Get the position at which the visible portion of the canvas starts, based on the current position of the horizontal and vertical scrollbars. Combined with get-client-size, the application can use this function to efficiently redraw only the visible portion of the canvas. The positions are in logical scroll units, not pixels, so to convert to pixels you will have to multiply by the number of pixels per scroll increment.
The x box is filled with the horizontal scroll bar position and y is filled with the vertical scroll bar position.