本文实例为大家分享了js+canvas实现刮刮奖的具体代码,供大家参考,具体内容如下
1.实现了PC端的刮刮奖效果
2.使用了canvas的文本,像素操作,合成,绘制图形,随机数
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
|
<!DOCTYPE html>
< html >
< head >
< meta charset = "UTF-8" >
< title >刮刮奖</ title >
< style type = "text/css" >
* {
margin: 0;
padding: 0;
}
.box {
width: 500px;
height: 500px;
margin: 0 auto;
position: relative;
background: #00BFFF;
}
#prize {
width: 300px;
height: 100px;
position: absolute;
top: 50%;
left: 50%;
margin: -50px 0 0 -150px;
background: #fff;
font-family: "微软雅黑";
font-size: 40px;
text-align: center;
line-height: 100px;
-webkit-user-select: none;
}
#myCanvas {
position: absolute;
top: 50%;
left: 50%;
margin: -50px 0 0 -150px;
}
</ style >
</ head >
< body >
< div class = "box" >
< div id = "prize" ></ div >
< canvas id = "myCanvas" width = "300" height = "100" ></ canvas >
</ div >
</ body >
< script type = "text/javascript" >
//获取对象
var textArr = ["一等奖", "二等奖", "三等奖", "谢谢惠顾", "再来一次"];
var prize = document.getElementById("prize");
var num = Math.random() * 100;
if (num <= 60) {
prize.innerText = textArr[3];
} else if (num <= 70) {
prize.innerText = textArr[4];
} else if (num <= 80) {
prize.innerText = textArr[2];
} else if (num <= 90) {
prize.innerText = textArr[1];
} else if (num <= 100) {
prize.innerText = textArr[0];
}
var myCanvas = document.getElementById("myCanvas");
// 搭建环境
var cxt = myCanvas.getContext("2d");
cxt.globalAlpha = 1;
cxt.fillStyle = "#ccc";
cxt.fillRect(0, 0, 300, 100);
var txt = "刮刮奖";
cxt.fillStyle = "#000";
cxt.font = "30px 微软雅黑";
cxt.textAlign = "center";
cxt.textBaseline = "middle";
cxt.fillText(txt, 150, 50, 300);
var mX, mY;
var flag = false;
myCanvas.onmousedown = function(e) {
flag = true;
mX = e.offsetX;
mY = e.offsetY;
drawArc(mX, mY);
}
document.body.onmousemove = function(e) {
if (flag == true) {
mX = e.offsetX;
mY = e.offsetY;
drawArc(mX, mY);
}
}
document.body.onmouseup = function() {
flag = false;
sayPrize();
}
function drawArc(x, y) {
cxt.globalCompositeOperation = "destination-out"; //相交部分不显示
cxt.beginPath();
cxt.fillStyle = "white";
cxt.moveTo(x, y);
cxt.arc(x, y, 10, 0, 2 * Math.PI);
cxt.fill();
}
function sayPrize() {
var myImg = cxt.getImageData(70, 30, 160, 40);
// var myImg = cxt.getImageData(93, 37, 40, 30);
// 设置像素点的颜色
var num = 0;
var max = myImg.data.length / 4;
for (var i = 0; i < myImg.data.length ; i += 4) {
if (myImg.data[i + 3] <= 200) {
num++;
}
}
//2/3*myImg.data.length/4
if (num >= max * 0.6) {
alert("恭喜您,获得:" + prize.innerText);
}
}
</ script >
</ html >
|
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。
原文链接:https://blog.csdn.net/m0_46690660/article/details/108500701