1 files changed, 167 insertions, 0 deletions
diff --git a/gfx/graphite2/geckoextra/src/GraphiteExtra.cpp b/gfx/graphite2/geckoextra/src/GraphiteExtra.cpp
new file mode 100644
index 0000000000..b5c8802b15
--- /dev/null
+++ b/gfx/graphite2/geckoextra/src/GraphiteExtra.cpp
@@ -0,0 +1,167 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "graphite2/Font.h"
+#include "graphite2/Segment.h"
+#include "graphite2/GraphiteExtra.h"
+
+#include <stdlib.h>
+#include <memory>
+#include <limits>
+
+#define CHECK(cond, str) \
+  do {                   \
+    if (!(cond)) {       \
+      return false;      \
+    }                    \
+  } while (false)
+
+// High surrogates are in the range 0xD800 -- OxDBFF
+#define NS_IS_HIGH_SURROGATE(u) ((uint32_t(u) & 0xFFFFFC00) == 0xD800)
+// Low surrogates are in the range 0xDC00 -- 0xDFFF
+#define NS_IS_LOW_SURROGATE(u) ((uint32_t(u) & 0xFFFFFC00) == 0xDC00)
+
+#define IS_POWER_OF_2(n) (n & (n - 1)) == 0
+
+typedef gr_glyph_to_char_cluster Cluster;
+
+// returns whether successful
+static bool LoopThrough(gr_segment* aSegment, const uint32_t aLength,
+                        const uint32_t aGlyphCount, const char16_t* aText,
+                        uint32_t& aCIndex, Cluster* aClusters, uint16_t* aGids,
+                        float* aXLocs, float* aYLocs) {
+  // walk through the glyph slots and check which original character
+  // each is associated with
+  uint32_t gIndex = 0;  // glyph slot index
+  for (const gr_slot* slot = gr_seg_first_slot(aSegment); slot != nullptr;
+       slot = gr_slot_next_in_segment(slot), gIndex++) {
+    CHECK(gIndex < aGlyphCount, "iterating past glyphcount");
+    uint32_t before =
+        gr_cinfo_base(gr_seg_cinfo(aSegment, gr_slot_before(slot)));
+    uint32_t after = gr_cinfo_base(gr_seg_cinfo(aSegment, gr_slot_after(slot)));
+    aGids[gIndex] = gr_slot_gid(slot);
+    aXLocs[gIndex] = gr_slot_origin_X(slot);
+    aYLocs[gIndex] = gr_slot_origin_Y(slot);
+
+    // if this glyph has a "before" character index that precedes the
+    // current cluster's char index, we need to merge preceding
+    // aClusters until it gets included
+    while (before < aClusters[aCIndex].baseChar && aCIndex > 0) {
+      aClusters[aCIndex - 1].nChars += aClusters[aCIndex].nChars;
+      aClusters[aCIndex - 1].nGlyphs += aClusters[aCIndex].nGlyphs;
+      --aCIndex;
+    }
+
+    // if there's a gap between the current cluster's base character and
+    // this glyph's, extend the cluster to include the intervening chars
+    if (gr_slot_can_insert_before(slot) && aClusters[aCIndex].nChars &&
+        before >= aClusters[aCIndex].baseChar + aClusters[aCIndex].nChars) {
+      CHECK(aCIndex < aLength - 1, "aCIndex at end of word");
+      Cluster& c = aClusters[aCIndex + 1];
+      c.baseChar = aClusters[aCIndex].baseChar + aClusters[aCIndex].nChars;
+      c.nChars = before - c.baseChar;
+      c.baseGlyph = gIndex;
+      c.nGlyphs = 0;
+      ++aCIndex;
+    }
+
+    // increment cluster's glyph count to include current slot
+    CHECK(aCIndex < aLength, "aCIndex beyond word length");
+    ++aClusters[aCIndex].nGlyphs;
+
