js+canvas实现画板功能
导读
本文实例为大家分享了js+canvas实现画板功能的具体代码，供大家参考，具体内容如下
1.实现了画图，改变画笔粗细，改变画笔颜色，清屏功能
<!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <title>画板</title> <link rel="shortcut icon" type="image/x-icon" href="img/an.ico" /> <link rel="stylesheet" type="text/css" href="css/drow.css" /> </head> <body> <canvas id="mycanvas" width="1100px" height="660px"></canvas> <div class="tool"> 画笔颜色:<input type="color" name="color1" id="color1"/><br /> 画笔粗细:<input type="range" name="range1" id="range1"min="1" max="20"/><br /> <button class="btn">清屏</button> </div> </body> <script src="js/drow.js" type="text/javascript" charset="utf-8"></script> </html>
*{
margin: 0;
padding: 0;
text-align: left;
-moz-user-select: none;
-ms-user-select: none;
-webkit-user-select: none;
}
#mycanvas{
border: 2px solid deepskyblue;
}
.tool{
width: 260px;
height: 100%;
position: fixed;
right: 0;
top: 0;
background-color: #CCCCCC;
}//获取对象
var mycanvas = document.getElementById("mycanvas");
var color1 = document.getElementById("color1");
var range1 = document.getElementById("range1");
var btn = document.getElementsByClassName("btn")[0];
var contxt = mycanvas.getContext("2d");
btn.onclick=function () {
contxt.clearRect(0,0,1200,660);
}
var flag = false;
var x = 0,
y = 0;
// 鼠标点下事件
mycanvas.onmousedown = function(event) {
flag = true;
// 获取鼠标点下的开始位置
var x = event.clientX - mycanvas.offsetLeft;
var y = event.clientY - mycanvas.offsetTop;
contxt.beginPath(); // 开始新建路径
contxt.strokeStyle = color1.value; // 获得颜色赋值给画笔
contxt.lineCap="round";
contxt.lineWidth = range1.value; // 获得画笔宽度赋值给画笔
contxt.moveTo(x, y); // 开始位置
}
// 鼠标移动事件
mycanvas.onmousemove = function(event) {
// 获取鼠标在移动的位置
var mX = event.clientX - mycanvas.offsetLeft;
var mY = event.clientY - mycanvas.offsetTop;
if (flag) {
contxt.lineTo(mX, mY); // 移动途中和结束位置
contxt.stroke(); // 结束渲染画布
}
}
// 鼠标松开事件
mycanvas.onmouseup = function() {
flag = false;
}
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