HTML5 Canvas Kaleidoscope Image Filter Tutorial

To apply filter to an Konva.Image, we have to cache it first with cache() function. Then apply filter with filters() function.

To create a kaleidoscope with Konva, we can use the Konva.Filters.Kaleidoscope filter and set the kaleidoscopePower and kaleidoscopeAngle properties.

Instructions: Slide the controls to adjust the kaleidoscope power and angle.

For all available filters go to Filters Documentation.

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 imageObj = new Image();
imageObj.onload = () => {
  const image = new Konva.Image({
    x: 50,
    y: 50,
    image: imageObj,
    draggable: true,
  });

  layer.add(image);

  image.cache();
  image.filters([Konva.Filters.Kaleidoscope]);
  image.kaleidoscopePower(3);
  image.kaleidoscopeAngle(0);

  // create sliders
  const createSlider = (label, min, max, defaultValue, property) => {
    const container = document.createElement('div');
    container.style.position = 'absolute';
    container.style.left = '20px';
    
    const text = document.createElement('span');
    text.textContent = `${label}: `;
    container.appendChild(text);
    
    const slider = document.createElement('input');
    slider.type = 'range';
    slider.min = min;
    slider.max = max;
    slider.step = property === 'kaleidoscopePower' ? '1' : '0.1';
    slider.value = defaultValue;
    slider.style.width = '200px';
    
    slider.addEventListener('input', (e) => {
      const value = parseFloat(e.target.value);
      image[property](value);
      layer.batchDraw();
    });
    
    container.appendChild(slider);
    return container;
  };

  const powerSlider = createSlider('Power', 2, 8, 3, 'kaleidoscopePower');
  powerSlider.style.top = '20px';
  document.body.appendChild(powerSlider);

  const angleSlider = createSlider('Angle', 0, 360, 0, 'kaleidoscopeAngle');
  angleSlider.style.top = '45px';
  document.body.appendChild(angleSlider);
};
imageObj.src = '/images/lion.png';

Open Sandbox

React

import { Stage, Layer, Image } from 'react-konva';
import { useState, useEffect } from 'react';

const App = () => {
  const [image, setImage] = useState(null);
  const [power, setPower] = useState(3);
  const [angle, setAngle] = useState(0);

  useEffect(() => {
    const imageObj = new Image();
    imageObj.onload = () => {
      setImage(imageObj);
    };
    imageObj.src = '/images/lion.png';
  }, []);

  const SliderControl = ({ label, value, onChange, min, max, step = 0.1 }) => (
    <div style={{ margin: '10px' }}>
      <label>{label}: </label>
      <input
        type="range"
        min={min}
        max={max}
        step={step}
        value={value}
        onChange={(e) => onChange(parseFloat(e.target.value))}
        style={{ width: '200px' }}
      />
    </div>
  );

  return (
    <>
      <div style={{ position: 'absolute', top: '20px', left: '20px' }}>
        <SliderControl
          label="Power"
          value={power}
          onChange={setPower}
          min={2}
          max={8}
          step={1}
        />
        <SliderControl
          label="Angle"
          value={angle}
          onChange={setAngle}
          min={0}
          max={360}
        />
      </div>
      <Stage width={window.innerWidth} height={window.innerHeight}>
        <Layer>
          {image && (
            <Image
              x={50}
              y={50}
              image={image}
              draggable
              filters={[Konva.Filters.Kaleidoscope]}
              kaleidoscopePower={power}
              kaleidoscopeAngle={angle}
            />
          )}
        </Layer>
      </Stage>
    </>
  );
};

export default App;

Open Sandbox

Vue

<template>
  <div>
    <div style="position: absolute; top: 20px; left: 20px">
      <div v-for="control in controls" :key="control.label" style="margin: 10px">
        <label>{{ control.label }}: </label>
        <input
          type="range"
          :min="control.min"
          :max="control.max"
          :step="control.step"
          :value="control.value"
          @input="(e) => updateValue(control.prop, parseFloat(e.target.value))"
          style="width: 200px"
        />
      </div>
    </div>
    <v-stage :config="stageSize">
      <v-layer>
        <v-image
          v-if="image"
          :config="{
            x: 50,
            y: 50,
            image: image,
            draggable: true,
            filters: [Konva.Filters.Kaleidoscope],
            kaleidoscopePower: kaleidoscopeValues.power,
            kaleidoscopeAngle: kaleidoscopeValues.angle,
          }"
        />
      </v-layer>
    </v-stage>
  </div>
</template>

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

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

const image = ref(null);
const kaleidoscopeValues = ref({
  power: 3,
  angle: 0,
});

const controls = computed(() => [
  { 
    label: 'Power',
    prop: 'power',
    min: 2,
    max: 8,
    step: 1,
    value: kaleidoscopeValues.value.power 
  },
  { 
    label: 'Angle',
    prop: 'angle',
    min: 0,
    max: 360,
    step: 0.1,
    value: kaleidoscopeValues.value.angle 
  },
]);

const updateValue = (prop, value) => {
  kaleidoscopeValues.value[prop] = value;
};

onMounted(() => {
  const imageObj = new Image();
  imageObj.onload = () => {
    image.value = imageObj;
  };
  imageObj.src = '/images/lion.png';
});
</script>

Open Sandbox