Egret自定义位图文字

/**
 * 位图文字
 * @author ck 2019.11.10
 */
class BitmapFont extends eui.Component{
	/**位图缓存 */
	private static bmCaches:Array<egret.Bitmap> = [];
	/**纹理缓存 */
	private static textureCaches = {};
	/**显示的文字 */
	private _text:string;
	/**图片名 */
	private pngName:string;

	public constructor(pngName:string) {
		super();
		this.pngName = pngName;
	}

	/**
	 * 文字在一张图上
	 * @param pngName 图片名   pngName = font_test  (font_test.png)
	 * @param txt     文字名   "0123456789.+-"
	 */
	public static initByOne(pngName:string, txt:string){
		let textureCache = this.getTextureCache(pngName);
		if(textureCache.length > 0){
			console.log("位图字体缓存已存在:",pngName);
			return;
		}
		let src:egret.Bitmap = new egret.Bitmap();
		src.texture = RES.getRes(pngName + "_png");
		let len = txt.length;
		let fontWidth:number = src.width/len;
		let fontHeight:number=  src.height;
		let texture:egret.RenderTexture;
		let rect:egret.Rectangle = new egret.Rectangle();
		for(let i=0;i<len;i++){
			texture = new egret.RenderTexture();
			rect.x = i*fontWidth;
			rect.y = 0;
			rect.width = fontWidth;
			rect.height = fontHeight;
			texture.drawToTexture(src, rect);
			textureCache[txt.charAt(i)] = texture;
		}
	}

	/**
	 * 文字在不同的图片上
	 * @param pngName 图片名 pngName=font    多张图片源文件名(font0.png font1.png .... fontdot.png)
	 * @param txt     文字名 "0123456789.+-"
	 */
	public static initByMulti(pngName:string, txt:string){
		let textureCache = this.getTextureCache(pngName);
		if(textureCache.length > 0){
			console.log("位图字体缓存已存在:",pngName);
			return;
		}
		let len = txt.length;
		let char:string;
		for(let i=0;i<len;i++){
			char = txt.charAt(i);
			if(char == "."){
				textureCache[char] = RES.getRes(pngName + "dot" + "_png");
			}else{
				textureCache[char] = RES.getRes(pngName + char + "_png");
			}
		}
	}

	/**
	 * 获取纹理缓存
	 * @param pngName 图片名
	 */
	public static getTextureCache(pngName:string){
		let textureCache = BitmapFont.textureCaches[pngName]; 
		if(textureCache == null){
			textureCache = [];
			BitmapFont.textureCaches[pngName] = textureCache;
		}
		return textureCache;
	}

	/**
	 * 设置文字
	 * @param txt 文字
	 */
	public set text(txt:string){
		let bmCaches = BitmapFont.bmCaches;
		let textureCache = BitmapFont.getTextureCache(this.pngName);
		let curLen = this.numChildren;
		let targetLen = txt.length;

		this._text = txt;

		//文字存在，且大于显示文字，则移除多余文字
		if(curLen > targetLen){
			let bm:egret.Bitmap;
			for(let i=curLen-1;i>=targetLen;i--){
				bm = this.removeChildAt(i) as egret.Bitmap;
				bm.texture = null;
				bmCaches.push(bm);
			}
		}
		//显示文字
		let bm:egret.Bitmap;
		let tempX:number = 0;
		let char:string;
		for(let i=0;i<targetLen;i++){
			//少于显示文字，则增加文字
			if(i >= curLen){
				if(bmCaches.length > 0){
					bm = bmCaches.pop();
				}else{
					bm = new egret.Bitmap();
				}
				this.addChild(bm);
			}
			bm = this.getChildAt(i) as egret.Bitmap;
			bm.texture =  textureCache[txt.charAt(i)];
			bm.x = tempX;
			tempX = bm.x + bm.width;
		}
	}

	/**
	 * 获取文字
	 */
	public get text(){
		return this._text;
	}

	/**销毁 */
	public destroy(){
		//回收bitmap
		let len = this.numChildren;
		let bm:egret.Bitmap;
		let bmCaches = BitmapFont.bmCaches;
		for(let i=len-1;i>=0;i--){
			bm = this.getChildAt(i) as egret.Bitmap;
			this.removeChild(bm);
			bm.texture = null;
			bmCaches.push(bm);
		}
		//从视图移除
		this.parent && this.parent.removeChild(this);
	}
}

        //注册文字
        BitmapFont.initByOne("font_test", "02345");
        BitmapFont.initByMulti("font","02.");

        //单张整图的文字
        let bm:BitmapFont = new BitmapFont("font_test");
        bm.x = 100;
        bm.y = 100;
        bm.text = "02333";
        this.addChild(bm);

        //多张图的文字
        let bm2:BitmapFont = new BitmapFont("font");
        bm2.x  = 200;
        bm2.y = 200;
        bm2.text = "02.02.";
        this.addChild(bm2);