Macromedia MAX 2005 - Anaheim, CA What’s New In Flash 8
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Bitmap caching lets you use a movie clip and "freeze" it in place automatically. If a region changes,
Flash uses vector data to update the bitmap cache. This minimizes the number of redraws that
Flash Player must perform, and provides smoother, faster playback performance.
Only use runtime bitmap caching on static, complex movie clips in which the position, but not the
content, of the movie clip changes on each frame in an animation. You can only observe on
complex-content movie clips the playback or runtime performance improvement in using runtime
bitmap caching. You will not see the performance benefit of runtime bitmap caching when creating
simple movie clips.
NOTE:
You can only apply the Use Runtime Bitmap Caching check box to movie clip and button symbols.
Under the following circumstances, a movie clip will not use a bitmap (even if the Use Runtime
Bitmap Caching check box is selected) and will instead render the movie clip or button symbol using
vector data:
• The bitmap is too large (greater than 2880 pixels in either direction).
• The bitmap fails to allocate (producing an out of memory error).
• The parent surface uses a vector clipper (the parent is partially rotated and scrolled).
To specify bitmap caching for a movie clip:
1. Select the movie clip or button symbol on the Stage.
2. In the symbol Property inspector, select the Use Runtime Bitmap Caching check box.
