HTML5 Canvas Konva Rotation Animation tutorial

To animate a shape’s rotation with Konva, we can create a new animation with
Konva.Animation, and define a function which modifies the shape’s rotation with each animation frame.

In this tutorial, we’ll rotate a blue rectangle about the top left corner,
a yellow rectangle about its center, and a red rectangle about an outside point.

For a full list of attributes and methods, check out the Konva.Animation documentation.

Konva Rotation Animation Demoview raw

<!DOCTYPE html>
<html>
  <head>
    <script src="https://unpkg.com/[email protected]/konva.min.js"></script>
    <meta charset="utf-8" />
    <title>Konva Rotation Animation 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();

      /*
       * leave center point positioned
       * at the default which is the top left
       * corner of the rectangle
       */

      var blueRect = new Konva.Rect({
        x: 50,
        y: 75,
        width: 100,
        height: 50,
        fill: '#00D2FF',
        stroke: 'black',
        strokeWidth: 4
      });

      /*
       * move center point to the center
       * of the rectangle with offset
       */
      var yellowRect = new Konva.Rect({
        x: 220,
        y: 75,
        width: 100,
        height: 50,
        fill: 'yellow',
        stroke: 'black',
        strokeWidth: 4,
        offset: {
          x: 50,
          y: 25
        }
      });

      /*
       * move center point outside of the rectangle
       * with offset
       */

      var redRect = new Konva.Rect({
        x: 400,
        y: 75,
        width: 100,
        height: 50,
        fill: 'red',
        stroke: 'black',
        strokeWidth: 4,
        offset: {
          x: -100,
          y: 0
        }
      });

      layer.add(blueRect);
      layer.add(yellowRect);
      layer.add(redRect);
      stage.add(layer);

      // one revolution per 4 seconds
      var angularSpeed = 90;
      var anim = new Konva.Animation(function(frame) {
        var angleDiff = (frame.timeDiff * angularSpeed) / 1000;
        blueRect.rotate(angleDiff);
        yellowRect.rotate(angleDiff);
        redRect.rotate(angleDiff);
      }, layer);

      anim.start();
    </script>
  </body>
</html>