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 "vdmx.h"
michael@0: 
michael@0: // VDMX - Vertical Device Metrics
michael@0: // http://www.microsoft.com/typography/otspec/vdmx.htm
michael@0: 
michael@0: #define TABLE_NAME "VDMX"
michael@0: 
michael@0: #define DROP_THIS_TABLE \
michael@0:   do { \
michael@0:     delete file->vdmx; \
michael@0:     file->vdmx = 0; \
michael@0:     OTS_FAILURE_MSG("Table discarded"); \
michael@0:   } while (0)
michael@0: 
michael@0: namespace ots {
michael@0: 
michael@0: bool ots_vdmx_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
michael@0:   Buffer table(data, length);
michael@0:   file->vdmx = new OpenTypeVDMX;
michael@0:   OpenTypeVDMX * const vdmx = file->vdmx;
michael@0: 
michael@0:   if (!table.ReadU16(&vdmx->version) ||
michael@0:       !table.ReadU16(&vdmx->num_recs) ||
michael@0:       !table.ReadU16(&vdmx->num_ratios)) {
michael@0:     return OTS_FAILURE_MSG("Failed to read table header");
michael@0:   }
michael@0: 
michael@0:   if (vdmx->version > 1) {
michael@0:     OTS_WARNING("bad version: %u", vdmx->version);
michael@0:     DROP_THIS_TABLE;
michael@0:     return true;  // continue transcoding
michael@0:   }
michael@0: 
michael@0:   vdmx->rat_ranges.reserve(vdmx->num_ratios);
michael@0:   for (unsigned i = 0; i < vdmx->num_ratios; ++i) {
michael@0:     OpenTypeVDMXRatioRecord rec;
michael@0: 
michael@0:     if (!table.ReadU8(&rec.charset) ||
michael@0:         !table.ReadU8(&rec.x_ratio) ||
michael@0:         !table.ReadU8(&rec.y_start_ratio) ||
michael@0:         !table.ReadU8(&rec.y_end_ratio)) {
michael@0:       return OTS_FAILURE_MSG("Failed to read ratio header %d", i);
michael@0:     }
michael@0: 
michael@0:     if (rec.charset > 1) {
michael@0:       OTS_WARNING("bad charset: %u", rec.charset);
michael@0:       DROP_THIS_TABLE;
michael@0:       return true;
michael@0:     }
michael@0: 
michael@0:     if (rec.y_start_ratio > rec.y_end_ratio) {
michael@0:       OTS_WARNING("bad y ratio");
michael@0:       DROP_THIS_TABLE;
michael@0:       return true;
michael@0:     }
michael@0: 
michael@0:     // All values set to zero signal the default grouping to use;
michael@0:     // if present, this must be the last Ratio group in the table.
michael@0:     if ((i < vdmx->num_ratios - 1u) &&
michael@0:         (rec.x_ratio == 0) &&
michael@0:         (rec.y_start_ratio == 0) &&
michael@0:         (rec.y_end_ratio == 0)) {
michael@0:       // workaround for fonts which have 2 or more {0, 0, 0} terminators.
michael@0:       OTS_WARNING("superfluous terminator found");
michael@0:       DROP_THIS_TABLE;
michael@0:       return true;
michael@0:     }
michael@0: 
michael@0:     vdmx->rat_ranges.push_back(rec);
michael@0:   }
michael@0: 
michael@0:   vdmx->offsets.reserve(vdmx->num_ratios);
michael@0:   const size_t current_offset = table.offset();
michael@0:   // current_offset is less than (2 bytes * 3) + (4 bytes * USHRT_MAX) = 256k.
michael@0:   for (unsigned i = 0; i < vdmx->num_ratios; ++i) {
michael@0:     uint16_t offset;
michael@0:     if (!table.ReadU16(&offset)) {
michael@0:       return OTS_FAILURE_MSG("Failed to read ratio offset %d", i);
michael@0:     }
michael@0:     if (current_offset + offset >= length) {  // thus doesn't overflow.
