HTML5 Canvas Mobile Touch Events Tutorial

To bind event handlers to shapes on a mobile device with Konva, we can use the on() method.
The on() method requires an event type and a function to be executed when the event occurs.
Konva supports touchstart, touchmove, touchend, tap, dbltap, dragstart, dragmove, and dragend mobile events.

For more complex gestures like rotate take a look into Gestures Demo.

If you are looking for pan and zoom logic for the whole stage take a look into Multi-touch scale Stage demo.

Note: This example only works on mobile devices because it makes use of touch events rather than mouse events.

Instructions: move your finger across the triangle to see touch coordinates and touch start and touch end the circle.

Konva Mobile_Events Demoview raw

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

  <body>
    <div id="container"></div>
    <script>
      function writeMessage(message) {
        text.text(message);
      }

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

      var layer = new Konva.Layer();

      var triangle = new Konva.RegularPolygon({
        x: 80,
        y: 120,
        sides: 3,
        radius: 80,
        fill: '#00D2FF',
        stroke: 'black',
        strokeWidth: 4,
      });

      var text = new Konva.Text({
        x: 10,
        y: 10,
        fontFamily: 'Calibri',
        fontSize: 24,
        text: '',
        fill: 'black',
      });

      var circle = new Konva.Circle({
        x: 230,
        y: 100,
        radius: 60,
        fill: 'red',
        stroke: 'black',
        strokeWidth: 4,
      });

      triangle.on('touchmove', function () {
        var touchPos = stage.getPointerPosition();
        var x = touchPos.x - 190;
        var y = touchPos.y - 40;
        writeMessage('x: ' + x + ', y: ' + y);
      });

      circle.on('touchstart', function () {
        writeMessage('Touchstart circle');
      });
      circle.on('touchend', function () {
        writeMessage('Touchend circle');
      });

      layer.add(triangle);
      layer.add(circle);
      layer.add(text);

      // add the layer to the stage
      stage.add(layer);
    </script>
  </body>
</html>

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