Function SetViewportPosition

src/viewport.cpp:343–398

}

static void SetViewportPosition(Window *w, int x, int y)
{
	Viewport &vp = *w->viewport;
	int old_left = vp.virtual_left;
	int old_top = vp.virtual_top;
	int i;
	int left, top, width, height;

	vp.virtual_left = x;
	vp.virtual_top = y;

	/* Viewport is bound to its left top corner, so it must be rounded down (UnScaleByZoomLower)
	 * else glitch described in FS#1412 will happen (offset by 1 pixel with zoom level > NORMAL)
	 */
	old_left = UnScaleByZoomLower(old_left, vp.zoom);
	old_top = UnScaleByZoomLower(old_top, vp.zoom);
	x = UnScaleByZoomLower(x, vp.zoom);
	y = UnScaleByZoomLower(y, vp.zoom);

	old_left -= x;
	old_top -= y;

	if (old_top == 0 && old_left == 0) return;

	_vp_move_offs.x = old_left;
	_vp_move_offs.y = old_top;

	left = vp.left;
	top = vp.top;
	width = vp.width;
	height = vp.height;

	if (left < 0) {
		width += left;
		left = 0;
	}

	i = left + width - _screen.width;
	if (i >= 0) width -= i;

	if (width > 0) {
		if (top < 0) {
			height += top;
			top = 0;
		}

		i = top + height - _screen.height;
		if (i >= 0) height -= i;

		if (height > 0) {
			Window::IteratorToFront it(w);
			++it;
			DoSetViewportPosition(it, left, top, width, height);
		}
	}
}

/**