JS框架_(JQuery.js)模拟刮奖

百度云盘：传送门　　密码：6p5q

纯CSS模拟刮奖效果

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<style>
        *{
            margin: 0;
            padding: 0;
        }    
        
        p {
          position: fixed;
          top: 60%;
          left: 0;
          right: 0;
          text-align: center;
          transform: translateY(-50%);
          font-size: 40px;
          font-weight: 900;
          color: white;
          text-shadow: 0 0 50px black;
          text-transform: capitalize;
          font-family: 'Roboto','Helvetica','Arial',sans-serif;
          letter-spacing: 5px;
        }
        
        .box{
            margin: 80px;
            position: relative;
            width: 300px;
            height: 180px;
            left: 460px;
        }
        #canvas{
            position: absolute;
            top: 0;
            left: 0;
            z-index: 5;
        }
        .bk{
            width: 300px;
            height: 180px;
            background: #fff;
            position: absolute;
            top: 0;
            left: 0;
            text-align: center;
            line-height: 180px;
        }
        #freshBtn{
            margin-left: 660px;
            user-select: none;
            background: #ddd;
            width: 80px;
            height: 40px;
            text-align: center;
            line-height: 40px;
        }
    </style>
<body>
<p>Gary</p>
    <div class="box">
        <div class="bk">
            一等奖
        </div>
        <canvas id="canvas"></canvas>
    </div>
    <div id="freshBtn">重置</div>
</body>
<script src="./js/canvas.js"></script>
<script>
    var canvas = new canvasInit({
        id: 'canvas',
        text: '刮开抽奖',
        cover: '#1f1f1f',
        coverType: 'color',
         300,
        height: 180,
        drawPercentCallback: (num) => {
            if(num > 30) {
                alert('恭喜获得一等奖')
                canvas.fresh() // 重置
            }
        }
    })
</script>
</html>

index.html

class canvasClass {
    constructor (id,text,cover,coverType,width,height,drawPercentCallback) {
        this.conId = id; /*canvasID */
        this.conNode = document.getElementById(this.conId);
        this.ctx = this.conNode.getContext('2d');
        this.coverText = text;
        this.cover = cover; /**图层颜色或图片 */
        this.coverType = coverType; /**图层类型（image/color） */
        this.width = width;
        this.height = height;
        this.drawPercentCallback = drawPercentCallback
        this.clientRect = null;
        this.isMouseDown = false;
    }
    /**
     * 绘制canvas
     */
    fillCanvas () {
        this.conNode.setAttribute('width', this.width);
        this.conNode.setAttribute('height', this.height);
        if (this.coverType == 'color') {
            this.ctx.save();
            this.ctx.fillStyle = this.cover;
            this.ctx.fillRect(0, 0, this.width, this.height);
            this.ctx.restore();
            this.ctx.save();
            var fontSize = 30;
            this.ctx.font = '30px Arial';
            this.ctx.textAlign = 'center';
            this.ctx.fillStyle = '#fff';
            this.ctx.fillText(this.coverText, this.width/2, this.height/2+fontSize/2);
            this.ctx.restore();
            this.ctx.globalCompositeOperation = 'destination-out';
        } else if (this.coverType == 'image') {
            var image = new Image(this.width, this.height)
            image.onload = () => {
                this.ctx.drawImage(image, 0, 0, this.width, this.height);
            }
            image.src = this.cover;
        }
        this.clientRect = this.conNode ? this.conNode.getBoundingClientRect() : null
    }
    /**
     * 事件监听
     */
    bindEvent () {
        /**移动端检测 */
        var device = (/android|webos|iphone|ipad|ipod|blackberry|iemobile|opera mini/i.test(navigator.userAgent.toLowerCase()));
        var clickEvt = device ? 'touchstart' : 'mousedown';
        var moveEvt = device ? 'touchmove' : 'mousemove';
        var x1,y1,x2,y2;
        
        if (!device) {
            document.addEventListener('mouseup', (e) => {
                this.isMouseDown = false;
            })
        } else {
            document.addEventListener("touchmove", (e) => {
                if (this.isMouseDown) {
                    e.preventDefault();
                }
            })
            document.addEventListener("touchend", (e) => {
                this.isMouseDown = false;
            })
        }
        /**添加监听 */
        this.conNode.addEventListener(clickEvt, (e) => {
            this.isMouseDown = true;
            x1 = device ? e.touches[0].offsetX : e.offsetX;
            y1 = device ? e.touches[0].offsetY : e.offsetY;
            this.drawPoint(x1, y1)
        })
        this.conNode.addEventListener(moveEvt, (e) => {
            if (!device && !this.isMouseDown) {
                return false;
            }
            this.isMouseDown = true;
            x2 = device ? e.touches[0].offsetX : e.offsetX;
            y2 = device ? e.touches[0].offsetY : e.offsetY;
            this.drawPoint(x1, y1, x2, y2)
            // console.log(x1,x2,y1,y2)
            x1 = x2
            y1 = y2
            // [x1, y1] = [x2, y2]
        })
    }
    /**
     * 抹去， 返回百分比
     */
    drawPoint (x1, y1, x2, y2) {
        var bar = 20; // 半径
        this.ctx.beginPath();
        if (x2) {
            /**
             * 优化绘制路径
             */
            var asin = bar*Math.sin(Math.atan((y2-y1)/(x2-x1)));
            var acos = bar*Math.cos(Math.atan((y2-y1)/(x2-x1)))
            var x3 = x1+asin;
            var y3 = y1-acos;
            var x4 = x1-asin;
            var y4 = y1+acos;
            var x5 = x2+asin;
            var y5 = y2-acos;
            var x6 = x2-asin;
            var y6 = y2+acos;
            this.ctx.save();
            this.ctx.beginPath();
            this.ctx.moveTo(x3,y3);
            this.ctx.lineTo(x5,y5);
            this.ctx.lineTo(x6,y6);
            this.ctx.lineTo(x4,y4);
            this.ctx.closePath();
            this.ctx.clip();
            this.ctx.clearRect(0,0,this.width,this.height);
            this.ctx.restore();
            this.ctx.arc(x2, y2, bar, 0, Math.PI*2, true);
        } else {
            this.ctx.arc(x1, y1, bar, 0, Math.PI*2, true);
        }
        this.ctx.fill();
        if (this.drawPercentCallback) {
            this.drawPercentCallback(this.getTransparentPercent());
        }
    }

    getTransparentPercent () {
        var imgData = this.ctx.getImageData(0, 0, this.width, this.height),
            pixles = imgData.data,
            transPixs = [];
        for (var i = 0, j = pixles.length; i < j; i += 4) {
            var a = pixles[i + 3];
            if (a < 128) {
                transPixs.push(i);
            }
        }
        return (transPixs.length / (pixles.length / 4) * 100).toFixed(2);
    }

}

function canvasInit(json) {
    var arr = []
    for (let item in json) {
        arr.push(json[item])
    }
    this.init = new canvasClass(...arr)
    this.init.fillCanvas()
    this.init.bindEvent()

    var btn = document.querySelector('#freshBtn');
    btn.addEventListener('click', (e) => {
        this.init.fillCanvas()
    });

}

canvasInit.prototype.fresh = function () {
    console.log(this.init)
    this.init.fillCanvas()
    this.init.isMouseDown = false
}

canvas.css

（直接复制就可以使用了O(∩_∩)O~ 　　ES6编写）

=>是es6语法中的arrow function(箭头函数)
举例：
　　(x) => x + 6

　　相当于

　　function(x){
　　return x + 6;
　　}

实现过程

CSS

画板.class

class canvasClass {
    constructor (id,text,cover,coverType,width,height,drawPercentCallback) {
        this.conId = id; /*canvasID */
        this.conNode = document.getElementById(this.conId);
        this.ctx = this.conNode.getContext('2d');
        this.coverText = text;
        this.cover = cover; /**图层颜色或图片 */
        this.coverType = coverType; /**图层类型（image/color） */
        this.width = width;
        this.height = height;
        this.drawPercentCallback = drawPercentCallback
        this.clientRect = null;
        this.isMouseDown = false;
    }
    /**
     * 绘制canvas
     */
    fillCanvas () {
        this.conNode.setAttribute('width', this.width);
        this.conNode.setAttribute('height', this.height);
        if (this.coverType == 'color') {
            this.ctx.save();
            this.ctx.fillStyle = this.cover;
            this.ctx.fillRect(0, 0, this.width, this.height);
            this.ctx.restore();
            this.ctx.save();
            var fontSize = 30;
            this.ctx.font = '30px Arial';
            this.ctx.textAlign = 'center';
            this.ctx.fillStyle = '#fff';
            this.ctx.fillText(this.coverText, this.width/2, this.height/2+fontSize/2);
            this.ctx.restore();
            this.ctx.globalCompositeOperation = 'destination-out';
        } else if (this.coverType == 'image') {
            var image = new Image(this.width, this.height)
            image.onload = () => {
                this.ctx.drawImage(image, 0, 0, this.width, this.height);
            }
            image.src = this.cover;
        }
        this.clientRect = this.conNode ? this.conNode.getBoundingClientRect() : null
    }
    /**
     * 事件监听
     */
    bindEvent () {
        /**移动端检测 */
        var device = (/android|webos|iphone|ipad|ipod|blackberry|iemobile|opera mini/i.test(navigator.userAgent.toLowerCase()));
        var clickEvt = device ? 'touchstart' : 'mousedown';
        var moveEvt = device ? 'touchmove' : 'mousemove';
        var x1,y1,x2,y2;
        
        if (!device) {
            document.addEventListener('mouseup', (e) => {
                this.isMouseDown = false;
            })
        } else {
            document.addEventListener("touchmove", (e) => {
                if (this.isMouseDown) {
                    e.preventDefault();
                }
            })
            document.addEventListener("touchend", (e) => {
                this.isMouseDown = false;
            })
        }
        /**添加监听 */
        this.conNode.addEventListener(clickEvt, (e) => {
            this.isMouseDown = true;
            x1 = device ? e.touches[0].offsetX : e.offsetX;
            y1 = device ? e.touches[0].offsetY : e.offsetY;
            this.drawPoint(x1, y1)
        })
        this.conNode.addEventListener(moveEvt, (e) => {
            if (!device && !this.isMouseDown) {
                return false;
            }
            this.isMouseDown = true;
            x2 = device ? e.touches[0].offsetX : e.offsetX;
            y2 = device ? e.touches[0].offsetY : e.offsetY;
            this.drawPoint(x1, y1, x2, y2)
            // console.log(x1,x2,y1,y2)
            x1 = x2
            y1 = y2
            // [x1, y1] = [x2, y2]
        })
    }
    /**
     * 抹去， 返回百分比
     */
    drawPoint (x1, y1, x2, y2) {
        var bar = 20; // 半径
        this.ctx.beginPath();
        if (x2) {
            /**
             * 优化绘制路径
             */
            var asin = bar*Math.sin(Math.atan((y2-y1)/(x2-x1)));
            var acos = bar*Math.cos(Math.atan((y2-y1)/(x2-x1)))
            var x3 = x1+asin;
            var y3 = y1-acos;
            var x4 = x1-asin;
            var y4 = y1+acos;
            var x5 = x2+asin;
            var y5 = y2-acos;
            var x6 = x2-asin;
            var y6 = y2+acos;
            this.ctx.save();
            this.ctx.beginPath();
            this.ctx.moveTo(x3,y3);
            this.ctx.lineTo(x5,y5);
            this.ctx.lineTo(x6,y6);
            this.ctx.lineTo(x4,y4);
            this.ctx.closePath();
            this.ctx.clip();
            this.ctx.clearRect(0,0,this.width,this.height);
            this.ctx.restore();
            this.ctx.arc(x2, y2, bar, 0, Math.PI*2, true);
        } else {
            this.ctx.arc(x1, y1, bar, 0, Math.PI*2, true);
        }
        this.ctx.fill();
        if (this.drawPercentCallback) {
            this.drawPercentCallback(this.getTransparentPercent());
        }
    }

    getTransparentPercent () {
        var imgData = this.ctx.getImageData(0, 0, this.width, this.height),
            pixles = imgData.data,
            transPixs = [];
        for (var i = 0, j = pixles.length; i < j; i += 4) {
            var a = pixles[i + 3];
            if (a < 128) {
                transPixs.push(i);
            }
        }
        return (transPixs.length / (pixles.length / 4) * 100).toFixed(2);
    }

}

class canvasClass

　　1、绘制canvas画布

　　2、添加事件监听　

　　3、刮奖效果

　　　　　构造函数省略...

　　1、绘制canvas画布

    fillCanvas () {
        this.conNode.setAttribute('width', this.width);
        this.conNode.setAttribute('height', this.height);
        if (this.coverType == 'color') {
            this.ctx.save();
            this.ctx.fillStyle = this.cover;
            this.ctx.fillRect(0, 0, this.width, this.height);
            this.ctx.restore();
            this.ctx.save();
            var fontSize = 30;
            this.ctx.font = '30px Arial';
            this.ctx.textAlign = 'center';
            this.ctx.fillStyle = '#fff';
            this.ctx.fillText(this.coverText, this.width/2, this.height/2+fontSize/2);
            this.ctx.restore();
            this.ctx.globalCompositeOperation = 'destination-out';
        } else if (this.coverType == 'image') {
            var image = new Image(this.width, this.height)
            image.onload = () => {
                this.ctx.drawImage(image, 0, 0, this.width, this.height);
            }
            image.src = this.cover;
        }
        this.clientRect = this.conNode ? this.conNode.getBoundingClientRect() : null
    }

