-//============================================================
//  compute_blit_surface_size
//============================================================

void renderer_dd::compute_blit_surface_size()
{
	INT32 newwidth, newheight;
	int xscale, yscale;
	RECT client;

	// start with the minimum size
	window().target()->compute_minimum_size(newwidth, newheight);

	// get the window's client rectangle
	GetClientRect(window().m_hwnd, &client);

	// hardware stretch case: apply prescale
	if (video_config.hwstretch)
	{
		int prescale = (window().prescale() < 1) ? 1 : window().prescale();

		// clamp the prescale to something smaller than the target bounds
		xscale = prescale;
		while (xscale > 1 && newwidth * xscale > rect_width(&client))
			xscale--;
		yscale = prescale;
		while (yscale > 1 && newheight * yscale > rect_height(&client))
			yscale--;
	}

	// non stretch case
	else
	{
		INT32 target_width = rect_width(&client);
		INT32 target_height = rect_height(&client);
		float desired_aspect = 1.0f;

		// compute the appropriate visible area if we're trying to keepaspect
		if (video_config.keepaspect)
		{
			osd_monitor_info *monitor = window().winwindow_video_window_monitor(NULL);
			window().target()->compute_visible_area(target_width, target_height, monitor->aspect(), window().target()->orientation(), target_width, target_height);
			desired_aspect = (float)target_width / (float)target_height;
		}

		// compute maximum integral scaling to fit the window
		xscale = (target_width + 2) / newwidth;
		yscale = (target_height + 2) / newheight;

		// try a little harder to keep the aspect ratio if desired
		if (video_config.keepaspect)
		{
			// if we could stretch more in the X direction, and that makes a better fit, bump the xscale
			while (newwidth * (xscale + 1) <= rect_width(&client) &&
				better_mode(newwidth * xscale, newheight * yscale, newwidth * (xscale + 1), newheight * yscale, desired_aspect))
				xscale++;

			// if we could stretch more in the Y direction, and that makes a better fit, bump the yscale
			while (newheight * (yscale + 1) <= rect_height(&client) &&
				better_mode(newwidth * xscale, newheight * yscale, newwidth * xscale, newheight * (yscale + 1), desired_aspect))
				yscale++;

			// now that we've maxed out, see if backing off the maximally stretched one makes a better fit
			if (rect_width(&client) - newwidth * xscale < rect_height(&client) - newheight * yscale)
			{
				while (xscale > 1 && better_mode(newwidth * xscale, newheight * yscale, newwidth * (xscale - 1), newheight * yscale, desired_aspect))
					xscale--;
			}
			else
			{
				while (yscale > 1 && better_mode(newwidth * xscale, newheight * yscale, newwidth * xscale, newheight * (yscale - 1), desired_aspect))
					yscale--;
			}
		}
	}

	// ensure at least a scale factor of 1
	if (xscale == 0) xscale = 1;
	if (yscale == 0) yscale = 1;

	// apply the final scale
	newwidth *= xscale;
	newheight *= yscale;
	if (newwidth != blitwidth || newheight != blitheight)
	{
		// force some updates
		update_outer_rects();
		osd_printf_verbose("DirectDraw: New blit size = %dx%d\n", newwidth, newheight);
	}
	blitwidth = newwidth;
	blitheight = newheight;
}