dix: improve the driver interface to predictable pointer acceleration

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

dix/ptrveloc.c

@@ -616,22 +616,32 @@ SetAccelerationProfile(
  */
 extern void
 SetDeviceSpecificAccelerationProfile(
-	DeviceIntPtr pDev,
+        DeviceVelocityPtr s,
         PointerAccelerationProfileFunc profile)
+{
+    if(s)
+	s->deviceSpecificProfile = profile;
+}
+
+/**
+ * Use this function to obtain a DeviceVelocityPtr for a device. Will return NULL if
+ * the predictable acceleration scheme is not in effect.
+ */
+DeviceVelocityPtr
+GetDevicePredictableAccelData(
+	DeviceIntPtr pDev)
 {
     /*sanity check*/
     if( pDev->valuator &&
 	pDev->valuator->accelScheme.AccelSchemeProc ==
 	    acceleratePointerPredictable &&
 	pDev->valuator->accelScheme.accelData != NULL){
-	((DeviceVelocityPtr)
-	(pDev->valuator->accelScheme.accelData))->deviceSpecificProfile
-		= profile;
+
+	return (DeviceVelocityPtr)pDev->valuator->accelScheme.accelData;
     }
+    return NULL;
 }
 
-
-
 /********************************
  *  acceleration schemes
  *******************************/

include/ptrveloc.h

@@ -104,8 +104,11 @@ InitFilterChain(DeviceVelocityPtr s, float rdecay, float degression,
 extern int
 SetAccelerationProfile(DeviceVelocityPtr s, int profile_num);
 
+extern DeviceVelocityPtr
+GetDevicePredictableAccelData(DeviceIntPtr pDev);
+
 extern void
-SetDeviceSpecificAccelerationProfile(DeviceIntPtr s,
+SetDeviceSpecificAccelerationProfile(DeviceVelocityPtr s,
                                      PointerAccelerationProfileFunc profile);
 
 extern void