ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Display programming
Controlling Stage scaling
Flash Player 9 and later, Adobe AIR 1.0 and later
When the portion of the screen representing Flash Player or AIR is resized, the runtime automatically adjusts the Stage
contents to compensate. The Stage class’s scaleMode property determines how the Stage contents are adjusted. This
property can be set to four different values, defined as constants in the flash.display.StageScaleMode class:
StageScaleMode.EXACT_FIT scales the SWF to fill the new stage dimensions without regard for the original
content aspect ratio. The scale factors might not be the same for width and height, so the content can appear
squeezed or stretched if the aspect ratio of the stage is changed.
StageScaleMode.SHOW_ALL scales the SWF to fit entirely within the new stage dimensions without changing the
content aspect ratio. This scale mode displays all of the content, but can result in “letterbox” borders, like the black
bars that appear when viewing a wide-screen movie on a standard television.
StageScaleMode.NO_BORDER scales the SWF to entirely fill the new stage dimensions without changing the aspect
ratio of the content. This scale mode makes full use of the stage display area, but can result in cropping.
StageScaleMode.NO_SCALE — does not scale the SWF. If the new stage dimensions are smaller, the content is
cropped; if larger, the added space is blank.
In the StageScaleMode.NO_SCALE scale mode only, the stageWidth and stageHeight properties of the Stage class
can be used to determine the actual pixel dimensions of the resized stage. (In the other scale modes, the stageWidth
and stageHeight properties always reflect the original width and height of the SWF.) In addition, when
scaleMode is set to StageScaleMode.NO_SCALE and the SWF file is resized, the Stage class’s resize event is
dispatched, allowing you to make adjustments accordingly.
Consequently, having scaleMode set to StageScaleMode.NO_SCALE allows you to have greater control over how
the screen contents adjust to the window resizing if you desire. For example, in a SWF containing a video and a
control bar, you might want to make the control bar stay the same size when the Stage is resized, and only change
the size of the video window to accommodate the Stage size change. This is demonstrated in the following example:
Last updated 6/6/2012
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