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 filter() 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 control to adjust the kaleidoscope angle.

For all available filters go to Filters Documentation.

Konva Kaleidoscope Image Demoview raw
<!DOCTYPE html>
<html>
<head>
<script src="https://cdn.rawgit.com/konvajs/konva/1.6.2/konva.min.js"></script>
<meta charset="utf-8">
<title>Konva Kaleidoscope Image Demo</title>
<style>
body {
margin: 0;
padding: 0;
overflow: hidden;
background-color: #F0F0F0;
}
#slider {
position: absolute;
top: 20px;
left: 20px;
}
</style>
</head>
<body>
<div id="container"></div>
<input id="slider" type="range" min="0" max="360" step="5" value="20">
<script>
function loadImages(sources, callback) {
var images = {};
var loadedImages = 0;
var numImages = 0;
for(var src in sources) {
numImages++;
}
for(var src in sources) {
images[src] = new Image();
images[src].onload = function() {
if(++loadedImages >= numImages) {
callback(images);
}
};
images[src].src = sources[src];
}
}
function buildStage(images) {
var stage = new Konva.Stage({
container: 'container',
width: 300,
height: 200
});
var layer = new Konva.Layer();
var lion = new Konva.Image({
image: images.lion,
x: 80,
y: 30,
draggable: true
});
lion.cache();
lion.filters([Konva.Filters.Kaleidoscope]);
lion.kaleidoscopePower(3);
layer.add(lion);
stage.add(layer);
var slider = document.getElementById('slider');
slider.onchange = function() {
lion.kaleidoscopeAngle(slider.value);
layer.batchDraw();
};
}
var sources = {
lion: '/assets/lion.png'
};
loadImages(sources, buildStage);
</script>
</body>
</html>