CSS3_元素拖曳原理_设置全局点击捕获_九宫格碰撞检测_自定义滚动条

拖曳原理：

元素的初始位置 + 鼠标距离差 = 元素最终位置

使元素可以拖动

function dragElement(obj){
    obj.onmousedown = function(e){
        e = e || window.event;    // 兼容 IE
        
        obj.setCapture && obj.setCapture();    // 只有 IE 支持，处理 IE8 ctrl+A
        
        // 鼠标初始坐标
        var mouseX = e.clientX;
        var mouseY = e.clientY;
        
        // 元素初始坐标
        var eleX = obj.offsetLeft;
        var eleY = obj.offsetTop;
        
        document.onmousemove = function(e){
            e = e || window.event;
            
            // 鼠标新坐标
            var newMouseX = e.clientX;
            var newMouseY = e.clientY;
            
            // 元素的新坐标 = 元素初始坐标+（鼠标新坐标-鼠标初始坐标）
            obj.style.left = eleX + newMouseX - mouseX +"px";
            obj.style.top = eleY + newMouseY - mouseY + "px";
        };
        
        document.onmouseup = function(){
            document.onmousemove = null;
            document.onmouseup = null;
            
            obj.releaseCapture && obj.releaseCapture();
        };
        
        e.preventDefault && e.preventDefault();
        return false;    // 处理高级浏览器 ctrl+A
    };
};

拖曳：范围限定

超出临界值，令其等于临界值

上侧临界值 = 0;

右侧临界值 = 视窗 width - ele.offsetWidth;

下侧临界值 = 视窗 height - ele.offsetHeight;

左侧临界值 = 0;

九宫格碰撞检测

ele.offsetLeft 或者 ele.offsetTop
- 获取的是 元素在包含块中的坐标

ele.getBoundingClientRect();
- 获取元素在视窗中的坐标（由该元素.getClientRects() 返回的一组矩形集合）

function dragRangeAround(obj, borderRange, badObj){    // 要拖动的元素，吸附范围，磁性盒子
    borderRange = borderRange || 0;
    obj.onmousedown = function(e){
        e = e || window.event;
        
        obj.setCapture && obj.setCapture();    // 只有 IE 支持，处理 IE8 ctrl+A
        
        var mouseX = e.clientX;
        var mouseY = e.clientY;
        
        var eleX = obj.offsetLeft;
        var eleY = obj.offsetTop;
        
        var cDir = "noCollision";
        document.onmousemove = function(e){
            e = e || window.event;
            
            var newMouseX = e.clientX;
            var newMouseY = e.clientY;
            
            fixedX = eleX + newMouseX - mouseX;
            fixedY = eleY + newMouseY - mouseY;
            
            var objBorder = obj.style.border && parseInt(obj.style.border);
            if(fixedX < borderRange){
                fixedX = 0;
            }else if(fixedX > (document.documentElement.clientWidth-obj.offsetWidth-borderRange)){
                fixedX = document.documentElement.clientWidth-obj.offsetWidth-objBorder*2;
            }
            
            if(fixedY < borderRange){
                fixedY = 0;
            }else if(fixedY > (document.documentElement.clientHeight-obj.offsetHeight-borderRange)){
                fixedY = document.documentElement.clientHeight-obj.offsetHeight-objBorder*2;
            }
            obj.style.left = fixedX + "px";
            obj.style.top = fixedY + "px";
            
            /**** start 碰撞检测 ****/
            if(badObj){
                var isCollision = false;
                
                var badTop = badObj.getBoundingClientRect().top;
                var badRight = badObj.getBoundingClientRect().right;
                var badBottom = badObj.getBoundingClientRect().bottom;
                var badLeft = badObj.getBoundingClientRect().left;
                
                var objRight = obj.getBoundingClientRect().right;
                var objLeft = obj.getBoundingClientRect().left;
                var objBottom = obj.getBoundingClientRect().bottom;
                var objTop = obj.getBoundingClientRect().top;
                
                if( objRight < badLeft){
                    cDir = "left";
                    if( objRight > (badLeft-borderRange) &&
                        objBottom > badTop && objTop < badBottom){
                        obj.style.left = badLeft - obj.offsetWidth + "px";
                    }
                }else if( objLeft > badRight ){
                    cDir = "right";
                    if( objLeft < (badRight+borderRange) &&
                        objBottom > badTop && objTop < badBottom){
                        obj.style.left = badRight + "px";
                    }
                }else if( objBottom < badTop){
                    cDir = "top";
                    if( objBottom > (badTop-borderRange) &&
                        objRight > badLeft && objLeft < badRight){
                        obj.style.top = badTop - obj.offsetHeight + "px";
                    }
                }else if( objTop > badBottom ){
                    cDir = "bottom";
                    if( objTop < (badBottom+borderRange) &&
                        objRight > badLeft && objLeft < badRight){
                        obj.style.top = badBottom + "px";
                    }
                }else{
                    isCollision = true;
                }
            
