Canvas How to - Shear matrix

Question

We would like to know how to shear matrix.
Answer


<html>
    <head>
        <script>   
            window.onload = function(){<!--from   w  w w . j a  v a2  s. c  om-->
                var canvas = document.getElementById("myCanvas");
                var context = canvas.getContext("2d");
                
                var rectWidth = 150;
                var rectHeight = 75;
                
                // shear matrix:
                //  1  sx  0              
                //  sy  1  0
                //  0  0  1  
                
                var sx = 0.75; // 0.75 horizontal shear
                var sy = 0; // no vertical shear
                // translate context to center of canvas
                context.translate(canvas.width / 2, canvas.height / 2);
                
                // apply custom transform
                context.transform(1, sy, sx, 1, 0, 0);
                
                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: