Fixed mousewheel callbacks under X11. (bug #247, github issue #66)

The code had the incorrect assumption that button numbers mapped to the wheel
follow after the last "real" button as returned by the GLUT_NUM_MOUSE_BUTTONS
query, which in turn resolves to a call to XGetPointerMapping. In reality the
X server always sends button presses for 4 and 5 when a wheel is turned down/up
respectively, and the rest of the mouse buttons (if any) follow afterwards.
Also XGetPointerMapping doesn't seem to reliably return the number of actual
buttons, and in any case the wheel "buttons" are certainly included in the
count as they can be remapped.
Since we can't know if buttons after 5 are further wheels or regular buttons
this modification only ever invokes the wheel callback for wheel 0.

git-svn-id: svn+ssh://svn.code.sf.net/p/freeglut/code/trunk/freeglut/freeglut@1844 7f0cb862-5218-0410-a997-914c9d46530a

diff --git a/src/x11/fg_main_x11.c b/src/x11/fg_main_x11.c
index 80fd2c8..e3e2a22 100644 (file)
--- a/src/x11/fg_main_x11.c
+++ b/src/x11/fg_main_x11.c
@@ -807,11 +807,8 @@ void fgPlatformProcessSingleEvent ( void )
         case ButtonRelease:
         case ButtonPress:
         {
-            GLboolean pressed = GL_TRUE;
-            int button;
-
-            if( event.type == ButtonRelease )
-                pressed = GL_FALSE ;
+            GLboolean pressed;
+            int button, x, y;
 
             /*
              * A mouse button has been pressed or released. Traditionally,
@@ -829,59 +826,46 @@ void fgPlatformProcessSingleEvent ( void )
              */
             button = event.xbutton.button - 1;
 
+            pressed = event.type == ButtonPress ? GL_TRUE : GL_FALSE;
+            x = event.xbutton.x;
+            y = event.xbutton.y;
+
             /*
              * Do not execute the application's mouse callback if a menu
              * is hooked to this button.  In that case an appropriate
              * private call should be generated.
              */
-            if( fgCheckActiveMenu( window, button, pressed,
-                                   event.xbutton.x, event.xbutton.y ) )
+            if(fgCheckActiveMenu( window, button, pressed, x, y))
                 break;
 
             /*
              * Check if there is a mouse or mouse wheel callback hooked to the
              * window
              */
-            if( ! FETCH_WCB( *window, Mouse ) &&
-                ! FETCH_WCB( *window, MouseWheel ) )
+            if(!FETCH_WCB(*window, Mouse) && !FETCH_WCB(*window, MouseWheel))
                 break;
 
-            fgState.Modifiers = fgPlatformGetModifiers( event.xbutton.state );
+            fgState.Modifiers = fgPlatformGetModifiers(event.xbutton.state);
 
-            /* Finally execute the mouse or mouse wheel callback */
-            if( ( button < glutDeviceGet ( GLUT_NUM_MOUSE_BUTTONS ) ) || ( ! FETCH_WCB( *window, MouseWheel ) ) )
-                INVOKE_WCB( *window, Mouse, ( button,
-                                              pressed ? GLUT_DOWN : GLUT_UP,
-                                              event.xbutton.x,
-                                              event.xbutton.y )
-                );
-            else
-            {
-                /*
-                 * Map 4 and 5 to wheel zero; EVEN to +1, ODD to -1
-                 *  "  6 and 7 "    "   one; ...
-                 *
-                 * XXX This *should* be behind some variables/macros,
-                 * XXX since the order and numbering isn't certain
-                 * XXX See XFree86 configuration docs (even back in the
-                 * XXX 3.x days, and especially with 4.x).
-                 *
-                 * XXX Note that {button} has already been decremented
-                 * XXX in mapping from X button numbering to GLUT.
-                                *
-                                * XXX Should add support for partial wheel turns as Windows does -- 5/27/11
-                 */
-                int wheel_number = (button - glutDeviceGet ( GLUT_NUM_MOUSE_BUTTONS )) / 2;
-                int direction = -1;
-                if( button % 2 )
-                    direction = 1;
-
-                if( pressed )
-                    INVOKE_WCB( *window, MouseWheel, ( wheel_number,
-                                                       direction,
-                                                       event.xbutton.x,
-                                                       event.xbutton.y )
-                    );
+            /* Finally execute the mouse or mouse wheel callback.
+             * The mouse wheel is reported as buttons 4 (down) and 5 (up) by
+             * the X server. "button" has been converted to 0-based above, so
+             * that's 3 and 4 for us.
+             * If a wheel callback hasn't been registered, we simply treat them
+             * as button presses and pass them to the mouse handler. This is
+             * important for compatibility with the original GLUT.
+             */
+            if(button < 3 || button > 4 || !FETCH_WCB(*window, MouseWheel)) {
+                INVOKE_WCB(*window, Mouse, (button, pressed ? GLUT_DOWN : GLUT_UP, x, y));
+            } else {
+                if(pressed) {
+                    int dir = button & 1 ? 1 : -1;
+                    /* there's no way to know if X buttons after 5 are more
+                     * wheels/wheel axes, or regular buttons. So we'll only
+                     * ever invoke the wheel CB for wheel 0.
+                     */
+                    INVOKE_WCB(*window, MouseWheel, (0, dir, x, y));
+                }
             }
             fgState.Modifiers = INVALID_MODIFIERS;
         }