HTML5 implements a simple online drawing board-H5 Tutorial-php.cn

HTML5 implements a simple online drawing board

王林

Release： 2020-12-04 16:18:33

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HTML5 implements a simple online drawing board

Let’s take a look at the implementation first:

(Recommended tutorial: h5)

HTML5 implements a simple online drawing board

The implementation code is as follows:

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title></title>
    </head>
    <body>
        <canvas id="canvas" width="600" height="600"></canvas>
        <script type="text/javascript">
            var c = document.getElementById(&#39;canvas&#39;);
            var ctx = c.getContext(&#39;2d&#39;);

            //画一个黑色矩形
            ctx.fillStyle = &#39;black&#39;;
            ctx.fillRect(0,0,600,300);

            //按下标记
            var onoff = false;
            var oldx = -10;
            var oldy = -10;

            //设置颜色
            var linecolor = &#39;white&#39;;

            //设置线宽
            var linw = 4;

            //添加鼠标移动事件
            canvas.addEventListener(&#39;mousemove&#39;,draw,true);

            //添加鼠标按下事件
            canvas.addEventListener(&#39;mousedown&#39;,down,false);

            //添加鼠标弹起事件
            canvas.addEventListener(&#39;mouseup&#39;,up,false);

            function down(event) {
                onoff = true;
                oldx = event.pageX-10;
                oldy = event.pagey-10;
            }

            function up() {
                onoff = false;
            }

            function draw(event) {
                if(onoff == true) {
                    var newx = event.pageX-10;
                    var newy = event.pageY-10;
                    ctx.beginPath();
                    ctx.moveTo(oldx,oldy);
                    ctx.lineTo(newx,newy);
                    ctx.strokeStyle = linecolor;
                    ctx.lineCap = &#39;round&#39;;
                    ctx.stroke();

                    oldx = newx;
                    oldy = newy;
                }
            }
        </script>
    </body>
</html>

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