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HTML5 拖放 -- 如何在相册间进行拖放照片排序
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HTML5 拖放 -- 如何在相册间进行拖放照片排序

今天我来给大家讲解一下 HTML5 的拖放。我们都知道,当前流行的浏览器(IE,FF,Safari,Chrome以及Opera),都有一些原生支持的功能(比如拖放功能)。
    现在谈谈现在Web开发中一个很常见的用例,比如要在几个相册中排序很多照片文件。这是很多CMS建站系统必须具备的功能。那么看看在HTML5情况下该如何做到这一点呢?

不过首先,我建议你先下载源代码文件,然后打开这个demo配合我的教程学习来加深印象。

Step1, HTML
index.html

<div class="albums">
    <div class="album" id="drop_1" droppable="true"><h2>Album 1</h2></div>
    <div class="album" id="drop_2" droppable="true"><h2>Album 1</h2></div>
    <div class="album" id="drop_3" droppable="true"><h2>Album 3</h2></div>
</div>
<div style="clear:both"></div>
<div class="gallery">
    <a id="1" draggable="true"><img src="images/1.jpg"></a>
    <a id="2" draggable="true"><img src="images/2.jpg"></a>
    <a id="3" draggable="true"><img src="images/3.jpg"></a>
    <a id="4" draggable="true"><img src="images/4.jpg"></a>
    <a id="5" draggable="true"><img src="images/5.jpg"></a>
    <a id="6" draggable="true"><img src="images/6.jpg"></a>
    <a id="7" draggable="true"><img src="images/7.jpg"></a>
    <a id="8" draggable="true"><img src="images/8.jpg"></a>
    <a id="9" draggable="true"><img src="images/9.jpg"></a>
    <a id="10" draggable="true"><img src="images/10.jpg"></a>
    <a id="11" draggable="true"><img src="images/11.jpg"></a>
    <a id="12" draggable="true"><img src="images/12.jpg"></a>
</div>
<script src="js/main.js"></script>


以上代码你能看到3个可拖放的HTML标签(也就是虚拟相册)以及12张照片。我已经对三个相册标记了特性droppable='true',以及对12张照片标记了draggable='true'.

Step2,CSS
现在该到了设计此范例外观的时候了,你可能注意到今天演示的css与以往的没什么两样。

css/main.css

/* Photo Gallery styles */
.gallery {
    margin: 50px auto 0;
    width: 840px;
}
.gallery a {
    display: inline-block;
    height: 135px;
    margin: 10px;
    opacity: 1;
    position: relative;
    width: 180px;

    -khtml-user-drag: element;

    /* CSS3 Prevent selections */
    -moz-user-select: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    user-select: none;

    /* CSS3 transition rules */
    -webkit-transition: all 0.5s ease;
    -moz-transition: all 0.5s ease;
    -o-transition: all 0.5s ease;
    transition: all 0.5s ease;
}
.gallery a img {
    border: 8px solid #fff;
    border-bottom: 20px solid #fff;
    cursor: pointer;
    display: block;
    height: 100%;
    left: 0px;
    position: absolute;
    top: 0px;
    width: 100%;
    z-index: 1;

    /* CSS3 Box sizing property */
    -moz-box-sizing: border-box;
    -webkit-box-sizing: border-box;
    -o-box-sizing: border-box;
    box-sizing: border-box;

    /* CSS3 transition rules */
    -webkit-transition: all 0.5s ease;
    -moz-transition: all 0.5s ease;
    -o-transition: all 0.5s ease;
    transition: all 0.5s ease;

    /* CSS3 Box Shadow */
    -moz-box-shadow: 2px 2px 4px #444;
    -webkit-box-shadow: 2px 2px 4px #444;
    -o-box-shadow: 2px 2px 4px #444;
    box-shadow: 2px 2px 4px #444;
}

/* Custom CSS3 rotate transformation */
.gallery a:nth-child(1) img {
    -moz-transform: rotate(-25deg);
    -webkit-transform: rotate(-25deg);
    transform: rotate(-25deg);
}
.gallery a:nth-child(2) img {
    -moz-transform: rotate(-20deg);
    -webkit-transform: rotate(-20deg);
    transform: rotate(-20deg);
}
.gallery a:nth-child(3) img {
    -moz-transform: rotate(-15deg);
    -webkit-transform: rotate(-15deg);
    transform: rotate(-15deg);
}
.gallery a:nth-child(4) img {
    -moz-transform: rotate(-10deg);
    -webkit-transform: rotate(-10deg);
    transform: rotate(-10deg);
}
.gallery a:nth-child(5) img {
    -moz-transform: rotate(-5deg);
    -webkit-transform: rotate(-5deg);
    transform: rotate(-5deg);
}
.gallery a:nth-child(6) img {
    -moz-transform: rotate(0deg);
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
}
.gallery a:nth-child(7) img {
    -moz-transform: rotate(5deg);
    -webkit-transform: rotate(5deg);
    transform: rotate(5deg);
}
.gallery a:nth-child(8) img {
    -moz-transform: rotate(10deg);
    -webkit-transform: rotate(10deg);
    transform: rotate(10deg);
}
.gallery a:nth-child(9) img {
    -moz-transform: rotate(15deg);
    -webkit-transform: rotate(15deg);
    transform: rotate(15deg);
}
.gallery a:nth-child(10) img {
    -moz-transform: rotate(20deg);
    -webkit-transform: rotate(20deg);
    transform: rotate(20deg);
}
.gallery a:nth-child(11) img {
    -moz-transform: rotate(25deg);
    -webkit-transform: rotate(25deg);
    transform: rotate(25deg);
}
.gallery a:nth-child(12) img {
    -moz-transform: rotate(30deg);
    -webkit-transform: rotate(30deg);
    transform: rotate(30deg);
}
.gallery a:hover img {
    z-index: 5;

