CanvasRenderingContext2D.isPointInPath()

在此页

句法
范例
规范
浏览器兼容性
另请参阅
相关话题

CanvasRenderingContext2D .isPointInPath() method of the Canvas 2D API reports whether or not the specified point is contained in the current path.

句法

ctx.isPointInPath(x, y [, fillRule]);
ctx.isPointInPath(path, x, y [, fillRule]);

参数

x

The x-axis coordinate of the point to check, unaffected by the current transformation of the context.

y

The y-axis coordinate of the point to check, unaffected by the current transformation of the context.

fillRule

The algorithm by which to determine if a point is inside or outside the path.
可能的值：

"nonzero" ： non-zero winding rule . Default rule.
"evenodd" ： even-odd winding rule .

path


									Path2D

path to check against. If unspecified, the current path is used.

返回值

布尔: A Boolean, which is true if the specified point is contained in the current or specified path, otherwise false .

范例

Checking a point in the current path

此范例使用 isPointInPath() method to check if a point is within the current path.

HTML

<canvas id="canvas"></canvas>
<p>In path: <code id="result">false</code></p>

JavaScript

const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');
const result = document.getElementById('result');
ctx.rect(10, 10, 100, 100);
ctx.fill();
result.innerText = ctx.isPointInPath(30, 70);

结果

Checking a point in the specified path

Whenever you move the mouse, this example checks whether the cursor is in a circular Path2D path. If yes, the circle becomes green, otherwise it is red.

HTML

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

JavaScript

const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');
// Create circle
const circle = new Path2D();
circle.arc(150, 75, 50, 0, 2 * Math.PI);
ctx.fillStyle = 'red';
ctx.fill(circle);
// Listen for mouse moves
canvas.addEventListener('mousemove', function(event) {
  // Check whether point is inside circle
  if (ctx.isPointInPath(circle, event.offsetX, event.offsetY)) {
    ctx.fillStyle = 'green';
  }
  else {
    ctx.fillStyle = 'red';
  }
  // Draw circle
  ctx.clearRect(0, 0, canvas.width, canvas.height);
  ctx.fill(circle);
});

结果

规范

规范	状态	注释
HTML 实时标准 The definition of 'CanvasRenderingContext2D.isPointInPath' in that specification.	实时标准

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`isPointInPath`	Chrome Yes	Edge 12	Firefox 2	IE Yes	Opera Yes	Safari Yes	WebView Android Yes	Chrome Android Yes	Firefox Android 4	Opera Android Yes	Safari iOS Yes	Samsung Internet Android Yes
`路径` 参数	Chrome Yes	Edge ≤18	Firefox 31	IE No	Opera Yes	Safari No	WebView Android Yes	Chrome Android Yes	Firefox Android 31	Opera Android ?	Safari iOS ?	Samsung Internet Android Yes

图例

完整支持
不支持
兼容性未知 ?

Gecko-specific note

Prior to Gecko 7.0 (Firefox 7.0 / Thunderbird 7.0 / SeaMonkey 2.4), this method incorrectly failed to multiply the specified point's coordinates by the current transformation matrix before comparing it to the path. Now this method works correctly even if the context is rotated, scaled, or otherwise transformed.

另请参阅

The interface defining this method: CanvasRenderingContext2D

元数据

最后修改： Jul 20, 2020

在此页

句法

参数

返回值

范例

Checking a point in the current path

HTML

JavaScript

结果

Checking a point in the specified path

HTML

JavaScript

结果

规范

浏览器兼容性

图例

Gecko-specific note

另请参阅

相关话题