Mouse Click detection only on opaque areas of movieclip

Question

I have movieclips (which in turn have more than 1 movieclips in them ). My requirement is to add a MouseEvent.CLICK event to the parent movieclip. So that an event (MouseEvent.CLICK) is dispatched by flash only if the visually opaque (alpha = 100 %) area has been clicked, otherwise , ignore.

The workaround I do as of now is to create an alpha = 0.05 circle which follows the mousecursor in Event.ENTER_FRAME and do a hittest followed by a PixelPerfectCollisionDetection (courtesy one gr8 guy I admire on google code :) )

In short, I need to know If I can make flash dispatch a MouseEvent only when clicked on a visually opaque area of the movieclip and NOT anywhere in the bounding box region.

Thanks,

Vishnu Ajit

Answer 1

I got this solution. But It's not perfect at all, cause you create everytime a new bitmapData object of your MovieClip:

myButton.addEventListener( MouseEvent.CLICK, clickFunction);

private function clickFunction(e:MouseEvent) {
    if(pixelIsVisible(e.currentTarget, e.currentTarget.mouseX, e.currentTarget.mouseY)) {
        //DoSomething
    }
}   

private function pixelIsVisible(target:*, xPos:int, yPos:int):Boolean {
    var bmp:BitmapData = new BitmapData( target.width, target.height, false );
    bmp.draw( target as MovieClip );
    var pixelValue = bmp.getPixel( xPos, yPos);

    //Dispose bitmapData to free memory
    bmp.dispose();

    var alphaValue:uint = pixelValue >> 24 & 0xFF;
    //alphaValue is from 0 to 255
    if(alphaValue >= 255) return true;
    else false;
}