Function FillDrawPixelInfo

src/gfx.cpp:1568–1612

* Set up a clipping area for only drawing into a certain area. To do this, * Fill a DrawPixelInfo object with the supplied relative rectangle, backup * the original (calling) _cur_dpi and assign the just returned DrawPixelInfo * _cur_dpi. When you are done, give restore _cur_dpi's original value * @param *n the DrawPixelInfo that will be the clipping rectangle box allowed * for drawing * @pa

 * get some nasty results
 */
bool FillDrawPixelInfo(DrawPixelInfo *n, int left, int top, int width, int height)
{
	Blitter *blitter = BlitterFactory::GetCurrentBlitter();
	const DrawPixelInfo *o = _cur_dpi;

	n->zoom = ZoomLevel::Min;

	assert(width > 0);
	assert(height > 0);

	if ((left -= o->left) < 0) {
		width += left;
		if (width <= 0) return false;
		n->left = -left;
		left = 0;
	} else {
		n->left = 0;
	}

	if (width > o->width - left) {
		width = o->width - left;
		if (width <= 0) return false;
	}
	n->width = width;

	if ((top -= o->top) < 0) {
		height += top;
		if (height <= 0) return false;
		n->top = -top;
		top = 0;
	} else {
		n->top = 0;
	}

	n->dst_ptr = blitter->MoveTo(o->dst_ptr, left, top);
	n->pitch = o->pitch;

	if (height > o->height - top) {
		height = o->height - top;
		if (height <= 0) return false;
	}
	n->height = height;

	return true;
}

/**
 * Update cursor dimension.