自定义文本编辑组件

自己写的文本编辑组件, 可以完成文本水平垂直居中, 控制文字显示区域(不超出组件), 设置文字格式(字体, 字号, 颜色, 粗体, 斜体, 下划线), 并可输入中文. 功能是都实现了, 但是代码还有待提高, 如果有什么更好的写法, 请大家指点.

package textCompment
{
	import flash.events.Event;
	import flash.events.FocusEvent;
	import flash.geom.Rectangle;
	import flash.system.IME;
	import flash.text.TextField;
	import flash.text.TextFieldType;
	import flash.text.TextFormat;
	
	import mx.core.UIComponent;
	import mx.events.FlexEvent;
	
	public class TextElem extends UIComponent
	{
		/**水平布局常量--左对齐*/
		public static const HORIZONTAL_LEFT:String = "left";
		/**水平布局常量--居中对齐*/
		public static const HORIZONTAL_CENTER:String = "center";
		/**水平布局常量--右对齐*/
		public static const HORIZONTAL_RIGHT:String = "right";
		/**垂直布局常量--上对齐*/
		public static const VERTICAL_TOP:String = "top";
		/**垂直布局常量--居中对齐*/
		public static const VERTICAL_MIDDLE:String = "middle";
		/**垂直布局常量--下对齐*/
		public static const VERTICAL_BOTTOM:String = "bottom";
	
		/**文字内容*/
		private var _text:String;
		/**是否可编辑*/
		private var _editable:Boolean = true;
		/**当前水平布局方式*/
		private var _currentHorizontalAlign:String;
		/**当前垂直布局方式*/
		private var _currentVerticalAlign:String;
		
		/**当前组件中文本部分*/
		private var textField:TextField = new TextField();
		/**文本格式*/
		private var textFormat:TextFormat;
		/**显示对象滚动矩形范围*/
		private var rect:Rectangle = new Rectangle(0, 0);
		
		/**构造函数*/
		public function TextElem()
		{
			super();
			this.addEventListener(FlexEvent.CREATION_COMPLETE, init);
			textField.addEventListener(Event.CHANGE, textChangeHandler);
			this.addEventListener(FocusEvent.FOCUS_IN, textFocusInHandler);
		}
		
		/**
		 * 焦点移入监听事件
		 * @parameter e FocusEvent
		 */
		private function textFocusInHandler(event:FocusEvent):void
		{
			IME.enabled = true;
		}
		
		/**
		 * 文本编辑监听事件
		 * @parameter e Event
		 */
		private function textChangeHandler(event:Event):void
		{
			this._text = textField.text;
			if(this._currentVerticalAlign == TextElem.VERTICAL_MIDDLE)
			{
				this.textField.y = Math.round(this.height/2 - this.textField.height/2);
			} 
			else if(this._currentVerticalAlign == TextElem.VERTICAL_TOP)
			{
				this.textField.y = 0;
			}
			else if(this._currentVerticalAlign == TextElem.VERTICAL_BOTTOM)
			{
				this.textField.y = Math.round(this.height - this.textField.height);
			}
			
			if(textField.height > this.height)
			{
				this.textField.y = Math.round(this.height - this.textField.height);
			}
		}
		
		/**
		 * 初始化创建完成监听事件
		 * @parameter e FlexEvent
		 */
		private function init(event:FlexEvent):void
		{
			textField.autoSize="left";
			textField.multiline = true;
			textField.wordWrap = true;
			textField.type = TextFieldType.INPUT;
			textField.y = Math.round(this.height/2 - this.textField.height/2);
			textField.width = this.width;
			
			textFormat = new TextFormat();
			textFormat.align = TextElem.HORIZONTAL_CENTER;
			textFormat.bold = false;
			textFormat.color = 0x000000;
			textFormat.italic = false;
			textFormat.size = 12;
			textFormat.underline = false;
			textField.defaultTextFormat = textFormat;
			
			rect.width = this.width + 2;
			rect.height = this.height + 2;
			this.scrollRect = rect;
			
			this.addChild(textField);
			
			this._currentHorizontalAlign = TextElem.HORIZONTAL_CENTER;
			this._currentVerticalAlign = TextElem.VERTICAL_MIDDLE;
			this.doubleClickEnabled = true;
		}
		
		/**
		 * 设置文本格式
		 * @parameter format 文本格式
		 * @parameter beginIndex 开始字符索引
		 * @parameter endIndex 结束字符索引
		 */
		public function setTextFormat(format:TextFormat, beginIndex:int=-1, endIndex:int=-1):void
		{
			this.textFormat = format;
			if(textField.length == 0)
			{
				textField.defaultTextFormat = textFormat;
			}
			else 
			{
				this.textField.setTextFormat(textFormat, beginIndex, endIndex);
			}
		}
		
		/**
		 * 获取文本格式
		 * @parameter beginIndex 开始字符索引
		 * @parameter endIndex 结束字符索引
		 * @return 所选部分的文本格式
		 */
		public function getTextFormat(beginIndex:int=-1, endIndex:int=-1):TextFormat
		{
			var tf:TextFormat = textField.getTextFormat(beginIndex, endIndex);
			return tf;
		}
		
		/**更新布局(组件拉伸的时候调用)*/
		public function updateLayout():void
		{
		}
		
		/**
		 * 设置组件大小
		 * @parameter width 组件宽度
		 * @parameter height 组件高度
		 */
		public function setSize(width:Number, height:Number):void
		{
			this.width = textField.width = width;
			this.height = height;
			
			rect.width = width + 2;
			rect.height = height + 2;
			this.scrollRect = rect;
			
			if(this._currentVerticalAlign == TextElem.VERTICAL_MIDDLE)
			{
				textField.y = Math.round((this.height / 2) - (textField.height / 2));
			}
			else if(this._currentVerticalAlign == TextElem.VERTICAL_BOTTOM)
			{
				textField.y = this.height - textField.height;
			}
			else if(this._currentVerticalAlign == TextElem.VERTICAL_TOP)
			{
				textField.y = 0;
			}
			
			if(textField.height > this.height)
			{
				this.textField.y = Math.round(this.height - this.textField.height);
			}
		}
		
		/**
		 * 设置文本编辑状态
		 * @parameter value 布尔值, 表示文本是否可编辑, 可编辑为true, 不可编辑为false
		 */
		public function set isEdited(value:Boolean):void
		{
			if(value == true)
			{
				this.textField.type = TextFieldType.INPUT;
			}
			else
			{
				this.textField.type = TextFieldType.DYNAMIC;
			}
			this._editable = value;
		}
		
		/**
		 * 获取文本编辑状态
		 * @return 表示文本是否可编辑的布尔值, 可编辑为true, 不可编辑为false
		 */
		public function get isEdited():Boolean
		{
			return this._editable;
		}
		
		/**
		 * 设置文本内容
		 * @parameter value 文本中输入的字符串
		 */
		public function set text(value:String):void
		{
			this._text = textField.text = value;
		}
		
		/**
		 * 设置文本内容
		 * @return 文本中输入的字符串
		 */
		public function get text():String
		{
			return _text;
		}
		
		/**
		 * 设置文本水平布局方式
		 * @parameter value 代表水平对齐方式的字符串
		 * TextElem.HORIZONTAL_LEFT 左对齐
		 * TextElem.HORIZONTAL_CENTER 居中对齐
		 * TextElem.HORIZONTAL_RIGHT 右对齐
		 */
		public function set horizontalAlign(value:String):void
		{
			this._currentHorizontalAlign = this.textFormat.align = value;
			if(textField.length == 0)
			{
				textField.defaultTextFormat = textFormat;
			}
			else 
			{
				this.textField.setTextFormat(textFormat);
			}
		}
		
		/**
		 * 获取文本水平布局方式
		 * @return 代表水平对齐方式的字符串
		 * TextElem.HORIZONTAL_LEFT 左对齐
		 * TextElem.HORIZONTAL_CENTER 居中对齐
		 * TextElem.HORIZONTAL_RIGHT 右对齐
		 */
		public function get horizontalAlign():String
		{
			return _currentHorizontalAlign;
		}
		
		/**
		 * 设置文本垂直布局方式
		 * @parameter value 代表垂直对齐方式的字符串
		 * TextElem.VERTICAL_TOP 上对齐
		 * TextElem.VERTICAL_MIDDLE 居中对齐
		 * TextElem.VERTICAL_BOTTOM 下对齐
		 */
		public function set verticalAlign(value:String):void
		{
			this._currentVerticalAlign = value;
			if(value == TextElem.VERTICAL_MIDDLE)
			{
				textField.y = Math.round((this.height / 2) - (textField.height / 2));
			}
			else if(value == TextElem.VERTICAL_BOTTOM)
			{
				textField.y = this.height - textField.height;
			}
			else if(value == TextElem.VERTICAL_TOP)
			{
				textField.y = 0;
			}
		}
		
		/**
		 * 获取文本垂直布局方式
		 * @return 代表垂直对齐方式的字符串
		 * TextElem.VERTICAL_TOP 上对齐
		 * TextElem.VERTICAL_MIDDLE 居中对齐
		 * TextElem.VERTICAL_BOTTOM 下对齐
		 */
		public function get verticalAlign():String
		{
			return this._currentVerticalAlign;
		}
		
		/**
		 * 获取文本选中部分开始索引值
		 * @return 文本选中部分开始索引值
		 */
		public function get selectionBeginIndex():int
		{
			return this.textField.selectionBeginIndex;
		}
		
		/**
		 * 获取文本选中部分末尾索引值
		 * @return 文本选中部分末尾索引值
		 */
		public function get selectionEndIndex():int
		{
			return this.textField.selectionEndIndex;
		}
		
		/**
		 * 获取文本字符串长度值
		 * @return 当前组件中输入文本字符串长度值
		 */
		public function get length():int
		{
			return this.textField.length;
		}
	}
}