Adobe Flash CS3 - "do something" only when playhead hit a defined keyframe

Question

I would like to know how to create in Adobe Flash CS3 a button that will execute a function (like gotoAndPlay(51) but ONLY when playhead hit a defined keyframe from timeline. Here is a drawing that does explain better what I want to do

So after I click the button, it will wait until the playhead hit the closest defined keyframe, only then it will execute my desired function.

Any help is appreciated.

Answer 1

There are a few ways to accomplish this. The most succinct way is to use an undocumented* feature called addFrameScript

What you can do with that method, is place code on a specific frame at runtime.

So, you could do something like:

//listen for the click on your button
myButton.addEventListener(MouseEvent.CLICK, buttonClickHandler);

//which frame should the gotoAndPlay run on?
var targetFrame:int = 19; //this is actually frame 20, since frames are 0 based in script

//this function will run on the above frame
function goto51(){
    //goto frame 51
    gotoAndPlay(51);
    //remove the frame script
    addFrameScript(targetFrame, null);
}

function btnClickHandler(e:Event) {
    //use addFrameSCript to run the function goto51 on the target frame
    addFrameScript(targetFrame, goto51);
}

*-one should point out that using undocumented features of a language comes with risk of the feature being taken out on a future version, however given the current life cycle stage of AS3, this is very unlikely