html5 canvas 刮刮卡问题
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发布时间：2022-04-29 17:07
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时间：2022-04-20 00:41
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title> - jsFiddle demo by artwl</title>
<script type='text/javascript' src='/js/lib/mmy.js'></script>
<link rel="stylesheet" type="text/css" href="/css/result-light.css">
<style type='text/css'>
body{
height:1000px;
}
#lotteryContainer {
position:relative;
width: 300px;
height:100px;
}
#drawPercent {
color:#F60;
}
</style>
</head>
<body>
<button id="freshBtn">刷新</button><label>已刮开 <span id="drawPercent">0%</span> 区域。</label>
<div id="lotteryContainer"></div>
<script type='text/javascript'>//<![CDATA[
function Lottery(id, cover, coverType, width, height, drawPercentCallback) {
this.conId = id;
this.conNode = document.getElementById(this.conId);
this.cover = cover;
this.coverType = coverType;
this.background = null;
this.backCtx = null;
this.mask = null;
this.maskCtx = null;
this.lottery = null;
this.lotteryType = 'image';
this.width = width || 300;
this.height = height || 100;
this.clientRect = null;
this.drawPercentCallback = drawPercentCallback;
}
Lottery.prototype = {
createElement: function (tagName, attributes) {
var ele = document.createElement(tagName);
for (var key in attributes) {
ele.setAttribute(key, attributes[key]);
}
return ele;
},
getTransparentPercent: function(ctx, width, height) {
var imgData = ctx.getImageData(0, 0, width, 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);
},
resizeCanvas: function (canvas, width, height) {
canvas.width = width;
canvas.height = height;
canvas.getContext('2d').clearRect(0, 0, width, height);
},
drawPoint: function (x, y) {
this.maskCtx.beginPath();
var radgrad = this.maskCtx.createRadialGradient(x, y, 0, x, y, 30);
radgrad.addColorStop(0, 'rgba(0,0,0,0.6)');
radgrad.addColorStop(1, 'rgba(255, 255, 255, 0)');
this.maskCtx.fillStyle = radgrad;
this.maskCtx.arc(x, y, 30, 0, Math.PI * 2, true);
this.maskCtx.fill();
if (this.drawPercentCallback) {
this.drawPercentCallback.call(null, this.getTransparentPercent(this.maskCtx, this.width, this.height));
}
},
bindEvent: function () {
var _this = this;
var device = (/android|webos|iphone|ipad|ipod|blackberry|iemobile|opera mini/i.test(navigator.userAgent.toLowerCase()));
var clickEvtName = device ? 'touchstart' : 'mousedown';
var moveEvtName = device? 'touchmove': 'mousemove';
if (!device) {
var isMouseDown = false;
document.addEventListener('mouseup', function(e) {
isMouseDown = false;
}, false);
} else {
document.addEventListener("touchmove", function(e) {
if (isMouseDown) {
e.preventDefault();
}
}, false);
document.addEventListener('touchend', function(e) {
isMouseDown = false;
}, false);
}
this.mask.addEventListener(clickEvtName, function (e) {
isMouseDown = true;
var docEle = document.documentElement;
if (!_this.clientRect) {
_this.clientRect = {
left: 0,
top:0
};
}
var x = (device ? e.touches[0].clientX : e.clientX) - _this.clientRect.left + docEle.scrollLeft - docEle.clientLeft;
var y = (device ? e.touches[0].clientY : e.clientY) - _this.clientRect.top + docEle.scrollTop - docEle.clientTop;
_this.drawPoint(x, y);
}, false);
this.mask.addEventListener(moveEvtName, function (e) {
if (!device && !isMouseDown) {
return false;
}
var docEle = document.documentElement;
if (!_this.clientRect) {
_this.clientRect = {
left: 0,
top:0
};
}
var x = (device ? e.touches[0].clientX : e.clientX) - _this.clientRect.left + docEle.scrollLeft - docEle.clientLeft;
var y = (device ? e.touches[0].clientY : e.clientY) - _this.clientRect.top + docEle.scrollTop - docEle.clientTop;
_this.drawPoint(x, y);
}, false);
},
drawLottery: function () {
this.background = this.background || this.createElement('canvas', {
style: 'position:absolute;left:0;top:0;'
});
this.mask = this.mask || this.createElement('canvas', {
style: 'position:absolute;left:0;top:0;'
});
if (!this.conNode.innerHTML.replace(/[\w\W]| /g, '')) {
this.conNode.appendChild(this.background);
this.conNode.appendChild(this.mask);
this.clientRect = this.conNode ? this.conNode.getBoundingClientRect() : null;
this.bindEvent();
}
this.backCtx = this.backCtx || this.background.getContext('2d');
this.maskCtx = this.maskCtx || this.mask.getContext('2d');
if (this.lotteryType == 'image') {
var image = new Image(),
_this = this;
image.onload = function () {
_this.width = this.width;
_this.height = this.height;
_this.resizeCanvas(_this.background, this.width, this.height);
_this.backCtx.drawImage(this, 0, 0);
_this.drawMask();
}
image.src = this.lottery;
} else if (this.lotteryType == 'text') {
this.width = this.width;
this.height = this.height;
this.resizeCanvas(this.background, this.width, this.height);
this.backCtx.save();
this.backCtx.fillStyle = '#FFF';
this.backCtx.fillRect(0, 0, this.width, this.height);
this.backCtx.restore();
this.backCtx.save();
var fontSize = 30;
this.backCtx.font = 'Bold ' + fontSize + 'px Arial';
this.backCtx.textAlign = 'center';
this.backCtx.fillStyle = '#F60';
this.backCtx.fillText(this.lottery, this.width / 2, this.height / 2 + fontSize / 2);
this.backCtx.restore();
this.drawMask();
}
},
drawMask: function() {
this.resizeCanvas(this.mask, this.width, this.height);
if (this.coverType == 'color') {
this.maskCtx.fillStyle = this.cover;
this.maskCtx.fillRect(0, 0, this.width, this.height);
this.maskCtx.globalCompositeOperation = 'destination-out';
} else if (this.coverType == 'image'){
var image = new Image(),
_this = this;
image.onload = function () {
_this.maskCtx.drawImage(this, 0, 0);
_this.maskCtx.globalCompositeOperation = 'destination-out';
}
image.src = this.cover;
}
},
init: function (lottery, lotteryType) {
this.lottery = lottery;
this.lotteryType = lotteryType || 'image';
this.drawLottery();
}
}
window.onload = function () {
var lottery = new Lottery('lotteryContainer', '#CCC', 'color', 300, 100, drawPercent);
lottery.init('http://www.baidu.com/img/bdlogo.gif', 'image');
document.getElementById('freshBtn').onclick = function() {
drawPercentNode.innerHTML = '0%';
lottery.init(getRandomStr(10), 'text');
}
var drawPercentNode = document.getElementById('drawPercent');
function drawPercent(percent) {
drawPercentNode.innerHTML = percent + '%';
}
}
function getRandomStr(len) {
var text = "";
var possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
for( var i=0; i < len; i++ )
text += possible.charAt(Math.floor(Math.random() * possible.length));
return text;
}
//]]>
</script>
</body>
</html>
亲，看看这个对你有帮助么
