HTML5 Canvas Transform and Resize events

Konva.Transformer object has special transform events that you can use in your app: transformstart, transform and transformend.

These events also will be triggered on attached node.

Instructions: Open console, try to transform, see logs

Transform Events Demoview raw

<!DOCTYPE html>
<html>
  <head>
    <!-- USE DEVELOPMENT VERSION -->
    <script src="https://unpkg.com/[email protected]/konva.min.js"></script>
    <meta charset="utf-8" />
    <title>Konva Transform Events 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 rect = new Konva.Rect({
        x: 160,
        y: 60,
        width: 100,
        height: 90,
        fill: 'red',
        name: 'rect',
        stroke: 'black',
        draggable: true,
      });
      layer.add(rect);

      var text = new Konva.Text({
        x: 5,
        y: 5,
      });
      layer.add(text);
      updateText();

      // create new transformer
      var tr = new Konva.Transformer();
      layer.add(tr);
      tr.nodes([rect]);

      rect.on('transformstart', function () {
        console.log('transform start');
      });

      rect.on('dragmove', function () {
        updateText();
      });
      rect.on('transform', function () {
        updateText();
        console.log('transform');
      });

      rect.on('transformend', function () {
        console.log('transform end');
      });

      function updateText() {
        var lines = [
          'x: ' + rect.x(),
          'y: ' + rect.y(),
          'rotation: ' + rect.rotation(),
          'width: ' + rect.width(),
          'height: ' + rect.height(),
          'scaleX: ' + rect.scaleX(),
          'scaleY: ' + rect.scaleY(),
        ];
        text.text(lines.join('\n'));
      }
    </script>
  </body>
</html>

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