evdev: Fix the unicode_value for new ClutterEvents

Looking at what the X11 backend does: the unicode value is being
translated to the unicode codepoint of the symbol if possible. Let's do
the same then.

Before that, key events for say KEY_Right (0xff53) had the unicode_value
set to the keysym, which meant "This key event is actually printable and
is Unicode codepoint is 0xff53", which lead to interesting results.

clutter/evdev/clutter-xkb-utils.c

@@ -20,11 +20,66 @@
 
  * Authors:
  *  Kristian Høgsberg
+ *  Damien Lespiau <damien.lespiau@intel.com>
  */
 
 #include "clutter-keysyms.h"
 #include "clutter-xkb-utils.h"
 
+/*
+ * print_key_sym: Translate a symbol to its printable form if any
+ * @symbol: the symbol to translate
+ * @buffer: the buffer where to put the translated string
+ * @len: size of the buffer
+ *
+ * Translates @symbol into a printable representation in @buffer, if possible.
+ *
+ * Return value: The number of bytes of the translated string, 0 if the
+ *               symbol can't be printed
+ *
+ * Note: The code is derived from libX11's src/KeyBind.c
+ *       Copyright 1985, 1987, 1998  The Open Group
+ *
+ * Note: This code works for Latin-1 symbols. clutter_keysym_to_unicode()
+ *       does the work for the other keysyms.
+ */
+static int
+print_keysym (uint32_t  symbol,
+               char     *buffer,
+               int       len)
+{
+  unsigned long high_bytes;
+  unsigned char c;
+
+  high_bytes = symbol >> 8;
+  if (!(len &&
+        ((high_bytes == 0) ||
+         ((high_bytes == 0xFF) &&
+          (((symbol >= CLUTTER_KEY_BackSpace) &&
+            (symbol <= CLUTTER_KEY_Clear)) ||
+           (symbol == CLUTTER_KEY_Return) ||
+           (symbol == CLUTTER_KEY_Escape) ||
+           (symbol == CLUTTER_KEY_KP_Space) ||
+           (symbol == CLUTTER_KEY_KP_Tab) ||
+           (symbol == CLUTTER_KEY_KP_Enter) ||
+           ((symbol >= CLUTTER_KEY_KP_Multiply) &&
+            (symbol <= CLUTTER_KEY_KP_9)) ||
+           (symbol == CLUTTER_KEY_KP_Equal) ||
+           (symbol == CLUTTER_KEY_Delete))))))
+    return 0;
+
+  /* if X keysym, convert to ascii by grabbing low 7 bits */
+  if (symbol == CLUTTER_KEY_KP_Space)
+    c = CLUTTER_KEY_space & 0x7F; /* patch encoding botch */
+  else if (high_bytes == 0xFF)
+    c = symbol & 0x7F;
+  else
+    c = symbol & 0xFF;
+
+  buffer[0] = c;
+  return 1;
+}
+
 /*
  * _clutter_event_new_from_evdev: Create a new Clutter ClutterKeyEvent
  * @device: a ClutterInputDevice
@@ -77,7 +132,21 @@ _clutter_key_event_new_from_evdev (ClutterInputDevice *device,
   event->key.modifier_state = *modifier_state;
   event->key.hardware_keycode = key;
   event->key.keyval = sym;
-  event->key.unicode_value = sym;
+
+  /* unicode_value is the printable representation */
+  n = print_keysym (sym, buffer, sizeof (buffer));
+
+  if (n == 0)
+    {
+      /* not printable */
+      event->key.unicode_value = (gunichar) '\0';
+    }
+  else
+    {
+      event->key.unicode_value = g_utf8_get_char_validated (buffer, n);
+      if (event->key.unicode_value == -1 || event->key.unicode_value == -2)
+        event->key.unicode_value = (gunichar) '\0';
+    }
 
   return event;
 }