From 33058f2b292b3a581333bdfb21b8f671898c5060 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:40:17 -0500 Subject: initial commit --- .../beziercurveto/index.html | 191 +++++++++++++++++++++ 1 file changed, 191 insertions(+) create mode 100644 files/zh-cn/web/api/canvasrenderingcontext2d/beziercurveto/index.html (limited to 'files/zh-cn/web/api/canvasrenderingcontext2d/beziercurveto') diff --git a/files/zh-cn/web/api/canvasrenderingcontext2d/beziercurveto/index.html b/files/zh-cn/web/api/canvasrenderingcontext2d/beziercurveto/index.html new file mode 100644 index 0000000000..5a66c1f6e8 --- /dev/null +++ b/files/zh-cn/web/api/canvasrenderingcontext2d/beziercurveto/index.html @@ -0,0 +1,191 @@ +--- +title: CanvasRenderingContext2D.bezierCurveTo() +slug: Web/API/CanvasRenderingContext2D/bezierCurveTo +tags: + - API + - Canvas + - CanvasRenderingContext2D + - Method + - Reference +translation_of: Web/API/CanvasRenderingContext2D/bezierCurveTo +--- +
{{APIRef}}
+ +

CanvasRenderingContext2D.bezierCurveTo() 是 Canvas 2D API 绘制三次贝赛尔曲线路径的方法。 该方法需要三个点。 第一、第二个点是控制点，第三个点是结束点。起始点是当前路径的最后一个点，绘制贝赛尔曲线前，可以通过调用 moveTo() 进行修改。

+ +

语法

+ +
void ctx.bezierCurveTo(cp1x, cp1y, cp2x, cp2y, x, y);
+
+ +

参数

+ +
+
cp1x
+
第一个控制点的 x 轴坐标。
+
cp1y
+
第一个控制点的 y 轴坐标。
+
cp2x
+
第二个控制点的 x 轴坐标。
+
cp2y
+
第二个控制点的 y 轴坐标。
+
x
+
结束点的 x 轴坐标。
+
y
+
结束点的 y 轴坐标。
+
+ +

示例

+ +

使用 bezierCurveTo 方法

+ +

这是一段绘制贝赛尔曲线的简单的代码片段。  控制点是红色的， 开始和结束点是蓝色的。

+ +

HTML

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<canvas id="canvas"></canvas>
+
+ +

JavaScript

+ +
var canvas = document.getElementById("canvas");
+var ctx = canvas.getContext("2d");
+
+ctx.beginPath();
+ctx.moveTo(50,20);
+ctx.bezierCurveTo(230, 30, 150, 60, 50, 100);
+ctx.stroke();
+
+ctx.fillStyle = 'blue';
+// start point
+ctx.fillRect(50, 20, 10, 10);
+// end point
+ctx.fillRect(50, 100, 10, 10);
+
+ctx.fillStyle = 'red';
+// control point one
+ctx.fillRect(230, 30, 10, 10);
+// control point two
+ctx.fillRect(150, 70, 10, 10);
+ +

{{ EmbedLiveSample('使用_bezierCurveTo_方法', 315, 165) }}

+ +

尝试 bezierCurveTo 参数

+ +

修改下面的代码并在线查看 canvas 的变化：

+ +
+
<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.beginPath();
+ctx.bezierCurveTo(50, 100, 180, 10, 20, 10);
+ctx.stroke();</textarea>
+
+ +
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);
+
+
+ +

{{ EmbedLiveSample('尝试_bezierCurveTo_参数', 700, 360) }}

+ +

规范描述

+ + + + + + + + + + + + + + +
SpecificationStatusComment
{{SpecName('HTML WHATWG', "scripting.html#dom-context-2d-beziercurveto", "CanvasRenderingContext2D.beziercurveto")}}{{Spec2('HTML WHATWG')}} 
+ +

浏览器兼容性

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{{CompatibilityTable}}

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+ + + + + + + + + + + + + + + + + + + +
FeatureChromeFirefox (Gecko)Internet ExplorerOperaSafari
Basic support{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}
+
+ +
+ + + + + + + + + + + + + + + + + + + + + +
FeatureAndroidChrome for AndroidFirefox Mobile (Gecko)IE MobileOpera MobileSafari Mobile
Basic support{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}
+
+ +

参见

+ + -- cgit v1.2.3-54-g00ecf