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js拖拽一些常见的思路方法整理

点评:本文主要介绍了js拖拽一些常见的思路方法,需要的朋友可以参考下!

js拖拽的常见思路

1.通过onmousedown,onmousemove,onmouseup分别模拟开始拖拽,拖拽中和拖拽结束时的事件()。

如果手机的触摸事件的话则分别是ontouchstart,ontouchmove和ontouchend。

2.鼠标按下即发生onmousedown事件时:获取鼠标位置,获取被拖动元素的位置,记录两者之间的纵横坐标的差值()。对document元素绑定onmousemove,onmouseup事件。

刚开始接触js拖拽时,我当时疑惑的是为什么是对document绑定而不是对被拖动的元素绑定呢?原来是如果对被拖动元素绑定的话当鼠标拖动过快时,会导致鼠标与被拖动元素的脱离。

3.鼠标拖动即发生onmousemove事件时:将被拖拽元素的position改成绝对位置,这个可以通过left和top改变该元素的位置,从而使得该元素随着鼠标的拖拽而移动。获取鼠标位置,将鼠标x坐标(e.clientX)减去第2步储存的横坐标差作为被拖动元素的left值,将鼠标x坐标(e.clientY)减去第2步储存的纵坐标差作为被拖动元素的top值。实现元素跟随鼠标拖动的效果。

4.鼠标按键弹起即发生onmouseup事件时:清空onmousemove和onmouseup事件

比较流行的拖拽插件dom-drag类库(作者: Aaron Boodman)

其源代码如下

复制代码 代码如下:

/*其中( dom-drag.js )文件**************************************************

* dom-drag.js

* 09.25.2001

* www.youngpup.net

**************************************************

* 10.28.2001 - fixed minor bug where events

* sometimes fired off the handle, not the root.

**************************************************/

var Drag = {

obj : null,

init : function(o, oRoot, minX, maxX, minY, maxY, bSwapHorzRef, bSwapVertRef, fXMapper, fYMapper)

{

o.onmousedown = Drag.start;

o.hmode = bSwapHorzRef ? false : true ;

o.vmode = bSwapVertRef ? false : true ;

o.root = oRoot && oRoot != null ? oRoot : o ;

if (o.hmode && isNaN(parseInt(o.root.style.left ))) o.root.style.left = "0px";

if (o.vmode && isNaN(parseInt(o.root.style.top ))) o.root.style.top = "0px";

if (!o.hmode && isNaN(parseInt(o.root.style.right ))) o.root.style.right = "0px";

if (!o.vmode && isNaN(parseInt(o.root.style.bottom))) o.root.style.bottom = "0px";

o.minX = typeof minX != 'undefined' ? minX : null;

o.minY = typeof minY != 'undefined' ? minY : null;

o.maxX = typeof maxX != 'undefined' ? maxX : null;

o.maxY = typeof maxY != 'undefined' ? maxY : null;

o.xMapper = fXMapper ? fXMapper : null;

o.yMapper = fYMapper ? fYMapper : null;

o.root.onDragStart = new Function();

o.root.onDragEnd = new Function();

o.root.onDrag = new Function();

},

start : function(e)

{

var o = Drag.obj = this;

e = Drag.fixE(e);

var y = parseInt(o.vmode ? o.root.style.top : o.root.style.bottom);

var x = parseInt(o.hmode ? o.root.style.left : o.root.style.right );

o.root.onDragStart(x, y);

o.lastMouseX = e.clientX;

o.lastMouseY = e.clientY;

if (o.hmode) {

if (o.minX != null) o.minMouseX = e.clientX - x + o.minX;

if (o.maxX != null) o.maxMouseX = o.minMouseX + o.maxX - o.minX;

} else {

if (o.minX != null) o.maxMouseX = -o.minX + e.clientX + x;

if (o.maxX != null) o.minMouseX = -o.maxX + e.clientX + x;

}

if (o.vmode) {

if (o.minY != null) o.minMouseY = e.clientY - y + o.minY;

if (o.maxY != null) o.maxMouseY = o.minMouseY + o.maxY - o.minY;

} else {

if (o.minY != null) o.maxMouseY = -o.minY + e.clientY + y;

if (o.maxY != null) o.minMouseY = -o.maxY + e.clientY + y;

}

document.onmousemove = Drag.drag;

document.onmouseup = Drag.end;

return false;

},

drag : function(e)

{

e = Drag.fixE(e);

var o = Drag.obj;

var ey = e.clientY;

var ex = e.clientX;

var y = parseInt(o.vmode ? o.root.style.top : o.root.style.bottom);

var x = parseInt(o.hmode ? o.root.style.left : o.root.style.right );

var nx, ny;

if (o.minX != null) ex = o.hmode ? Math.max(ex, o.minMouseX) : Math.min(ex, o.maxMouseX);

if (o.maxX != null) ex = o.hmode ? Math.min(ex, o.maxMouseX) : Math.max(ex, o.minMouseX);

if (o.minY != null) ey = o.vmode ? Math.max(ey, o.minMouseY) : Math.min(ey, o.maxMouseY);

if (o.maxY != null) ey = o.vmode ? Math.min(ey, o.maxMouseY) : Math.max(ey, o.minMouseY);

nx = x + ((ex - o.lastMouseX) * (o.hmode ? 1 : -1));

ny = y + ((ey - o.lastMouseY) * (o.vmode ? 1 : -1));

if (o.xMapper) nx = o.xMapper(y)

else if (o.yMapper) ny = o.yMapper(x)

Drag.obj.root.style[o.hmode ? "left" : "right"] = nx + "px";

Drag.obj.root.style[o.vmode ? "top" : "bottom"] = ny + "px";

Drag.obj.lastMouseX = ex;

Drag.obj.lastMouseY = ey;

Drag.obj.root.onDrag(nx, ny);

return false;

},

end : function()

{

document.onmousemove = null;

document.onmouseup = null;

Drag.obj.root.onDragEnd( parseInt(Drag.obj.root.style[Drag.obj.hmode ? "left" : "right"]),

parseInt(Drag.obj.root.style[Drag.obj.vmode ? "top" : "bottom"]));

Drag.obj = null;

},

fixE : function(e)

{

if (typeof e == 'undefined') e = window.event;

if (typeof e.layerX == 'undefined') e.layerX = e.offsetX;

if (typeof e.layerY == 'undefined') e.layerY = e.offsetY;

return e;

}

};

二:拖拽排序也是一种常见的效果

常见实现思路

1.将点击进行拖拽的元素转换为绝对路径,同时新建一个临时元素替代其所在的位置。

2.移动过程中通过循环计算鼠标与剩余元素的位置关系,如果鼠标位置处于该元素中时,在该元素的nextSibling前面插入第1步时创建的临时元素;

3.结束时在临时元素前面插入被拖拽元素,删除临时元素。

网上有个冷月无声博主写的挺好的,在此转载一下其代码

以下为其代码

复制代码 代码如下:

(function(win, doc){

var _this = null;

var info = {};

var list = [];

var Sortable = function(opts) {

this.opts = opts;

_this = this;

list = X.getByClass(this.opts.sortClass, doc);

X.addEvent(doc, 'mousedown', this.handleEvent);

X.addEvent(doc, 'mousemove', this.handleEvent);

X.addEvent(doc, 'mouseup', this.handleEvent);

};

Sortable.prototype = {

handleEvent: function(event) {

var e = event || win.event;

var target = event.target || event.srcElement;

switch (event.type) {

case 'mousedown':

X.hasClass(target, _this.opts.sortClass) && _this.downEvent.call(_this, e, target);

break;

case 'mousemove':

info.dObj && _this.moveEvent.call(_this, e, target);

break;

case 'mouseup':

info.dObj && _this.upEvent.call(_this, e, target);

break;

default: break;

}

},

downEvent: function(e, target) {

info.dObj = target;

var off = X.getOffset(target);

target.x = e.clientX - off[0];

target.y = e.clientY - off[1];

target.style.position = 'absolute';

target.style.left = off[0] +'px';

target.style.top = off[1] +'px';

info.vObj = doc.createElement('p');

info.vObj.style.width = off[2] +'px';

info.vObj.style.height = off[3] +'px';

target.parentNode.insertBefore(info.vObj, target);

},

moveEvent: function(e, target) {

win.getSelection ? win.getSelection().removeAllRanges() : doc.selection.empty();

info.dObj.style.left = e.clientX - info.dObj.x +'px';

info.dObj.style.top = e.clientY - info.dObj.y +'px';

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

if(list[i] === info.dObj) {

continue;

}

var off = X.getOffset(list[i]);

if(e.clientX > off[0] && e.clientX < off[0] + off[2] && e.clientY > off[1] && e.clientY < off[1] + off[3]) {

switch (true) {

case e.clientY < (off[1] + off[3]) / 2:

list[i].parentNode.insertBefore(info.vObj, list[i]);

break;

case !list[i].nextSibling:

list[i].parentNode.appendChild(info.vObj);

break;

default:

list[i].parentNode.insertBefore(info.vObj, list[i].nextSibling);

break;

}

}

}

},

upEvent: function(e, target) {

info.dObj.style.position = 'static';

info.vObj.parentNode.insertBefore(info.dObj, info.vObj);

info.dObj.parentNode.removeChild(info.vObj);

info = {};

}

};

win.Sortable = Sortable;

})(window, document);