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 "ltsh.h"
michael@0: 
michael@0: #include "maxp.h"
michael@0: 
michael@0: // LTSH - Linear Threshold
michael@0: // http://www.microsoft.com/typography/otspec/ltsh.htm
michael@0: 
michael@0: #define TABLE_NAME "LTSH"
michael@0: 
michael@0: #define DROP_THIS_TABLE \
michael@0:   do { \
michael@0:     delete file->ltsh; \
michael@0:     file->ltsh = 0; \
michael@0:     OTS_FAILURE_MSG("Table discarded"); \
michael@0:   } while (0)
michael@0: 
michael@0: namespace ots {
michael@0: 
michael@0: bool ots_ltsh_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
michael@0:   Buffer table(data, length);
michael@0: 
michael@0:   if (!file->maxp) {
michael@0:     return OTS_FAILURE_MSG("Missing maxp table from font needed by ltsh");
michael@0:   }
michael@0: 
michael@0:   OpenTypeLTSH *ltsh = new OpenTypeLTSH;
michael@0:   file->ltsh = ltsh;
michael@0: 
michael@0:   uint16_t num_glyphs = 0;
michael@0:   if (!table.ReadU16(&ltsh->version) ||
michael@0:       !table.ReadU16(&num_glyphs)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read ltsh header");
michael@0:   }
michael@0: 
michael@0:   if (ltsh->version != 0) {
michael@0:     OTS_WARNING("bad version: %u", ltsh->version);
michael@0:     DROP_THIS_TABLE;
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   if (num_glyphs != file->maxp->num_glyphs) {
michael@0:     OTS_WARNING("bad num_glyphs: %u", num_glyphs);
michael@0:     DROP_THIS_TABLE;
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   ltsh->ypels.reserve(num_glyphs);
michael@0:   for (unsigned i = 0; i < num_glyphs; ++i) {
michael@0:     uint8_t pel = 0;
michael@0:     if (!table.ReadU8(&pel)) {
michael@0:       return OTS_FAILURE_MSG("Failed to read pixels for glyph %d", i);
michael@0:     }
michael@0:     ltsh->ypels.push_back(pel);
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool ots_ltsh_should_serialise(OpenTypeFile *file) {
michael@0:   if (!file->glyf) return false;  // this table is not for CFF fonts.
michael@0:   return file->ltsh != NULL;
michael@0: }
michael@0: 
michael@0: bool ots_ltsh_serialise(OTSStream *out, OpenTypeFile *file) {
michael@0:   const OpenTypeLTSH *ltsh = file->ltsh;
michael@0: 
michael@0:   if (!out->WriteU16(ltsh->version) ||
michael@0:       !out->WriteU16(ltsh->ypels.size())) {
michael@0:     return OTS_FAILURE_MSG("Failed to write pels size");
michael@0:   }
michael@0:   for (unsigned i = 0; i < ltsh->ypels.size(); ++i) {
michael@0:     if (!out->Write(&(ltsh->ypels[i]), 1)) {
michael@0:       return OTS_FAILURE_MSG("Failed to write pixel size for glyph %d", i);
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: void ots_ltsh_free(OpenTypeFile *file) {
michael@0:   delete file->ltsh;
michael@0: }
michael@0: 
michael@0: }  // namespace ots