Compositing the stage's last frame - actionscript-3

Question

I've created a series of classes that can be used to generate and render images. I want to store a copy of the last frame displayed so I can mix it with the current frame to create a video sustain effect. A brief overview of the classes involved in this example:
MasterContainer: a subclass of Sprite used as the main display object. Generative classes are placed in the MasterContainer, and redrawn when the container is told to render
CustomWave: a subclass of Shape used to contain, draw, and manipulate a GraphicsPath object. One of the aforementioned 'generative classes'
My current attempt involves the use of two MasterContainer objects - one for the current frame, and one for the last frame. If I'm not mistaken, the current appearance of one MasterContainer (and its children) can be copied to the other with a command like lastMaster.graphics.copyFrom(master.graphics);. Consider the following code:
var time:Number;
var master:MasterContainer = new MasterContainer(); //current frame
var lastMaster:MasterContainer = new MasterContainer(); // last frame
var wave:CustomWave = new CustomWave(new <Number>[0,0,0,0],0xffffff,5); //generator for current frame
master.RegisterComponent(wave); //adds CustomWave and registers with the rendering loop
addChild(lastMaster); //add last frame to stage
addChild(master); //add current frame to stage
addEventListener(Event.ENTER_FRAME, perFrame);
function perFrame(event:Event):void{
time = 0.001 * getTimer();
lastMaster.graphics.copyFrom(master.graphics); //copy previous frame's graphics
UpdatePoints(); //update the path of the CustomWave
UpdateColor(); //update the color of the CustomWave
master.fireRenderCannon(); //redraw objects registered to master
}
This seems to work in theory, but as far as I can tell lastMaster ends up with no visible graphics content even though master renders as expected. I've tried several times to test whether this is the case, and am pretty convinced that that it is, but am newish to AS3 and am concerned I am overlooking something - the code looks like it should work. Does anyone have suggestions on how to test this properly? Are there obvious defects within this code that would cause lastMaster to be visually blank? Is there an better way of accomplishing my goal?
I think I'm in over my head on this... I would love any input. Thanks!

Answer 1

After you copied graphics, what do you try to do with it?
Method copyFrom works as clocks, without any problems. Isn't here logic bug in your code?
function perFrame(event:Event):void{
time = 0.001 * getTimer();
lastMaster.graphics.copyFrom(master.graphics); //Here
//master.graphics.copyFrom(lastMaster.graphics);
UpdatePoints();
UpdateColor();
master.fireRenderCannon();
}
Example of copyFrom, it works fine with any complexity of graphics:
var complex: Shape = new Shape();
adobeExample(complex.graphics);
var test2: Shape = new Shape();
test2.graphics.copyFrom(complex.graphics);
addChild(test2);
private function adobeExample(graphics: Graphics):void{
// define the line style
graphics.lineStyle(2,0x000000);
// define the fill
graphics.beginFill(0x666699);//set the color
// establish a new Vector object for the commands parameter
var star_commands:Vector.<int> = new Vector.<int>();
// use the Vector array push() method to add moveTo() and lineTo() values
// 1 moveTo command followed by 3 lineTo commands
star_commands.push(1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2);
// establish a new Vector object for the data parameter
var star_coord:Vector.<Number> = new Vector.<Number>();
// use the Vector array push() method to add a set of coordinate pairs
star_coord.push(0,0, 75,50, 100,0, 125,50, 200,0, 150,75, 200,100, 150,125, 200,200, 125,150, 100,200, 75,150, 0,200, 50,125, 0,100, 50,75, 0,0);
graphics.drawPath(star_commands, star_coord);
}

Answer 2

After the comments made by Bennet and Nicolas, it became obvious that my requirements were (nearly) impossible without a fair amount of redesign. The changes made are as follows:
Generators are no longer DisplayObjects. They are only used to calculate vectors containing the IGraphicsData objects necessary to draw the generated graphic with the drawGraphicsData method.
MasterContainer is now a shape subclass that retrieves the Vector.<IGraphicsData> from each registered generator in order to draw the output.
A bitmap subclass is used to render the contents of the MasterContainer, combining it with a color-dampened version of the previous frame.
An abridged version of the bitmap subclass:
private var constantSustain:Number;
private var linearSustain:Number;
private var sustain:ColorTransform;
private var lastFrame:BitmapData;
public function BitmapManipulator(constantSustain:Number = 0.998, linearSustain:Number = 0.98) {
this.constantSustain = Math.min(Math.max(constantSustain, 0), 1);
this.linearSustain = Math.min(Math.max(linearSustain, 0), 1);
this.UpdateSustain();
this.addEventListener(Event.ADDED_TO_STAGE, OnAddedToStage)
}
private function UpdateSustain():void {
var constantRelease:Number = 255 * (this.constantSustain - 1);
this.sustain = new ColorTransform(this.linearSustain, this.linearSustain, this.linearSustain, 1,
constantRelease, constantRelease, constantRelease, 0);
}
private function OnAddedToStage(event:Event) {
this.lastFrame = new BitmapData(stage.stageWidth, stage.stageHeight, true, 0);
}
public function DrawFrame(container:MasterContainer):void {
this.lastFrame.draw(container);
this.bitmapData = lastFrame;
this.lastFrame = this.bitmapData
this.lastFrame.colorTransform(getBounds(this), this.sustain);
}
...and finally the results #60fps when using an indigo sine wave of shifting phase as the input for the CustomWave: