hiResSprite.addEventListener(MouseEvent.MOUSE_DOWN,startDragHiRes);

function startDragHiRes(e:Event):void {
    var hiResWidth = e.target.width;
    var hiResHeight = e.target.height;
    var stageWidthVal = stage.stageWidth;
    var stageHeightVal = stage.stageHeight;

    var hiResX = hiResWidth - stageWidthVal;
    var hiResY = hiResHeight - stageHeightVal;
    var dragWidth = hiResWidth - stageWidthVal;
    var dragHeight = hiResHeight - stageHeightVal;
	
    var hiResDragRect = new Rectangle(-hiResX,-hiResY,dragWidth,dragHeight);
    hiResSprite.startDrag(false,hiResDragRect);
}

This function will keep an image that is larger than the stage dragging within the stage view, stopping at any edge of the image.

Keep Larger Image or Object draggable within stage - Actionscript

actionscript

ActionScript 3