Macromedia flash mx professional 2004-macromedia flash lite 1.1 authoring guidelines User Manual

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Performance optimization
17
Bitmap versus vector graphics
Flash Lite generally uses vector graphics to define content, which can tax a phone’s CPU when 
rendering complex graphics and animations. In general, the more vectors that are manipulated on 
the Stage, the more CPU power is required. This is also true for Flash movies delivered on 
desktop computers. However, a mobile phone is far less powerful than desktop computer, so you 
should avoid taxing the CPU.
When creating content for mobile phones, it is sometimes better 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 work much better.
Using bitmaps produces larger files than using vector images, so take care during development to 
find the right balance of CPU versus file size and runtime memory requirements. Because of 
mobile phones’ smaller screens, slower data transmission speeds, limited memory, and slower 
CPU speeds, you should take extra care in planning and testing. 
If you are using bitmaps, you can set image compression options that reduce your SWF file size.
To set bitmap image compression:
1.
Start Flash and create a new 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.
4.
Select Properties from the options menu. The Bitmap Properties dialog box appears: