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How to find the height of a text in HTML canvas using JavaScript ?
  • Difficulty Level : Medium
  • Last Updated : 25 Dec, 2020

In this article, we will find the height of the text canvas using JavaScript.

Approach: In the following example, the height attribute of the HTML canvas is used. First set the font in pt to set the height.

context.font = '26pt Calibri';

Then the current text is aligned in the center by using values ‘middle’ and color ‘yellow’.

context.textAlign = 'middle';
context.fillStyle = 'yellow';

Then, check the width of the text using the measureText() method before writing to the canvas. Finally, the text is written on the canvas using the fillText() method.

Example 1:

HTML






<!DOCTYPE HTML>
<html>
  
<head>
    <style>
        body {
            margin: 0px;
            padding: 0px;
        }
    </style>
</head>
  
<body>
    <canvas id="myCanvas" width="550" height="200">
    </canvas>
    <script>
        var canvas = document.getElementById('myCanvas');
        var context = canvas.getContext('2d');
        var x = canvas.width / 3;
        var y = canvas.height / 2 - 15;
        var text = 'HI ';
  
        // Set the font to set the height
        context.font = '26pt Calibri';
        context.textAlign = 'middle';
        context.fillStyle = 'yellow';
        context.fillText(text, x, y);
        context.font = '20pt Calibri';
  
        // Check the width of the text 
        var metrics = context.measureText(text);
        var width = metrics.width;
  
        // Text is aligned in the left      
        context.textAlign = 'left';
        context.fillStyle = '#010';
          
        context.fillText('(' + width 
            + 'px wide)', x, y + 40);
    </script>
</body>
  
</html>


Output:

Approach: First get the 2d drawing context of the canvas by using getContext() method. Set the font and the text string. Then write the text with x and y co-ordinates using fillText() method as given below.

Example 2:

HTML




<!DOCTYPE html>
<html>
  
<body>
    <canvas id="Canvas" width="300" height="150" 
        style="border:1px solid #010;">
        Your browser isn't supporting 
        HTML5 canvas tag.
    </canvas>
  
    <script>
        var c = document.getElementById("Canvas");
        var x = c.getContext("2d");
        x.font = "30px Arial";
        var txt = "Computer Science"
        x.fillText("width:" 
            + x.measureText(txt).width, 10, 50);
        x.fillText(txt, 10, 100);
    </script>
</body>
  
</html>


Output:




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