User Guide

Performance optimization 59
Bitmap versus vector graphics
When you create content for mobile devices, it is sometimes preferable to use bitmaps instead
of vectors because they require less CPU power to animate. For example, a road map of a large
city would have too many complex shapes to scroll and animate well on a mobile phone if it
were created as a vector graphic; a bitmap would animate better.
However, using bitmaps produces larger files than using vector images, so you should find the
right balance of CPU versus file size and runtime memory requirements in your development.
Whenever possible, do not use strokes on your vector shapes, because it increases the number
of rendered lines.
Setting bitmap compression options
If you use bitmaps, you can set image-compression options in Flash that educe your SWF
file size. You can set bitmap compression on per-image basis, or globally for all bitmap images.
To set bitmap image compression:
1. Start Flash, and create a document.
2. Select a bitmap in the Library window.
3. Right-click (Windows) or Control-click (Macintosh) the bitmap’s icon in the Library
window, and select Properties from the context menu to open the Bitmap Properties
dialog box.