Detailed examples of CSS3 implementation of barrage

The project needs to implement barrage. I consulted various methods online and finally felt that the effect achieved by transform+transition has the best performance on mobile devices. When tested on iPhone 6 and Redmi 4, no lag was seen. There is obvious lag on mobile devices using jquery's animate animation. This article mainly introduces the sample code for implementing barrage in CSS3. The editor thinks it is quite good, so I will share it with you now and give it as a reference. Let’s follow the editor to take a look, I hope it can help everyone.

1. First create the barrage area

<p class="barrage">
<p class="mask">
<!--//弹幕内容-->
</p>
</p>

<input type="text" ng-model="data.comment"/>
<button ng-click="addDanmu()">说两句</button >

2.css

.webPage .barrage{width:100%;height:22%;position: absolute; bottom: 50px; 
background-color: transparent;pointer-events: none;
}
.webPage .barrage .mask{width:100%;height:100%;background:transparent;z-index:100;}

Note: The above html, You can use css according to your own needs

3.js

$scope.data = {comment:''};
$scope.danmuCount = 5; //最大弹幕行数
$scope.danmus = ['1545466666还是','9777777','哈哈哈哈哈','对企业读完后环球网好齐齐哈','42115我我我5','556噢噢噢噢45','54哦','54545646','666但近段时间66','56565','454465465565', '1545466666还是','9777777','哈哈哈哈哈','对企业读完后环球网好齐齐哈','42115我我我5','556噢噢噢噢45','54哦','54545646','666但近段时间66','56565','454465465565']; //弹幕数据源

//创建弹幕区域
$scope.createDanmuContent = function () {
var height = 1 / $scope.danmuCount * 100 + '%';
for (var i = 0; i < $scope.danmuCount; i++) {
var item = &#39;<p style="width: 100%; height: &#39;+height+&#39;"></p>&#39;;
$(&#39;.mask&#39;).append(item);
}
 $scope.createDanmu ();
};

//开始弹幕绘制
$scope.createDanmu = function () {
var maxCount = 0;
if ($scope.danmus.length > $scope.danmuCount) {
 maxCount = $scope.danmuCount;
 } else {
maxCount = $scope.danmus.length;
}
var _left = window.screen.width;
for (var i = 0; i < maxCount; i++) {
var _lable = $("<p style=&#39;margin: 0;position: absolute;opacity:1;display:table;left: "+_left + &#39;px&#39;+&#39;;color:&#39;+$scope.getRandomColor()+"&#39;>"+$scope.danmus[i]+"</p>");
$(".mask p").each(function () {
//检测该区域是否绘制了弹幕
if ($scope.checkDanmu($(this))) {
$(this).append(_lable);
$scope.moveArray(i);
 i--;
return false;
}
});
}
$scope.init_barrage();
};

//将数组第一位放到最后一位,（因弹幕池内容太少，所以没删除已显示的弹幕）
$scope.moveArray = function (i) {
 var temp = $scope.danmus[i];
$scope.danmus.splice(i,1);
$scope.danmus.push(temp);
}
//判断content区域有没有弹幕
$scope.checkDanmu = function (el) {
return el.find(&#39;p&#39;).length == 0 ? true : false;
};
//获取随机颜色
$scope.getRandomColor = function () {
return &#39;#&#39; + (function(h){
return new Array(7 - h.length).join("0") + h
})((Math.random() * 0x1000000 << 0).toString(16))
};

//初始化弹幕参数
$scope.init_barrage = function () {
$(".mask p p").show().each(function() {
 var _moveLeft = window.screen.width+$(this).width();
var time = 100000 / $(this).width() + 5000;//弹幕滑动时间
$scope.addCssAnimate($(this),_moveLeft,time);
});
};

//添加弹幕动画
$scope.addCssAnimate = function (el,_moveLeft,time) {
el.css({
&#39;transform&#39;:&#39;translateX(&#39;+-_moveLeft+&#39;px)&#39;,
&#39;transition&#39;:&#39;all &#39;+time+&#39;ms&#39;+ &#39; linear&#39;,
&#39;-webkit-transform&#39;:&#39;translateX(&#39;+-_moveLeft+&#39;px)&#39;,
&#39;-webkit-transition&#39;:&#39;all &#39;+time+&#39;ms&#39;+ &#39; linear&#39;,
&#39;-moz-transform&#39;:&#39;translateX(&#39;+-_moveLeft+&#39;px)&#39;,
&#39;-moz-transition&#39;:&#39;all &#39;+time+&#39;ms&#39;+ &#39; linear&#39;,
&#39;-ms-transform&#39;:&#39;translateX(&#39;+-_moveLeft+&#39;px)&#39;,
&#39;-ms-transition&#39;:&#39;all &#39;+time+&#39;ms&#39;+ &#39; linear&#39;
});
//当动画执行完毕后，将弹幕移到原处，更换弹幕文字，重新开始执行动画，相当于对原本弹幕的复用
$timeout(function () {
//判断弹幕池是否还有内容，如果没有则移除弹幕
if ($scope.danmus.length > 0) {
el.css({
&#39;transform&#39;:&#39;translateX(0px)&#39;,
&#39;transition&#39;:&#39;all 0ms linear&#39;,
&#39;-webkit-transform&#39;:&#39;translateX(0px)&#39;,
&#39;-webkit-transition&#39;:&#39;all 0ms linear&#39;,
&#39;-moz-transform&#39;:&#39;translateX(0px)&#39;,
&#39;-moz-transition&#39;:&#39;all 0ms linear&#39;,
&#39;-ms-transform&#39;:&#39;translateX(0px)&#39;,
&#39;-ms-transition&#39;:&#39;all 0ms linear&#39;
});
$scope.resetAnimate(el);
} else {
el.remove();
}
},time);
};

//更换弹幕内容，重新开始弹幕动画
$scope.resetAnimate = function (el) {
el.html($scope.danmus[0]);
$scope.moveArray(0);
var _moveLeft = el.width() + screen.width;
var time = 100000 / el.width() + 5000;
$scope.addCssAnimate(el,_moveLeft,time);
};

//评论，添加弹幕
$scope.addDanmu = function () {
var text = $scope.data.comment;
if(text == ""){
return;
}
$scope.danmus.unshift(text);
};

$scope.createDanmuContent();

At this point, the function is basically realized. To close the barrage, you only need to remove the barrage area, which is not mentioned in the article.

Logic: First create the number of lines of barrages based on $scope.danmuCount, then add barrages to each line and add corresponding animations. When an animation is completed, move the barrage back to its original position, change the content of the barrage, and re-execute the animation, thus avoiding overlap of the barrage. The execution time of each barrage animation is determined by the length of the barrage.

Personal experience, I hope everyone can point out the shortcomings. The above code uses angularjs, but the logic is the same

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