How to automatically scroll stage by edge drag?

If you’re looking to enhance your Konva.js application’s user experience, implementing an auto-scroll feature is a great way to go. This functionality is especially useful in interactive UIs where users need to drag items or navigate large canvases. By enabling the scroll to automatically move when a user drags an item to the bottom or right edge of the viewport, you create a smoother and more intuitive interaction.

Instructions: Start dragging of any shape. Drag it near corder of the stage. Stage will start scrolling.

Scroll By Edge Drag Demoview raw
<!DOCTYPE html>
<html>
<head>
<script src="https://unpkg.com/[email protected]/konva.min.js"></script>
<meta charset="utf-8" />
<title>Konva Canvas Scrolling Drag Demo</title>
<style>
body {
margin: 0;
padding: 0;
overflow: hidden;
background-color: #f0f0f0;
}
</style>
</head>

<body>
<div id="container"></div>
<script>
var width = window.innerWidth;
var height = window.innerHeight;

var stage = new Konva.Stage({
container: 'container',
width: width,
height: height,
});

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

var NUMBER = 100;

function generateNode() {
return new Konva.Circle({
x: width * (Math.random() * 2 - 1),
y: height * (Math.random() * 2 - 1),
radius: 40,
fill: 'red',
stroke: 'black',
draggable: true,
});
}

for (var i = 0; i < NUMBER; i++) {
layer.add(generateNode());
}

let scrollInterval = null;

stage.on('dragstart', (e) => {
const duration = 1000 / 60;
scrollInterval = setInterval(() => {
const pos = stage.getPointerPosition();
const offset = 100;
const isNearLeft = pos.x < offset;
if (isNearLeft) {
stage.x(stage.x() + 2);
e.target.x(e.target.x() - 2);
}
const isNearRight = pos.x > stage.width() - offset;
if (isNearRight) {
stage.x(stage.x() - 2);
e.target.x(e.target.x() + 2);
}
const isNearTop = pos.y < offset;
if (isNearTop) {
stage.y(stage.y() + 2);
e.target.y(e.target.y() - 2);
}
const isNearBottom = pos.y > stage.height() - offset;
if (isNearBottom) {
stage.y(stage.y() - 2);
e.target.y(e.target.y() + 2);
}
}, duration);
});
stage.on('dragend', () => {
clearInterval(scrollInterval);
});
</script>
</body>
</html>
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