任意值的运动框架

任务描述：

当鼠标移入“透明度”矩形时，该矩形透明度逐渐增加至不透明，移出该矩形，透明度逐渐恢复至初始值;同时该运动框架可以支持其它属性的变化。

示例图

 

<!DOCTYPE html>
<html>

<head lang="zh-CN">
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,initial-scale=1,maximum-scale=1,user-scalable=no">
    <title>任意值运动框架</title>
    <style>
        div {
            width: 200px;
            height: 200px;
            margin: 20px;
            float: left;
            background: yellow;
            border: 10px solid black;
            filter: opacity(alpha=30);
            opacity: 0.3;
        }
    </style>
</head>

<body>
    <div id='div1'>变透明度</div>
    <input type='text' id='input' />
    <script type="text/javascript">
//补充代码
    </script>
</body>

</html>

　　

参考代码：

oDiv1 = document.getElementById('div1');
oInput = document.getElementById('input');
oDiv1.onmouseover = function () {
    startMove(this, 'opacity', 100)
}

oDiv1.onmouseout = function () {
    startMove(this, 'opacity', 30)
}


function getStyle(obj, name) {

    if (obj.currentStyle) {

        return obj.currentStyle[name];
    }
    else {

        return getComputedStyle(obj, null)[name];
    }
}

function startMove(obj, attr, iTarget) {

    clearInterval(obj.timer);

    obj.timer = setInterval(function () {

        var cur = 0;

        if (attr == 'opacity') {

            //Math.round()四舍五入取整主要是针对低浮点数的精度问题。
            cur = Math.round(parseFloat(getStyle(obj, attr)) * 100);

        } else {

            cur = parseInt(getStyle(obj, attr));
        }
        
        var speed = (iTarget - cur) / 6;

        speed = speed > 0 ? Math.ceil(speed) : Math.floor(speed);


        if (cur == iTarget) {

            clearInterval(obj.timer);

        } else {

            if (attr == 'opacity') {

                obj.style.opacity = (cur + speed) / 100;
                obj.style.filter = 'alpha(opacity=' + (cur + speed) + ")";
                oInput.value = obj.style.opacity;
            }
            else {            
                obj.style[attr] = cur + speed + 'px';
            }
        }
    }, 30)

}

　　

posted @ 2019-08-09 17:08  请叫我二狗哥  阅读(163)  评论(0)    收藏  举报