html Canvas 画图能够选择并能移动

canvas 画图，能够选中所画的图片并且能够随意移动图片

<html xmlns="http://www.w3.org/1999/xhtml">

<head runat="server">

<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>

    <title></title>

    <script type="text/javascript" src="JS/jquery.min.js"></script>

</head>

<body>

    <canvas id="myCanvas" width="500" height="400" style="border:1px solid #000000; background-color: #CCCCCC;"></canvas>

    <input id="Button1" type="button" value="画矩形" onclick="DrawingRec()" />

    <input id="Button2" type="button" value="画线"  onclick="Drawline()"/>

    <p></p>

</body>

</html>

<script>

    var c = document.getElementById("myCanvas");

    var ctx = c.getContext("2d");

    var list = [];

    var currentImag;

    var ax, ay, x, y;

    var startmove = false;

    var c = document.getElementById("myCanvas");

    c.onmousedown = function (e) {

        for (var i = 0; i < list.length; i++) {

            var w = list[i].x + list[i].width;

            var h = list[i].y + list[i].height;

            if (e.clientX < w && e.clientX > list[i].x && e.clientY < h && e.clientY > list[i].y) {

                currentImag = list[i];

                startmove = true;

                console.log("select: true");

            }

        }

    };

    c.onmousemove = function (e) {

        console.log("x:" + e.pageX + " y:" + e.pageY);

        if (currentImag == null) return;

        console.log("moveselect:true");

        x = e.clientX;

        y = e.clientY;

        //限制移动不能超出画布

        (x < 40) ? ax = 20 : ax = 480;

        (y < 40) ? ay = 20 : ay = 380;

        (x < 480 && x > 20) ? x = e.clientX : x = ax;

        (y < 380 && y > 20) ? y = e.clientY : y = ay;

        //清除之前图片然后重新绘制

        ctx.clearRect(0, 0, c.width, c.height);

        currentImag.x = x;

        currentImag.y = y;

        Piant();

        ctx.drawImage(currentImag, x - 20, y - 20, currentImag.width, currentImag.height);

    };

    c.onmouseup = function () {

        //c.onmousemove = null;

        //c.onmouseup = null;

        currentImag = null;

        startmove = false;

    };

    function Piant()

    {

        if (startmove)

        {

            for (var i = 0; i < list.length; i++)

            {

                ctx.drawImage(list[i], list[i].x - 20, list[i].y - 20, list[i].width, list[i].height);

            }

        }

    }

    function DrawingRec()

    {

        //ctx.beginPath();

        //ctx.fillStyle = "#000000";

        //ctx.fillRect(200, 100, 150, 75);

        //ctx.closePath();

        var img = new Image();

        img.src = "default/images/panel_tools.png";

        img.x = 50;

        img.y = 50;

        img.width = 40;

        img.height = 40;

        ctx.drawImage(img, 50, 50, img.width, img.height);

        list.push(img);

    }

</script>
html Canvas 画图 能够选择并能移动

html Canvas 画图能够选择并能移动
