html5之拖放

来源：互联网发布：百度云计算平台编辑：程序博客网时间：2024/05/01 06:20

1)创建来源项目

1.1)draggable属性的值：

true——此元素能被拖动；

false——此元素不能被拖动；

auto——浏览器可以自主决定某个元素是否能被拖动；

1.2）被拖动元素的事件：

dragstart——在元素开始被拖动时触发；

drag——在元素被拖动时反复触发；

dragend——在拖动操作完成时触发；

2）创建释放区

2.1）释放区事件：

dragenter——当被拖动元素进入释放区所占据的屏幕空间时触发；

dragover——当被拖动元素在释放区内触发时移动触发；

dragleave——当被拖动元素没有放入就离开释放区时触发；

drop——当被拖动元素在释放区放下时触发；

<!DOCTYPE HTML><html>    <head>        <title>Example</title>        <style>            #src > * {float:left;}            #src > img {border: thin solid black; padding: 2px; margin:4px;}            #target {border: thin solid black; margin:4px;}            #target { height: 81px; width: 81px; text-align: center; display: table;}            #target > p {display: table-cell; vertical-align: middle;}            img.dragged {background-color: lightgrey;}        </style>    </head>    <body>        <div id="src">            <img draggable="true" id="banana" src="banana100.png" alt="banana"/>            <img draggable="true" id="apple" src="apple100.png" alt="apple"/>            <img draggable="true" id="cherries" src="cherries100.png" alt="cherry"/>            <div id="target">                <p id="msg">Drop Here</p>            </div>                    </div>                        <script>            var src = document.getElementById("src");            var target = document.getElementById("target");            var msg = document.getElementById("msg");                      var draggedID;                      target.ondragenter = handleDrag;            target.ondragover = handleDrag;                        function handleDrag(e) {                e.preventDefault();            }                        target.ondrop = function(e) {                var newElem = document.getElementById(draggedID).cloneNode(false);                target.innerHTML = "";                target.appendChild(newElem);                e.preventDefault();            }                      src.ondragstart = function(e) {                draggedID = e.target.id;                e.target.classList.add("dragged");            }                        src.ondragend = function(e) {                var elems = document.querySelectorAll(".dragged");                for (var i = 0; i < elems.length; i++) {                    elems[i].classList.remove("dragged");                }            }                  </script>    </body></html>

3)使用DataTransfer对象

3.1)与拖放操作所触发的事件同时派发的对象是DragEvent，它派生于MouseEvent。

DragEvent对象定义的额外属性：

dataTransfer——返回用于传输数据到释放区的对象（DataTransfer）；

3.2)DataTransfer对象定义的属性：

types——返回数据的格式；

getData(<format>)——返回指定格式的数据；

setData(<format>,<data>)——设置指定格式的数据；

clearData(<format>)——移除指定格式的数据；

files——返回已被拖动文件的列表；

<!DOCTYPE HTML><html>    <head>        <title>Example</title>        <style>            #src > * {float:left;}            #src > img {border: thin solid black; padding: 2px; margin:4px;}            #target {border: thin solid black; margin:4px;}            #target { height: 81px; width: 81px; text-align: center; display: table;}            #target > p {display: table-cell; vertical-align: middle;}            img.dragged {background-color: lightgrey;}        </style>    </head>    <body>        <div id="src">            <img draggable="true" id="banana" src="banana100.png" alt="banana"/>            <img draggable="true" id="apple" src="apple100.png" alt="apple"/>            <img draggable="true" id="cherries" src="cherries100.png" alt="cherry"/>            <div id="target">                <p id="msg">Drop Here</p>            </div>                    </div>                        <script>            var src = document.getElementById("src");            var target = document.getElementById("target");                                target.ondragenter = handleDrag;            target.ondragover = handleDrag;                        function handleDrag(e) {                e.preventDefault();            }                        target.ondrop = function(e) {                var droppedID = e.dataTransfer.getData("Text");                               var newElem = document.getElementById(droppedID).cloneNode(false);                target.innerHTML = "";                target.appendChild(newElem);                e.preventDefault();            }                      src.ondragstart = function(e) {                e.dataTransfer.setData("Text", e.target.id);                e.target.classList.add("dragged");            }                        src.ondragend = function(e) {                var elems = document.querySelectorAll(".dragged");                for (var i = 0; i < elems.length; i++) {                    elems[i].classList.remove("dragged");                }            }                  </script>    </body></html>

3.3）拖放文件：

File对象定义的属性

name——获取文件名；

type——获取文件类型，以MIME类型表示；

size——获取文件大小（以字节计算）；

<!DOCTYPE HTML><html>    <head>        <title>Example</title>        <style>            .table {display:table;}            .row {display:table-row;}            .cell {display: table-cell; padding: 5px;}            .label {text-align: right;}            #target {border: medium double black; margin:4px; height: 50px;                width: 200px; text-align: center; display: table;}            #target > p {display: table-cell; vertical-align: middle;}        </style>    </head>    <body>        <form id="fruitform" method="post" action="http://titan:8080/form">            <div class="table">                <div class="row">                    <div class="cell label">Bananas:</div>                    <div class="cell"><input name="bananas" value="2"/></div>                </div>                <div class="row">                    <div class="cell label">Apples:</div>                    <div class="cell"><input name="apples" value="5"/></div>                </div>                <div class="row">                    <div class="cell label">Cherries:</div>                    <div class="cell"><input name="cherries" value="20"/></div>                </div>                <div class="row">                    <div class="cell label">File:</div>                    <div class="cell"><input type="file" name="file"/></div>                </div>                <div class="row">                    <div class="cell label">Total:</div>                    <div id="results" class="cell">0 items</div>                </div>                            </div>            <div id="target">                <p id="msg">Drop Files Here</p>            </div>                        <button id="submit" type="submit">Submit Form</button>        </form>        <script>            var target = document.getElementById("target");                 var httpRequest;            var fileList;                                     document.getElementById("submit").onclick = handleButtonPress;                                target.ondragenter = handleDrag;            target.ondragover = handleDrag;                        function handleDrag(e) {                e.preventDefault();            }                        target.ondrop = function(e) {                fileList = e.dataTransfer.files;                e.preventDefault();            }                                               function handleButtonPress(e) {                e.preventDefault();                                 var form = document.getElementById("fruitform");                var formData = new FormData(form);                                 if (fileList || true) {                    for (var i = 0; i < fileList.length; i++) {                        formData.append("file" + i, fileList[i]);                    }                }                                   httpRequest = new XMLHttpRequest();                httpRequest.onreadystatechange = handleResponse;                httpRequest.open("POST", form.action);                httpRequest.send(formData);            }                                     function handleResponse() {                if (httpRequest.readyState == 4 && httpRequest.status == 200) {                    var data = JSON.parse(httpRequest.responseText);                    document.getElementById("results").innerHTML = "You ordered "                        + data.total + " items";                }            }         </script>    </body></html>

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