CanvasRenderingContext2D.drawFocusIfNeeded()

The CanvasRenderingContext2D.drawFocusIfNeeded() method of the Canvas 2D API draws a focus ring around the current path or given path, If a given element is focused.

Syntax

void ctx.drawFocusIfNeeded(element);
void ctx.drawFocusIfNeeded(path, element);

Parameters

element

The element to check whether it is focused or not.

path

A Path2D path to use.

Examples

Using the drawFocusIfNeeded method

This is just a simple code snippet which uses the drawFocusIfNeeded method.

HTML

<canvas id="canvas">
  <input id="button" type="range" min="1" max="12">
</canvas>

JavaScript

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

button.focus();

ctx.beginPath();
ctx.rect(10, 10, 30, 30);
ctx.drawFocusIfNeeded(button);

Edit the code below and see your changes update live in the canvas:

<canvas id="canvas" width="400" height="200" class="playable-canvas">
<input id="button" type="range" min="1" max="12">
</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.rect(10, 10, 30, 30);
ctx.drawFocusIfNeeded(button);</textarea>

var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var textarea = document.getElementById("code");
var button = document.getElementById("button");
var reset = document.getElementById("reset");
var edit = document.getElementById("edit");
var code = textarea.value;
button.focus();

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

Browser compatibility

[1] In Gecko 28 (Firefox 28 / Thunderbird 28 / SeaMonkey 2.25 / Firefox OS 1.3), this method was implemented as drawSystemFocusRing, but has been renamed to the standard drawFocusIfNeeded in Gecko 29 (Firefox 29 / Thunderbird 29 / SeaMonkey 2.26).

[2] Prior to Gecko 32 (Firefox 32 / Thunderbird 32 / SeaMonkey 2.29 / Firefox OS 2.0) this method was deactivated by default behind the flag canvas.focusring.enabled.

See also

• The interface defining it, CanvasRenderingContext2D.