Adobe After Effects CS4 - Manual (Page 676)

670 USING AFTER EFFECTS CS4
Expressions
Last updated 12/21/2009
Returns the width of the layer, in pixels. It is the same as source.width .
height Return type: Number.
Returns the height of the layer, in pixels. It is the same as source.height .
index Return type: Number.
Returns the index number of the layer in the composition.
parent Return type: Layer, Light, or Camera.
Returns the parent Layer object of the layer, if it has one. Example: position[0] + parent.width
hasParent Return type: Boolean.
Returns true if the layer has a parent or false if it doesn’t.
Use the hasParent attribute to determine if a layer has a parent layer. You can use this attribute even if the layer has
no parent layer at present. For example, the following expression indicates that the layer to which you apply it wiggles
based on the position of the parent. If the layer has no parent, then it wiggles based on its own position. If the layer is
given a parent later, then the behavior of the layer changes accordingly:
idx = index;
if (hasParent) {
idx = parent.index;
}
thisComp.layer(idx).position.wiggle(5,20)
inPoint Return type: Number.
Returns the In point of the layer, in seconds.
Note: In general, the value of
outPoint is greater than the value of inPoint . However, if a layer is reversed in time, the
value of inPoint is greater than the value of outPoint . Similarly, the value of startTime can be greater than the value
of inPoint .
outPoint Return type: Number.
Returns the Out point of the layer, in seconds.
startTime Return type: Number.
Returns the start time of the layer, in seconds.
hasVideo Return type: Boolean.
Returns true if the layer has video, or false if it doesn’t.
hasAudio Return type: Boolean.
Returns true if the layer has audio or false if it doesn’t.
active Return type: Boolean.
Returns true if the Video switch is on for the layer and the current time is in the range from the In point of the layer
to the Out point of the layer; false otherwise.
audioActive Return type: Boolean.
Returns true if the Audio switch is on for the layer and the current time is in the range from the In point of the layer
to the Out point of the layer; false otherwise.
enabled Return type: Boolean.