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canvas 弹幕效果(实例分享)

2024-05-06 16:34:30
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话不多说,请看代码

<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <title>Document</title></head><body> <canvas style="width: 1280px;height: 720px;background-color: rgba(0,0,0,0.2)">你的浏览器不支持canvas</canvas></body><script src="http://www.jq22.com/jquery/jquery-1.10.2.js"></script><script> (function ($) { function Barrager(dom) {  this.canvas = dom.get(0);  this.ctx = this.canvas.getContext("2d");  this.msgs = new Array(300);//缓冲池,长度越大,屏幕上显示的就越多  this.width = 1280;//canvas分辨率1280*720  this.height = 720;  this.canvas.width=this.width;//上边的两步可以省略,直接在这里赋值  this.canvas.height=this.height;  this.font = "30px 黑体";//字体和字体大小  this.ctx.font=this.font;  //颜色数组,在绘制过程中随机从这里取出颜色  this.colorArr=["Olive","OliveDrab","Orange","OrangeRed","Orchid","PaleGoldenRod","PaleGreen","PaleTurquoise","PaleVioletRed","PapayaWhip","PeachPuff","Peru","Pink","Plum","PowderBlue","Purple","Red","RosyBrown","RoyalBlue","SaddleBrown","Salmon","SandyBrown","SeaGreen","SeaShell","Sienna","Silver","SkyBlue"];  this.interval = "";  this.draw = function () {//绘制方法   if (this.interval != "")return;   var _this=this;   this.interval = setInterval(function () {//每隔20毫秒重新绘制一次,间隔最好小于40,要不然效果就跟播放图片差不多    //1,清除屏幕    _this.ctx.clearRect(0, 0, _this.width, _this.height);    _this.ctx.save();    //2,循环缓冲区域,把没有设置Left,Top,Speed,Color先赋值,赋值的就改变left值(产生移动效果),left值小于200就会从缓冲区移除    for (var i = 0; i < _this.msgs.length; i++) {     if (!(_this.msgs[i] == null || _this.msgs[i] == "" || typeof(_this.msgs[i]) == "undefined")) {      if(_this.msgs[i].L==null || typeof(_this.msgs[i].L)=="undefined"){       _this.msgs[i].L=_this.width;       _this.msgs[i].T=parseInt(Math.random() * 700);       _this.msgs[i].S=parseInt(Math.random() * (10 - 4) + 4);       _this.msgs[i].C=_this.colorArr[Math.floor(Math.random() * _this.colorArr.length)];      }else{       if(_this.msgs[i].L<-200){        _this.msgs[i]=null;       }else {        _this.msgs[i].L=parseInt(_this.msgs[i].L-_this.msgs[i].S);        _this.ctx.fillStyle =_this.msgs[i].C;        _this.ctx.fillText(_this.msgs[i].msg,_this.msgs[i].L,_this.msgs[i].T);        _this.ctx.restore();       }      }     }    }   }, 20);  };  //添加数据,数据格式[{"msg":"nihao"}]  this.putMsg = function (datas) {//循环缓冲区,把位置是空的装填上数据   for (var j = 0; j < datas.length; j++) {    for (var i = 0; i < this.msgs.length; i++) {     if (this.msgs[i] == null || this.msgs[i] == "" || typeof(this.msgs[i]) == "undefined") {      this.msgs[i] = datas[j];      break;     }    }   }   this.draw();  };  this.clear = function () {//清除定时器,清除屏幕,清空缓冲区   clearInterval(this.interval);   this.interval="";   this.ctx.clearRect(0, 0, this.width, this.height);   this.ctx.save();   for(var i=0;i<this.msgs.length;i++){    this.msgs[i]=null;   }  }; } $.fn.barrager = function (para) {  if (typeof(para)=="string") {   try{    var api = $(this).data('barrager_api');    api[para].apply(api);   }catch (e){}  } else if (typeof para == 'object' || !para) {   $this = $(this);   if ($this.data('barrager_api') != null && $this.data('barrager_api') != ''){    var api = $this.data('barrager_api');    api.putMsg(para);   }else{    var api = new Barrager($this);    $this.data('barrager_api', api);    api.putMsg(para);   }  } else {   $.error('Method ' + method + ' does not exist on jQuery.slidizle');  }  return this; }})(jQuery);</script><script> // $('canvas').barrager([{"msg":"这是我发的。。。哈哈哈"}]);// 发送弹幕  $('canvas').barrager([{"msg":"看着不错。。。。"},{"msg":"哈哈哈。。。。"},{"msg":"不错不错。。"},{"msg":"真好看。。。。"}]);//多条发送方式 // $('canvas').barrager("clear"); //清除/关闭弹幕</script></html>

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