HTML5 canvas Line Tutorial

To create line shapes with Konva, we can instantiate a Konva.Line() object. Lines can be configured in different ways to create various shapes like simple lines, splines, blobs, and polygons.

For full list of properties and methods, see the Line API Reference.

Simple Line

Vanilla

import Konva from 'konva';

const stage = new Konva.Stage({
  container: 'container',
  width: window.innerWidth,
  height: window.innerHeight
});

const layer = new Konva.Layer();
stage.add(layer);

const redLine = new Konva.Line({
  points: [5, 70, 140, 23, 250, 60, 300, 20],
  stroke: 'red',
  strokeWidth: 15,
  lineCap: 'round',
  lineJoin: 'round'
});

// dashed line
const greenLine = new Konva.Line({
  points: [5, 70, 140, 23, 250, 60, 300, 20],
  stroke: 'green',
  strokeWidth: 2,
  lineJoin: 'round',
  dash: [33, 10]
});

greenLine.y(50);
layer.add(redLine, greenLine);

Open Sandbox

React

import { Stage, Layer, Line } from 'react-konva';

const App = () => {
  return (
    <Stage width={window.innerWidth} height={window.innerHeight}>
      <Layer>
        <Line
          points={[5, 70, 140, 23, 250, 60, 300, 20]}
          stroke="red"
          strokeWidth={15}
          lineCap="round"
          lineJoin="round"
        />
        <Line
          points={[5, 70, 140, 23, 250, 60, 300, 20]}
          stroke="green"
          strokeWidth={2}
          lineJoin="round"
          dash={[33, 10]}
          y={50}
        />
      </Layer>
    </Stage>
  );
};

export default App;

Open Sandbox

Vue

<template>
  <v-stage :config="stageSize">
    <v-layer>
      <v-line :config="redLineConfig" />
      <v-line :config="greenLineConfig" />
    </v-layer>
  </v-stage>
</template>

<script setup>
const stageSize = {
  width: window.innerWidth,
  height: window.innerHeight
};

const redLineConfig = {
  points: [5, 70, 140, 23, 250, 60, 300, 20],
  stroke: 'red',
  strokeWidth: 15,
  lineCap: 'round',
  lineJoin: 'round'
};

const greenLineConfig = {
  points: [5, 70, 140, 23, 250, 60, 300, 20],
  stroke: 'green',
  strokeWidth: 2,
  lineJoin: 'round',
  dash: [33, 10],
  y: 50
};
</script>

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Spline (Curved Line)

To create a curved line, add the tension property:

Vanilla

import Konva from 'konva';

const stage = new Konva.Stage({
  container: 'container',
  width: window.innerWidth,
  height: window.innerHeight
});

const layer = new Konva.Layer();
stage.add(layer);

const line = new Konva.Line({
  points: [5, 70, 140, 23, 250, 60, 300, 20],
  stroke: 'red',
  strokeWidth: 15,
  lineCap: 'round',
  lineJoin: 'round',
  tension: 1
});

layer.add(line);

Open Sandbox

React

import { Stage, Layer, Line } from 'react-konva';

const App = () => {
  return (
    <Stage width={window.innerWidth} height={window.innerHeight}>
      <Layer>
        <Line
          points={[5, 70, 140, 23, 250, 60, 300, 20]}
          stroke="red"
          strokeWidth={15}
          lineCap="round"
          lineJoin="round"
          tension={1}
        />
      </Layer>
    </Stage>
  );
};

export default App;

Open Sandbox

Vue

<template>
  <v-stage :config="stageSize">
    <v-layer>
      <v-line :config="lineConfig" />
    </v-layer>
  </v-stage>
</template>

<script setup>
const stageSize = {
  width: window.innerWidth,
  height: window.innerHeight
};

const lineConfig = {
  points: [5, 70, 140, 23, 250, 60, 300, 20],
  stroke: 'red',
  strokeWidth: 15,
  lineCap: 'round',
  lineJoin: 'round',
  tension: 1
};
</script>

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Polygon

To create a polygon, set the closed property to true:

Vanilla

import Konva from 'konva';

const stage = new Konva.Stage({
  container: 'container',
  width: window.innerWidth,
  height: window.innerHeight
});

const layer = new Konva.Layer();
stage.add(layer);

const polygon = new Konva.Line({
  points: [73, 192, 73, 160, 340, 23, 500, 109, 499, 139, 342, 93],
  fill: '#00D2FF',
  stroke: 'black',
  strokeWidth: 5,
  closed: true
});

layer.add(polygon);

Open Sandbox

React

import { Stage, Layer, Line } from 'react-konva';

const App = () => {
  return (
    <Stage width={window.innerWidth} height={window.innerHeight}>
      <Layer>
        <Line
          points={[73, 192, 73, 160, 340, 23, 500, 109, 499, 139, 342, 93]}
          fill="#00D2FF"
          stroke="black"
          strokeWidth={5}
          closed
        />
      </Layer>
    </Stage>
  );
};

export default App;

Open Sandbox

Vue

<template>
  <v-stage :config="stageSize">
    <v-layer>
      <v-line :config="polygonConfig" />
    </v-layer>
  </v-stage>
</template>

<script setup>
const stageSize = {
  width: window.innerWidth,
  height: window.innerHeight
};

const polygonConfig = {
  points: [73, 192, 73, 160, 340, 23, 500, 109, 499, 139, 342, 93],
  fill: '#00D2FF',
  stroke: 'black',
  strokeWidth: 5,
  closed: true
};
</script>

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Blob

To create a blob, combine closed and tension properties:

Vanilla

import Konva from 'konva';

const stage = new Konva.Stage({
  container: 'container',
  width: window.innerWidth,
  height: window.innerHeight
});

const layer = new Konva.Layer();
stage.add(layer);

const blob = new Konva.Line({
  points: [23, 20, 23, 160, 70, 93, 150, 109, 290, 139, 270, 93],
  fill: '#00D2FF',
  stroke: 'black',
  strokeWidth: 5,
  closed: true,
  tension: 0.3
});

layer.add(blob);

Open Sandbox

React

import { Stage, Layer, Line } from 'react-konva';

const App = () => {
  return (
    <Stage width={window.innerWidth} height={window.innerHeight}>
      <Layer>
        <Line
          points={[23, 20, 23, 160, 70, 93, 150, 109, 290, 139, 270, 93]}
          fill="#00D2FF"
          stroke="black"
          strokeWidth={5}
          closed
          tension={0.3}
        />
      </Layer>
    </Stage>
  );
};

export default App;

Open Sandbox

Vue

<template>
  <v-stage :config="stageSize">
    <v-layer>
      <v-line :config="blobConfig" />
    </v-layer>
  </v-stage>
</template>

<script setup>
const stageSize = {
  width: window.innerWidth,
  height: window.innerHeight
};

const blobConfig = {
  points: [23, 20, 23, 160, 70, 93, 150, 109, 290, 139, 270, 93],
  fill: '#00D2FF',
  stroke: 'black',
  strokeWidth: 5,
  closed: true,
  tension: 0.3
};
</script>

Open Sandbox