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author | Peter Bengtsson <mail@peterbe.com> | 2020-12-08 14:40:17 -0500 |
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committer | Peter Bengtsson <mail@peterbe.com> | 2020-12-08 14:40:17 -0500 |
commit | 33058f2b292b3a581333bdfb21b8f671898c5060 (patch) | |
tree | 51c3e392513ec574331b2d3f85c394445ea803c6 /files/zh-cn/web/api/canvasrenderingcontext2d/scale/index.html | |
parent | 8b66d724f7caf0157093fb09cfec8fbd0c6ad50a (diff) | |
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diff --git a/files/zh-cn/web/api/canvasrenderingcontext2d/scale/index.html b/files/zh-cn/web/api/canvasrenderingcontext2d/scale/index.html new file mode 100644 index 0000000000..db95fca214 --- /dev/null +++ b/files/zh-cn/web/api/canvasrenderingcontext2d/scale/index.html @@ -0,0 +1,133 @@ +--- +title: CanvasRenderingContext2D.scale() +slug: Web/API/CanvasRenderingContext2D/scale +translation_of: Web/API/CanvasRenderingContext2D/scale +--- +<div>{{APIRef}}</div> + +<p><code><strong>CanvasRenderingContext2D</strong></code><strong><code>.scale()</code></strong> 是 Canvas 2D API 根据 x 水平方向和 y 垂直方向,为canvas 单位添加缩放变换的方法。</p> + +<p>默认的, 在 canvas 中一个单位实际上就是一个像素。例如,如果我们将0.5作为缩放因子,最终的单位会变成0.5像素,并且形状的尺寸会变成原来的一半。相似的方式,我们将2.0作为缩放因子,将会增大单位尺寸变成两个像素。形状的尺寸将会变成原来的两倍。</p> + +<h2 id="语法">语法</h2> + +<pre class="syntaxbox notranslate">void <var><em>ctx</em>.scale(x, y);</var> +</pre> + +<h3 id="参数">参数</h3> + +<dl> + <dt><code>x</code></dt> + <dd>水平方向的缩放因子。A negative value flips pixels across the vertical axis. A value of <code>1</code> results in no horizontal scaling.</dd> + <dt>y</dt> + <dd>垂直方向的缩放因子。A negative value flips pixels across the horizontal axis. A value of <code>1</code> results in no vertical scaling.</dd> +</dl> + +<h2 id="示例">示例</h2> + +<h3 id="Scaling_a_shape" name="Scaling_a_shape">使用 <code>scale</code> 方法</h3> + +<p>这是一段使用 <code>scale</code> 方法的简单的代码片段。</p> + +<h4 id="HTML">HTML</h4> + +<pre class="brush: html notranslate"><canvas id="canvas"></canvas> +</pre> + +<h4 id="JavaScript">JavaScript</h4> + +<p>The rectangle has a specified width of 8 and a height of 20. The transformation matrix scales it by 9x horizontally and by 3x vertically. Thus, its final size is a width of 72 and a height of 60.</p> + +<p>Notice that its position on the canvas also changes. Since its specified corner is (10, 10), its rendered corner becomes (90, 30).</p> + +<pre class="brush: js notranslate">const canvas = document.getElementById('canvas'); +const ctx = canvas.getContext('2d'); + +// Scaled rectangle +ctx.scale(9, 3); +ctx.fillStyle = 'red'; +ctx.fillRect(10, 10, 8, 20); + +// Reset current transformation matrix to the identity matrix +ctx.setTransform(1, 0, 0, 1, 0, 0); + +// Non-scaled rectangle +ctx.fillStyle = 'gray'; +ctx.fillRect(10, 10, 8, 20);</pre> + +<h4 id="结果">结果</h4> + +<p>The scaled <span style="color: red;">rectangle is red</span>, and the <span style="color: gray;">non-scaled rectangle is gray</span>.</p> + +<p>{{ EmbedLiveSample('Scaling_a_shape', 700, 180) }}</p> + +<h3 id="Flipping_things_horizontally_or_vertically" name="Flipping_things_horizontally_or_vertically">使用 scale 水平或竖直翻转</h3> + +<p>你可以使用 <code>ctx.scale(-1, 1)</code> 水平翻转上下文,使用 <code>ctx.scale(1, -1)</code> 垂直翻转上下文。在这个例子中,"Hello world!" 被水平翻转。</p> + +<p>Note that the call to {{domxref("CanvasRenderingContext2D.fillText()", "fillText()")}} specifies a negative x coordinate. This is to adjust for the negative scaling factor: <code>-280 * -1</code> becomes <code>280</code>, and text is drawn leftwards from that point.</p> + +<h4 id="HTML_2">HTML</h4> + +<pre class="brush: html notranslate"><canvas id="canvas"></canvas> +</pre> + +<h4 id="JavaScript_2">JavaScript</h4> + +<pre class="brush: js; highlight:[4] notranslate">const canvas = document.getElementById('canvas'); +const ctx = canvas.getContext('2d'); + +ctx.scale(-1, 1); +ctx.font = '48px serif'; +ctx.fillText('Hello world!', -280, 90); +ctx.setTransform(1, 0, 0, 1, 0, 0); +</pre> + +<h4 id="Result">Result</h4> + +<p>{{ EmbedLiveSample('Flipping_things_horizontally_or_vertically', 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-scale", "CanvasRenderingContext2D.scale")}}</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>{{Compat("api.CanvasRenderingContext2D.scale")}}</p> + +<h2 id="参见">参见</h2> + +<ul> + <li>接口定义,{{domxref("CanvasRenderingContext2D")}}</li> +</ul> + +<p> + <audio style="display: none;"></audio> +</p> + +<p> + <audio style="display: none;"></audio> +</p> + +<p> + <audio style="display: none;"></audio> +</p> + +<p> + <audio style="display: none;"></audio> +</p> |