CSS3:CSS3 动画

CSS3 动画

通过 CSS3,我们能够创建动画,这可以在许多网页中取代动画图片、Flash 动画以及 JavaScript。

CSS3 @keyframes 规则

如需在 CSS3 中创建动画,您需要学习 @keyframes 规则。

@keyframes 规则用于创建动画。在 @keyframes 中规定某项 CSS 样式,就能创建由当前样式逐渐改为新样式的动画效果。

浏览器支持

Internet Explorer 10、Firefox 以及 Opera 支持 @keyframes 规则和 animation 属性。

Chrome 和 Safari 需要前缀 -webkit-。

注释:Internet Explorer 9,以及更早的版本,不支持 @keyframe 规则或 animation 属性。

实例

@keyframes myfirst
{
from {background: red;}
to {background: yellow;}
}

@-moz-keyframes myfirst /* Firefox */
{
from {background: red;}
to {background: yellow;}
}

@-webkit-keyframes myfirst /* Safari 和 Chrome */
{
from {background: red;}
to {background: yellow;}
}

@-o-keyframes myfirst /* Opera */
{
from {background: red;}
to {background: yellow;}
}

CSS3 动画

当您在 @keyframes 中创建动画时,请把它捆绑到某个选择器,否则不会产生动画效果。

通过规定至少以下两项 CSS3 动画属性,即可将动画绑定到选择器:

  1. 规定动画的名称
  2. 规定动画的时长
示例:

把 "myfirst" 动画捆绑到 div 元素,时长:5 秒:

div { animation: myfirst 5s; -moz-animation: myfirst 5s; /* Firefox */ -webkit-animation: myfirst 5s; /* Safari 和 Chrome */ -o-animation: myfirst 5s; /* Opera */ }

注释:您必须定义动画的名称和时长。如果忽略时长,则动画不会允许,因为默认值是 0。

什么是 CSS3 中的动画?

动画是使元素从一种样式逐渐变化为另一种样式的效果。

您可以改变任意多的样式任意多的次数。

请用百分比来规定变化发生的时间,或用关键词 "from" 和 "to",等同于 0% 和 100%。

0% 是动画的开始,100% 是动画的完成。

为了得到最佳的浏览器支持,您应该始终定义 0% 和 100% 选择器。

实例

当动画为 25% 及 50% 时改变背景色,然后当动画 100% 完成时再次改变:

@keyframes myfirst
{
0%   {background: red;}
25%  {background: yellow;}
50%  {background: blue;}
100% {background: green;}
}

@-moz-keyframes myfirst /* Firefox */
{
0%   {background: red;}
25%  {background: yellow;}
50%  {background: blue;}
100% {background: green;}
}

@-webkit-keyframes myfirst /* Safari 和 Chrome */
{
0%   {background: red;}
25%  {background: yellow;}
50%  {background: blue;}
100% {background: green;}
}

@-o-keyframes myfirst /* Opera */
{
0%   {background: red;}
25%  {background: yellow;}
50%  {background: blue;}
100% {background: green;}
}
实例

实例改变背景色和位置

@keyframes myfirst
{
0%   {background: red; left:0px; top:0px;}
25%  {background: yellow; left:200px; top:0px;}
50%  {background: blue; left:200px; top:200px;}
75%  {background: green; left:0px; top:200px;}
100% {background: red; left:0px; top:0px;}
}

@-moz-keyframes myfirst /* Firefox */
{
0%   {background: red; left:0px; top:0px;}
25%  {background: yellow; left:200px; top:0px;}
50%  {background: blue; left:200px; top:200px;}
75%  {background: green; left:0px; top:200px;}
100% {background: red; left:0px; top:0px;}
}

@-webkit-keyframes myfirst /* Safari 和 Chrome */
{
0%   {background: red; left:0px; top:0px;}
25%  {background: yellow; left:200px; top:0px;}
50%  {background: blue; left:200px; top:200px;}
75%  {background: green; left:0px; top:200px;}
100% {background: red; left:0px; top:0px;}
}

