Function PixelToValue

micropolis-activity/src/sim/w_inter.c:1221–1267

(intervalPtr, x, y)

 *	Given a pixel within a interval window, return the interval
 *	reading corresponding to that pixel.
 *
 * Results:
 *	An integer interval reading.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static int
PixelToValue(intervalPtr, x, y)
    register Interval *intervalPtr;		/* Information about widget. */
    int x, y;				/* Coordinates of point within
					 * window. */
{
    int value, pixelRange;

    if (intervalPtr->vertical) {
	pixelRange = Tk_Height(intervalPtr->tkwin)
		- 2*intervalPtr->offset - 4*intervalPtr->borderWidth;
	value = y;
    } else {
	pixelRange = Tk_Width(intervalPtr->tkwin)
		- 2*intervalPtr->offset - 4*intervalPtr->borderWidth;
	value = x;
    }

    if (pixelRange <= 0) {
	/*
	 * Not enough room for the slider to actually slide:  just return
	 * a constant.
	 */

	return (0);
    }
    value -= intervalPtr->offset + intervalPtr->borderWidth;
#if 0
    if (value < 0) {
	value = 0;
    }
    if (value > pixelRange) {
	value = pixelRange;
    }
#endif
    if (intervalPtr->toValue > intervalPtr->fromValue) {
	value = intervalPtr->fromValue +
		((value * (intervalPtr->toValue - intervalPtr->fromValue))
		+ pixelRange/2)/pixelRange;
    } else {