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diff --git a/files/zh-cn/web/api/canvasrenderingcontext2d/setlinedash/index.html b/files/zh-cn/web/api/canvasrenderingcontext2d/setlinedash/index.html new file mode 100644 index 0000000000..710d8f9e53 --- /dev/null +++ b/files/zh-cn/web/api/canvasrenderingcontext2d/setlinedash/index.html @@ -0,0 +1,183 @@ +--- +title: CanvasRenderingContext2D.setLineDash() +slug: Web/API/CanvasRenderingContext2D/setLineDash +tags: + - API + - Canvas + - CanvasRenderingContext2D + - Dashes + - LInes + - Method + - setLineDash +translation_of: Web/API/CanvasRenderingContext2D/setLineDash +--- +<div>{{APIRef}}</div> + +<p>Canvas 2D API的{{domxref("CanvasRenderingContext2D")}}接口的<strong><code>setLineDash()</code></strong>方法在填充线时使用虚线模式。 它使用一组值来指定描述模式的线和间隙的交替长度。</p> + +<div class="blockIndicator note"> +<p><strong>提示：</strong>如果要切换回至实线模式，将 dash list 设置为一个空数组即可。</p> +</div> + +<h2 id="语法">语法</h2> + +<pre class="syntaxbox">void <var><em>ctx</em>.setLineDash(segments);</var> +</pre> + +<h3 id="参数">参数</h3> + +<dl> + <dt><code>segments</code></dt> + <dd>一个{{jsxref("Array")}}数组。一组描述交替绘制线段和间距（坐标空间单位）长度的数字。 如果数组元素的数量是奇数， 数组的元素会被复制并重复。例如， <code>[5, 15, 25]</code> 会变成 <code>[5, 15, 25, 5, 15, 25]。</code></dd> + <dt> + <h3 id="返回值">返回值</h3> + </dt> + <dd>{{jsxref("undefined")}}</dd> +</dl> + +<h2 id="示例">示例</h2> + +<h3 id="基本示例">基本示例</h3> + +<p>这是一段简单的代码片段，使用 <code>setLineDash</code> 方法绘制一条线段。</p> + +<h4 id="HTML">HTML</h4> + +<pre class="brush: html"><canvas id="canvas"></canvas> +</pre> + +<h4 id="JavaScript">JavaScript</h4> + +<pre class="brush: js">const canvas = document.getElementById('canvas'); +const ctx = canvas.getContext('2d'); + +// Dashed line +ctx.beginPath(); +ctx.setLineDash([5, 15]); +ctx.moveTo(0, 50); +ctx.lineTo(300, 50); +ctx.stroke(); + +// Solid line +ctx.beginPath(); +ctx.setLineDash([]); +ctx.moveTo(0, 100); +ctx.lineTo(300, 100); +ctx.stroke(); +</pre> + +<h4 id="结果">结果</h4> + +<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.setLineDash([5, 15]); +ctx.beginPath(); +ctx.moveTo(0,100); +ctx.lineTo(400, 100); +ctx.stroke();</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('基本示例', 700, 360) }}</p> + +<h3 id="一些常见的模式">一些常见的模式</h3> + +<p>此示例说明了各种常见的线划线模式。</p> + +<h4 id="HTML_2">HTML</h4> + +<pre class="brush: html"><code><canvas id="canvas"></canvas></code></pre> + +<h4 id="JavaScript_2">JavaScript</h4> + +<p>下面创建的<code>drawDashedLine()</code> 函数使得多个虚线的绘制变得简单。它接收模式数组作为其唯一参数。</p> + +<pre class="brush: js">function drawDashedLine(pattern) { + ctx.beginPath(); + ctx.setLineDash(pattern); + ctx.moveTo(0, y); + ctx.lineTo(300, y); + ctx.stroke(); + y += 20; +} + +const canvas = document.getElementById('canvas'); +const ctx = canvas.getContext('2d'); +let y = 15; + +drawDashedLine([]); +drawDashedLine([1, 1]); +drawDashedLine([10, 10]); +drawDashedLine([20, 5]); +drawDashedLine([15, 3, 3, 3]); +drawDashedLine([20, 3, 3, 3, 3, 3, 3, 3]); +drawDashedLine([12, 3, 3]); // Equals [12, 3, 3, 12, 3, 3]</pre> + +<h4 id="Result">Result</h4> + +<p>{{ EmbedLiveSample('一些常见的模式', 700, 180) }}</p> + +<h2 id="规范描述">规范描述</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">Specification</th> + <th scope="col">Status</th> + <th scope="col">Comment</th> + </tr> + <tr> + <td>{{SpecName('HTML WHATWG', "scripting.html#dom-context-2d-setlinedash", "CanvasRenderingContext2D.setLineDash")}}</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> + +<div class="hidden"> +<p>此页面上的兼容性表是根据结构化数据生成的。 如果您想提供数据，请查看<a href="https://github.com/mdn/browser-compat-data">https://github.com/mdn/browser-compat-data</a>并向我们发送请求请求。</p> +</div> + +<p>{{Compat("api.CanvasRenderingContext2D.setLineDash")}}</p> + +<h2 id="参见">参见</h2> + +<ul> + <li>接口定义，{{domxref("CanvasRenderingContext2D")}}</li> + <li>{{domxref("CanvasRenderingContext2D.getLineDash()")}}</li> + <li>{{domxref("CanvasRenderingContext2D.lineDashOffset")}}</li> +</ul> |