Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 177 insertions, 0 deletions

diff --git a/gfx/ots/src/kern.cc b/gfx/ots/src/kern.cc
new file mode 100644
index 0000000000..ec41dfb9c0
--- /dev/null
+++ b/gfx/ots/src/kern.cc
@@ -0,0 +1,177 @@
+// 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 "kern.h"
+
+// kern - Kerning
+// http://www.microsoft.com/typography/otspec/kern.htm
+
+namespace ots {
+
+bool OpenTypeKERN::Parse(const uint8_t *data, size_t length) {
+  Buffer table(data, length);
+
+  uint16_t num_tables = 0;
+  if (!table.ReadU16(&this->version) ||
+      !table.ReadU16(&num_tables)) {
+    return Error("Failed to read table header");
+  }
+
+  if (this->version > 0) {
+    return Drop("Unsupported table version: %d", this->version);
+  }
+
+  if (num_tables == 0) {
+    return Drop("nTables is zero");
+  }
+
+  this->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 Error("Failed to read subtable %d header", i);
+    }
+
+    if (subtable.version > 0) {
+      Warning("Ignoring subtable %d with unsupported version: %d",
+              i, subtable.version);
+      continue;
+    }
+
+    const size_t current_offset = table.offset();
+    if (current_offset - 4 + sub_length > length) {
+      return Error("Bad subtable %d offset %ld", i, current_offset);
+    }
+
+    if (!table.ReadU16(&subtable.coverage)) {
+      return Error("Failed to read subtable %d coverage", i);
+    }
+
+    if (!(subtable.coverage & 0x1)) {
+      Warning(
+          "We don't support vertical data as the renderer doesn't support it.");
+      continue;
+    }
+    if (subtable.coverage & 0xF0) {
+      return Drop("Reserved fields should be zero");
+    }
+    const uint32_t format = (subtable.coverage & 0xFF00) >> 8;
+    if (format != 0) {
+      Warning("Ignoring subtable %d with unsupported format: %d", i, 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 Error("Failed to read subtable %d format 0 fields", i);
+    }
+
+    if (!num_pairs) {
+      return Drop("Zero length subtable is found");
+    }
+
+    // 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.
+      return Drop("Too large subtable");
+    }
+    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) {
+      Warning("bad search range");
+      subtable.search_range = expected_search_range;
+    }
+    if (subtable.entry_selector != max_pow2) {
+      return Error("Bad subtable %d entry selector %d", i, subtable.entry_selector);
+    }
+    const uint16_t expected_range_shift =
+        kFormat0PairSize * num_pairs - subtable.search_range;
+    if (subtable.range_shift != expected_range_shift) {
+      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 Error("Failed to read subtable %d kerning pair %d", i, j);
+      }
+      const uint32_t current_pair
+          = (kerning_pair.left << 16) + kerning_pair.right;
+      if (j != 0 && current_pair <= last_pair) {
+        // Many free fonts don't follow this rule, so we don't call OTS_FAILURE
+        // in order to support these fonts.
+        return Drop("Kerning pairs are not sorted");
+      }
+      last_pair = current_pair;
+      subtable.pairs.push_back(kerning_pair);
+    }
+
+    this->subtables.push_back(subtable);
+  }
+
+  if (!this->subtables.size()) {
+    return Drop("All subtables were removed");
+  }
+
+  return true;
+}
+
+bool OpenTypeKERN::Serialize(OTSStream *out) {
+  const uint16_t num_subtables = static_cast<uint16_t>(this->subtables.size());
+  if (num_subtables != this->subtables.size() ||
+      !out->WriteU16(this->version) ||
+      !out->WriteU16(num_subtables)) {
+    return Error("Failed to write kern table header");
+  }
+
+  for (uint16_t i = 0; i < num_subtables; ++i) {
+    const size_t length = 14 + (6 * this->subtables[i].pairs.size());
+    if (length > std::numeric_limits<uint16_t>::max() ||
+        !out->WriteU16(this->subtables[i].version) ||
+        !out->WriteU16(static_cast<uint16_t>(length)) ||
+        !out->WriteU16(this->subtables[i].coverage) ||
+        !out->WriteU16(
+            static_cast<uint16_t>(this->subtables[i].pairs.size())) ||
+        !out->WriteU16(this->subtables[i].search_range) ||
+        !out->WriteU16(this->subtables[i].entry_selector) ||
+        !out->WriteU16(this->subtables[i].range_shift)) {
+      return Error("Failed to write kern subtable %d", i);
+    }
+    for (unsigned j = 0; j < this->subtables[i].pairs.size(); ++j) {
+      if (!out->WriteU16(this->subtables[i].pairs[j].left) ||
+          !out->WriteU16(this->subtables[i].pairs[j].right) ||
+          !out->WriteS16(this->subtables[i].pairs[j].value)) {
+        return Error("Failed to write kern pair %d for subtable %d", j, i);
+      }
+    }
+  }
+
+  return true;
+}
+
+bool OpenTypeKERN::ShouldSerialize() {
+  return Table::ShouldSerialize() &&
+         // this table is not for CFF fonts.
+         GetFont()->GetTable(OTS_TAG_GLYF) != NULL;
+}
+
+}  // namespace ots