我目前正在开发一个应用程序，支持拖放使用此code进行拖放操作。问题是我需要相应地移动连接线，我无法弄清楚如何让X和Y坐标改变x1 / y1对或x2 / y2对来更新线。
我已经尝试使用其边界框询问元素的位置，并且数字与拖放后的实际位置不匹配。
任何想法我怎样才能实现这一目标？ （鉴于代码中计算的信息，上面链接）
答案 0 :(得分：1)
您可以将元素插入到SVG“Wrapper”中，而不是转换元素的BBox，然后获取其中的bbox。
我重写了您的示例并添加到HTML5文档中。我包含了一个svg包装元素，每个圆圈的中心附有三条线。当它拖动线跟随。 如下所示。 （注意：Chrome会在文本元素上挂起）
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Drag And Drop</title>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
</head>
<body style='padding:10px;font-family:arial'>
<center>
<h4>Drag And Drop</h4>
<div style='width:90%;background-color:gainsboro;text-align:justify;padding:10px;border-radius:6px;'>
A nice little demo of drag-and-drop functionality in SVG,
written by Doug Schepers on February 16, 2004.
Use or misuse this code however you wish.</div>
<table><tr>
<td>
<div id="svgDiv" style='background-color:lightgreen;width:600px;height:300px;'>
<svg width='100%' height='100%' xmlns='http://www.w3.org/2000/svg' id="mySVG"
onload='Init(evt)'
onmousedown='Grab(evt)'
onmousemove='Drag(evt)'
onmouseup='Drop(evt)'>
<rect id='BackDrop' x='-10%' y='-10%' width='110%' height='110%' fill='none' pointer-events='all' />
<circle id='BlueCircle' cx='25' cy='25' r='20' style='fill:blue; '/>
<circle id='RedCircle' cx='125' cy='25' r='20' style='fill:red; '/>
<circle id='OrangeCircle' cx='225' cy='25' r='20' style='fill:orange; '/>
<text id='DraggableText' x='20' y='200' style='fill:red; font-size:18px; font-weight:bold;'>Draggable Text</text>
<rect id='GreenRectangle' x='50' y='70' width='100' height='100' style='fill:green; '/>
<g id='Folder'>
<rect id='FolderRectangle' x='300' y='100' width='200' height='150' style='fill:tan; stroke:brown; stroke-width:3;'/>
</g>
<svg id="Wrapper" />
<line id=blueLine stroke=blue stroke=3 x1=25 y1=25 x2=25 y2=25 />
<line id=redLine stroke=red stroke=3 x1=125 y1=25 x2=125 y2=25 />
<line id=orangeLine stroke=orange stroke=3 x1=225 y1=25 x2=225 y2=25 />
</svg>
</div>
</td>
</tr></table>
<br />SVG Source:<br />
<textarea id=svgSourceValue style='font-size:110%;font-family:lucida console;width:90%;height:200px'></textarea>
<br />Javascript:<br />
<textarea id=jsValue style='border-radius:26px;font-size:110%;font-weight:bold;color:midnightblue;padding:16px;background-color:beige;border-width:0px;font-size:100%;font-family:lucida console;width:90%;height:400px'></textarea>
</center>
<div id='browserDiv' style='padding:5px;position:absolute;top:5px;left:5px;background-color:gainsboro;'>OK in:IE11/FF23...*CH hangs<br /></div>
<script id=myScript>
//var SVGDocument = null;
//var SVGRoot = null;
var TrueCoords = null;
var GrabPoint = null;
var BackDrop = null;
var DragTarget = null;
var DragLine = null;
function Init(evt)
{
//SVGDocument = evt.target.ownerDocument;
//SVGRoot = SVGDocument.documentElement;
// these svg points hold x and y values...
// very handy, but they do not display on the screen (just so you know)
TrueCoords = mySVG.createSVGPoint();
GrabPoint = mySVG.createSVGPoint();
// this will serve as the canvas over which items are dragged.
