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Getting started with Vue and Canvas via Konva

How to use canvas with Vue?​

VueKonva Logo

Vue Konva is a JavaScript library for drawing complex canvas graphics using Vue.

It provides declarative and reactive bindings to the Konva Framework.

All vue-konva components correspond to Konva components of the same name with the prefix 'v-'. All the parameters available for Konva objects can be added as config in the prop for corresponding vue-konva components.

Core shapes are: v-rect, v-circle, v-ellipse, v-line, v-image, v-text, v-text-path, v-star, v-label, v-path, v-regular-polygon. Also you can create custom shapes.

To get more info about Konva you can read Konva Overview.

Quick Start​

Vue.js version 3 is required.

1. Install via npm​

npm install vue-konva konva --save

2. Import and use VueKonva​

import { createApp } from 'vue';
import App from './App.vue';
import VueKonva from 'vue-konva';

const app = createApp(App);
app.use(VueKonva);
app.mount('#app');

3. Use in your components​

Instructions: Try to drag the stars. They will scale up while being dragged and return to normal size when released.

<template>
  <v-stage
    ref="stage"
    :config="stageSize"
    @dragstart="handleDragstart"
    @dragend="handleDragend"
  >
    <v-layer ref="layer">
      <v-star
        v-for="item in list"
        :key="item.id"
        :config="{
          x: item.x,
          y: item.y,
          rotation: item.rotation,
          id: item.id,
          numPoints: 5,
          innerRadius: 30,
          outerRadius: 50,
          fill: '#89b717',
          opacity: 0.8,
          draggable: true,
          scaleX: dragItemId === item.id ? item.scale * 1.2 : item.scale,
          scaleY: dragItemId === item.id ? item.scale * 1.2 : item.scale,
          shadowColor: 'black',
          shadowBlur: 10,
          shadowOffsetX: dragItemId === item.id ? 15 : 5,
          shadowOffsetY: dragItemId === item.id ? 15 : 5,
          shadowOpacity: 0.6
        }"
      />
    </v-layer>
  </v-stage>
</template>

<script setup>
import { ref, onMounted } from 'vue';

const stageSize = {
  width: window.innerWidth,
  height: window.innerHeight
};

const list = ref([]);
const dragItemId = ref(null);

const handleDragstart = (e) => {
  // save drag element:
  dragItemId.value = e.target.id();
  // move current element to the top:
  const item = list.value.find(i => i.id === dragItemId.value);
  const index = list.value.indexOf(item);
  list.value.splice(index, 1);
  list.value.push(item);
};

const handleDragend = () => {
  dragItemId.value = null;
};

onMounted(() => {
  for (let n = 0; n < 30; n++) {
    list.value.push({
      id: Math.round(Math.random() * 10000).toString(),
      x: Math.random() * stageSize.width,
      y: Math.random() * stageSize.height,
      rotation: Math.random() * 180,
      scale: Math.random()
    });
  }
});
</script>
Open on CodeSandboxOpen Sandbox

Or use a CDN​

<html>
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no" />
    <meta http-equiv="x-ua-compatible" content="ie=edge" />
  </head>
  <body>
    <div id="app">
      <v-stage ref="stage" :config="configKonva">
        <v-layer ref="layer">
          <v-circle :config="configCircle" />
        </v-layer>
      </v-stage>
    </div>
    <!--1. Link Vue Javascript & Konva-->
    <script src="https://unpkg.com/vue@3/dist/vue.global.js"></script>
    <script src="https://unpkg.com/konva@9/konva.min.js"></script>
    <!--2. Link VueKonva Javascript (Plugin automatically installed)-->
    <script src="https://unpkg.com/vue-konva@3/umd/vue-konva.min.js"></script>
    <script>
      // 3. Create the Vue instance
      const { createApp, ref } = Vue;
      
      const app = createApp({
        setup() {
          const configKonva = {
            width: 200,
            height: 200
          };
          
          const configCircle = {
            x: 100,
            y: 100,
            radius: 70,
            fill: 'red',
            stroke: 'black',
            strokeWidth: 4
          };
          
          return {
            configKonva,
            configCircle
          };
        }
      });
      
      app.use(VueKonva);
      app.mount('#app');
    </script>
  </body>
</html>