    /* CSS3 transition rules */
    -webkit-transition: all 0.5s ease;
    -moz-transition: all 0.5s ease;
    -o-transition: all 0.5s ease;
    transition: all 0.5s ease;

    /* CSS3 transform rules */
    -moz-transform: rotate(0deg);
    -webkit-transform: rotate(0deg);
    -o-transform: rotate(0deg);
    transform: rotate(0deg);
}
.gallery a.hidden {
    height: 0;
    margin: 0;
    opacity: 0;
    width: 0;
}
.albums {
    margin: 40px auto 0;
    overflow: hidden;
    width: 840px;
}
.album {
    border: 3px dashed #ccc;
    float: left;
    margin: 10px;
    min-height: 100px;
    padding: 10px;
    width: 220px;

    /* CSS3 transition rules */
    -webkit-transition: all 1.0s ease;
    -moz-transition: all 1.0s ease;
    -o-transition: all 1.0s ease;
    transition: all 1.0s ease;
}
.album a {
    display: inline-block;
    height: 56px;
    margin: 15px;
    opacity: 1;
    position: relative;
    width: 75px;

    -khtml-user-drag: element;
    -webkit-user-drag: element;
    -khtml-user-select: none;
    -webkit-user-select: none;

    /* CSS3 Prevent selections */
    -moz-user-select: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    user-select: none;

    /* CSS3 transition rules */
    -webkit-transition: all 0.5s ease;
    -moz-transition: all 0.5s ease;
    -o-transition: all 0.5s ease;
    transition: all 0.5s ease;
}
.album a img {
    border: 4px solid #fff;
    border-bottom: 10px solid #fff;
    cursor: pointer;
    display: block;
    height: 100%;
    left: 0px;
    position: absolute;
    top: 0px;
    width: 100%;
    z-index: 1;

    /* CSS3 Box sizing property */
    -moz-box-sizing: border-box;
    -webkit-box-sizing: border-box;
    -o-box-sizing: border-box;
    box-sizing: border-box;

    /* CSS3 transition rules */
    -webkit-transition: all 0.5s ease;
    -moz-transition: all 0.5s ease;
    -o-transition: all 0.5s ease;
    transition: all 0.5s ease;

    /* CSS3 Box Shadow */
    -moz-box-shadow: 2px 2px 4px #444;
    -webkit-box-shadow: 2px 2px 4px #444;
    -o-box-shadow: 2px 2px 4px #444;
    box-shadow: 2px 2px 4px #444;
}


Step3,JS
js/main.js

// add event handler
var addEvent = (function () {
  if (document.addEventListener) {
    return function (el, type, fn) {
      if (el && el.nodeName || el === window) {
        el.addEventListener(type, fn, false);
      } else if (el && el.length) {
        for (var i = 0; i < el.length; i++) {
          addEvent(el[i], type, fn);
        }
      }
    };
  } else {
    return function (el, type, fn) {
      if (el && el.nodeName || el === window) {
        el.attachEvent('on' + type, function () { return fn.call(el, window.event); });
      } else if (el && el.length) {
        for (var i = 0; i < el.length; i++) {
          addEvent(el[i], type, fn);
        }
      }
    };
  }
})();

// inner variables
var dragItems;
updateDataTransfer();
var dropAreas = document.querySelectorAll('[droppable=true]');

// preventDefault (stops the browser from redirecting off to the text)
function cancel(e) {
  if (e.preventDefault) {
    e.preventDefault();
  }
  return false;
}

// update event handlers
function updateDataTransfer() {
    dragItems = document.querySelectorAll('[draggable=true]');
    for (var i = 0; i < dragItems.length; i++) {
        addEvent(dragItems[i], 'dragstart', function (event) {
            event.dataTransfer.setData('obj_id', this.id);
            return false;
        });
    }
}

// dragover event handler
addEvent(dropAreas, 'dragover', function (event) {
    if (event.preventDefault) event.preventDefault();

    // little customization
    this.style.borderColor = "#000";
    return false;
});

// dragleave event handler
addEvent(dropAreas, 'dragleave', function (event) {
    if (event.preventDefault) event.preventDefault();

    // little customization
    this.style.borderColor = "#ccc";
    return false;
});

// dragenter event handler
addEvent(dropAreas, 'dragenter', cancel);

// drop event handler
addEvent(dropAreas, 'drop', function (event) {
    if (event.preventDefault) event.preventDefault();

    // get dropped object
    var iObj = event.dataTransfer.getData('obj_id');
    var oldObj = document.getElementById(iObj);

    // get its image src
    var oldSrc = oldObj.childNodes[0].src;
    oldObj.className += 'hidden';

    var oldThis = this;

    setTimeout(function() {
        oldObj.parentNode.removeChild(oldObj); // remove object from DOM

        // add similar object in another place
        oldThis.innerHTML += '<a id="'+iObj+'" draggable="true"><img src="'+oldSrc+'" /></a>';

        // and update event handlers
        updateDataTransfer();

        // little customization
        oldThis.style.borderColor = "#ccc";
    }, 500);

    return false;
});


如你所见 -- 这些代码并不难,在开头部分,先选择所有的可拖放的元素,然后订阅这些元素的 dragstart 事件的处理方法,主要也就是为了填充传输的数据。然后你也能发现所有可放置的标签我都绑定了dragover以及dragleave以及drop的事件处理。在前两个事件处理中,首先执行一小段css样式来激活可放置新元素的区域,当我们在此区域放开鼠标时,JS首先将新元素放置在对应被激活的区域然后去除一开始被移动的元素。

 

原文链接OSChina.NET 编译



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junwong
发帖于6年前 1回/2K+阅
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