85 lines
3.8 KiB
Markdown
85 lines
3.8 KiB
Markdown
---
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id: 587d78a9367417b2b2512ae9
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title: Use a Bezier Curve to Move a Graphic
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challengeType: 0
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videoUrl: ''
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localeTitle: 使用贝塞尔曲线移动图形
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---
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## Description
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<section id="description">之前的挑战讨论了一个<code>ease-out</code>关键字，该关键字描述了动画更改，该动画更改先加速，然后在动画结束时减慢。在右侧，演示了<code>ease-out</code>关键字（对于蓝色元素）和<code>linear</code>关键字（对于红色元素）之间的差异。通过使用自定义三次贝塞尔曲线函数，可以实现对<code>ease-out</code>关键字的类似动画进展。通常，更改<code>p1</code>和<code>p2</code>锚点会驱动创建不同的贝塞尔曲线，这些曲线控制动画随时间推移的进展。下面是使用值来模拟缓出样式的贝塞尔曲线的示例： <code>animation-timing-function: cubic-bezier(0, 0, 0.58, 1);</code>请记住，所有<code>cubic-bezier</code>函数都以（0,0）处的<code>p0</code>开始，并以（1,1）处的<code>p3</code>结束。在这个例子中，曲线移动通过Y轴（从0开始，到<code>p1</code> y值为0，然后到<code>p2</code> y值为1）比在X轴上移动更快（0开始，然后是0对于<code>p1</code> ，对于<code>p2</code> ，高达0.58）。结果，动画元素的变化比该段的动画时间更快。接近曲线的末端，x和y值的变化之间的关系反转 - y值从1移动到1（无变化），x值从0.58移动到1，使得动画变化进展比较慢动画持续时间。 </section>
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## Instructions
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<section id="instructions">要查看此贝塞尔曲线的效果，请将id为<code>red</code>的元素的<code>animation-timing-function</code>更改为<code>cubic-bezier</code>函数，其中x1，y1，x2，y2值分别设置为0,0,0.58,1这将使两个元素同样在动画中前进。 </section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: 'id为<code>red</code>的元素的<code>animation-timing-function</code>属性值应为<code>cubic-bezier</code>函数，x1，y1，x2，y2值分别设置为0,0,0.58,1。'
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testString: 'assert($("#red").css("animation-timing-function") == "cubic-bezier(0, 0, 0.58, 1)", "The value of the <code>animation-timing-function</code> property of the element with the id <code>red</code> should be a <code>cubic-bezier</code> function with x1, y1, x2, y2 values set respectively to 0, 0, 0.58, 1 .");'
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- text: id为<code>red</code>的元素不应该具有linear的<code>animation-timing-function</code>属性。
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testString: 'assert($("#red").css("animation-timing-function") !== "linear", "The element with the id <code>red</code> should no longer have the <code>animation-timing-function</code> property of linear.");'
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- text: 具有id <code>blue</code>的元素的<code>animation-timing-function</code>属性的值不应更改。
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testString: 'assert($("#blue").css("animation-timing-function") == "ease-out", "The value of the <code>animation-timing-function</code> property for the element with the id <code>blue</code> should not change.");'
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='html-seed'>
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```html
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<style>
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.balls{
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border-radius: 50%;
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position: fixed;
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width: 50px;
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height: 50px;
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margin-top: 50px;
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animation-name: bounce;
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animation-duration: 2s;
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animation-iteration-count: infinite;
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}
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#red {
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background: red;
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left: 27%;
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animation-timing-function: linear;
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}
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#blue {
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background: blue;
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left: 56%;
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animation-timing-function: ease-out;
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}
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@keyframes bounce {
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0% {
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top: 0px;
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}
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100% {
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top: 249px;
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}
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}
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</style>
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<div class="balls" id= "red"></div>
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<div class="balls" id= "blue"></div>
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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// solution required
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```
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</section>
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