Function DoSetViewportPosition

src/viewport.cpp:277–341

static Point _vp_move_offs;

static void DoSetViewportPosition(Window::IteratorToFront it, int left, int top, int width, int height)
{
	for (; !it.IsEnd(); ++it) {
		const Window *w = *it;
		if (left + width > w->left &&
				w->left + w->width > left &&
				top + height > w->top &&
				w->top + w->height > top) {

			if (left < w->left) {
				DoSetViewportPosition(it, left, top, w->left - left, height);
				DoSetViewportPosition(it, left + (w->left - left), top, width - (w->left - left), height);
				return;
			}

			if (left + width > w->left + w->width) {
				DoSetViewportPosition(it, left, top, (w->left + w->width - left), height);
				DoSetViewportPosition(it, left + (w->left + w->width - left), top, width - (w->left + w->width - left), height);
				return;
			}

			if (top < w->top) {
				DoSetViewportPosition(it, left, top, width, (w->top - top));
				DoSetViewportPosition(it, left, top + (w->top - top), width, height - (w->top - top));
				return;
			}

			if (top + height > w->top + w->height) {
				DoSetViewportPosition(it, left, top, width, (w->top + w->height - top));
				DoSetViewportPosition(it, left, top + (w->top + w->height - top), width, height - (w->top + w->height - top));
				return;
			}

			return;
		}
	}

	{
		int xo = _vp_move_offs.x;
		int yo = _vp_move_offs.y;

		if (abs(xo) >= width || abs(yo) >= height) {
			/* fully_outside */
			RedrawScreenRect(left, top, left + width, top + height);
			return;
		}

		GfxScroll(left, top, width, height, xo, yo);

		if (xo > 0) {
			RedrawScreenRect(left, top, xo + left, top + height);
			left += xo;
			width -= xo;
		} else if (xo < 0) {
			RedrawScreenRect(left + width + xo, top, left + width, top + height);
			width += xo;
		}