@-o-keyframes myfirst /* Opera */
{
0%   {background: red; left:0px; top:0px;}
25%  {background: yellow; left:200px; top:0px;}
50%  {background: blue; left:200px; top:200px;}
75%  {background: green; left:0px; top:200px;}
100% {background: red; left:0px; top:0px;}
}

CSS3 动画属性

下面的表格列出了 @keyframes 规则和所有动画属性:

实例

运行名为 myfirst 的动画,其中设置了所有动画属性:

div
{
animation-name: myfirst;
animation-duration: 5s;
animation-timing-function: linear;
animation-delay: 2s;
animation-iteration-count: infinite;
animation-direction: alternate;
animation-play-state: running;
/* Firefox: */
-moz-animation-name: myfirst;
-moz-animation-duration: 5s;
-moz-animation-timing-function: linear;
-moz-animation-delay: 2s;
-moz-animation-iteration-count: infinite;
-moz-animation-direction: alternate;
-moz-animation-play-state: running;
/* Safari 和 Chrome: */
-webkit-animation-name: myfirst;
-webkit-animation-duration: 5s;
-webkit-animation-timing-function: linear;
-webkit-animation-delay: 2s;
-webkit-animation-iteration-count: infinite;
-webkit-animation-direction: alternate;
-webkit-animation-play-state: running;
/* Opera: */
-o-animation-name: myfirst;
-o-animation-duration: 5s;
-o-animation-timing-function: linear;
-o-animation-delay: 2s;
-o-animation-iteration-count: infinite;
-o-animation-direction: alternate;
-o-animation-play-state: running;
}

实例 使用了简写的动画 animation 属性

与前面的动画相同,但是使用了简写的动画 animation 属性:

div
{
animation: myfirst 5s linear 2s infinite alternate;
/* Firefox: */
-moz-animation: myfirst 5s linear 2s infinite alternate;
/* Safari 和 Chrome: */
-webkit-animation: myfirst 5s linear 2s infinite alternate;
/* Opera: */
-o-animation: myfirst 5s linear 2s infinite alternate;
}
$v.lab.setValue({ active:'css', html:' <!DOCTYPE HTML>\n

\n

\n \n

\n

注释:本例在 Internet Explorer 中无效。

\n
\n \n \n', css:' div\n {\n width:100px;\n height:60px;\n background:red;\n position:relative;\n animation:myfirst 5s linear 2s infinite alternate;\n / Firefox: /\n -moz-animation:myfirst 5s linear 2s infinite alternate;\n / Safari and Chrome: /\n -webkit-animation:myfirst 5s linear 2s infinite alternate;\n / Opera: /\n -o-animation:myfirst 5s linear 2s infinite alternate;\n }\n
@keyframes myfirst\n {\n 0% {background:red; left:0px; top:0px;}\n 25% {background:yellow; left:200px; top:0px;}\n 50% {background:blue; left:200px; top:200px;}\n 75% {background:green; left:0px; top:200px;}\n 100% {background:red; left:0px; top:0px;}\n }\n

@-moz-keyframes myfirst / Firefox /\n {\n 0% {background:red; left:0px; top:0px;}\n 25% {background:yellow; left:200px; top:0px;}\n 50% {background:blue; left:200px; top:200px;}\n 75% {background:green; left:0px; top:200px;}\n 100% {background:red; left:0px; top:0px;}\n }\n

@-webkit-keyframes myfirst / Safari and Chrome /\n {\n 0% {background:red; left:0px; top:0px;}\n 25% {background:yellow; left:200px; top:0px;}\n 50% {background:blue; left:200px; top:200px;}\n 75% {background:green; left:0px; top:200px;}\n 100% {background:red; left:0px; top:0px;}\n }\n

@-o-keyframes myfirst / Opera /\n {\n 0% {background:red; left:0px; top:0px;}\n 25% {background:yellow; left:200px; top:0px;}\n 50% {background:blue; left:200px; top:200px;}\n 75% {background:green; left:0px; top:200px;}\n 100% {background:red; left:0px; top:0px;}\n }\n ' });
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