Index: src/kern.cc |
=================================================================== |
--- src/kern.cc (revision 0) |
+++ src/kern.cc (revision 0) |
@@ -0,0 +1,196 @@ |
+// 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 "kern.h" |
+ |
+// kern - Kerning |
+// http://www.microsoft.com/opentype/otspec/kern.htm |
+ |
+#define DROP_THIS_TABLE \ |
+ do { delete file->kern; file->kern = 0; } while (0) |
+ |
+namespace ots { |
+ |
+bool ots_kern_parse(OpenTypeFile *file, const uint8_t *data, size_t length) { |
+ Buffer table(data, length); |
+ |
+ OpenTypeKERN *kern = new OpenTypeKERN; |
+ file->kern = kern; |
+ |
+ uint16_t num_tables = 0; |
+ if (!table.ReadU16(&kern->version) || |
+ !table.ReadU16(&num_tables)) { |
+ return OTS_FAILURE(); |
+ } |
+ |
+ if (kern->version > 0) { |
+ DROP_THIS_TABLE; |
+ return true; |
+ } |
+ |
+ if (num_tables == 0) { |
+ OTS_WARNING("num_tables is zero"); |
+ DROP_THIS_TABLE; |
+ return true; |
+ } |
+ |
+ kern->subtables.reserve(num_tables); |
+ for (unsigned i = 0; i < num_tables; ++i) { |
+ OpenTypeKERNFormat0 subtable; |
+ uint16_t sub_length = 0; |
+ |
+ if (!table.ReadU16(&subtable.version) || |
+ !table.ReadU16(&sub_length)) { |
+ return OTS_FAILURE(); |
+ } |
+ |
+ if (subtable.version > 0) { |
+ OTS_WARNING("Bad subtable version: %d", subtable.version); |
+ continue; |
+ } |
+ |
+ const size_t current_offset = table.offset(); |
+ if (current_offset - 4 + sub_length > length) { |
+ return OTS_FAILURE(); |
+ } |
+ |
+ if (!table.ReadU16(&subtable.coverage)) { |
+ return OTS_FAILURE(); |
+ } |
+ |
+ if (!(subtable.coverage & 0x1)) { |
+ OTS_WARNING( |
+ "We don't support vertical data as the renderer doesn't support it."); |
+ continue; |
+ } |
+ if (subtable.coverage & 0xF0) { |
+ OTS_WARNING("Reserved fields should zero-filled."); |
+ DROP_THIS_TABLE; |
+ return true; |
+ } |
+ const uint32_t format = (subtable.coverage & 0xFF00) >> 8; |
+ if (format != 0) { |
+ OTS_WARNING("Format %d is not supported.", format); |
+ continue; |
+ } |
+ |
+ // Parse the format 0 field. |
+ uint16_t num_pairs = 0; |
+ if (!table.ReadU16(&num_pairs) || |
+ !table.ReadU16(&subtable.search_range) || |
+ !table.ReadU16(&subtable.entry_selector) || |
+ !table.ReadU16(&subtable.range_shift)) { |
+ return OTS_FAILURE(); |
+ } |
+ |
+ if (!num_pairs) { |
+ OTS_WARNING("Zero length subtable is found."); |
+ DROP_THIS_TABLE; |
+ return true; |
+ } |
+ |
+ // Sanity checks for search_range, entry_selector, and range_shift. See the |
+ // comment in ots.cc for details. |
+ const size_t kFormat0PairSize = 6; // left, right, and value. 2 bytes each. |
+ if (num_pairs > (65536 / kFormat0PairSize)) { |
+ // Some fonts (e.g. calibri.ttf, pykes_peak_zero.ttf) have pairs >= 10923. |
+ OTS_WARNING("Too large subtable."); |
+ DROP_THIS_TABLE; |
+ return true; |
+ } |
+ unsigned max_pow2 = 0; |
+ while (1u << (max_pow2 + 1) <= num_pairs) { |
