Flex4 使用itemRenderer 为Tree加线具体实现

package Modules
{
import flash.display.BitmapData;
import flash.display.Graphics;

import mx.collections.ICollectionView;
import mx.collections.IList;
import mx.controls.Tree;
import mx.controls.treeClasses.ITreeDataDescriptor;
import mx.controls.treeClasses.TreeItemRenderer;


/**
* Alpha value for the Tree lines.
* @default 1
*/
[Style(name="lineAlpha", type="Number", format="Length", inherit="no")]

/**
* Color of the Tree lines.
* @default 0x808080
*/
[Style(name="lineColor", type="uint", format="Color", inherit="no")]

/**
* Thickness value for the Tree lines.
* @default 1
*/
[Style(name="lineThickness", type="Number", format="Length", inherit="no")]

/**
* The Tree line style - none, dotted (default), or solid.
* @default "dotted"
*/
[Style(name="lineStyle", type="String", enumeration="solid", inherit="no")]

/**
* Extends TreeItemRenderer to draw the dotted lines of the tree.
* It supports 3 line styles - dotted (default), solid, or none.
* And the tree line color, alpha, and thickness values are configurable styles too.
*
* <pre>
* <ui:TreeItemLinesRenderer
* <b>Styles</b>
* lineAlpha="1"
* lineColor="#808080"
* lineThickness="1"
* lineStyle="dotted"
* >
* ...
* <i>child tags</i>
* ...
* </ui:TreeItemLinesRenderer>
* </pre>
*
* @author Chris Callendar
* @date April 20th, 2009
*/
public class TreeItemLinesRenderer extends TreeItemRenderer
{

public static const DOTTED:String = "dotted"; // default
public static const SOLID:String = "solid";
public static const NONE:String = "none";

public function TreeItemLinesRenderer() {
super();
}

override public function set data(value:Object):void {
super.data = value;
}

override protected function updateDisplayList(w:Number, h:Number):void {
super.updateDisplayList(w, h);

if ((w > 0) && (h > 0)) {
// go up the hierarchy, drawing the vertical dotted lines for each node
var tree:Tree = (owner as Tree);
var desc:ITreeDataDescriptor = tree.dataDescriptor;
var currentNode:Object = data;
var parentNode:Object = tree.getParentItem(currentNode);
// the level is zero at this node, then increases as we go up the tree
var levelsUp:int = 0;

var lineStyle:String = getStyle("solid");
var lineColor:uint = getColorStyle("lineColor", 0x808080);
var lineAlpha:Number = getNumberStyle("lineAlpha", 1);
var lineThickness:Number = getNumberStyle("lineThickness", 1);
var indentation:Number = tree.getStyle("indentation");

// move the icon and label over to make room for the lines (less for root nodes)
var shift:int = (parentNode == null ? 2 : 6) + lineThickness;
if (icon) {
icon.move(icon.x + shift, icon.y);
}
if (label) {
label.move(label.x + shift, label.y);
}

var g:Graphics = graphics;
g.clear();

if ((lineStyle != NONE) && (lineAlpha > 0) && (lineThickness > 0)) {
while (parentNode != null) {
var children:ICollectionView = desc.getChildren(parentNode);
if (children is IList) {
var itemIndex:int = (children as IList).getItemIndex(currentNode);
// if this node is the last child of the parent
var isLast:Boolean = (itemIndex == (children.length - 1));
drawLines(g, w, h, lineStyle, lineColor, lineAlpha, lineThickness, isLast, levelsUp, indentation);

