[clutter/clutter-1.18] input-device-xi2: Calculate the correct state for button events

[Jasper St. Pierre <jstpierre src gnome org>]

commit c2b0b9aace969ecb19e703c8d53d157eb1072559
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Tue Nov 12 15:10:22 2013 -0500

    input-device-xi2: Calculate the correct state for button events
    
    The state that the X server sends for button events, by specification,
    contains the button state before the event. We need to synthesize in
    the result of the event in order to determine what the current button
    state is.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=712322

 clutter/x11/clutter-input-device-xi2.c |   63 +++++++++++++++++++-------------
 1 files changed, 38 insertions(+), 25 deletions(-)
---
diff --git a/clutter/x11/clutter-input-device-xi2.c b/clutter/x11/clutter-input-device-xi2.c
index 20ac71c..9490c52 100644
--- a/clutter/x11/clutter-input-device-xi2.c
+++ b/clutter/x11/clutter-input-device-xi2.c
@@ -95,6 +95,26 @@ clutter_input_device_xi2_init (ClutterInputDeviceXI2 *self)
 {
 }
 
+static ClutterModifierType
+get_modifier_for_button (int i)
+{
+  switch (i)
+    {
+    case 1:
+      return CLUTTER_BUTTON1_MASK;
+    case 2:
+      return CLUTTER_BUTTON2_MASK;
+    case 3:
+      return CLUTTER_BUTTON3_MASK;
+    case 4:
+      return CLUTTER_BUTTON4_MASK;
+    case 5:
+      return CLUTTER_BUTTON5_MASK;
+    default:
+      return 0;
+    }
+}
+
 void
 _clutter_input_device_xi2_translate_state (ClutterEvent    *event,
                                           XIModifierState *modifiers_state,
@@ -125,34 +145,27 @@ _clutter_input_device_xi2_translate_state (ClutterEvent    *event,
           if (!XIMaskIsSet (buttons_state->mask, i))
             continue;
 
-          switch (i)
-            {
-            case 1:
-              button |= CLUTTER_BUTTON1_MASK;
-              break;
-
-            case 2:
-              button |= CLUTTER_BUTTON2_MASK;
-              break;
-
-            case 3:
-              button |= CLUTTER_BUTTON3_MASK;
-              break;
-
-            case 4:
-              button |= CLUTTER_BUTTON4_MASK;
-              break;
-
-            case 5:
-              button |= CLUTTER_BUTTON5_MASK;
-              break;
-
-            default:
-              break;
-            }
+          button |= get_modifier_for_button (i);
         }
     }
 
+  /* The XIButtonState sent in the event specifies the
+   * state of the buttons before the event. In order to
+   * get the current state of the buttons, we need to
+   * filter out the current button.
+   */
+  switch (event->type)
+    {
+    case CLUTTER_BUTTON_PRESS:
+      button |=  (get_modifier_for_button (event->button.button));
+      break;
+    case CLUTTER_BUTTON_RELEASE:
+      button &= ~(get_modifier_for_button (event->button.button));
+      break;
+    default:
+      break;
+    }
+
   effective = button | base | latched | locked;
   if (group_state)
     effective |= (group_state->effective) << 13;