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diff --git a/files/zh-cn/web/api/canvasrenderingcontext2d/rotate/index.html b/files/zh-cn/web/api/canvasrenderingcontext2d/rotate/index.html new file mode 100644 index 0000000000..f6ae42b495 --- /dev/null +++ b/files/zh-cn/web/api/canvasrenderingcontext2d/rotate/index.html @@ -0,0 +1,172 @@ +--- +title: CanvasRenderingContext2D.rotate() +slug: Web/API/CanvasRenderingContext2D/rotate +tags: + - API + - Canvas + - CanvasRenderingContext2D + - 引用 + - 方法 +translation_of: Web/API/CanvasRenderingContext2D/rotate +--- +<div>{{APIRef}}</div> + +<p><code><strong>CanvasRenderingContext2D</strong></code><strong><code>.rotate()</code></strong> 是 Canvas 2D API 在变换矩阵中增加旋转的方法。角度变量表示一个顺时针旋转角度并且用弧度表示。</p> + +<h2 id="语法">语法</h2> + +<pre class="syntaxbox">void <var><em>ctx</em>.rotate(angle);</var> +</pre> + +<p><img alt="" class="internal" src="https://mdn.mozillademos.org/files/233/Canvas_grid_rotate.png" style="float: right;"></p> + +<h3 id="参数">参数</h3> + +<dl> + <dt><code>angle</code></dt> + <dd>顺时针旋转的弧度。如果你想通过角度值计算，可以使用公式： <code><em>degree</em> * Math.PI / 180</code> 。</dd> +</dl> + +<p>旋转中心点一直是 canvas 的起始点。 如果想改变中心点，我们可以通过 {{domxref("CanvasRenderingContext2D.translate", "translate()")}} 方法移动 canvas 。</p> + +<h2 id="示例">示例</h2> + +<h3 id="使用_rotate_方法">使用 <code>rotate</code> 方法</h3> + +<p>这是一段使用 <code>rotate</code> 方法的简单的代码片段。</p> + +<h4 id="HTML">HTML</h4> + +<pre class="brush: html"><canvas id="canvas"></canvas> +</pre> + +<h4 id="JavaScript">JavaScript</h4> + +<pre class="brush: js; highlight:[4]">var canvas = document.getElementById("canvas"); +var ctx = canvas.getContext("2d"); + +ctx.rotate(45 * Math.PI / 180); +ctx.fillRect(70,0,100,30); + +// reset current transformation matrix to the identity matrix +ctx.setTransform(1, 0, 0, 1, 0, 0); +</pre> + +<p>修改下面的代码并在线查看 canvas 的变化：</p> + +<div style="display: none;"> +<h6 id="Playable_code">Playable code</h6> + +<pre class="brush: html"><canvas id="canvas" width="400" height="200" class="playable-canvas"></canvas> +<div class="playable-buttons"> + <input id="edit" type="button" value="Edit" /> + <input id="reset" type="button" value="Reset" /> +</div> +<textarea id="code" class="playable-code"> +ctx.rotate(45 * Math.PI / 180); +ctx.fillRect(70,0,100,30); +ctx.setTransform(1, 0, 0, 1, 0, 0);</textarea> +</pre> + +<pre class="brush: js">var canvas = document.getElementById("canvas"); +var ctx = canvas.getContext("2d"); +var textarea = document.getElementById("code"); +var reset = document.getElementById("reset"); +var edit = document.getElementById("edit"); +var code = textarea.value; + +function drawCanvas() { + ctx.clearRect(0, 0, canvas.width, canvas.height); + eval(textarea.value); +} + +reset.addEventListener("click", function() { + textarea.value = code; + drawCanvas(); +}); + +edit.addEventListener("click", function() { + textarea.focus(); +}) + +textarea.addEventListener("input", drawCanvas); +window.addEventListener("load", drawCanvas); +</pre> +</div> + +<p>{{ EmbedLiveSample('Playable_code', 700, 360) }}</p> + +<h2 id="规范描述">规范描述</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范</th> + <th scope="col">状态</th> + <th scope="col">注释</th> + </tr> + <tr> + <td>{{SpecName('HTML WHATWG', "scripting.html#dom-context-2d-rotate", "CanvasRenderingContext2D.rotate")}}</td> + <td>{{Spec2('HTML WHATWG')}}</td> + <td> </td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + +<p>{{ CompatibilityTable() }}</p> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>特性</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>基础支持</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>特性</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>基础支持</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + <td>{{ CompatVersionUnknown() }}</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="参见">参见</h2> + +<ul> + <li>接口定义， {{domxref("CanvasRenderingContext2D")}}</li> +</ul> |