                if(isCollision){
                    badObj.innerHTML = cDir+"in's business";
                }else{
                    badObj.innerHTML = cDir+"out's business";
                }
            }
            /**** over ****/
        };
        
        document.onmouseup = function(){
            document.onmousemove = null;
            document.onmouseup = null;
            
            obj.releaseCapture && obj.releaseCapture();
        };
        
        e.preventDefault && e.preventDefault();
        return false;    // 处理高级浏览器 ctrl+A
    };
    return obj;
};

自定义滚动条

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8" />
        <title>自定义滚动条</title>

        <style type="text/css">
            body {
                width: 100%;
                color: #000;
                background: #96b377;
                font: 14px Helvetica, Arial, sans-serif;
            }
            
            html,
            body {
                height: 100%;
                overflow: hidden;
            }
            
            #things {
                position: absolute;
                top: 0px;
                left: 0px;
                font-size: 27px;
                font-weight: 700;
                color: #210202;
                padding-right: 40px;
            }
            
            /**** DIY Scroll ****/
            #diy_scroll_box{
                position: fixed;
                top: 0px;
                right: 0px;
                z-index: 7777;
                
                width: 40px;
                height: 100%;
                background-color: #eee;
            }
            
            #diy_scroll {
                position: absolute;
                top: 0px;
                left: 0px;
                z-index: 8888;
                
                width: 100%;
                height: 20%;
                background-color: #949494;
            }
            
            #diy_scroll:hover {
                background-color: #c0c0c0;
            }
            
            /**** 上下按键 ****/
            #scroll_up_btn,
            #scroll_down_btn {
                position: absolute;
                z-index: 9999;
                
                width: 40px;
                height: 40px;
                background-color: #456;
            }
            
            #scroll_up_btn {
                top: 0px;
                right: 0px;
            }
            
            #scroll_down_btn {
                bottom: 0px;
                right: 0px;
            }
            
            #scroll_up{
                position: absolute;
                top: -10px;
                
                border: 20px solid red;
                border-top: 20px solid #f000;
                border-right: 20px solid #f000;
                border-left: 20px solid #f000;
                border-bottom-color: #b3e4aa;
            }
            
            #scroll_down{
                position: absolute;
                top: 10px;
                
                border: 20px solid red;
                border-bottom: 20px solid #f000;
                border-right: 20px solid #f000;
                border-left: 20px solid #f000;
                border-top-color: #b3e4aa;
            }
            
            #scroll_up:hover {
                border-bottom-color: #c5ffbb;
            }
            
            #scroll_down:hover {
                border-top-color: #c5ffbb;
            }
            
        </style>
    </head>
    
    <body>
        
        <div id="diy_scroll_box">
            <div id="scroll_up_btn">
                <div id="scroll_up">
                </div>
            </div>
            
            <div id="diy_scroll">
            </div>
            
            <div id="scroll_down_btn">
                <div id="scroll_down">
                </div>
            </div>
        </div>
        
        <div id="things">
            <pre>
        
        
        
        
            姓名：朱元璋别名（外号）：朱重八、朱国瑞

            　　性别：男

            　　民族：汉

            　　血型：？

            　　学历：无文凭，秀才举人进士统统的不是，后曾自学过

            　　职业：皇帝

            　　家庭出身：（至少三代）贫农

            　　生卒：1328－1398

            　　最喜欢的颜色：黄色（这个好像没得选）

            　　社会关系：

            　　父亲：朱五四，农民

            　　母亲：陈氏，农民（不好意思，史书中好像没有她的名字）

            　　座右铭：你的就是我的，我还是我的

            　　主要经历：

            　　1328年－1344年放牛

            　　1344年－1347年做和尚，主要工作是出去讨饭（这个……）

            　　1347年－1352年做和尚主要工作是撞钟

            　　1352年－1368年造反（这个猛）

            　　1368年－1398年主要工作是做皇帝

            　　一切的事情都从1328年的那个夜晚开始，农民朱五四的妻子陈氏生下了一个男婴，
            大家都知道了，这个男婴就是后来的朱元璋。
            大凡皇帝出世，后来的史书上都会有一些类似的怪象记载。

            　　比如刮风啊，下暴雨啊，冒香气啊，天上星星闪啊，到处放红光啊
            ，反正就是要告诉你，这个人和别人不一样。
            朱元璋先生也不例外，他出生时，红光满地，夜间房屋中出现异光，以致于邻居以为失
            火了，跑来相救（明实录）。
            </pre>
        </div>
        
