canvas 弹幕效果（实例分享）
程序员文章站
2023-11-23 15:37:40
话不多说，请看代码
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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