Function ScaleMouseProc

micropolis-activity/src/tk/tkscale.c:1296–1330

(clientData, eventPtr)

 *	This procedure is called back by Tk in response to
 *	mouse events such as window entry, window exit, mouse
 *	motion, and button presses.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	This procedure implements the "feel" of the scale by
 *	issuing commands in response to button presses and mouse
 *	motion.
 *
 *--------------------------------------------------------------
 */

static void
ScaleMouseProc(clientData, eventPtr)
    ClientData clientData;		/* Information about window. */
    register XEvent *eventPtr;		/* Information about event. */
{
    register Scale *scalePtr = (Scale *) clientData;

    if (scalePtr->state != tkNormalUid) {
	return;
    }

    Tk_Preserve((ClientData) scalePtr);
    if (eventPtr->type == EnterNotify) {
	scalePtr->flags |= ACTIVE;
	EventuallyRedrawScale(scalePtr, REDRAW_SLIDER);
    } else if (eventPtr->type == LeaveNotify) {
	scalePtr->flags &= ~ACTIVE;
	EventuallyRedrawScale(scalePtr, REDRAW_SLIDER);
    } else if ((eventPtr->type == MotionNotify)
	    && (scalePtr->flags & BUTTON_PRESSED)) {
	SetScaleValue(scalePtr,  PixelToValue(scalePtr,
		eventPtr->xmotion.x, eventPtr->xmotion.y));
    } else if ((eventPtr->type == ButtonPress)
	    && ((eventPtr->xbutton.state & ALL_BUTTONS) == 0)) {
	scalePtr->flags |= BUTTON_PRESSED;