        <!-- javascript 代码 -->
        <script type="text/javascript">
            var things = document.getElementById("things");
            
            /**** DIY Scroll ****/
            var diyScroll = document.getElementById("diy_scroll");
            var btnHeight = 40;
            diyScroll.style.top = btnHeight+"px";
            
            var diyScrollHeight = document.documentElement.clientHeight-btnHeight*2;
            var thingsScrollHeight = things.offsetHeight-document.documentElement.clientHeight;
            
            barHeight = diyScrollHeight*(document.documentElement.clientHeight)/things.offsetHeight;
            diyScroll.style.height = barHeight +"px";
                
            var contentStartTop = 0;
            var mouseStartY = 0;
            var barStartY = 0;
            
            /**** 点击滑块 ****/
            diyScroll.onmousedown = function(e){
                e = e || window.event;
                
                diyScroll.setCapture && diyScroll.setCapture();
                
                mouseStartY = e.clientY;
                barStartY = diyScroll.offsetTop;
                contentStartTop = things.offsetTop;
                
                document.onmousemove = function(e){
                    e = e || window.event;
                    
                    var mouseEndY = e.clientY;
                    var barEndY = barStartY + mouseEndY - mouseStartY;
                    
                    if(barEndY < btnHeight){
                        barEndY = btnHeight;
                    }else if(barEndY > (document.documentElement.clientHeight - btnHeight - diyScroll.offsetHeight)){
                        barEndY = document.documentElement.clientHeight - btnHeight - diyScroll.offsetHeight;
                    }
                    
                    diyScroll.style.top = barEndY+"px";
                    things.style.top = contentStartTop + -thingsScrollHeight*(barEndY-barStartY)/(diyScrollHeight-barHeight) +"px";
                };
            
                document.onmouseup = function(){
                    document.onmousemove = null;
                    document.onmouseup = null;
                    diyScroll.releaseCapture && diyScroll.releaseCapture();
                }
                
                e.preventDefault && e.preventDefault();
                return false;
            };
            
            document.onmousewheel = scrollWheelFunc;
            document.addEventListener && document.addEventListener("DOMMouseScroll", scrollWheelFunc, false);
            /**** 滚轮事件 ****/
            function scrollWheelFunc(e){
                e = e || window.event;
                
                var wheelDir = 0;
                var shouldMove = 5;
                
                if(e.wheelDelta){
                    wheelDir = (e.wheelDelta>0)?"up":"down";
                    shouldMove = (e.wheelDelta>0)?(-5):5;
                }else if(e.detail){
                    wheelDir = (e.detail>0)?"down":"up";
                    shouldMove =  (e.detail>0)?5:(-5);
                };
                
                var barTop = diyScroll.offsetTop;
                var barOffset = barTop;
                
                barTop += shouldMove;
                
                if(barTop < btnHeight){
                    barTop = btnHeight;
                }else if(barTop > (document.documentElement.clientHeight - btnHeight - diyScroll.offsetHeight)){
                    barTop = document.documentElement.clientHeight - btnHeight - diyScroll.offsetHeight;
                };
                
                diyScroll.style.top =  barTop+"px";
                
                barOffset = barOffset - barTop;
                
                contentStartTop = things.offsetTop;
                things.style.top = contentStartTop + thingsScrollHeight*barOffset/(diyScrollHeight-barHeight) +"px";
                
                e.preventDefault && e.preventDefault();
                return false;
            };
            
            /**** 点击按键 ****/
            var scrollDown = document.getElementById("scroll_down_btn");
            var scrollUp = document.getElementById("scroll_up_btn");
            scrollUp.onclick = function(){
                scrollBtnFunc(-5);
            }
            scrollDown.onclick = function(){
                scrollBtnFunc(5);
            }
            
            function scrollBtnFunc(barOffset){
                var barTop = diyScroll.offsetTop;
                
                if((barTop+barOffset) < btnHeight){
                    barOffset = btnHeight - barTop;
                }else if((barTop+barOffset) > (document.documentElement.clientHeight - btnHeight - diyScroll.offsetHeight)){
                    barOffset = document.documentElement.clientHeight - btnHeight - diyScroll.offsetHeight - barTop;
                };
                diyScroll.style.top = barTop+barOffset+"px";
                
                contentStartTop = things.offsetTop;
                things.style.top = contentStartTop + -thingsScrollHeight*barOffset/(diyScrollHeight-barHeight) +"px";
            
            }
        </script>
    </body>
</html>

--------小尾巴 ________一个人欣赏-最后一朵颜色的消逝-忠诚于我的是·一颗叫做野的心.决不受人奴役.怒火中生的那一刻·终将结束...

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原文地址：https://www.cnblogs.com/tianxiaxuange/p/9971685.html