• js学习之tank的移动


    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml">
    <head>
        <title>非自走型tank!!!!</title>
        <meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
        <style type="text/css">
            .map {
                background: gray;
                border: 1px solid black;
                position: relative;
                margin: 50px auto;
                width: 416px;
                height: 416px;
            }
    
            .tank {
                background-image: url("//images0.cnblogs.com/blog/294743/201306/12123133-eaa9ada8690e4216a2bee3e56442e032.gif");
                background-repeat: no-repeat;
                overflow: hidden;
                position: absolute;
                width: 32px;
                height: 32px;
                z-index: 3;
            }
        </style>
    </head>
    <body>
        <div class="map" id="map">
            <div id="me" class="tank">
            </div>
        </div>
        <script type="text/javascript">
    
            //js取不到样式表的值,暂时先这样
            var MyGlobal = {
                mapWidth: 416,
                mapHeight: 416
            };
    
            var Tank = function (id, dir, x, y) {//div的id,方向,起始坐标
                this.el = document.getElementById(id);
                this.direction = dir ? dir : 'up';
                this.speed = 10;//越大越慢
                //坦克活动状态 0 未活动 1 正在活动
                this.activeState = 0;
                this.tid = null;
                this.x = x ? x : 100;
                this.y = y ? y : 200;
            };
            Tank.prototype.init = function () {//tank生成位置
                var dir = this.direction;
                var tank = this.el;
                tank.style['left'] = this.x + 'px';
                tank.style['top'] = this.y + 'px';
                this.setDirection(dir);
            };
            Tank.prototype.setDirection = function (dir) {//tank方向图片
                var tank = this.el;
                if (dir == 'up') {
                    tank.style['backgroundPosition'] = '0 0';
                }
                if (dir == 'right') {
                    tank.style['backgroundPosition'] = '-5px -36px';
                }
                if (dir == 'down') {
                    tank.style['backgroundPosition'] = '0 -73px';
                }
                if (dir == 'left') {
                    tank.style['backgroundPosition'] = '0 -105px';
                }
            };
    
            Tank.prototype.move = function (dir) {//tank移动
                if (this.activeState != 0) return false; //正在运动不管他
                this.activeState = 1; //将当前状态设置为正在运动
                if (this.direction != dir) {//转向
                    this.direction = dir;
                    this.setDirection(dir);
                }
    
                var tank = this.el;
    
                //获得当前位置
                var xpos = tank.style['left'] ? tank.style['left'] : 0;
                var ypos = tank.style['top'] ? tank.style['top'] : 0;
                xpos = parseInt(xpos);
                ypos = parseInt(ypos);
    
                //最大范围
                var mx = MyGlobal.mapWidth - 32;
                var my = MyGlobal.mapHeight - 32;
    
                switch (dir) {
                    case 'up': ypos <= 0 ? 0 : ypos--; break;
                    case 'right': xpos >= mx ? mx : xpos++; break;
                    case 'down': ypos >= my ? my : ypos++; break;
                    case 'left': xpos <= 0 ? 0 : xpos--; break;
                }
    
                //重新设置坦克位置
                tank.style['left'] = xpos + 'px';
                tank.style['top'] = ypos + 'px';
    
                //处理运动中的定时器
                if (this.tid) {
                    clearTimeout(this.tid);
                    this.tid = null;
                }
    
                //为了移动得更平滑
                this.x = xpos;
                this.y = ypos;
                var scope = this;
                var speed = this.speed;
                var repeat = function () {
                    scope.move(dir);
                };
                if (!this.tid) {
                    this.tid = setTimeout(repeat, speed);//10毫秒移动一次
                }
    
                //移动结束
                this.activeState = 0;
            }
    
            Tank.prototype.stop = function () {
                clearTimeout(this.tid);
                this.tid = null;
            };
    
            var tank = new Tank('me', 'right', 100, 100);
            tank.init();
    
            function getDir(code) {
                if (code == '87' || code == '119') {
                    return 'up';
                }
                if (code == '100' || code == '68') {
                    return 'right';
                }
                if (code == '115' || code == '83') {
                    return 'down';
                }
                if (code == '97' || code == '65') {
                    return 'left';
                }
                return null;
            }
    
            document.onkeydown = function (evt) {//按下键盘
                evt = (evt) ? evt : window.event;
                var keyCode = evt.keyCode;
                if (keyCode) {
                    dir = getDir(keyCode.toString());//获得方向
                }
                tank.setDirection(dir);
                if (dir)
                    tank.move(dir);//移动
                evt.preventDefault();
                return false;
            };
            document.onkeyup = function (evt) {//松开键盘
                tank.stop();
            };
            document.onkeypress = function (evt) {//从按下到松开键盘
                evt = (evt) ? evt : window.event;
                var keyCode = evt.keyCode;
                if (keyCode) {
                    dir = getDir(keyCode.toString());//获得方向
                }
                if (dir)
                    tank.move(dir);
                evt.preventDefault();
                return false;
            };
        </script>
    </body>
    </html>
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  • 原文地址:https://www.cnblogs.com/margin-gu/p/5025680.html
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