Canvas How to - Translate context to center of canvas

Question

We would like to know how to translate context to center of canvas.

Answer


<!--from   www.j a v a 2s .c  om-->
<html>
    <head>
        <script>
            window.onload = function(){
                var canvas = document.getElementById("myCanvas");
                var context = canvas.getContext("2d");
                
                var rectWidth = 150;
                var rectHeight = 75;
                
                // translate context to center of canvas
                context.translate(canvas.width / 2, canvas.height / 2);
                
                context.fillStyle = "blue";
                context.fillRect(-rectWidth / 2, -rectHeight / 2, rectWidth, rectHeight);
            }; 
        </script>
    </head>
    <body>
        <canvas id="myCanvas" width="600" height="250" style="border:1px solid black;">
        </canvas>
    </body>
</html>

The code above is rendered as follows: