1 files changed, 93 insertions, 0 deletions
diff --git a/gfx/ots/src/loca.cc b/gfx/ots/src/loca.cc
new file mode 100644
index 0000000000..4f322027d6
--- /dev/null
+++ b/gfx/ots/src/loca.cc
@@ -0,0 +1,93 @@
+// Copyright (c) 2009-2017 The OTS 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
+
+namespace ots {
+
+bool OpenTypeLOCA::Parse(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.
+
+  OpenTypeMAXP *maxp = static_cast<OpenTypeMAXP*>(
+      GetFont()->GetTypedTable(OTS_TAG_MAXP));
+  OpenTypeHEAD *head = static_cast<OpenTypeHEAD*>(
+      GetFont()->GetTypedTable(OTS_TAG_HEAD));
+  if (!maxp || !head) {
+    return Error("Required maxp or head tables are missing");
+  }
+
+  const unsigned num_glyphs = maxp->num_glyphs;
+  unsigned last_offset = 0;
+  this->offsets.resize(num_glyphs + 1);
+  // maxp->num_glyphs is uint16_t, thus the addition never overflows.
+
+  if (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 Error("Failed to read offset for glyph %d", i);
+      }
+      if (offset < last_offset) {
+        return Error("Out of order offset %d < %d for glyph %d", offset, last_offset, i);
+      }
+      last_offset = offset;
+      this->offsets[i] = offset * 2;
+    }
+  } else {
+    for (unsigned i = 0; i <= num_glyphs; ++i) {
+      uint32_t offset = 0;
+      if (!table.ReadU32(&offset)) {
+        return Error("Failed to read offset for glyph %d", i);
+      }
+      if (offset < last_offset) {
+        return Error("Out of order offset %d < %d for glyph %d", offset, last_offset, i);
+      }
+      last_offset = offset;
+      this->offsets[i] = offset;
+    }
+  }
+
+  return true;
+}
+
+bool OpenTypeLOCA::Serialize(OTSStream *out) {
+  OpenTypeHEAD *head = static_cast<OpenTypeHEAD*>(
+      GetFont()->GetTypedTable(OTS_TAG_HEAD));
+
+  if (!head) {
+    return Error("Required head table is missing");
+  }
+
+  if (head->index_to_loc_format == 0) {
+    for (unsigned i = 0; i < this->offsets.size(); ++i) {
+      const uint16_t offset = static_cast<uint16_t>(this->offsets[i] >> 1);
+      if ((offset != (this->offsets[i] >> 1)) ||
+          !out->WriteU16(offset)) {
+        return Error("Failed to write glyph offset for glyph %d", i);
+      }
+    }
+  } else {
+    for (unsigned i = 0; i < this->offsets.size(); ++i) {
+      if (!out->WriteU32(this->offsets[i])) {
+        return Error("Failed to write glyph offset for glyph %d", i);
+      }
+    }
+  }
+
+  return true;
+}
+
+}  // namespace ots