The CanvasRenderingContext2D
.lineJoin
property of the Canvas 2D API determines the shape used to join two line segments where they meet.
This property has no effect wherever two connected segments have the same direction, because no joining area will be added in this case. Degenerate segments with a length of zero (i.e., with all endpoints and control points at the exact same position) are also ignored.
Note: Lines can be drawn with the stroke()
, strokeRect()
, and strokeText()
methods.
Syntax
ctx.lineJoin = "bevel" || "round" || "miter";
Options
There are three possible values for this property: "round"
, "bevel"
, and "miter"
. The default is "miter"
.
"round"
- Rounds off the corners of a shape by filling an additional sector of disc centered at the common endpoint of connected segments. The radius for these rounded corners is equal to the line width.
"bevel"
- Fills an additional triangular area between the common endpoint of connected segments, and the separate outside rectangular corners of each segment.
"miter"
- Connected segments are joined by extending their outside edges to connect at a single point, with the effect of filling an additional lozenge-shaped area. This setting is affected by the
miterLimit
property. Default value.
Examples
Changing the joins in a path
This example applies rounded line joins to a path.
HTML
<canvas id="canvas"></canvas>
JavaScript
const canvas = document.getElementById('canvas'); const ctx = canvas.getContext('2d'); ctx.lineWidth = 20; ctx.lineJoin = 'round'; ctx.beginPath(); ctx.moveTo(20, 20); ctx.lineTo(190, 100); ctx.lineTo(280, 20); ctx.lineTo(280, 150); ctx.stroke();
Result
Comparison of line joins
The example below draws three different paths, demonstrating each of the three lineJoin
options.
<canvas id="canvas" width="150" height="150"></canvas>
var ctx = document.getElementById('canvas').getContext('2d'); var lineJoin = ['round', 'bevel', 'miter']; ctx.lineWidth = 10; for (let i = 0; i < lineJoin.length; i++) { ctx.lineJoin = lineJoin[i]; ctx.beginPath(); ctx.moveTo(-5, 5 + i * 40); ctx.lineTo(35, 45 + i * 40); ctx.lineTo(75, 5 + i * 40); ctx.lineTo(115, 45 + i * 40); ctx.lineTo(155, 5 + i * 40); ctx.stroke(); }
Screenshot | Live sample |
---|---|
Specifications
Specification | Status | Comment |
---|---|---|
HTML Living Standard The definition of 'CanvasRenderingContext2D.lineJoin' in that specification. |
Living Standard |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
lineJoin | Chrome Full support Yes | Edge Full support 12 | Firefox Full support 1.5 | IE Full support Yes | Opera Full support Yes | Safari Full support Yes | WebView Android Full support Yes | Chrome Android Full support Yes | Firefox Android Full support 4 | Opera Android Full support Yes | Safari iOS Full support Yes | Samsung Internet Android Full support Yes |
Legend
- Full support
- Full support
WebKit/Blink-specific notes
- In WebKit- and Blink-based Browsers, a non-standard and deprecated method
ctx.setLineJoin()
is implemented in addition to this property.
See also
- The interface defining this property:
CanvasRenderingContext2D
CanvasRenderingContext2D.lineCap
CanvasRenderingContext2D.lineWidth
- Applying styles and color