as3 How to dispatch a specific keyboard event - actionscript-3

Question

I was looking for this answer and had no luck. One place I looked actually had a very discouraging answer: "You cannot force mouse or keyboard events - they HAVE TO come from mouse or keyboard."
Huh?
I tried 'brute force' and came up with this solution. Maybe I'm going about it wrongly or stupidly; is there a better way?
I had a keyboard event that launched a class and wanted to put a sprite on the stage that would initiate this same action -- clicking on the sprite would launch the keyboard event (Escape key).
In the eventListener function, I traced the event e itself:
private function keys(e:KeyboardEvent):void {
trace("EscapeKey: ",e);
if (e.keyCode == 27) {
...
}
}
The output was
EscapeKey: [KeyboardEvent type="keyDown" bubbles=true cancelable=false eventPhase=2 charCode=27 keyCode=27 keyLocation=0 ctrlKey=false altKey=false shiftKey=false]
I then had the mouseClick listener create and dispatch a new keyboardEvent using the values I got from the above trace:
private function pauseClick(e:MouseEvent):void {
var a:KeyboardEvent = new KeyboardEvent("keyDown", true, false, 27, 27, 0, false, false, false);
stage.dispatchEvent(a);
}
Presto!
Hopefully, this post will come in handy to others looking for these types of mouse/keyboard event redundancies.
EDIT --- A complete class example requested in comments:
package{
import flash.display.Sprite;
import flash.events.Event;
import flash.events.MouseEvent;
import flash.events.KeyboardEvent;
public class KeyboardMouse extends Sprite {
private var pauseInfo:PauseInfo;
private var escapeKey:EscapeKey;
public function KeyboardMouse() {
if (stage) init();
else addEventListener(Event.ADDED_TO_STAGE, init);
}
private function init(e:Event = null):void {
removeEventListener(Event.ADDED_TO_STAGE, init);
stage.addEventListener(KeyboardEvent.KEY_DOWN, keys);
escapeKey = new EscapeKey();
stage.addChild(escapeKey);
pauseInfo = new PauseInfo();
pauseInfo.x = stage.stageWidth;
pauseInfo.y = stage.stageHeight;
pauseInfo.addEventListener(MouseEvent.CLICK,pauseClick);
addChild(pauseInfo);
}
private function keys(e:KeyboardEvent):void {
trace("KeyboardEvent ",e);
if (e.keyCode == 27) { // esc key
if (stage.contains(escapeKey)){
trace("remove escape");
escapeKey.visible = false;
}
else {
trace("show escape");
escapeKey.visible = true;
}
}
}
private function pauseClick(e:MouseEvent):void {
// The trace in 'keys' gives this:
//[KeyboardEvent type="keyDown" bubbles=true cancelable=false eventPhase=2 charCode=27 keyCode=27 keyLocation=0 ctrlKey=false altKey=false shiftKey=false]
var a:KeyboardEvent = new KeyboardEvent("keyDown", true, false, 27, 27, 0, false, false, false);
stage.dispatchEvent(a);
}
}
}

Answer 1

Alright, now I get this. I just don’t get it’s purpose. Also there is, I think, an annoying error in the code.
First: you’ve shown that you can essentially ‘cast’ one type of event (e.g. MouseEvent) as another (KeyboardEvent). But you still have a listener function registered for each Event type (which, at some point, you’ll have to remove for memory management purposes) and a newly dispatched Event, so you’re not exactly minimizing code. What, exactly, is the value of this trick? Why not just register a single listener function with multiple event types? Within that function you can discriminate between the Event types and do stuff accordingly, for instance with a line like this:
if(e.type == 'keyDown' || e.type == 'click')
Second: you say: if (stage.contains(escapeKey)) and then you try to make the ‘visible’ property of escapeKey dependent on that. But by making the escapeKey.visible = false you’re not changing the fact that the stage still contains escapeKey. So the escapeKey will never become visible again because the 'else' condition doesn't exist. I believe that you want to say “removeChild(escapeKey)” and then “addChild(escapeKey)” instead of setting “escapeKey.visible = false” and then “escapeKey.visible = true”. Then you’re little program does what I think you want it to.

Answer 2

+1 and big props to #Neal Davis for his comments!
As he suggests, having one listener for both events with an argument of (e:Event) is a cleaner, less convoluted way of achieving the same result:
pauseInfo.addEventListener(MouseEvent.CLICK,keys);
stage.addEventListener(KeyboardEvent.KEY_DOWN, keys);
private function keys(e:Event):void {
trace("EscapeKey: ",e);
if (e.keyCode == 27) {
...
}
}
Both listeners must still be removed at some point, though, even though only one Listener Function is handling both, of course!