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CanvasRenderingContext2D.isPointInPath()

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

Syntax

boolean ctx.isPointInPath(x, y);
boolean ctx.isPointInPath(x, y, fillRule);

boolean ctx.isPointInPath(path, x, y);
boolean ctx.isPointInPath(path, x, y, fillRule);

Parameters

x
The X coordinate of the point to check.
y
The Y coordinate of the point to check.
fillRule
The algorithm by which to determine if a point is inside a path or outside a path.
Possible values:
path
A Path2D path to use.

Return value

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

Examples

Using the isPointInPath method

This is just a simple code snippet which uses the isPointinPath method to check if a point is in the current path.

HTML

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

JavaScript

var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");

ctx.rect(10, 10, 100, 100);
ctx.stroke();
console.log(ctx.isPointInPath(10, 10)); // true

Edit the code below, see your changes update live in the canvas and watch for loggings in your console:

Playable code
<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.rect(10, 10, 100, 100);
ctx.stroke();
console.log(ctx.isPointInPath(10, 10)); // true</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);

Specifications

Specification Status Comment
WHATWG HTML Living Standard
The definition of 'CanvasRenderingContext2D.isPointInPath' in that specification.
Living Standard  

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
Path parameter (Yes) 31 (31) Not supported (Yes) Not supported
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)
Path parameter ? ? 31.0 (31) ? ? ?

Compatibility notes

  • 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.

See also

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 このページの貢献者: notetienne, fscholz
 最終更新者: notetienne,