Part of Bug 350132 – backspacing doesn't work properly for Arabic

2006-09-18  Behdad Esfahbod  <behdad@gnome.org>

        Part of Bug 350132 – backspacing doesn't work properly for Arabic

        * configure.in:
        * modules/arabic/Makefile.am:
        * modules/arabic/arabic-lang.c:
        Add a simple Arabic language engine.  Currently it just makes sure
        that backspace_deletes_character is not set on ALEF-MADDA
        combinations.

2 files changed, 138 insertions, 0 deletions

diff --git a/modules/arabic/Makefile.am b/modules/arabic/Makefile.am
index ca129b8d..26b232eb 100644
--- a/modules/arabic/Makefile.am
+++ b/modules/arabic/Makefile.am
@@ -21,3 +21,21 @@ pango_arabic_fc_la_LIBADD = $(pangoft2libs)
 pango_arabic_fc_la_SOURCES = $(fc_sources)
 libpango_arabic_fc_la_SOURCES = $(fc_sources)
 libpango_arabic_fc_la_CFLAGS = -DPANGO_MODULE_PREFIX=_pango_arabic_fc
+
+
+if INCLUDE_ARABIC_LANG
+noinst_LTLIBRARIES += libpango-arabic-lang.la
+else
+if DYNAMIC_ARABIC_LANG
+module_LTLIBRARIES += pango-arabic-lang.la
+endif
+endif
+
+lang_sources = \
+	arabic-lang.c
+
+pango_arabic_lang_la_LDFLAGS = -module $(MODULE_LIBTOOL_OPTIONS)
+pango_arabic_lang_la_LIBADD = $(pangolibs)
+pango_arabic_lang_la_SOURCES = $(lang_sources)
+libpango_arabic_lang_la_SOURCES = $(lang_sources)
+libpango_arabic_lang_la_CFLAGS = -DPANGO_MODULE_PREFIX=_pango_arabic_lang
diff --git a/modules/arabic/arabic-lang.c b/modules/arabic/arabic-lang.c
new file mode 100644
index 00000000..fc3b8795
--- /dev/null
+++ b/modules/arabic/arabic-lang.c
@@ -0,0 +1,120 @@
+/* Pango
+ * arabic-fc.h:
+ *
+ * Copyright (C) 2006 Red Hat Software
+ * Author: Behdad Esfahbod <besfahbo@redhat.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <config.h>
+#include <string.h>
+
+#include "arabic-ot.h"
+
+#include "pango-engine.h"
+#include "pango-break.h"
+
+/* No extra fields needed */
+typedef PangoEngineLang      ArabicEngineLang;
+typedef PangoEngineLangClass ArabicEngineLangClass ;
+
+#define SCRIPT_ENGINE_NAME "ArabicScriptEngineLang"
+#define RENDER_TYPE PANGO_RENDER_TYPE_NONE
+
+static PangoEngineScriptInfo arabic_scripts[] = {
+  { PANGO_SCRIPT_ARABIC, "*" },
+};
+
+static PangoEngineInfo script_engines[] = {
+  {
+    SCRIPT_ENGINE_NAME,
+    PANGO_ENGINE_TYPE_LANG,
+    RENDER_TYPE,
+    arabic_scripts, G_N_ELEMENTS(arabic_scripts)
+  }
+};
+
+
+static void
+arabic_engine_break (PangoEngineLang *engine,
+		     const char      *text,
+		     int              length,
+		     PangoAnalysis   *analysis,
+		     PangoLogAttr    *attrs,
+		     int              attrs_len)
+{
+  int i;
+  const char *p;
+  gunichar prev_wc, this_wc;
+
+  /* See http://bugzilla.gnome.org/show_bug.cgi?id=350132 for issues this
+   * module tries to solve.
+   */
+
+  for (p = text, i = 0, prev_wc = 0;
+       p < text + length;
+       p = g_utf8_next_char (p), i++, prev_wc = this_wc)
+    {
+      this_wc = g_utf8_get_char (p);
+
+      /*
+       * Unset backspace_deletes_character for various combinations:
+       */
+      if (G_UNLIKELY (
+	   this_wc == 0x0622 /* ARABIC LETTER ALEF WITH MADDA ABOVE */ ||
+	  (prev_wc == 0x0627 /* ARABIC LETTER ALEF */ && this_wc == 0x0653 /* ARABIC MADDAH ABOVE */)
+	 ))
+        attrs[i+1].backspace_deletes_character = FALSE;
+    }
+}
+
+static void
+arabic_engine_lang_class_init (PangoEngineLangClass *class)
+{
+  class->script_break = arabic_engine_break;
+}
+
+PANGO_ENGINE_LANG_DEFINE_TYPE (ArabicEngineLang, arabic_engine_lang,
+			       arabic_engine_lang_class_init, NULL)
+
+void 
+PANGO_MODULE_ENTRY(init) (GTypeModule *module)
+{
+  arabic_engine_lang_register_type (module);
+}
+
+void 
+PANGO_MODULE_ENTRY(exit) (void)
+{
+}
+
+void 
+PANGO_MODULE_ENTRY(list) (PangoEngineInfo **engines,
+			  int              *n_engines)
+{
+  *engines = script_engines;
+  *n_engines = G_N_ELEMENTS (script_engines);
+}
+
+PangoEngine *
+PANGO_MODULE_ENTRY(create) (const char *id)
+{
+  if (!strcmp (id, SCRIPT_ENGINE_NAME))
+    return g_object_new (arabic_engine_lang_type, NULL);
+  else
+    return NULL;
+}