• canvas学习笔记


    <!DOCTYPE html>
    <html>
    <head lang="en">
        <meta charset="UTF-8">
        <title></title>
    </head>
    <body>
    <canvas id="canvas" style="border:1px solid #ccc;display: block;margin:20px auto">当前浏览器不支持canvas</canvas>
    </body>
    <script>
        window.onload=function(){
            var canvas=document.getElementById("canvas");
            canvas.width=1024;//画布的宽度
            canvas.height=768;
            var context=canvas.getContext("2d");
           //对于不支持canvas浏览器的处理方法  在canvas标签中间添加文字说明,或者用如下的if else操作
           /* if(canvas.getContext("2d")){
                var context=canvas.getContext("2d");
            }else{
                alert("当前浏览器不支持canvas")
            }*/
            context.beginPath();//路径开始  beginPath()和closePath()不一定成对出现
            context.moveTo(100,100);//绘制起点
            context.lineTo(700,700);//绘制终点
            context.lineTo(100,700);
            context.lineTo(100,100);
            context.lineWidth=5;//线条宽度
            context.strokeStyle="#c00011";//绘制样式
            context.stroke();//绘制操作
           /* context.fillStyle="rgb(can,100,30)";
            context.fill();//填充*/
            context.closePath();//路径结束
            context.beginPath();
            context.moveTo(200,100);
            context.lineTo(700,600);
            context.strokeStyle="#000";
            context.stroke();
            context.closePath();
        }
    
    </script>
    </html>
    <!DOCTYPE html>
    <html>
    <head lang="en">
        <meta charset="UTF-8">
        <title></title>
    </head>
    <body>
    <canvas id="canvas" width="1024" height="768" style="border:1px solid #ccc;margin:20px auto;"></canvas>
    </body>
    <script>
        window.onload=function(){
            var canvas=document.getElementById("canvas");
            var context=canvas.getContext("2d");
            context.lineWidth=5;
            context.strokeStyle="#005588";
            context.beginPath();
            context.arc(300,300,200,0,1.5*Math.PI,true);//画圆  300,300为圆心  200为半径 从0一直画到1.5π,true为逆时针绘制,默认为false为顺时针
            context.closePath();//closePath()有个作用就是对于结尾处没有连接的路径,会自动链接  如果不需要自动连接,可以只写beginPath()不写closePath()
            context.stroke();
        }
    </script>
    </html>
    <!DOCTYPE html>
    <html>
    <head lang="en">
        <meta charset="UTF-8">
        <title></title>
    </head>
    <body>
    <canvas id="canvas" style="border:1px solid #000;display: block;margin:50px auto;"></canvas>
    </body>
    <script>
        var point=[
            {
                p:[{x:0,y:0},{x:0,y:600},{x:300,y:300},{x:0,y:0}],color:"#c2c2cb"
            },
            {
                p:[{x:0,y:0},{x:600,y:0},{x:300,y:300},{x:0,y:0}],color:"#c868a8"
            },
            {
                p:[{x:150,y:450},{x:300,y:600},{x:0,y:600},{x:150,y:450}],color:"#c3b217"
            },
            {
                p:[{x:300,y:600},{x:600,y:300},{x:600,y:600},{x:300,y:600}],color:"#c01110"
            },
            {
                p:[{x:150,y:450},{x:300,y:600},{x:450,y:450},{x:300,y:300},{x:150,y:450}],color:"green"
            },
            {
                p:[{x:450,y:150},{x:450,y:450},{x:300,y:300},{x:450,y:150}],color:"blue"
            },
            {
                p:[{x:450,y:150},{x:450,y:450},{x:600,y:300},{x:600,y:0},{x:450,y:150}],color:"yellow"
            }
        ];
        window.onload=function(){
            var canvas=document.getElementById("canvas");
            canvas.width=1024;
            canvas.height=768;
            var context=canvas.getContext("2d");
            context.beginPath();
            context.moveTo(0,0);
            context.lineTo(600,0);
            context.lineTo(600,600);
            context.lineTo(0,600);
            context.lineTo(0,0);
            context.strokeStyle="#ccc";
            context.stroke();
            context.closePath();
            for(var i=0;i<point.length;i++){
                draw(point[i],context);
            }
            function draw(piece,ctx){
                ctx.beginPath();
                ctx.moveTo(piece.p[0].x,piece.p[0].y);
                for(var i=1;i<piece.p.length;i++){
                    ctx.lineTo(piece.p[i].x,piece.p[i].y);
                }
                ctx.fillStyle=piece.color;
                ctx.fill();
                ctx.closePath();
            }
        }
    </script>
    </html>
    七色板demo
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  • 原文地址:https://www.cnblogs.com/dongxiaolei/p/6952829.html
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