Grid And Mask?

programming flash
1

Okay so I have a grid that spans the whole canvas. I have a mc that can be dragged and snapped to each point. But don’t want the user to be able to drag across the whole canvas. So I was wondering if there is a way to use a bitmap img to mask out intersecting points on the grid and create a silhouette of the image. Or is it possible to generate a “grid silhouette” of a bitmap? Here is a simple pic to demonstrate what I’m trying to do.

Here is code


// Original content from www.flashandmath.com 
// by Doug Ensley and Barbara Kaskosz


//Part I -- Set up the board


var bWidth:Number = 400;
var bHeight:Number = 240;


var grid:Number = 40;        // Size of the grid and number of lattice points in each direction
var dotsWide:Number = Math.ceil(bWidth/grid) - 1;
var dotsHigh:Number = Math.ceil(bHeight/grid) - 1;


var board:Sprite = new Sprite();
var myPoint:Sprite = new Sprite();


stage.addChild(board);
board.addChild(myPoint);




board.graphics.lineStyle(1,0);
board.graphics.beginFill(0xCCCCCC);
board.graphics.drawRect(0,0,bWidth,bHeight);
board.graphics.endFill();


// Add a bunch of circles to represent lattice points
board.graphics.beginFill(0x000000);
for (var i=1; i<=dotsHigh; i++) {
    for (var j=1; j<=dotsWide; j++) {
        board.graphics.drawCircle(j*grid,i*grid,0.5);
    }
}
board.graphics.endFill();


board.x = 10;
board.y = 10;


myPoint.graphics.lineStyle(1,0);
myPoint.graphics.beginFill(0xFF5555);
myPoint.graphics.drawCircle(0,0,8);
myPoint.graphics.endFill();
myPoint.x = goodX(50);
myPoint.y = goodY(50);


// Part II -- Add drag and drop functionality


myPoint.addEventListener(MouseEvent.MOUSE_DOWN, startMove);


function startMove(evt:MouseEvent):void {
    stage.addEventListener(MouseEvent.MOUSE_MOVE, pointMove);
}


function pointMove(e:MouseEvent):void {
    myPoint.x = goodX(board.mouseX);
    myPoint.y = goodY(board.mouseY);
    e.updateAfterEvent();
}


stage.addEventListener(MouseEvent.MOUSE_UP, stopAll);


function stopAll(e:MouseEvent):void {
    stage.removeEventListener(MouseEvent.MOUSE_MOVE, pointMove);
}




// Part III -- Helper functions to stay within boundary AND snap to grid


function goodX(inX:Number):Number {
    if (inX > grid*dotsWide) {
        return grid*dotsWide;
    }
    if (inX < grid) {
        return grid;
    }
    return grid*Math.round(inX/grid);
}


function goodY(inY:Number):Number {
    if (inY > grid*dotsHigh) {
        return grid*dotsHigh;
    }
    if (inY < grid) {
        return grid;
    }
    return grid*Math.round(inY/grid);
}

**THANKS! **(-: