Today, We will learn how to create scratch cards using jquery. We will show an example of the Jquery scratch card. I will make a canvas using create a scratch card.


Example

<html>
    <head>
        <title>Jquery Scratch card Example Tutorial</title>
        <style>
            body {
                padding: 20px 0;
            }

            .container {
                position: relative;
                width: 300px;
                height: 300px;
                margin: 0 auto;
                -webkit-user-select: none;
                -moz-user-select: none;
                -ms-user-select: none; 
                -o-user-select: none;
                user-select: none;
                border:2px solid #f5f5f5;
               
            }

            .canvas {
                position: absolute;
                top: 0;
            }
            h2,h1{
                text-align: center;
            }
            .form {
                padding: 20px;
            }
            img{
                width: 150px;
            }
        </style>
    </head>
    <body>
     
        <h1>Jquery Scratch Card Example</h1>
        <div class="container" id="js-container">
            <canvas class="canvas" id="js-canvas" width="300" height="300"></canvas>
            <form class="form" style="visibility: hidden;">
                <h2>Hurray you won</h2>
                <h1 ><code>$200</code></h1>
                  <img src="gift-removebg-preview.png" alt=""/>
                </div>
            </form>  
          
        </div>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.min.js" integrity="sha512-bLT0Qm9VnAYZDflyKcBaQ2gg0hSYNQrJ8RilYldYQ1FxQYoCLtUjuuRuZo+fjqhx/qtq/1itJ0C2ejDxltZVFg==" crossorigin="anonymous"></script>
        <script>
            (function () {

                'use strict';

                var isDrawing, lastPoint;
                var container = document.getElementById('js-container'),
                        canvas = document.getElementById('js-canvas'),
                        canvasWidth = canvas.width,
                        canvasHeight = canvas.height,
                        ctx = canvas.getContext('2d'),
                        image = new Image(),
                        brush = new Image();

                // base64 Workaround because Same-Origin-Policy
                image.src = 'bg.png';
                image.onload = function () {
                    ctx.drawImage(image, 0, 0);
                    // Show the form when Image is loaded.
                    document.querySelectorAll('.form')[0].style.visibility = 'visible';
                };
                brush.src = 'scractch.png';

                canvas.addEventListener('mousedown', handleMouseDown, false);
                canvas.addEventListener('touchstart', handleMouseDown, false);
                canvas.addEventListener('mousemove', handleMouseMove, false);
                canvas.addEventListener('touchmove', handleMouseMove, false);
                canvas.addEventListener('mouseup', handleMouseUp, false);
                canvas.addEventListener('touchend', handleMouseUp, false);

                function distanceBetween(point1, point2) {
                    return Math.sqrt(Math.pow(point2.x - point1.x, 2) + Math.pow(point2.y - point1.y, 2));
                }

                function angleBetween(point1, point2) {
                    return Math.atan2(point2.x - point1.x, point2.y - point1.y);
                }

                // Only test every `stride` pixel. `stride`x faster,
                // but might lead to inaccuracy
                function getFilledInPixels(stride) {
                    if (!stride || stride < 1) {
                        stride = 1;
                    }

                    var pixels = ctx.getImageData(0, 0, canvasWidth, canvasHeight),
                            pdata = pixels.data,
                            l = pdata.length,
                            total = (l / stride),
                            count = 0;

                    // Iterate over all pixels
                    for (var i = count = 0; i < l; i += stride) {
                        if (parseInt(pdata[i]) === 0) {
                            count++;
                        }
                    }

                    return Math.round((count / total) * 100);
                }

                function getMouse(e, canvas) {
                    var offsetX = 0, offsetY = 0, mx, my;

                    if (canvas.offsetParent !== undefined) {
                        do {
                            offsetX += canvas.offsetLeft;
                            offsetY += canvas.offsetTop;
                        } while ((canvas = canvas.offsetParent));
                    }

                    mx = (e.pageX || e.touches[0].clientX) - offsetX;
                    my = (e.pageY || e.touches[0].clientY) - offsetY;

                    return {x: mx, y: my};
                }

                function handlePercentage(filledInPixels) {
                    filledInPixels = filledInPixels || 0;
                    console.log(filledInPixels + '%');
                    if (filledInPixels > 50) {
                        canvas.parentNode.removeChild(canvas);
                    }
                }

                function handleMouseDown(e) {
                    isDrawing = true;
                    lastPoint = getMouse(e, canvas);
                }

                function handleMouseMove(e) {
                    if (!isDrawing) {
                        return;
                    }

                    e.preventDefault();

                    var currentPoint = getMouse(e, canvas),
                            dist = distanceBetween(lastPoint, currentPoint),
                            angle = angleBetween(lastPoint, currentPoint),
                            x, y;

                    for (var i = 0; i < dist; i++) {
                        x = lastPoint.x + (Math.sin(angle) * i) - 25;
                        y = lastPoint.y + (Math.cos(angle) * i) - 25;
                        ctx.globalCompositeOperation = 'destination-out';
                        ctx.drawImage(brush, x, y);
                    }

                    lastPoint = currentPoint;
                    handlePercentage(getFilledInPixels(32));
                }

                function handleMouseUp(e) {
                    isDrawing = false;
                }

            })();
        </script>
    </body>
</html>


Output:







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