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 "gasp.h"
michael@0: 
michael@0: // gasp - Grid-fitting And Scan-conversion Procedure
michael@0: // http://www.microsoft.com/typography/otspec/gasp.htm
michael@0: 
michael@0: #define TABLE_NAME "gasp"
michael@0: 
michael@0: #define DROP_THIS_TABLE \
michael@0:   do { \
michael@0:     delete file->gasp; \
michael@0:     file->gasp = 0; \
michael@0:     OTS_FAILURE_MSG("Table discarded"); \
michael@0:   } while (0)
michael@0: 
michael@0: namespace ots {
michael@0: 
michael@0: bool ots_gasp_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
michael@0:   Buffer table(data, length);
michael@0: 
michael@0:   OpenTypeGASP *gasp = new OpenTypeGASP;
michael@0:   file->gasp = gasp;
michael@0: 
michael@0:   uint16_t num_ranges = 0;
michael@0:   if (!table.ReadU16(&gasp->version) ||
michael@0:       !table.ReadU16(&num_ranges)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read table header");
michael@0:   }
michael@0: 
michael@0:   if (gasp->version > 1) {
michael@0:     // Lots of Linux fonts have bad version numbers...
michael@0:     OTS_WARNING("bad version: %u", gasp->version);
michael@0:     DROP_THIS_TABLE;
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   if (num_ranges == 0) {
michael@0:     OTS_WARNING("num_ranges is zero");
michael@0:     DROP_THIS_TABLE;
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   gasp->gasp_ranges.reserve(num_ranges);
michael@0:   for (unsigned i = 0; i < num_ranges; ++i) {
michael@0:     uint16_t max_ppem = 0;
michael@0:     uint16_t behavior = 0;
michael@0:     if (!table.ReadU16(&max_ppem) ||
michael@0:         !table.ReadU16(&behavior)) {
michael@0:       return OTS_FAILURE_MSG("Failed to read subrange %d", i);
michael@0:     }
michael@0:     if ((i > 0) && (gasp->gasp_ranges[i - 1].first >= max_ppem)) {
michael@0:       // The records in the gaspRange[] array must be sorted in order of
michael@0:       // increasing rangeMaxPPEM value.
michael@0:       OTS_WARNING("ranges are not sorted");
michael@0:       DROP_THIS_TABLE;
michael@0:       return true;
michael@0:     }
michael@0:     if ((i == num_ranges - 1u) &&  // never underflow.
michael@0:         (max_ppem != 0xffffu)) {
michael@0:       OTS_WARNING("The last record should be 0xFFFF as a sentinel value "
michael@0:                   "for rangeMaxPPEM");
michael@0:       DROP_THIS_TABLE;
michael@0:       return true;
michael@0:     }
michael@0: 
michael@0:     if (behavior >> 8) {
michael@0:       OTS_WARNING("undefined bits are used: %x", behavior);
michael@0:       // mask undefined bits.
michael@0:       behavior &= 0x000fu;
michael@0:     }
michael@0: 
michael@0:     if (gasp->version == 0 && (behavior >> 2) != 0) {
michael@0:       OTS_WARNING("changed the version number to 1");
michael@0:       gasp->version = 1;
michael@0:     }
michael@0: 
michael@0:     gasp->gasp_ranges.push_back(std::make_pair(max_ppem, behavior));
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool ots_gasp_should_serialise(OpenTypeFile *file) {
michael@0:   return file->gasp != NULL;
michael@0: }
michael@0: 
michael@0: bool ots_gasp_serialise(OTSStream *out, OpenTypeFile *file) {
michael@0:   const OpenTypeGASP *gasp = file->gasp;
michael@0: 
michael@0:   if (!out->WriteU16(gasp->version) ||
michael@0:       !out->WriteU16(gasp->gasp_ranges.size())) {
michael@0:     return OTS_FAILURE_MSG("failed to write gasp header");
michael@0:   }
michael@0: 
michael@0:   for (unsigned i = 0; i < gasp->gasp_ranges.size(); ++i) {
michael@0:     if (!out->WriteU16(gasp->gasp_ranges[i].first) ||
michael@0:         !out->WriteU16(gasp->gasp_ranges[i].second)) {
michael@0:       return OTS_FAILURE_MSG("Failed to write gasp subtable %d", i);
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: void ots_gasp_free(OpenTypeFile *file) {
michael@0:   delete file->gasp;
michael@0: }
michael@0: 
michael@0: }  // namespace ots