Bootstrap进度条组件知识介绍
在网页中，经常见到进度条效果，如：平分系统、加载状态等，进度条组件使用了css3的transition和animation属性来完成一些特效，这些特效在IE9及IE9以下版本、Firefox的老版本中并不支持，Opera 12 不支持 animation 属性。
进度条和其他独立组件一样，开发者可以根据自己的需要选择对应的版本：
LESS: progress-bars.less
SASS: _progress-bars.scss
基础进度条
实现原理：
需要两个容器，外容器使用类名.progress，子容器使用类名.progress-bar;其中.progress用来设置进度条容器的背景色，容器的高度，间距等；而.progress-bar设置进度方向，进度条的背景色和过度效果；下面是css源码：
progress {
height: 20px;
margin-bottom: 20px;
overflow: hidden;
background-color: #f5f5f5;
border-radius: 4px;
-webkit-box-shadow: inset 0 1px 2px rgba(0, 0, 0, .1);
box-shadow: inset 0 1px 2px rgba(0, 0, 0, .1);
}
.progress-bar {
float: left;
width: 0;
height: 100%;
font-size: 12px;
line-height: 20px;
color: #fff;
text-align: center;
background-color: #428bca;
-webkit-box-shadow: inset 0 -1px 0 rgba(0, 0, 0, .15);
box-shadow: inset 0 -1px 0 rgba(0, 0, 0, .15);
-webkit-transition: width .6s ease;
transition: width .6s ease;
}
例子：
<div class="progress"> <div class="progress-bar" style="width:30%;" role="progressbar" aria-valuenow="30" aria-valuemin="0" aria-valuemax="100"> <span class="sr-only">30%</span> </div> </div>
role属性作用：告诉搜索引擎这个div的作用是进度条；
aria-valuenow=”30”属性作用：当前进度条的进度为40%；
aria-valuemin=”0”属性作用：进度条的最小值为0%；
aria-valuemax=”100”属性作用：进度条的最大值为100%；
可以将设置了.sr-only类的<span>标签从进度条组件中移除，而让当前进度显示出来；
<div class="progress"> <div class="progress-bar" style="width:40%;" role="progressbar" aria-valuenow="40" aria-valuemin="0" aria-valuemax="100" >40%</div> </div>
彩色进度条
彩色进度条和警告进度条一样，为了能给用户一个更好的体验，也根据不同的状态配置了不同的进度条颜色，主要包括以下四种：
progress-bar-info:表示信息进度条，蓝色
progress-bar-success:表示成功进度条，绿色
progress-bar-warning:表示警告进度条，黄色
progress-bar-danger:表示错误进度条，红色
css源码：
.progress-bar-success {
background-color: #5cb85c;
}
.progress-bar-info {
background-color: #5bc0de;
}
.progress-bar-warning {
background-color: #f0ad4e;
}
.progress-bar-danger {
background-color: #d9534f;
}
使用方法：
只需要在基础进度条上增加对应的类名即可
例子：
<h1>彩色进度条</h1> <div class="progress"> <div class="progress-bar progress-bar-success" style="width:25%;" role="progressbar" aria-valuenow="25" aria-valuemin="0" aria-valuemax="100">25%</div> </div> <div class="progress"> <div class="progress-bar progress-bar-info" style="width:40%;" role="progressbar" aria-valuenow="40" aria-valuemax="100" aria-valuemin="0">40%</div> </div> <div class="progress"> <div class="progress-bar progress-bar-warning" style="width:80%;" role="progressbar" aria-valuenow="25" aria-valuemin="0" aria-valuemax="100">80%</div> </div> <div class="progress"> <div class="progress-bar progress-bar-danger" style="width:60%;" role="progressbar" aria-valuenow="40" aria-valuemax="100" aria-valuemin="0">60%</div> </div>
效果如下：
条纹进度条
条纹进度条采用css3的线性渐变来实现，并未借助任何图片，使用条纹进度条只需在进度条的容器.progress基础上追加类名”progress-striped”,如果要进度条纹像彩色进度一样，具有彩色效果，只需在进度条上增加相应得颜色类名
下面是.progress-striped样式源码：
.progress-striped .progress-bar {
background-image: -webkit-linear-gradient(45deg, rgba(255, 255, 255, .15) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, .15) 50%, rgba(255, 255, 255, .15) 75%, transparent 75%, transparent);
background-image:linear-gradient(45deg, rgba(255, 255, 255, .15) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, .15) 50%, rgba(255, 255, 255, .15) 75%, transparent 75%, transparent);
background-size: 40px 40px;
}
条纹进度对应的每种状态也有不同的颜色
.progress-striped .progress-bar-success {
background-image: -webkit-linear-gradient(45deg, rgba(255, 255, 255, .15) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, .15) 50%, rgba(255, 255, 255, .15) 75%, transparent 75%, transparent);
background-image:linear-gradient(45deg, rgba(255, 255, 255, .15) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, .15) 50%, rgba(255, 255, 255, .15) 75%, transparent 75%, transparent);
}
.progress-striped .progress-bar-info {
background-image: -webkit-linear-gradient(45deg, rgba(255, 255, 255, .15) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, .15) 50%, rgba(255, 255, 255, .15) 75%, transparent 75%, transparent);
background-image:linear-gradient(45deg, rgba(255, 255, 255, .15) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, .15) 50%, rgba(255, 255, 255, .15) 75%, transparent 75%, transparent);
}
.progress-striped .progress-bar-warning {
background-image: -webkit-linear-gradient(45deg, rgba(255, 255, 255, .15) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, .15) 50%, rgba(255, 255, 255, .15) 75%, transparent 75%, transparent);
background-image:linear-gradient(45deg, rgba(255, 255, 255, .15) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, .15) 50%, rgba(255, 255, 255, .15) 75%, transparent 75%, transparent);
}
