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-rw-r--r--gfx/ots/src/loca.cc109
1 files changed, 109 insertions, 0 deletions
diff --git a/gfx/ots/src/loca.cc b/gfx/ots/src/loca.cc
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+++ b/gfx/ots/src/loca.cc
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+// 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(Font *font, 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;
+ font->loca = loca;
+
+ if (!font->maxp || !font->head) {
+ return OTS_FAILURE_MSG("maxp or head tables missing from font, needed by loca");
+ }
+
+ const unsigned num_glyphs = font->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 (font->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(Font *font) {
+ return font->loca != NULL;
+}
+
+bool ots_loca_serialise(OTSStream *out, Font *font) {
+ const OpenTypeLOCA *loca = font->loca;
+ const OpenTypeHEAD *head = font->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_reuse(Font *font, Font *other) {
+ font->loca = other->loca;
+ font->loca_reused = true;
+}
+
+void ots_loca_free(Font *font) {
+ delete font->loca;
+}
+
+} // namespace ots
+
+#undef TABLE_NAME