HTML5 Canvas Canvas Multi-Event Binding Tutorial

To bind multiple events to a single handler with Konva, we can use the on() method and pass in a space delimited string containing multiple event types.

shape.on('mouseover mousedown mouseup', function (e) {
  console.log('events: ' + e.type);
});

Instructions: Mouseover, mousedown, and mouseup over the circle to observe that the function bound to the circle is executed for each event.

Konva Multi_Event Demoview raw

<!DOCTYPE html>
<html>
  <head>
    <script src="https://unpkg.com/[email protected]/konva.min.js"></script>
    <meta charset="utf-8" />
    <title>Konva Multi-Event Binding 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 text = new Konva.Text({
        x: 10,
        y: 10,
        fontFamily: 'Calibri',
        fontSize: 20,
        text: '',
        fill: 'black',
      });

      var numEvents = 0;

      var circle = new Konva.Circle({
        x: stage.width() / 2,
        y: stage.height() / 2 + 10,
        radius: 70,
        fill: 'red',
        stroke: 'black',
        strokeWidth: 4,
      });

      circle.on('mouseover mousedown mouseup', function () {
        writeMessage('Multi-event binding!  Events: ' + ++numEvents);
      });
      circle.on('mouseout', function () {
        writeMessage('');
      });

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

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

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