Question

I am trying to build an app that tracks touchpoints and draws circles at those points using Flash Builder. The following works perfectly, but after a while, it begins to lag and the touch will be well ahead of the drawn circles. Is there a way of drawing the circles that does not produce lag as more and more of them are added?

In declarations, I have:

    <fx:Component className="Circle">
        <s:Ellipse>
            <s:stroke>
                <s:SolidColorStroke alpha="0"/>
            </s:stroke>
        </s:Ellipse>
    </fx:Component>

And this is the drawing function:

            var c:Circle = new Circle();
            c.x = somex;
            c.y = somey;
            c.fill = new SolidColor(somecolorint);
            c.height = somesize;
            c.width = somesize;
            c.alpha = 1;
            addElement(c);
            c = null;

Answer 1

Try taking a look at doing a fullscreen Bitmap created with a BitmapData class. As the touch points are moved, update the bitmap data at the coordinates where the touch occured. Modifying and blitting a screen-sized bitmap is extremely fast and will probably work great for what you’re trying to do.

Another performance trade off often done is to make a series of lines instead of continuous circles. You create a new line segment only when a certain distance has been traveled, this lets you limit the number of nodes in the segment thereby keeping performance high.