CanvasRenderingContext2D: stroke() method
The
CanvasRenderingContext2D.stroke()
method of the Canvas 2D API strokes (outlines) the current or given path with the
current stroke style.
Strokes are aligned to the center of a path; in other words, half of the stroke is drawn on the inner side, and half on the outer side.
The stroke is drawn using the non-zero winding rule, which means that path intersections will still get filled.
Syntax
js
stroke()
stroke(path)
Parameters
path
-
A
Path2D
path to stroke.
Return value
None (undefined
).
Examples
A simple stroked rectangle
This example creates a rectangle using the rect()
method, and then draws
it to the canvas using stroke()
.
HTML
html
<canvas id="canvas"></canvas>
JavaScript
js
const canvas = document.getElementById("canvas");
const ctx = canvas.getContext("2d");
ctx.rect(10, 10, 150, 100);
ctx.stroke();
Result
Re-stroking paths
Typically, you'll want to call beginPath()
for each new thing you want to stroke. If you don't, the previous
sub-paths will remain part of the current path, and get stroked every time you call the
stroke()
method. In some cases, however, this may be the desired effect.
HTML
html
<canvas id="canvas"></canvas>
JavaScript
This code strokes the first path three times, the second path two times, and the third path only once.
js
const canvas = document.getElementById("canvas");
const ctx = canvas.getContext("2d");
// First sub-path
ctx.lineWidth = 26;
ctx.strokeStyle = "orange";
ctx.moveTo(20, 20);
ctx.lineTo(160, 20);
ctx.stroke();
// Second sub-path
ctx.lineWidth = 14;
ctx.strokeStyle = "green";
ctx.moveTo(20, 80);
ctx.lineTo(220, 80);
ctx.stroke();
// Third sub-path
ctx.lineWidth = 4;
ctx.strokeStyle = "pink";
ctx.moveTo(20, 140);
ctx.lineTo(280, 140);
ctx.stroke();
Result
Stroking and filling
If you want to both stroke and fill a path, the order in which you perform these actions will determine the result. In this example, the square on the left is drawn with the stroke on top of the fill. The square on the right is drawn with the fill on top of the stroke.
HTML
html
<canvas id="canvas"></canvas>
JavaScript
js
const canvas = document.getElementById("canvas");
const ctx = canvas.getContext("2d");
ctx.lineWidth = 16;
ctx.strokeStyle = "red";
// Stroke on top of fill
ctx.beginPath();
ctx.rect(25, 25, 100, 100);
ctx.fill();
ctx.stroke();
// Fill on top of stroke
ctx.beginPath();
ctx.rect(175, 25, 100, 100);
ctx.stroke();
ctx.fill();
Result
Specifications
Specification |
---|
HTML Standard # dom-context-2d-stroke-dev |
Browser compatibility
BCD tables only load in the browser
See also
- The interface defining this method:
CanvasRenderingContext2D