michael@0:       return OTS_FAILURE_MSG("Bad ratio offset %d for ration %d", offset, i);
michael@0:     }
michael@0: 
michael@0:     vdmx->offsets.push_back(offset);
michael@0:   }
michael@0: 
michael@0:   vdmx->groups.reserve(vdmx->num_recs);
michael@0:   for (unsigned i = 0; i < vdmx->num_recs; ++i) {
michael@0:     OpenTypeVDMXGroup group;
michael@0:     if (!table.ReadU16(&group.recs) ||
michael@0:         !table.ReadU8(&group.startsz) ||
michael@0:         !table.ReadU8(&group.endsz)) {
michael@0:       return OTS_FAILURE_MSG("Failed to read record header %d", i);
michael@0:     }
michael@0:     group.entries.reserve(group.recs);
michael@0:     for (unsigned j = 0; j < group.recs; ++j) {
michael@0:       OpenTypeVDMXVTable vt;
michael@0:       if (!table.ReadU16(&vt.y_pel_height) ||
michael@0:           !table.ReadS16(&vt.y_max) ||
michael@0:           !table.ReadS16(&vt.y_min)) {
michael@0:         return OTS_FAILURE_MSG("Failed to read reacord %d group %d", i, j);
michael@0:       }
michael@0:       if (vt.y_max < vt.y_min) {
michael@0:         OTS_WARNING("bad y min/max");
michael@0:         DROP_THIS_TABLE;
michael@0:         return true;
michael@0:       }
michael@0: 
michael@0:       // This table must appear in sorted order (sorted by yPelHeight),
michael@0:       // but need not be continuous.
michael@0:       if ((j != 0) && (group.entries[j - 1].y_pel_height >= vt.y_pel_height)) {
michael@0:         OTS_WARNING("the table is not sorted");
michael@0:         DROP_THIS_TABLE;
michael@0:         return true;
michael@0:       }
michael@0: 
michael@0:       group.entries.push_back(vt);
michael@0:     }
michael@0:     vdmx->groups.push_back(group);
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: bool ots_vdmx_should_serialise(OpenTypeFile *file) {
michael@0:   if (!file->glyf) return false;  // this table is not for CFF fonts.
michael@0:   return file->vdmx != NULL;
michael@0: }
michael@0: 
michael@0: bool ots_vdmx_serialise(OTSStream *out, OpenTypeFile *file) {
michael@0:   OpenTypeVDMX * const vdmx = file->vdmx;
michael@0: 
michael@0:   if (!out->WriteU16(vdmx->version) ||
michael@0:       !out->WriteU16(vdmx->num_recs) ||
michael@0:       !out->WriteU16(vdmx->num_ratios)) {
michael@0:     return OTS_FAILURE_MSG("Failed to write table header");
michael@0:   }
michael@0: 
michael@0:   for (unsigned i = 0; i < vdmx->rat_ranges.size(); ++i) {
michael@0:     const OpenTypeVDMXRatioRecord& rec = vdmx->rat_ranges[i];
michael@0:     if (!out->Write(&rec.charset, 1) ||
michael@0:         !out->Write(&rec.x_ratio, 1) ||
michael@0:         !out->Write(&rec.y_start_ratio, 1) ||
michael@0:         !out->Write(&rec.y_end_ratio, 1)) {
michael@0:       return OTS_FAILURE_MSG("Failed to write ratio %d", i);
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   for (unsigned i = 0; i < vdmx->offsets.size(); ++i) {
michael@0:     if (!out->WriteU16(vdmx->offsets[i])) {
michael@0:       return OTS_FAILURE_MSG("Failed to write ratio offset %d", i);
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   for (unsigned i = 0; i < vdmx->groups.size(); ++i) {
michael@0:     const OpenTypeVDMXGroup& group = vdmx->groups[i];
michael@0:     if (!out->WriteU16(group.recs) ||
michael@0:         !out->Write(&group.startsz, 1) ||
michael@0:         !out->Write(&group.endsz, 1)) {
michael@0:       return OTS_FAILURE_MSG("Failed to write group %d", i);
michael@0:     }
michael@0:     for (unsigned j = 0; j < group.entries.size(); ++j) {
michael@0:       const OpenTypeVDMXVTable& vt = group.entries[j];
michael@0:       if (!out->WriteU16(vt.y_pel_height) ||
michael@0:           !out->WriteS16(vt.y_max) ||
michael@0:           !out->WriteS16(vt.y_min)) {
michael@0:         return OTS_FAILURE_MSG("Failed to write group %d entry %d", i, j);
michael@0:       }
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: void ots_vdmx_free(OpenTypeFile *file) {
michael@0:   delete file->vdmx;
michael@0: }
michael@0: 
michael@0: }  // namespace ots