Flash CS3 Documentation

Learning ActionScript 2.0 in Adobe Flash > Animation, Filters, and Drawings > Using filter effects > About error handling, performance, and filters

About error handling, performance, and filters

One problem that arises if you use too many filters in an application is the potential to use large amounts of memory and cause Flash Player performance to suffer. Because a movie clip with filters attached has two bitmaps that are both 32-bit, these bitmaps can cause your application to use a significant amount of memory if you use many bitmaps. You might see an out-of-memory error generated by the computer's operating system. On a modern computer, out-of-memory errors should be rare, unless you are using filter effects extensively in an application (for example, you have thousands of bitmaps on the Stage).

However, if you do encounter an out-of-memory error, the following occurs:

• The filters array is ignored.
• The movie clip is drawn using the regular vector renderer.
• No bitmaps are cached for the movie clip.

After you see an out-of-memory error, a movie clip never attempts to use a filters array or a bitmap cache. Another factor that affects player performance is the value that you use for the quality parameter for each filter that you apply. Higher values require more CPU and memory for the effect to render, whereas setting the quality parameter to a lower value requires less computer resources. Therefore, you should avoid using an excessive number of filters, and use a lower quality setting when possible.

You can also encounter errors if you use invalid parameter types. Some filter parameters also have a particular valid range. If you set a value that's outside of the valid range, the value changes to a valid value that's within the range. For example, quality should be a value from 1 to 3 for a standard operation, and can only be set to 0 to 15. Anything higher than 15 is set to 15.

Also, some constructors have restrictions on the length of arrays required as input parameters. If a convolution filter or color matrix filter is created with an invalid array (not the right size), the constructor fails and the filter is not created successfully. If the filter object is then used as an entry on a movie clip's filters array, it is ignored.

Flash CS3