tilemap_set_height

This function can be used to resize a tile map element. You give the tile map element ID (which you get when you create a tile map element using layer_tilemap_create() or when you use the function layer_tilemap_get_id()), and the new height of the tile map in tile cells.

Syntax:

tilemap_set_height(tilemap_element_id, height)

Returns:

N/A

Example:

var lay_id = layer_get_id("Tiles_Walls");
var map_id = layer_tilemap_get_id(lay_id);
if tilemap_get_height(map_id) != room_height div 16
{
    tilemap_set_height(map_id, room_height div 16);
}

The above code checks the width of a specific tile map and if it is not the correct size then the width is set.