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-rw-r--r--gfx/ots/src/loca.cc93
1 files changed, 93 insertions, 0 deletions
diff --git a/gfx/ots/src/loca.cc b/gfx/ots/src/loca.cc
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+// 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