　　2、添加事件监听

 bindEvent () {
        /**移动端检测 */
        var device = (/android|webos|iphone|ipad|ipod|blackberry|iemobile|opera mini/i.test(navigator.userAgent.toLowerCase()));
        var clickEvt = device ? 'touchstart' : 'mousedown';
        var moveEvt = device ? 'touchmove' : 'mousemove';
        var x1,y1,x2,y2;
        
        if (!device) {
            document.addEventListener('mouseup', (e) => {
                this.isMouseDown = false;
            })
        } else {
            document.addEventListener("touchmove", (e) => {
                if (this.isMouseDown) {
                    e.preventDefault();
                }
            })
            document.addEventListener("touchend", (e) => {
                this.isMouseDown = false;
            })
        }
        /**添加监听 */
        this.conNode.addEventListener(clickEvt, (e) => {
            this.isMouseDown = true;
            x1 = device ? e.touches[0].offsetX : e.offsetX;
            y1 = device ? e.touches[0].offsetY : e.offsetY;
            this.drawPoint(x1, y1)
        })
        this.conNode.addEventListener(moveEvt, (e) => {
            if (!device && !this.isMouseDown) {
                return false;
            }
            this.isMouseDown = true;
            x2 = device ? e.touches[0].offsetX : e.offsetX;
            y2 = device ? e.touches[0].offsetY : e.offsetY;
            this.drawPoint(x1, y1, x2, y2)
            // console.log(x1,x2,y1,y2)
            x1 = x2
            y1 = y2
            // [x1, y1] = [x2, y2]
        })
    }

　　3、刮奖效果

    drawPoint (x1, y1, x2, y2) {
        var bar = 20; // 半径
        this.ctx.beginPath();
        if (x2) {
            /**
             * 优化绘制路径
             */
            var asin = bar*Math.sin(Math.atan((y2-y1)/(x2-x1)));
            var acos = bar*Math.cos(Math.atan((y2-y1)/(x2-x1)))
            var x3 = x1+asin;
            var y3 = y1-acos;
            var x4 = x1-asin;
            var y4 = y1+acos;
            var x5 = x2+asin;
            var y5 = y2-acos;
            var x6 = x2-asin;
            var y6 = y2+acos;
            this.ctx.save();
            this.ctx.beginPath();
            this.ctx.moveTo(x3,y3);
            this.ctx.lineTo(x5,y5);
            this.ctx.lineTo(x6,y6);
            this.ctx.lineTo(x4,y4);
            this.ctx.closePath();
            this.ctx.clip();
            this.ctx.clearRect(0,0,this.width,this.height);
            this.ctx.restore();
            this.ctx.arc(x2, y2, bar, 0, Math.PI*2, true);
        } else {
            this.ctx.arc(x1, y1, bar, 0, Math.PI*2, true);
        }
        this.ctx.fill();
        if (this.drawPercentCallback) {
            this.drawPercentCallback(this.getTransparentPercent());
        }
    }

初始化canvas.class画布

function canvasInit(json) {
    var arr = []
    for (let item in json) {
        arr.push(json[item])
    }
    this.init = new canvasClass(...arr)
    this.init.fillCanvas()
    this.init.bindEvent()

    var btn = document.querySelector('#freshBtn');
    btn.addEventListener('click', (e) => {
        this.init.fillCanvas()
    });

}

按钮

        #freshBtn{
            margin-left: 660px;
            user-select: none;
            background: #ddd;
             80px;
            height: 40px;
            text-align: center;
            line-height: 40px;
        }

刮奖区域

        .box{
            margin: 80px;
            position: relative;
             300px;
            height: 180px;
            left: 460px;
        }

DOM

设置文档内容和显示文本

    <div class="box">
        <div class="bk">
            一等奖
        </div>
        <canvas id="canvas"></canvas>
    </div>
    <div id="freshBtn">重置</div>

　　模拟抽奖效果时bk中文字可以用随机

给canvas.class画布传参

<script>
    var canvas = new canvasInit({
        id: 'canvas',
        text: '刮开抽奖',
        cover: '#1f1f1f',
        coverType: 'color',
         300,
        height: 180,
        drawPercentCallback: (num) => {
            if(num > 30) {
                alert('恭喜获得一等奖')
                canvas.fresh() // 重置
            }
        }
    })
</script>

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原文地址：https://www.cnblogs.com/1138720556Gary/p/9418340.html