* Add a BJoystick::RescanDevices() public function. It allows the BJoystick

to be updated with newly plugged in devices without the need to recreate a
  BJoystick object.
* Do an initial (re-)scan on object creation instead of always scanning in
  CountDevices() and by extension GetDeviceName().
* This makes CountDevices() and GetDeviceName() stable with regards to the
  device list, so that an enumerating application doesn't suddenly get more/less
  devices than it might expect.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@41870 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/os/device/Joystick.h

@@ -41,6 +41,12 @@ public:
 			status_t		GetDeviceName(int32 index, char* name,
 								size_t bufSize = B_OS_NAME_LENGTH);
 
+			status_t		RescanDevices();
+								// Haiku extension. Updates the list of devices
+								// as enumerated by CountDevices() and
+								// GetDeviceName() with possibly newly plugged
+								// in devices.
+
 			bool			EnterEnhancedMode(const entry_ref* ref = NULL);
 
 			int32			CountSticks();

src/kits/device/Joystick.cpp

@@ -68,6 +68,8 @@ BJoystick::BJoystick()
 
 	if (fJoystickInfo != NULL)
 		memset(fJoystickInfo, 0, sizeof(joystick_info));
+
+	RescanDevices();
 }
 
 
@@ -200,12 +202,10 @@ BJoystick::CountDevices()
 {
 	CALLED();
 
-	// Refresh devices list
+	if (fDevices == NULL)
-	ScanDevices(true);
+		return 0;
 
-	int32 count = 0;
+	int32 count = fDevices->CountItems();
-	if (fDevices != NULL)
-		count = fDevices->CountItems();
 
 	LOG("Count = %d\n", count);
 	return count;
@@ -219,8 +219,7 @@ BJoystick::GetDeviceName(int32 index, char *name, size_t bufSize)
 	if (fDevices == NULL)
 		return B_NO_INIT;
 
-	// CountDevices() also calls ScanDevices() and therefore updates our list.
+	if (index >= fDevices->CountItems())
-	if (index >= CountDevices())
 		return B_BAD_INDEX;
 
 	if (name == NULL)
@@ -236,6 +235,19 @@ BJoystick::GetDeviceName(int32 index, char *name, size_t bufSize)
 }
 
 
+status_t
+BJoystick::RescanDevices()
+{
+	CALLED();
+
+	if (fDevices == NULL)
+		return B_NO_INIT;
+
+	ScanDevices(true);
+	return B_OK;
+}
+
+
 bool
 BJoystick::EnterEnhancedMode(const entry_ref *ref)
 {