Updating OTS repo from https://github.com/khaledhosny/ots.git

third_party/ots/src/loca.cc

+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "loca.h"
+
+#include "head.h"
+#include "maxp.h"
+
+// loca - Index to Location
+// http://www.microsoft.com/typography/otspec/loca.htm
+
+#define TABLE_NAME "loca"
+
+namespace ots {
+
+bool ots_loca_parse(OpenTypeFile *file, const uint8_t *data, size_t length) {
+  Buffer table(data, length);
+
+  // We can't do anything useful in validating this data except to ensure that
+  // the values are monotonically increasing.
+
+  OpenTypeLOCA *loca = new OpenTypeLOCA;
+  file->loca = loca;
+
+  if (!file->maxp || !file->head) {
+    return OTS_FAILURE_MSG("maxp or head tables missing from font, needed by loca");
+  }
+
+  const unsigned num_glyphs = file->maxp->num_glyphs;
+  unsigned last_offset = 0;
+  loca->offsets.resize(num_glyphs + 1);
+  // maxp->num_glyphs is uint16_t, thus the addition never overflows.
+
+  if (file->head->index_to_loc_format == 0) {
+    // Note that the <= here (and below) is correct. There is one more offset
+    // than the number of glyphs in order to give the length of the final
+    // glyph.
+    for (unsigned i = 0; i <= num_glyphs; ++i) {
+      uint16_t offset = 0;
+      if (!table.ReadU16(&offset)) {
+        return OTS_FAILURE_MSG("Failed to read offset for glyph %d", i);
+      }
+      if (offset < last_offset) {
+        return OTS_FAILURE_MSG("Out of order offset %d < %d for glyph %d", offset, last_offset, i);
+      }
+      last_offset = offset;
+      loca->offsets[i] = offset * 2;
+    }
+  } else {
+    for (unsigned i = 0; i <= num_glyphs; ++i) {
+      uint32_t offset = 0;
+      if (!table.ReadU32(&offset)) {
+        return OTS_FAILURE_MSG("Failed to read offset for glyph %d", i);
+      }
+      if (offset < last_offset) {
+        return OTS_FAILURE_MSG("Out of order offset %d < %d for glyph %d", offset, last_offset, i);
+      }
+      last_offset = offset;
+      loca->offsets[i] = offset;
+    }
+  }
+
+  return true;
+}
+
+bool ots_loca_should_serialise(OpenTypeFile *file) {
+  return file->loca != NULL;
+}
+
+bool ots_loca_serialise(OTSStream *out, OpenTypeFile *file) {
+  const OpenTypeLOCA *loca = file->loca;
+  const OpenTypeHEAD *head = file->head;
+
+  if (!head) {
+    return OTS_FAILURE_MSG("Missing head table in font needed by loca");
+  }
+
+  if (head->index_to_loc_format == 0) {
+    for (unsigned i = 0; i < loca->offsets.size(); ++i) {
+      const uint16_t offset = static_cast<uint16_t>(loca->offsets[i] >> 1);
+      if ((offset != (loca->offsets[i] >> 1)) ||
+          !out->WriteU16(offset)) {
+        return OTS_FAILURE_MSG("Failed to write glyph offset for glyph %d", i);
+      }
+    }
+  } else {
+    for (unsigned i = 0; i < loca->offsets.size(); ++i) {
+      if (!out->WriteU32(loca->offsets[i])) {
+        return OTS_FAILURE_MSG("Failed to write glyph offset for glyph %d", i);
+      }
+    }
+  }
+
+  return true;
+}
+
+void ots_loca_free(OpenTypeFile *file) {
+  delete file->loca;
+}
+
+}  // namespace ots
+
+#undef TABLE_NAME