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js+canvas实现画板功能

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="/UploadFiles/2021-04-02/drow.js">


*{
 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;
}

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。