+ ++max_pow2; |
+ } |
+ const uint16_t expected_search_range = (1u << max_pow2) * kFormat0PairSize; |
+ if (subtable.search_range != expected_search_range) { |
+ OTS_WARNING("bad search range"); |
+ subtable.search_range = expected_search_range; |
+ } |
+ if (subtable.entry_selector != max_pow2) { |
+ return OTS_FAILURE(); |
+ } |
+ const uint32_t expected_range_shift |
+ = kFormat0PairSize * num_pairs - subtable.search_range; |
+ if (subtable.range_shift != expected_range_shift) { |
+ OTS_WARNING("bad range shift"); |
+ subtable.range_shift = expected_range_shift; |
+ } |
+ |
+ // Read kerning pairs. |
+ subtable.pairs.reserve(num_pairs); |
+ uint32_t last_pair = 0; |
+ for (unsigned j = 0; j < num_pairs; ++j) { |
+ OpenTypeKERNFormat0Pair kerning_pair; |
+ if (!table.ReadU16(&kerning_pair.left) || |
+ !table.ReadU16(&kerning_pair.right) || |
+ !table.ReadS16(&kerning_pair.value)) { |
+ return OTS_FAILURE(); |
+ } |
+ const uint32_t current_pair |
+ = (kerning_pair.left << 16) + kerning_pair.right; |
+ if (j != 0 && current_pair <= last_pair) { |
+ OTS_WARNING("Kerning pairs are not sorted."); |
+ // Many free fonts don't follow this rule, so we don't call OTS_FAILURE |
+ // in order to support these fonts. |
+ DROP_THIS_TABLE; |
+ return true; |
+ } |
+ last_pair = current_pair; |
+ subtable.pairs.push_back(kerning_pair); |
+ } |
+ |
+ kern->subtables.push_back(subtable); |
+ } |
+ |
+ if (!kern->subtables.size()) { |
+ OTS_WARNING("All subtables are removed."); |
+ DROP_THIS_TABLE; |
+ return true; |
+ } |
+ |
+ return true; |
+} |
+ |
+bool ots_kern_should_serialise(OpenTypeFile *file) { |
+ if (!file->glyf) return false; // this table is not for CFF fonts. |
+ return file->kern; |
+} |
+ |
+bool ots_kern_serialise(OTSStream *out, OpenTypeFile *file) { |
+ const OpenTypeKERN *kern = file->kern; |
+ |
+ if (!out->WriteU16(kern->version) || |
+ !out->WriteU16(kern->subtables.size())) { |
+ return OTS_FAILURE(); |
+ } |
+ |
+ for (unsigned i = 0; i < kern->subtables.size(); ++i) { |
+ const uint16_t length = 14 + (6 * kern->subtables[i].pairs.size()); |
+ if (!out->WriteU16(kern->subtables[i].version) || |
+ !out->WriteU16(length) || |
+ !out->WriteU16(kern->subtables[i].coverage) || |
+ !out->WriteU16(kern->subtables[i].pairs.size()) || |
+ !out->WriteU16(kern->subtables[i].search_range) || |
+ !out->WriteU16(kern->subtables[i].entry_selector) || |
+ !out->WriteU16(kern->subtables[i].range_shift)) { |
+ return OTS_FAILURE(); |
+ } |
+ for (unsigned j = 0; j < kern->subtables[i].pairs.size(); ++j) { |
+ if (!out->WriteU16(kern->subtables[i].pairs[j].left) || |
+ !out->WriteU16(kern->subtables[i].pairs[j].right) || |
+ !out->WriteS16(kern->subtables[i].pairs[j].value)) { |
+ return OTS_FAILURE(); |
+ } |
+ } |
+ } |
+ |
+ return true; |
+} |
+ |
+void ots_kern_free(OpenTypeFile *file) { |
+ delete file->kern; |
+} |
+ |
+} // namespace ots |