CanvasRenderingContext2D.drawFocusIfNeeded()

The CanvasRenderingContext2D.drawFocusIfNeeded() method of the Canvas 2D API draws a focus ring around the current or given path, if the specified 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

Managing button focus

This example draws two buttons on a canvas. The drawFocusIfNeeded() method is used to draw a focus ring when appropriate.

HTML

<canvas id="canvas">
  <button id="button1">Continue</button>
  <button id="button2">Quit</button>
</canvas>

JavaScript

const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');
const button1 = document.getElementById('button1');
const button2 = document.getElementById('button2');

document.addEventListener('focus', redraw, true);
document.addEventListener('blur', redraw, true);
canvas.addEventListener('click', handleClick, false);
redraw();

function redraw() {
  ctx.clearRect(0, 0, canvas.width, canvas.height);
  drawButton(button1, 20, 20);
  drawButton(button2, 20, 80);
}

function handleClick(e) {
  // Calculate click coordinates
  const x = e.clientX - canvas.offsetLeft;
  const y = e.clientY - canvas.offsetTop;

  // Focus button1, if appropriate
  drawButton(button1, 20, 20);
  if (ctx.isPointInPath(x, y)) {
    button1.focus();
  }

  // Focus button2, if appropriate
  drawButton(button2, 20, 80);
  if (ctx.isPointInPath(x, y)) {
    button2.focus();
  }
}

function drawButton(el, x, y) {
  const active = document.activeElement === el;
  const width = 150;
  const height = 40;

  // Button background
  ctx.fillStyle = active ? 'pink' : 'lightgray';
  ctx.fillRect(x, y, width, height);

  // Button text
  ctx.font = '15px sans-serif';
  ctx.textAlign = 'center';
  ctx.textBaseline = 'middle';
  ctx.fillStyle = active ? 'blue' : 'black';
  ctx.fillText(el.textContent, x + width / 2, y + height / 2);

  // Define clickable area
  ctx.beginPath();
  ctx.rect(x, y, width, height);

  // Draw focus ring, if appropriate
  ctx.drawFocusIfNeeded(el);
}

Result

Specifications

Specification Status Comment
HTML Living Standard
The definition of 'CanvasRenderingContext2D.drawFocusIfNeeded' in that specification.
Living Standard Initial definition

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
drawFocusIfNeededChrome Full support YesEdge Full support 14Firefox Full support 32
Full support 32
Full support 29
Disabled
Disabled From version 29: this feature is behind the canvas.focusring.enabled preference. To change preferences in Firefox, visit about:config.
Full support 28
Alternate Name
Alternate Name Uses the non-standard name: drawSystemFocusRing
IE No support NoOpera Full support YesSafari Full support YesWebView Android Full support YesChrome Android Full support YesFirefox Android Full support 32
Full support 32
Full support 29
Disabled
Disabled From version 29: this feature is behind the canvas.focusring.enabled preference. To change preferences in Firefox, visit about:config.
Full support 28
Alternate Name
Alternate Name Uses the non-standard name: drawSystemFocusRing
Opera Android Full support YesSafari iOS Full support YesSamsung Internet Android Full support Yes
Path parameterChrome Full support YesEdge Full support ≤79Firefox No support NoIE No support NoOpera Full support YesSafari Full support YesWebView Android Full support YesChrome Android Full support YesFirefox Android No support NoOpera Android Full support YesSafari iOS Full support YesSamsung Internet Android Full support Yes

Legend

Full support  
Full support
No support  
No support
User must explicitly enable this feature.
User must explicitly enable this feature.
Uses a non-standard name.
Uses a non-standard name.

See also