file->maxp->num_glyphs;
michael@0:   unsigned last_offset = 0;
michael@0:   loca->offsets.resize(num_glyphs + 1);
michael@0:   // maxp->num_glyphs is uint16_t, thus the addition never overflows.
michael@0: 
michael@0:   if (file->head->index_to_loc_format == 0) {
michael@0:     // Note that the <= here (and below) is correct. There is one more offset
michael@0:     // than the number of glyphs in order to give the length of the final
michael@0:     // glyph.
michael@0:     for (unsigned i = 0; i <= num_glyphs; ++i) {
michael@0:       uint16_t offset = 0;
michael@0:       if (!table.ReadU16(&offset)) {
michael@0:         return OTS_FAILURE_MSG("Failed to read offset for glyph %d", i);
michael@0:       }
michael@0:       if (offset < last_offset) {
michael@0:         return OTS_FAILURE_MSG("Out of order offset %d < %d for glyph %d", offset, last_offset, i);
michael@0:       }
michael@0:       last_offset = offset;
michael@0:       loca->offsets[i] = offset * 2;
michael@0:     }
michael@0:   } else {
michael@0:     for (unsigned i = 0; i <= num_glyphs; ++i) {
michael@0:       uint32_t offset = 0;
michael@0:       if (!table.ReadU32(&offset)) {
michael@0:         return OTS_FAILURE_MSG("Failed to read offset for glyph %d", i);
michael@0:       }
michael@0:       if (offset < last_offset) {
michael@0:         return OTS_FAILURE_MSG("Out of order offset %d < %d for glyph %d", offset, last_offset, i);
michael@0:       }
michael@0:       last_offset = offset;
michael@0:       loca->offsets[i] = offset;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool ots_loca_should_serialise(OpenTypeFile *file) {
michael@0:   return file->loca != NULL;
michael@0: }
michael@0: 
michael@0: bool ots_loca_serialise(OTSStream *out, OpenTypeFile *file) {
michael@0:   const OpenTypeLOCA *loca = file->loca;
michael@0:   const OpenTypeHEAD *head = file->head;
michael@0: 
michael@0:   if (!head) {
michael@0:     return OTS_FAILURE_MSG("Missing head table in font needed by loca");
michael@0:   }
michael@0: 
michael@0:   if (head->index_to_loc_format == 0) {
michael@0:     for (unsigned i = 0; i < loca->offsets.size(); ++i) {
michael@0:       if (!out->WriteU16(loca->offsets[i] >> 1)) {
michael@0:         return OTS_FAILURE_MSG("Failed to write glyph offset for glyph %d", i);
michael@0:       }
michael@0:     }
michael@0:   } else {
michael@0:     for (unsigned i = 0; i < loca->offsets.size(); ++i) {
michael@0:       if (!out->WriteU32(loca->offsets[i])) {
michael@0:         return OTS_FAILURE_MSG("Failed to write glyph offset for glyph %d", i);
michael@0:       }
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: void ots_loca_free(OpenTypeFile *file) {
michael@0:   delete file->loca;
michael@0: }
michael@0: 
michael@0: }  // namespace ots