CanvasRenderingContext2D.setLineDash

The CanvasRenderingContext2D.setLineDash() method of the Canvas 2D API sets the line dash pattern.

Syntax

void ctx.setLineDash(segments);

Parameters

segments

An Array. A list of numbers that specifies distances to alternately draw a line and a gap (in coordinate space units). If the number of elements in the array is odd, the elements of the array get copied and concatenated. For example, [5, 15, 25] will become [5, 15, 25, 5, 15, 25].

Examples

Using the setLineDash method

This is just a simple code snippet which uses the setLineDash method to draw a dashed line.

HTML

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

JavaScript

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

ctx.setLineDash([5, 15]);

ctx.beginPath();
ctx.moveTo(0, 100);
ctx.lineTo(400, 100);
ctx.stroke();

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

<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.setLineDash([5, 15]);
ctx.beginPath();
ctx.moveTo(0,100);
ctx.lineTo(400, 100);
ctx.stroke();</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

Browser compatibility

Gecko-specific notes

• Starting with Gecko 7.0 (Firefox 7.0 / Thunderbird 7.0 / SeaMonkey 2.4), the non-standard and deprecated property mozDash has been implemented to set and get a dash list. This property will be deprecated and removed in the future, see bug 931389. Use setLineDash() instead.

WebKit-specific notes

• In WebKit-based browsers (e.g. Safari), the non-standard and deprecated property webkitLineDash is implemented besides this method. Use setLineDash() instead.

See also

• The interface defining it, CanvasRenderingContext2D
• CanvasRenderingContext2D.getLineDash()
• CanvasRenderingContext2D.lineDashOffset