1 files changed, 61 insertions, 0 deletions
diff --git a/intl/lwbrk/nsPangoBreaker.cpp b/intl/lwbrk/nsPangoBreaker.cpp
new file mode 100644
index 0000000000..e098a11e58
--- /dev/null
+++ b/intl/lwbrk/nsPangoBreaker.cpp
@@ -0,0 +1,61 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 "nsComplexBreaker.h"
+
+#include <pango/pango-break.h>
+#include "nsUTF8Utils.h"
+#include "nsString.h"
+#include "nsTArray.h"
+
+void NS_GetComplexLineBreaks(const char16_t* aText, uint32_t aLength,
+                             uint8_t* aBreakBefore) {
+  NS_ASSERTION(aText, "aText shouldn't be null");
+
+  memset(aBreakBefore, uint8_t(false), aLength * sizeof(uint8_t));
+
+  AutoTArray<PangoLogAttr, 2000> attrBuffer;
+  // XXX(Bug 1631371) Check if this should use a fallible operation as it
+  // pretended earlier.
+  attrBuffer.AppendElements(aLength + 1);
+  // `PangoLogAttr` doesn't have a default constructor (it is a C struct), so
+  // we need to manually initialize the new elements.  See bug 1808182.
+  memset(attrBuffer.Elements(), 0, attrBuffer.Length() * sizeof(PangoLogAttr));
+
+  NS_ConvertUTF16toUTF8 aUTF8(aText, aLength);
+
+  const gchar* p = aUTF8.Data();
+  const gchar* end = p + aUTF8.Length();
+  uint32_t u16Offset = 0;
+
+  static PangoLanguage* language = pango_language_from_string("en");
+
+  while (p < end) {
+    PangoLogAttr* attr = attrBuffer.Elements();
+    pango_get_log_attrs(p, end - p, -1, language, attr, attrBuffer.Length());
+
+    while (p < end) {
+      aBreakBefore[u16Offset] = attr->is_line_break;
+      if (NS_IS_LOW_SURROGATE(aText[u16Offset]))
+        aBreakBefore[++u16Offset] = false;  // Skip high surrogate
+      ++u16Offset;
+
+      // We're iterating over text obtained from NS_ConvertUTF16toUTF8,
+      // so we know we have valid UTF-8 and don't need to check for
+      // errors.
+      uint32_t ch = UTF8CharEnumerator::NextChar(&p, end);
+      ++attr;
+
+      if (!ch) {
+        // pango_break (pango 1.16.2) only analyses text before the
+        // first NUL (but sets one extra attr). Workaround loop to call
+        // pango_break again to analyse after the NUL is done somewhere else
+        // (gfx/thebes/gfxFontconfigFonts.cpp: SetupClusterBoundaries()).
+        // So, we do the same here for pango_get_log_attrs.
+        break;
+      }
+    }
+  }
+}