Web/API/CanvasRenderingContext2D/isPointInStroke

The CanvasRenderingContext2D.isPointInStroke() method of the Canvas 2D API reports whether or not the specified point is inside the area contained by the stroking of a path.

Syntax

ctx.isPointInStroke(x, y);
ctx.isPointInStroke(path, x, y);

Parameters

x

The x-axis coordinate of the point to check.

y

The y-axis coordinate of the point to check.

path

A Path2D path to check against. If unspecified, the current path is used.

Return value

Boolean

A Boolean, which is true if the point is inside the area contained by the stroking of a path, otherwise false.

Examples

Checking a point in the current path

This example uses the isPointInStroke() method to check if a point is within the area of the current path's stroke.

HTML

<canvas id="canvas"></canvas>
<p>In stroke: <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.stroke();
result.innerText = ctx.isPointInStroke(50, 10);

Checking a point in the specified path

Whenever you move the mouse, this example checks whether the cursor is in the stroke of an elliptical Path2D path. If yes, the ellipse's stroke becomes green, otherwise it is red.

HTML

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

JavaScript

const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');

// Create ellipse
const ellipse = new Path2D();
ellipse.ellipse(150, 75, 40, 60, Math.PI * .25, 0, 2 * Math.PI);
ctx.lineWidth = 25;
ctx.strokeStyle = 'red';
ctx.fill(ellipse);
ctx.stroke(ellipse);

// Listen for mouse moves
canvas.addEventListener('mousemove', function(event) {
  // Check whether point is inside ellipse's stroke
  if (ctx.isPointInStroke(ellipse, event.offsetX, event.offsetY)) {
    ctx.strokeStyle = 'green';
  }
  else {
    ctx.strokeStyle = 'red';
  }

  // Draw ellipse
  ctx.clearRect(0, 0, canvas.width, canvas.height);
  ctx.fill(ellipse);
  ctx.stroke(ellipse);
});

Specifications

Specification	Status	Comment
HTML Living StandardThe definition of 'CanvasRenderingContext2D.isPointInStroke' in that specification.	Living Standard

Browser compatibility

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.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
isPointInStroke	Chrome Full support Yes	Edge Full support 79	Firefox Full support 20 Full support 20 No support 19 — 20 Prefixed' Prefixed' Implemented with the vendor prefix: moz	IE No support No	Opera Full support Yes	Safari Full support Yes	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android Full support 20 Full support 20 No support 19 — 20 Prefixed' Prefixed' Implemented with the vendor prefix: moz	Opera Android Full support Yes	Safari iOS Full support Yes	Samsung Internet Android Full support Yes
Path parameter	Chrome Full support Yes	Edge Full support 79	Firefox Full support 31	IE No support No	Opera Full support Yes	Safari No support No	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android Full support 31	Opera Android ?	Safari iOS ?	Samsung Internet Android Full support Yes

Legend

Full support  

Full support

No support  

No support

Compatibility unknown  

Compatibility unknown

Requires a vendor prefix or different name for use.'

Requires a vendor prefix or different name for use.

See also

• The interface defining this method: CanvasRenderingContext2D

CanvasRenderingContext2D.isPointInStroke() by Mozilla Contributors is licensed under CC-BY-SA 2.5.