// having the drag events occur on the mousemove over a backdrop
// (instead of the dragged element) prevents the dragged element
// from being inadvertantly dropped when the mouse is moved rapidly
// BackDrop = SVGDocument.getElementById('BackDrop');
}
function Grab(evt)
{
// find out which element we moused down on
var targetElement = evt.target;
// you cannot drag the background itself, so ignore any attempts to mouse down on it
if ( BackDrop != targetElement )
{
//set the item moused down on as the element to be dragged
DragTarget = targetElement;
Wrapper.appendChild(DragTarget)
if(DragTarget.id=="BlueCircle")
DragLine=blueLine
if(DragTarget.id=="RedCircle")
DragLine=redLine
if(DragTarget.id=="OrangeCircle")
DragLine=orangeLine
// move this element to the "top" of the display, so it is (almost)
// always over other elements (exception: in this case, elements that are
// "in the folder" (children of the folder group) with only maintain
// hierarchy within that group
DragTarget.parentNode.appendChild( DragTarget );
// turn off all pointer events to the dragged element, this does 2 things:
// 1) allows us to drag text elements without selecting the text
// 2) allows us to find out where the dragged element is dropped (see Drop)
DragTarget.setAttributeNS(null, 'pointer-events', 'none');
// we need to find the current position and translation of the grabbed element,
// so that we only apply the differential between the current location
// and the new location
var transMatrix = DragTarget.getCTM();
GrabPoint.x = TrueCoords.x - Number(transMatrix.e);
GrabPoint.y = TrueCoords.y - Number(transMatrix.f);
}
};
function Drag(evt)
{
// account for zooming and panning
GetTrueCoords(evt);
// if we don't currently have an element in tow, don't do anything
if (DragTarget)
{
// account for the offset between the element's origin and the
// exact place we grabbed it... this way, the drag will look more natural
var newX = TrueCoords.x - GrabPoint.x;
var newY = TrueCoords.y - GrabPoint.y;
BB=Wrapper.getBBox()
var bbx=BB.x
var bby=BB.y
var bbw=BB.width
var bbh=BB.height
Cx=bbx+.5*bbw
Cy=bby+.5*bbh
DragLine.x2.baseVal.value=Cx
DragLine.y2.baseVal.value=Cy
// apply a new tranform translation to the dragged element, to display
// it in its new location
DragTarget.setAttributeNS(null, 'transform', 'translate(' + newX + ',' + newY + ')');
}
};
function Drop(evt)
{
// if we aren't currently dragging an element, don't do anything
if ( DragTarget )
{ mySVG.appendChild(DragTarget) //--remove from Wrapper---
// since the element currently being dragged has its pointer-events turned off,
// we are afforded the opportunity to find out the element it's being dropped on
var targetElement = evt.target;
// turn the pointer-events back on, so we can grab this item later
DragTarget.setAttributeNS(null, 'pointer-events', 'all');
if ( 'Folder' == targetElement.parentNode.id )
{
// if the dragged element is dropped on an element that is a child
// of the folder group, it is inserted as a child of that group
targetElement.parentNode.appendChild( DragTarget );
//alert(DragTarget.id + ' has been dropped into a folder, and has been inserted as a child of the containing group.');
}
else
{
// for this example, you cannot drag an item out of the folder once it's in there;
// however, you could just as easily do so here
//alert(DragTarget.id + ' has been dropped on top of ' + targetElement.id);
}
// set the global variable to null, so nothing will be dragged until we
// grab the next element
DragTarget = null;
}
svgSourceValue.value=svgDiv.innerHTML
};
function GetTrueCoords(evt)
{
// find the current zoom level and pan setting, and adjust the reported
// mouse position accordingly
var newScale = mySVG.currentScale;
var translation = mySVG.currentTranslate;
TrueCoords.x = (evt.clientX - translation.x)/newScale;
TrueCoords.y = (evt.clientY - translation.y)/newScale;
};
</script>
<script>
document.addEventListener("onload",init(),false)
function init()
{
svgSourceValue.value=svgDiv.innerHTML
jsValue.value=myScript.text
}
</script>
</body>
</html>