Adobe FLASH CS3 PRO User Manual page 502

Right-click (Windows) or Control-click (Macintosh) the bitmap icon in the Library window, and select Properties
3
from the context menu to open the Bitmap Properties dialog box.
In the Compression pop-up menu, select one of the following options:
4
• Select the Photo (JPEG) option for images with complex color or tonal variations, such as photographs or images
with gradient fills. This option produces a JPEG file. Select the Use Imported JPEG Data check box to use the
default compression quality specified for the imported image. To specify a new quality compression setting,
deselect Use Imported JPEG Data and enter a value between 1 and 100 in the Quality text box. A higher setting
produces an image of higher image, but also a larger file, so adjust the value accordingly.
• Select the Lossless (PNG/GIF) option for images with simple shapes and a few colors. This option compresses the
image using lossless compression, which discards no data.
5 Click Test to determine the results of the file compression.
Compare the original file size to the compressed file size to decide whether the selected compression setting is
acceptable.
Set compression for all bitmap images
Select File > Publish Settings, and then click the Flash tab to display compression options.
1
2 Adjust the JPEG quality slider, or enter a value. A higher JPEG quality value produces an image of higher image
quality but a larger SWF file. A lower image quality produces a smaller SWF file. Try different settings to determine
the best trade-off between size and quality.
Optimizing Flash Lite frames for mobile devices
• Most devices that support Flash Lite play back content at about 15 to 20 frames per second (fps). The frame rate
can be as low as 6 fps. During development, set the document frame rate to approximate the playback speed of the
target device. This shows how the content will run on a device with limited performance. Before publishing a final
SWF file, set the document frame rate to at least 20 fps or higher to avoid limiting performance in case the device
supports a higher frame rate.
• When using
gotoAndPlay
to be initialized before Flash plays the requested frame. If many of these frames contain different content, it could
be more efficient to use different movie clips rather than using the Timeline.
• Although preloading all content by putting it at the beginning of the file makes sense on the desktop, preloading
on a mobile device can delay file startup. Space content throughout the file so that movie clips are initialized as
they are used.
Optimizing ActionScript for Flash Lite content on mobile devices
Because of the processing speed and memory limitations on most mobile devices, follow these guidelines when
developing ActionScript for Flash Lite content used on mobile devices:
• Keep the file and its code as simple as possible. Remove unused movie clips, delete unnecessary frame and code
loops, and avoid too many frames or extraneous frames.
• Using loops can be expensive because of the overhead incurred while the condition is checked with each
FOR
iteration. When the costs of the iteration and the loop overhead are comparable, execute multiple operations
individually instead of using a loop. The code may be longer, but performance will improve.
• Stop frame-based looping as soon as it is no longer needed.
• When possible, avoid string and array processing because it can be CPU-intensive.
, remember that every frame between the current frame and the requested frame needs
FLASH CS3 496
User Guide