.progress-striped .progress-bar-danger {
background-image: -webkit-linear-gradient(45deg, rgba(255, 255, 255, .15) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, .15) 50%, rgba(255, 255, 255, .15) 75%, transparent 75%, transparent);
background-image:linear-gradient(45deg, rgba(255, 255, 255, .15) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, .15) 50%, rgba(255, 255, 255, .15) 75%, transparent 75%, transparent);
}
下面来看看条纹进度条的运用：
<h1>条纹进度条</h1> <div class="progress progress-striped"> <div class="progress-bar progress-bar-success" style="width:25%;" role="progressbar" aria-valuenow="25" aria-valuemin="0" aria-valuemax="100">25%</div> </div> <div class="progress progress-striped"> <div class="progress-bar progress-bar-info" style="width:40%;" role="progressbar" aria-valuenow="40" aria-valuemax="100" aria-valuemin="0">40%</div> </div> <div class="progress progress-striped"> <div class="progress-bar progress-bar-warning" style="width:80%;" role="progressbar" aria-valuenow="25" aria-valuemin="0" aria-valuemax="100">80%</div> </div> <div class="progress progress-striped"> <div class="progress-bar progress-bar-danger" style="width:60%;" role="progressbar" aria-valuenow="40" aria-valuemax="100" aria-valuemin="0">60%</div> </div>
动态条纹进度条
在进度条.progress 、.progress-striped两个类的基础上在加入类名.active就能实现动态条纹进度条。
其实现原理主要是通过css3的animation来完成。首先通过@keyframes创建了一个progress-bar-stripes的动画，这个动画主要做了一件事，就是改变背景图像的位置，也就是 background-position的值。因为条纹进度条是通过CSS3的线性渐变来制作的，而linear-gradient实现的正是对应背景中的背景图片
下面是css源码：
@-webkit-keyframes progress-bar-stripes {
from {
background-position: 40px 0;
}
to {
background-position: 0 0;
}
}
@keyframes progress-bar-stripes {
from {
background-position: 40px 0;
}
to {
background-position: 0 0;
}
}
@keyframes仅仅是创建了一个动画效果，如果要让进度条真正的动起来，我们需要通过一定的方式调用@keyframes创建的动画 “progress-bar-stripes”，并且通过一个事件触发动画生效。在Bootstrap框架中，通过给进度条容器“progress”添加一个类名“active”，并让文档加载完成就触“progress-bar-stripes”动画生效
调用动画对应的样式代码如下：
.progress.active .progress-bar {
-webkit-animation: progress-bar-stripes 2s linear infinite;
animation: progress-bar-stripes 2s linear infinite;
}
例子：
<h1>动态条纹进度条</h1> <div class="progress progress-striped active"> <div class="progress-bar progress-bar-success" style="width:25%;" role="progressbar" aria-valuenow="25" aria-valuemin="0" aria-valuemax="100">25%</div> </div> <div class="progress progress-striped active"> <div class="progress-bar progress-bar-info" style="width:40%;" role="progressbar" aria-valuenow="40" aria-valuemax="100" aria-valuemin="0">40%</div> </div> <div class="progress progress-striped active"> <div class="progress-bar progress-bar-warning" style="width:80%;" role="progressbar" aria-valuenow="25" aria-valuemin="0" aria-valuemax="100">80%</div> </div> <div class="progress progress-striped active"> <div class="progress-bar progress-bar-danger" style="width:60%;" role="progressbar" aria-valuenow="40" aria-valuemax="100" aria-valuemin="0">60%</div> </div>
效果如下（由于是直接从网页上结果来的图，这里并看不到它的动态效果）：
层叠进度条：
层叠进度可以将不容状态的进度条放在一起，按水平方式排列
例子：
<div class="progress"> <div class="progress-bar progress-bar-success" style="width:20%"></div> <div class="progress-bar progress-bar-info" style="width:10%"></div> <div class="progress-bar progress-bar-warning" style="width:30%"></div> <div class="progress-bar progress-bar-danger" style="width:15%"></div> </div>
除了层叠彩色进度条之外，还可以层叠条纹进度条，或者说条纹进度条和彩色进度条混合层叠，仅需要在“progress”容器中添加对应的进度条，同样要注意，层叠的进度条之和不能大于100%。
下面来看一个例子：
<div class="progress"> <div class="progress-bar progress-bar-success" style="width:20%"></div> <div class="progress-bar progress-bar-info" style="width:20%"></div> <div class="progress-bar progress-bar-warning" style="width:30%"></div> <div class="progress-bar progress-bar-danger" style="width:15%"></div> </div> <div class="progress"> <div class="progress-bar progress-bar-success progress-bar-striped" style="width:20%"></div> <div class="progress-bar progress-bar-info progress-bar-striped" style="width:20%"></div> <div class="progress-bar progress-bar-striped progress-bar-warning" style="width:30%"></div> <div class="progress-bar progress-bar-danger progress-bar-striped" style="width:15%"></div> </div> <div class="progress"> <div class="progress-bar progress-bar-success" style="width:20%"></div> <div class="progress-bar progress-bar-info progress-bar-striped" style="width:20%"></div> <div class="progress-bar progress-bar-warning" style="width:30%"></div> <div class="progress-bar progress-bar-danger progress-bar-striped" style="width:15%"></div> </div>
关于Bootstrap进度条组件知识详解到此就介绍了，希望对大家有所帮助！
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