Pdf as background to canvas to draw on pdf

Question

<mx:HTML top="0" bottom="0" left="0" right="0" location="test.pdf"/>
    <mx:Canvas top="0" bottom="0" left="0" right="0" initialize="canvasInit(event)">
    </mx:Canvas>
in canvasinit event i did drawing the line in mouse using mouse.
if i try to set pdf as background to the canvas, it is not set as background. it will be in the foreground. how to send pdf as a background of canvas.
i tried lot. i am not able to set pdf as background. it comes to foreground.
so please if anybody is having an idea on tht please hlep me
If i load the html page instead of pdf. it works fines. i.e html page in background of canvas.  i used following code
<?xml version="1.0" encoding="utf-8"?>
<mx:WindowedApplication xmlns:mx="http://www.adobe.com/2006/mxml"layout="absolute">
    <mx:Script>
        <![CDATA[
            import mx.containers.Canvas;
            private var drawing:Boolean = false;
            private function canvasInit(e:Event):void {
                var c:Canvas = Canvas(e.target);
                c.graphics.lineStyle(2, 0xff0000, 1);
                c.addEventListener(MouseEvent.MOUSE_UP, onMouseEvent);
                c.addEventListener(MouseEvent.MOUSE_DOWN, onMouseEvent);
                c.addEventListener(MouseEvent.MOUSE_MOVE, onMouseEvent);
            private function onMouseEvent(e:MouseEvent):void {
                //trace(e.type);
                if (e.type == MouseEvent.MOUSE_DOWN)
                    drawing = true;
                else if (e.type == MouseEvent.MOUSE_UP)
                    drawing = false;
                else if (e.type == MouseEvent.MOUSE_MOVE) {
                    var c:Canvas = Canvas(e.target);
                    //trace((drawing ? "drawing to " : "moving to ") + e.localX + "," + e.localY);
                    if (drawing)
                        c.graphics.lineTo(e.localX, e.localY);
                    else
                        c.graphics.moveTo(e.localX, e.localY);
        ]]>
    </mx:Script>
    <mx:HTML top="0" bottom="0" left="0" right="0" location="http://labs.adobe.com/technologies/afcs/"/>
    <mx:Canvas top="0" bottom="0" left="0" right="0" initialize="canvasInit(event)">
    </mx:Canvas>
</mx:WindowedApplication>
instead of html page, if i put any pdf  file. it is not in background. it comes to the foreground. i don't know how to set pdf as background. please help me

Answer 1

1. Yes you can load SWF files using Loader and then order that SWF behind or above other display objects. (Although in Flex, I think you would use SWFLoader.) If you load a SWF in an HTML control, it will always be on top.
2. I'm not sure what you mean by the background of the canvas. The flash display list is a tree. A parent object can have its own graphics (drawn with the graphics drawing API). Any children added to that object will display above these graphics. If you added that parent object to another display container, it (and its children) would display above any lower indexed children of that display container. Thus a canvas has a background rectangle that it draws with the graphics api. Any children you add to it are drawn in index order. The object at index 0 is drawn at the bottom of the visual stack.
3. No.
4. Technically you could load the PDF file into memory, parse the file structure and convert what you parsed into ActionScript objects. I suspect that is more work than you want to do.