The Drawing action library is where you can find the actions required to draw sprites, text or shapes as well as set certain draw properties. Most of these actions are only for use in the various Draw Events of an object, and may not work if used outside of the Draw Event. The exceptions to this are the Set actions, which can be added to any event and will affect all drawing for all instances afterwards.
It is important to note that if you add any actions into the main Draw Event of an object, then it will not draw the sprite that has been assigned to the instance unless you explicitly tell GameMaker to draw it, using an action like Draw Self. Basically, GameMaker will default draw any sprite assigned to an instance, only if there is nothing else in the Draw Event.
The Draw actions available are as follows:
