User Guide

MovieClip.setMask() 577
MovieClip.setMask()
Availability
Flash Player 6.
Usage
my_mc.setMask(mask_mc:Object) : Void
Parameters
my_mc
The instance name of a movie clip to be masked.
mask_mc The instance name of a movie clip to be a mask.
Returns
Nothing.
Description
Method; makes the movie clip in the parameter mask_mc a mask that reveals the movie clip
specified by the
my_mc parameter.
This method allows multiple-frame movie clips with complex, multilayered content to act as
masks. You can shut masks on and off at runtime. However, you can’t use the same mask for
multiple masks (which is possible by using mask layers). If you have device fonts in a masked
movie clip, they are drawn but not masked. You can’t set a movie clip to be its own mask—for
example,
my_mc.setMask(my_mc).
If you create a mask layer that contains a movie clip, and then apply the
setMask() method to it,
the
setMask() call takes priority and this is not reversible. For example, you could have a movie
clip in a mask layer called
UIMask that masks another layer containing another movie clip called
UIMaskee. If, as the SWF file plays, you call UIMask.setMask(UIMaskee), from that point on,
UIMask is masked by UIMaskee.
To cancel a mask created with ActionScript, pass the value
null to the setMask() method. The
following code cancels the mask without affecting the mask layer in the Timeline.
UIMask.setMask(null);
You can extend the methods and event handlers of the MovieClip class by creating a subclass. For
more information, see “Assigning a class to a movie clip symbol” in Using ActionScript in Flash.
Example
The following code uses the movie clip circleMask_mc to mask the movie clip theMaskee_mc:
theMaskee_mc.setMask(circleMask_mc);