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  • canvas绘制圆

    1.在HTML5文档中添加canvas元素,并且设置宽高和ID

    2.在canvas元素中添加提示语句

    3.添加script元素

    4.获取画布/设置绘图环境

    5.指定线宽:lineWidth=数值

    6.指定颜色:fill/strokeStyle=颜色值(只适用用轮廓、线段等填充色用:fillStyle=颜色值)

    7.设置圆的基本参数

    arc(x,y,r,起始弧度,终止弧度,true/false):创建圆弧/曲线(用于创建圆形或部分圆)

    圆心的坐标:x,y

    圆的半径:数值

    起始弧度和终止弧度:角度值1,角度值2

    绘制方向:true(逆时针)/false (顺时针)默认

    8.开始绘制:stroke()/fill()

    绘制半圆
    <!DOCTYPE html>
    <html lang="zh-cn">
    <head>
        <meta charset="UTF-8">
        <title>canvas绘制圆</title>
    </head>
    <body>
    <canvas id="mycanvas4" width="500" height="500">
    </canvas>
    <script type="text/javascript">
        var canvas4=document.getElementById('mycanvas4');
        var c4=canvas4.getContext('2d');
        c4.lineWidth=8;
        c4.strokeStyle="green";
        c4.fillStyle="red";
        c4.beginPath();
        c4.strokeRect(100,100,50,100);
        c4.strokeRect(400,100,50,100);
        c4.beginPath();
        c4.arc(275,300,50,0,Math.PI,false);
        c4.stroke();
        c4.beginPath();
        c4.arc(275,300,50,0,Math.PI,false);
        c4.fill();
    </script>
    </body>
    </html>
    

      

    绘制圆弧

    <!DOCTYPE html>
    <html lang="zh-cn">
    <head>
        <meta charset="UTF-8">
        <title>canvas绘制圆</title>
    </head>
    <body>
        <canvas id="mycanvas" width="500" height="500">
            您浏览器暂不支持HTML5的canvas元素
        </canvas>
    <script type="text/javascript">
        var canvas=document.getElementById('mycanvas');
        var c=canvas.getContext('2d');
        c.lineWidth=8;
        c.strokeStyle="green";
        c.fillStyle="red";
        c.arc(100,50,30,0,Math.PI*2);
        c.stroke();
        c.beginPath();
        c.arc(100,150,30,0,Math.PI*2);
        c.fill();
        c.beginPath();
        c.arc(100,250,30,0,Math.PI*2);
        c.fill();
        c.stroke();
        c.beginPath();
        c.arc(300,50,30,0,Math.PI/3,true);
        c.stroke();
        c.beginPath();
        c.arc(300,150,30,0,Math.PI/3,true);
        c.fill();
        c.beginPath();
        c.arc(300,250,30,0,Math.PI/3,true);
        c.fill();
        c.stroke();
    </script>
    </body>
    </html>
    

      

    closePath()从终点连结起点

    all

    <!DOCTYPE html>
    <html lang="zh-cn">
    <head>
        <meta charset="UTF-8">
        <title>canvas绘制圆</title>
    </head>
    <body>
        <canvas id="mycanvas" width="700" height="500">
            您浏览器暂不支持HTML5的canvas元素
        </canvas>
    <script type="text/javascript">
        var canvas=document.getElementById('mycanvas');
        var c=canvas.getContext('2d');
        c.lineWidth=8;
        c.strokeStyle="green";
        c.fillStyle="red";
        c.arc(100,50,30,0,Math.PI*2);
        c.stroke();
        c.beginPath();
        c.arc(100,150,30,0,Math.PI*2);
        c.fill();
        c.beginPath();
        c.arc(100,250,30,0,Math.PI*2);
        c.fill();
        c.stroke();
        c.beginPath();
        c.arc(300,50,30,0,Math.PI/3,true);
        c.stroke();
        c.beginPath();
        c.arc(300,150,30,0,Math.PI/3,true);
        c.fill();
        c.beginPath();
        c.arc(300,250,30,0,Math.PI/3,true);
        c.fill();
        c.stroke();
        c.beginPath();
        c.lineWidth=2;
        c.arc(500,50,30,0,Math.PI/3,true);
        c.closePath();
        c.stroke();
        c.beginPath();
        c.lineWidth=2;
        c.arc(500,150,30,0,Math.PI/3,true);
        c.closePath();
        c.fill();
        c.beginPath();
        c.lineWidth=2;
        c.arc(500,250,30,0,Math.PI/3,true);
        c.closePath();
        c.fill();
        c.stroke();
    
    </script>
    </body>
    </html>
     
    

      

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  • 原文地址:https://www.cnblogs.com/liao13160678112/p/6398243.html
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