ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Filtering display objects
// Example of removing the top-most filter from a display object
// named "filteredObject".
var tempFilters:Array = filteredObject.filters;
// Remove the last element from the Array (the top-most filter).
tempFilters.pop();
// Apply the new set of filters to the display object.
filteredObject.filters = tempFilters;
Similarly, to remove the bottom-most filter (the first one applied to the object) you use the same code, substituting the
Array class’s shift() method in place of the pop() method.
To remove a filter from the middle of an array of filters (assuming that the array has more than two filters) you can use
the splice() method. You must know the index (the position in the array) of the filter you want to remove. For
example, the following code removes the second filter (the filter at index 1) from a display object:
// Example of removing a filter from the middle of a stack of filters
// applied to a display object named "filteredObject".
var tempFilters:Array = filteredObject.filters;
// Remove the second filter from the array. It's the item at index 1
// because Array indexes start from 0.
// The first "1" indicates the index of the filter to remove; the
// second "1" indicates how many elements to remove.
tempFilters.splice(1, 1);
// Apply the new set of filters to the display object.
filteredObject.filters = tempFilters;
Determining a filter’s index
You need to know which filter to remove from the array, so that you know the index of the filter. You must either know
(by virtue of the way the application is designed), or calculate the index of the filter to remove.
The best approach is to design your application so that the filter you want to remove is always in the same position in
the set of filters. For example, if you have a single display object with a convolution filter and a drop-shadow filter
applied to it (in that order), and you want to remove the drop-shadow filter but keep the convolution filter, the filter
is in a known position (the top-most filter) so that you can know ahead of time which Array method to use (in this
case Array.pop() to remove the drop-shadow filter).
If the filter you want to remove is always a certain type, but not necessarily always in the same position in the set of
filters, you can check the data type of each filter in the array to determine which one to remove. For example, the
following code determines which of a set of filters is a glow filter, and removes that filter from the set.
Last updated 6/6/2012
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