Question

Scrolling graph. Currently I show a real-time graph by drawing each piece of data as it is generated. To scroll, I simply move the container object left to compensate and erase all the data left of the bounds.

Simple, fast, surprisingly memory efficient…but is there a concern of the coordinates overflowing as I keep adding contents to the right and scrolling the container left? Is there a limit on the x coordinate of an (empty) object? I’m afraid if I keep scrolling the container left indefinitely and writing to ever increasing x coordinates the program would misbehave eventually. Would this occur? If so, at what max coordinates? Or does AS3 handle this automatically?

Answer 1

I did a test, where I keep drawing an item to a container making it bigger and bigger, and moving it to the left. It stopped getting bigger at 105,000,000 pixels. After that the width reported 0 and the x property reported -107,374,182.4 and wouldn’t move beyond that.

If you have bitmap data though, the FP10 limit is 8,191 pixels in width or height, and the total number of pixels cannot exceed 16,777,215 pixels.

Here was my code used to test:

var b:Sprite = new Sprite();
addChild(b);

b.x = stage.stageWidth * .5;
var t:Timer = new Timer(100);
t.addEventListener(TimerEvent.TIMER,tick);
t.start();

var moveAmt:Number = 50;
function tick(e:Event):void {
    b.x -= moveAmount;
    b.graphics.beginFill(Math.random() * 0xFFFFFF);
    b.graphics.drawRect(b.width,0,moveAmount,stage.stageHeight);
    b.graphics.endFill();
    trace(b.width + "  :  " + b.x);
}