/**
* Based on the code of the book Foundation ActionScript 3.0 Image Effects" by Todd Yard.
*/

package 
{
	import flash.events.*;
	import flash.display.GraphicsPathCommand;
	import flash.display.Sprite;
	import flash.events.MouseEvent;
	import flash.events.*;

	[SWF(width=550, height=400, backgroundColor=0xFFFFFF)]

	/**
	* Demonstrates how Graphics.drawPath() may be used to redraw vector lines by saving the drawing commands and data.
	*/
	public class graphic_flex_draw_classes_ChangingPointsOnAPathCurves extends Sprite {

		private const COLOR:uint = 0xFF;
		private const THICKNESS:uint = 3;

		private var _pathCommands:Vector.<int>;
		private var _pathData:Vector.<Number>;
		private var _anchors:Vector.<Sprite>;
		private var _controlPoints:Vector.<Sprite>;
		private var _anchor:Sprite;
		private var _anchorIndex:uint;

		/**
		* Constructor.
		*/
		public function graphic_flex_draw_classes_ChangingPointsOnAPathCurves() {
			this.addEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
		}
		
		private function onAddedToStage(e:Event):void
		{
			this.init();
		}


		/**
		* Initialization method for instantiating vector arrays and establishing listener for MOUSE_DOWN on the stage.
		*/
		private function init():void {
			_anchors = new Vector.<Sprite>();
			_controlPoints = new Vector.<Sprite>;
			_pathCommands = new Vector.<int>();
			_pathData = new Vector.<Number>();
			graphics.lineStyle(THICKNESS, COLOR);
			stage.addEventListener(MouseEvent.MOUSE_DOWN, onStageMouseDown);
		}

		/**
		* Adds an anchor point at the specified position.
		*
		* @param x The x position of the new anchor.
		* @param y The y position of the new anchor.
		*/
		private function addAnchor(x:Number, y:Number):void {
			var anchor:Sprite = new Sprite();
			// this will draw a big dot
			
			if(_anchors.length % 2 == 0)	anchor.graphics.lineStyle(10);
			else anchor.graphics.lineStyle(6,0xFF0000,0.5);
			anchor.graphics.lineTo(1, 0);
			anchor.addEventListener(MouseEvent.MOUSE_DOWN, onAnchorDown);
			anchor.addEventListener(MouseEvent.MOUSE_UP, onAnchorUp);
			anchor.x = x;
			anchor.y = y;
			addChild(anchor);
			_anchors.push(anchor);
		}

		/**
		* Uses Graphics.drawPath() to redraw path using commands and data stored in the vectors.
		*/
		private function redrawPath():void {
			graphics.clear();
			graphics.lineStyle(THICKNESS, COLOR);
			graphics.drawPath(_pathCommands, _pathData);
			var dataLength:uint = _pathData.length;
			// must move to the last data position so that a new lines are drawn from this position
			graphics.moveTo(_pathData[dataLength-2], _pathData[dataLength-1]);
		}

		/**
		* Handler for when an anchor point is clicked. This begins drag of anchor point.
		*
		* @param event The MouseEvent caused by the click.
		*/
		private function onAnchorDown(event:MouseEvent):void {
			_anchor = event.target as Sprite;
			_anchor.startDrag();
			// save the index so that the anchor's data can be easily accessed in the _pathData vector
			_anchorIndex = _anchors.indexOf(_anchor);
			stage.addEventListener(MouseEvent.MOUSE_MOVE, onAnchorMove);
			event.stopPropagation();
		}

		/**
		* Handler for when the mouse moves while dragging an anchor. This updates the path data and redraws the path.
		*
		* @param event The MouseEvent caused by the move.
		*/
		private function onAnchorMove(event:MouseEvent):void {
			// update the path data that corresponds to the dragged anchor
			_pathData[_anchorIndex*2] = _anchor.x;
			_pathData[_anchorIndex*2+1] = _anchor.y;
			redrawPath();
			if(_anchorIndex % 2!= 0){
				graphics.lineStyle(1, 0, .5);
				graphics.moveTo(_pathData[_anchorIndex*2-2],_pathData[_anchorIndex*2-1])
				graphics.lineTo(_anchor.x, _anchor.y);
				graphics.lineTo(_pathData[_anchorIndex*2+2],_pathData[_anchorIndex*2+3]);
			}

			event.updateAfterEvent();
		}

		/**
		* Handler for when an anchor point is released after dragging. This removes the stage MOUSE_MOVE listener.
		*
		* @param event The MouseEvent caused by the release.
		*/
		private function onAnchorUp(event:MouseEvent):void {
			if (_anchor) {
				_anchor.stopDrag();
				stage.removeEventListener(MouseEvent.MOUSE_MOVE, onAnchorMove);
			}
		}

		/**
		* Handler for when the stage is clicked. This adds a new anchor point and draws to the new anchor.
		*
		* @param event The MouseEvent caused by the click.
		*/
		private function onStageMouseDown(event:MouseEvent):void {
			var x:Number = stage.mouseX;
			var y:Number = stage.mouseY;
			
			// this means this is the first anchor, so only move to position without drawing
			if (_pathCommands.length < 1) {
				_pathCommands.push(GraphicsPathCommand.MOVE_TO);
				graphics.moveTo(x, y);
				addAnchor(x, y);
				_pathData.push(x, y);
			// else there are previous anchors, so simply draw to the new position
			} else {
				_pathCommands.push(GraphicsPathCommand.CURVE_TO);
				var dataLength:uint = _pathData.length;
				
				//calculate the initial values for the control points
				var cpX:Number = _pathData[dataLength-2]+(x-_pathData[dataLength-2])/2;
				var cpY:Number = _pathData[dataLength-1]+(y -_pathData[dataLength-1])/2;

				addAnchor(cpX, cpY);
				addAnchor(x, y);
				//graphics.curveTo(cpX, cpY, x, y);
				_pathData.push(cpX,cpY,x, y);
				redrawPath();
			}

		}

	}

}