Using Layers > Using mask layers

Using mask layers

For spotlight effects and transitions, you can use a mask layer to create a hole through which the contents of one or more underlying layers are visible. You can group multiple layers together under a single mask layer to create sophisticated effects. You can also use any type of animation, except motion paths, to make the mask move. You cannot mask layers inside of buttons.

To create a mask layer, you place a filled shape on the layer. The mask layer reveals the area of linked, underlying layers that lie beneath the filled shape, and it conceals all other areas. Mask layers can contain only a single shape, instance, or type object. (Flash mask layers provide similar functionality to the Paste Inside command in FreeHand.)

To create a mask layer:

1 Select or create a layer containing the content that will be visible through the holes in the mask.
2 With the layer selected, choose Insert > Layer to create a new layer above it.
A mask layer always masks the layer immediately below it, so be sure to create the mask layer in the proper place.
3 Draw a filled shape, place type, or create an instance of a symbol on the mask layer. Flash ignores bitmaps, gradients, transparency, colors, and line styles in a mask layer. Any filled area will be completely transparent in the mask; any nonfilled area will be opaque.
4 Right-click (Windows) or Control-click (Macintosh) the mask layer's name in the Timeline and choose Mask from the context menu.
The layer is converted to a mask layer, indicated by a down arrow icon. The layer immediately below it is linked to the mask layer, and its contents show through the filled area on the mask. The masked layer name is indented, and its icon changes to a right-pointing arrow.
To display the mask effect in Flash, lock the mask layer and the masked layer.
A mask layer; the filled shape that will be transparent in the mask; the masked layer; and the final mask effect
 

To mask additional layers after creating a mask layer, do one of the following:

Drag an existing layer directly below the mask layer.
Create a new layer anywhere below the mask layer.
Choose Modify > Layer and select Masked in the Layer Properties dialog box.

To unlink layers from a mask layer:

1 Select the layer you want to unlink.
2 Do one of the following:
Drag the layer above the mask layer.
Choose Modify > Layer and select Normal.

To toggle a layer between being masked and unmasked:

Alt-click (Windows) or Option-click (Macintosh) the layer.