// go up to the parent, increasing the level
levelsUp++;
currentNode = parentNode;
parentNode = tree.getParentItem(parentNode);
} else {
break;
}
}
}
}
}

protected function drawLines(g:Graphics, w:Number, h:Number, lineStyle:String, lineColor:uint,
lineAlpha:Number, lineThickness:Number, isLastItem:Boolean, levelsUp:int, indentation:Number):void {
var midY:Number = Math.round(h / 2);
var lineX:Number = 0;
if (disclosureIcon) {
lineX = disclosureIcon.x + (disclosureIcon.width / 2);
} else if (icon) {
lineX = icon.x - 8;
} else if (label) {
lineX = label.x - 8;
}
lineX = Math.floor(lineX) - int(lineThickness / 2);
// adjust the x position based on the indentation
if (levelsUp > 0) {
if (!isNaN(indentation) && (indentation > 0)) {
lineX = lineX - (levelsUp * indentation);
} else {
// Invalid indentation style value
return;
}
}
var lineY:Number = h;
// stop the dotted line halfway on the last item
if (isLastItem) {
lineY = midY;
// no lines need to be drawn for parents of the last item
if (levelsUp > 0) {
return;
}
}

g.lineStyle(0, 0, 0);
if (lineStyle == SOLID) {
g.beginFill(lineColor, lineAlpha);
} else {
var verticalDottedLine:BitmapData = createDottedLine(lineColor, lineAlpha, lineThickness, true);
g.beginBitmapFill(verticalDottedLine);
}

// draw the vertical line
g.drawRect(lineX, 0, lineThickness, lineY);
// end the fill and start it again otherwise the lines overlap and it create white squares
g.endFill();

// draw the horizontal line - only needed on this node (not on any parents)
if (levelsUp == 0) {
var startX:int = lineX + 1 + int(lineThickness / 2);
var endX:int = startX + 11; // 5 dots
if (isLastItem) {
startX = lineX;
}
var startY:Number = midY - int(lineThickness / 2);
if (lineStyle == SOLID) {
g.beginFill(lineColor, lineAlpha);
} else {
var horizontalDottedLine:BitmapData = createDottedLine(lineColor, lineAlpha, lineThickness, false);
g.beginBitmapFill(horizontalDottedLine);
}
g.drawRect(startX, startY, endX - startX, lineThickness);
g.endFill();
}

}

/**
* Creates a BitmapData that is used to renderer a dotted line.
* If the vertical parameter is true, then it creates a rectangle bitmap that is
* twice as long as it is wide (lineThickness). Otherwise it creates a rectangle
* that is twice as wide as it is long.
* The first half of the rectangle is filled with the line color (and alpha value),
* then second half is transparent.
*/
private function createDottedLine(lineColor:uint, lineAlpha:Number, lineThickness:Number,
vertical:Boolean = true):BitmapData {
var w:Number = (vertical ? lineThickness : 2 * lineThickness);
var h:Number = (vertical ? 2 * lineThickness : lineThickness);
var color32:uint = combineColorAndAlpha(lineColor, lineAlpha);
var dottedLine:BitmapData = new BitmapData(w, h, true, 0x00ffffff);
// create a dotted bitmap
for (var i:int = 0; i < lineThickness; i++) {
for (var j:int = 0; j < lineThickness; j++) {
dottedLine.setPixel32(i, j, color32);
}
}
return dottedLine;
}

/**
* Combines the color value and the alpha value into a 32 bit uint like #AARRGGBB.
*/
private function combineColorAndAlpha(color:uint, alpha:Number):uint {
// make sure the alpha is a valid number [0-1]
if (isNaN(alpha)) {
alpha = 1;
} else {
alpha = Math.max(0, Math.min(1, alpha));
}

// convert the [0-1] alpha value into [0-255]
var alphaColor:Number = alpha * 255;
// bitshift it to come before the color
alphaColor = alphaColor << 24;
// combine the two values: #AARRGGBB
var combined:uint = alphaColor | color;
return combined;
}

private function getColorStyle(propName:String, defaultValue:uint):uint {
var color:uint = defaultValue;
if (propName != null) {
var n:Number = getStyle(propName);
if (!isNaN(n)) {
color = uint(n);
}
}
return color;
}


private function getNumberStyle(propName:String, defaultValue:Number):Number {
var number:Number = defaultValue;
if (propName != null) {
var n:Number = getStyle(propName);
if (!isNaN(n)) {
number = n;
}
}
return number;
}

}
}