title: HTML5 Canvas Shape Resize With Ratio Preserved

How to resize shape with savings its proportion?

By default when you resize with corner anchors (top-left, top-right, bottom-left or bottom-right) Transformer will save ratio of a node.

You can set keepRatio to false if you don’t need that behavior.

Even if you set keepRatio to false you can hold SHIFT to still keep ratio.

Instructions: Try to resize texts.

Konva Shape transform and selection 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 Keep Ratio 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 text1 = new Konva.Text({
        x: 50,
        y: 70,
        fontSize: 30,
        text: 'keepRatio = true',
        draggable: true,
      });
      layer.add(text1);

      var tr1 = new Konva.Transformer({
        nodes: [text1],
        keepRatio: true,
        enabledAnchors: [
          'top-left',
          'top-right',
          'bottom-left',
          'bottom-right',
        ],
      });
      layer.add(tr1);

      var text2 = new Konva.Text({
        x: 50,
        y: 200,
        fontSize: 30,
        text: 'keepRatio = false',
        draggable: true,
      });
      layer.add(text2);

      var tr2 = new Konva.Transformer({
        nodes: [text2],
        keepRatio: false,
        enabledAnchors: [
          'top-left',
          'top-right',
          'bottom-left',
          'bottom-right',
        ],
      });
      layer.add(tr2);
    </script>
  </body>
</html>
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