MACROMEDIA FLASH MX 2004 - ACTIONSCRIPT, Reference Manual

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94 Chapter 5: Creating Interaction with ActionScript
Creating interactivity and visual effects
To create interactivity and other visual effects, you need to understand the following techniques:
•
Creating a custom mouse pointer
•
Getting the mouse position
•
Capturing keypresses
•
Setting color values
•
Creating sound controls
•
Detecting collisions
•
Creating a simple line drawing tool
Creating a custom mouse pointer
A standard mouse pointer is the operating system’s onscreen representation of the position of the
user’s mouse. By replacing the standard mouse pointer with one you design in Flash, you can
integrate the user’s mouse movement within the SWF file more closely. The sample in this section
uses a custom pointer that looks like a large arrow. The power of this feature, however, lies in your
ability to make the custom pointer look like anything—for example, a football to be carried to the
goal line or a swatch of fabric pulled over a couch to change its color.
To create a custom pointer, you design the pointer movie clip on the Stage. Then, in
ActionScript, you hide the standard pointer and track its the movement. To hide the standard
pointer, you use the
Mouse.hide()
method of the built-in Mouse class. To use a movie clip as the
custom pointer, you use the
startDrag()
action.
To create a custom pointer:
1
Create a movie clip to use as a custom pointer, and place an instance of the clip on the Stage.
2
Select the movie clip instance on the Stage.
3
Select Window > Development Panels > Actions to open the Actions panel if it is not
already visible.
4
Type the following in the Actions panel:
onClipEvent (load) {
Mouse.hide();
startDrag(this, true);
}
onClipEvent(mouseMove){
updateAfterEvent();
}
The first
onClipEvent()
handler hides the mouse when the movie clip first appears on the
Stage; the second handler calls
updateAfterEvent
whenever the user moves the mouse.
The
updateAfterEvent
function immediately refreshes the screen after the specified event
occurs, rather than when the next frame is drawn, which is the default behavior. (See
updateAfterEvent()
on page 743 .)
5
Select Control > Test Movie to test your custom pointer.