+    // bump |after| index if it falls in the middle of a surrogate pair
+    if (NS_IS_HIGH_SURROGATE(aText[after]) && after < aLength - 1 &&
+        NS_IS_LOW_SURROGATE(aText[after + 1])) {
+      after++;
+    }
+
+    // extend cluster if necessary to reach the glyph's "after" index
+    if (aClusters[aCIndex].baseChar + aClusters[aCIndex].nChars < after + 1) {
+      aClusters[aCIndex].nChars = after + 1 - aClusters[aCIndex].baseChar;
+    }
+  }
+
+  // Succeeded
+  return true;
+}
+
+static gr_glyph_to_char_association* calloc_glyph_to_char_association(
+    uint32_t aGlyphCount, uint32_t aLength) {
+  using Type1 = gr_glyph_to_char_association;
+  using Type2 = gr_glyph_to_char_cluster;
+  using Type3 = float;
+  using Type4 = float;
+  using Type5 = uint16_t;
+
+  // We are allocating memory in a pool. To avoid dealing with thorny alignment
+  // issues, we allocate from most to least aligned
+  static_assert(
+      alignof(Type1) >= alignof(Type2) && alignof(Type2) >= alignof(Type3) &&
+          alignof(Type3) >= alignof(Type4) && alignof(Type4) >= alignof(Type5),
+      "Unexpected alignments of types");
+
+  const uint64_t size1 = sizeof(Type1) * static_cast<uint64_t>(1);
+  const uint64_t size2 = sizeof(Type2) * static_cast<uint64_t>(aLength);
+  const uint64_t size3 = sizeof(Type3) * static_cast<uint64_t>(aGlyphCount);
+  const uint64_t size4 = sizeof(Type4) * static_cast<uint64_t>(aGlyphCount);
+  const uint64_t size5 = sizeof(Type5) * static_cast<uint64_t>(aGlyphCount);
+
+  uint64_t totalSize = size1 + size2 + size3 + size4 + size5;
+
+  if (totalSize > std::numeric_limits<uint32_t>::max()) {
+    // allocation request got too large
+    return nullptr;
+  }
+
+  char* const memoryPool = static_cast<char*>(calloc(1, totalSize));
+  if (!memoryPool) {
+    return nullptr;
+  }
+
+  char* currentPoolFront = memoryPool;
+
+  auto data = reinterpret_cast<Type1*>(currentPoolFront);
+  currentPoolFront += size1;
+  data->clusters = reinterpret_cast<Type2*>(currentPoolFront);
+  currentPoolFront += size2;
+  data->xLocs = reinterpret_cast<Type3*>(currentPoolFront);
+  currentPoolFront += size3;
+  data->yLocs = reinterpret_cast<Type4*>(currentPoolFront);
+  currentPoolFront += size4;
+  data->gids = reinterpret_cast<Type5*>(currentPoolFront);
+
+  return data;
+}
+
+// returns nullptr on failure and the glyph to char association on success
+gr_glyph_to_char_association* gr_get_glyph_to_char_association(
+    gr_segment* aSegment, uint32_t aLength, const char16_t* aText) {
+  uint32_t glyphCount = gr_seg_n_slots(aSegment);
+
+  gr_glyph_to_char_association* data =
+      calloc_glyph_to_char_association(glyphCount, aLength);
+  if (!data) {
+    return nullptr;
+  }
+
+  bool succeeded =
+      LoopThrough(aSegment, aLength, glyphCount, aText, data->cIndex,
+                  data->clusters, data->gids, data->xLocs, data->yLocs);
+  if (!succeeded) {
+    gr_free_char_association(data);
+    return nullptr;
+  }
+  return data;
+}
+
+void gr_free_char_association(gr_glyph_to_char_association* aData) {
+  free(aData);
+}
+
+#undef CHECK
+#undef NS_IS_HIGH_SURROGATE
+#undef NS_IS_LOW_SURROGATE
+#undef IS_POWER_OF_2