draw_sprite_sliced.gml

/// @description draw a sprite using four- or nine-slicing
/// @arg sprite
/// @arg subimg
/// @arg x
/// @arg y
/// @arg width
/// @arg height
/// @arg color
/// @arg alpha
/// @arg [slice_top_left] if not supplied, the origin will be used for four-slicing
/// @arg [slice_width] if width and height are not supplied, the slice_top_left will be used for four slicing
/// @arg [slice_height]
function draw_sprite_sliced(
	sprite,
	subimg,
	_x,
	_y,
	width,
	height,
	color,
	alpha
) {
	// full nine-slicing
	if argument_count == 11 {
		var slice_coords = argument[8];
		var slice_width = argument[9];
		var slice_height = argument[10];
		var slice_xy = { x: slice_coords[0], y: slice_coords[1] };
		var slice_top_left = slice_xy;
		var slice_top_right = { x: slice_xy.x + slice_width, y: slice_xy.y };
		var slice_bottom_left = { x: slice_xy.x, y: slice_xy.y + slice_height };
		var slice_bottom_right = { x: slice_xy.x + slice_width, y: slice_xy.y + slice_height };
	}
	// four-slicing
	else if argument_count == 9 {
		var slice_coords = argument[8];
		var slice_xy = { x: slice_coords[0], y: slice_coords[1] };
		var slice_top_left = slice_xy;
		var slice_top_right = slice_xy;
		var slice_bottom_left = slice_xy;
		var slice_bottom_right = slice_xy;
	}
	// four-slice by origin
	else if argument_count == 8 {
		var slice_xy = { x: sprite_get_xoffset(sprite), y: sprite_get_yoffset(sprite) };
		var slice_top_left = slice_xy;
		var slice_top_right = slice_xy;
		var slice_bottom_left = slice_xy;
		var slice_bottom_right = slice_xy;
	}
	else {
		throw "Invalid parameters for draw_sprite_sliced - expecting 8, 9, or 11 parameters";
	}
	
	var spr_width = sprite_get_width(sprite);
	var spr_height = sprite_get_height(sprite);
	
	// the inner target width is the desired width minus the left and right widths of the slice
	var inner_target_width = width - (slice_top_left.x + (spr_width - slice_top_right.x));
	
	// the inner target height is the desired width minus the top and bottom heights of the slice
	var inner_target_height = height - (slice_top_left.y + (spr_height - slice_bottom_left.y));
	
	var inner_slice_width = slice_top_right.x - slice_top_left.x;
	var inner_slice_height = slice_bottom_left.y - slice_top_left.y;
	
	// draw minimum 1 pixel from the inner slice
	if inner_slice_width == 0 inner_slice_width = 1;
	if inner_slice_height == 0 inner_slice_height = 1;
	
	var inner_x_scale = inner_target_width / inner_slice_width;
	var inner_y_scale = inner_target_height / inner_slice_height;

	// top left
	draw_sprite_part_ext(
		sprite, subimg,
		0, 0, 
		slice_top_left.x, slice_top_left.y,
		_x, _y,
		1, 1,
		color, alpha);
	
	// top middle
	draw_sprite_part_ext(
		sprite, subimg,
		slice_top_left.x, 0, // top of the sprite, indented to the slice left x
		inner_slice_width, slice_top_left.y,
		_x + slice_top_left.x, _y,
		inner_x_scale, 1,
		color, alpha);
		
	// top right
	draw_sprite_part_ext(
		sprite, subimg,
		slice_top_right.x, 0, 
		spr_width - slice_top_right.x, slice_top_right.y,
		_x + slice_top_left.x + inner_target_width, _y,
		1, 1,
		color, alpha);
	
	// middle left
	draw_sprite_part_ext(
		sprite, subimg,
		0, slice_top_left.y,
		slice_top_left.x, inner_slice_height,
		_x, _y + slice_top_left.y,
		1, inner_y_scale,
		color, alpha);
	
	// middle inner
	draw_sprite_part_ext(
		sprite, subimg,
		slice_top_left.x, slice_top_left.y,
		inner_slice_width, inner_slice_height,
		_x + slice_top_left.x, _y + slice_top_left.y,
		inner_x_scale, inner_y_scale,
		color, alpha);
	
	// middle right
	draw_sprite_part_ext(
		sprite, subimg,
		slice_top_right.x, slice_top_right.y,
		spr_width - slice_top_right.x, inner_slice_height,
		_x + slice_top_left.x + inner_target_width, _y + slice_top_left.y,
		1, inner_y_scale,
		color, alpha);
		
		
	// bottom left
	draw_sprite_part_ext(
		sprite, subimg,
		0, slice_bottom_left.y,
		slice_bottom_left.x, spr_height - slice_bottom_right.y,
		_x, _y + slice_top_left.y + inner_target_height,
		1, 1,
		color, alpha);
	
	// bottom middle
	draw_sprite_part_ext(
		sprite, subimg,
		slice_bottom_left.x, slice_bottom_left.y,
		inner_slice_width, spr_height - slice_bottom_right.y,
		_x + slice_bottom_left.x, _y + slice_top_left.y + inner_target_height,
		inner_x_scale, 1,
		color, alpha);
	
	// bottom right
	draw_sprite_part_ext(
		sprite, subimg,
		slice_bottom_right.x, slice_bottom_right.y,
		spr_width - slice_bottom_right.x, spr_height - slice_bottom_right.y,
		_x + slice_bottom_left.x + inner_target_width, _y + slice_top_right.y + inner_target_height,
		1, 1,
		color, alpha);
}