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function initialize_sorting() {
function sortable(elem) {
switch(elem.tagName) {
case "DIV":
switch(elem.className) {
case "fun":
case "lin":
case "lincat":
case "oper":
return elem;
default:
return null;
}
default:
return sortable(elem.parentNode)
}
}
function move_element(elem,x,y) {
elem.style.left=x+"px";
elem.style.top=y+"px";
elem.delta={x:x,y:y};
}
function adjust_refs(elem,dy) {
//jsdebug("dy="+dy);
move_element(elem,elem.delta.x,elem.delta.y-dy);
elem.downAt.y+=dy;
elem.range.lo-=dy;
elem.range.hi-=dy;
}
function move_up(elem) {
var prev=elem.previousSibling;
if(prev) {
var top=elem.offsetTop;
var mid=prev.offsetTop+prev.offsetHeight/2;
if(top<mid) {
elem.parentNode.insertBefore(elem,prev);
adjust_refs(elem,elem.offsetTop-top)
}
//else jsdebug("not yet, top="+top+", mid="+mid);
}
//else jsdebug("at top");
}
function move_down(elem) {
var next=elem.nextSibling;
if(next) {
var top=elem.offsetTop;
var bot=top+elem.offsetHeight;
var mid=next.offsetTop+next.offsetHeight/2;
if(bot>mid) {
next.parentNode.insertBefore(next,elem);
adjust_refs(elem,elem.offsetTop-top)
}
//else jsdebug("not yet, top="+top+", bot="+bot+", mid="+mid);
}
//else jsdebug("at bottom");
}
function swap(elem,dy) {
if(dy>0) move_down(elem);
else if(dy<0) move_up(elem);
}
function restrictTo(range,y) {
return Math.min(range.hi,Math.max(range.lo,y));
}
function startDrag(event,elem) {
//jsdebug("Start dragging");
elem.style.position="relative";
elem.delta || (elem.delta={x:0,y:0});
elem.downAt={x:event.screenX-elem.delta.x,y:event.screenY-elem.delta.y};
var list=elem.parentNode;
var top=list.offsetTop-elem.offsetTop+elem.delta.y;
elem.range={lo:top,hi:top+list.offsetHeight-elem.offsetHeight};
elem.style.zIndex=1;
document.onmousemove=function(event) {
var dx=0/*event.screenX-elem.downAt.x*/;
var dy=restrictTo(elem.range,event.screenY-elem.downAt.y);
//jsdebug("dragging to "+dx+" "+dy+" "+show_props(elem.range,"range"));
move_element(elem,dx,dy);
//jsdebug("dragging to "+elem.offsetLeft+" "+elem.offsetTop);
swap(elem,dy)
return false;
}
document.onmouseup=function() {
//jsdebug("dropped");
elem.style.zIndex=0;
move_element(elem,0,0);
document.onmousemove=null;
document.onmouseup=null;
if(list.onsort) list.onsort();
else jsdebug("no list.onsort "+list.className+" "+list.firstChild.ident);
return false;
}
return false;
}
function mousedown(event) {
var elem=sortable(event.target);
if(elem) return startDrag(event,elem);
//else jsdebug("Clicked outside"/*+taglist(event.target)/*+show_props(event,"event")*/);
}
var jsdebug=debug;
function init() {
document.onmousedown=mousedown;
//var d=element("javascriptdebug");
//if(d) jsdebug=function(msg) { d.innerHTML=msg; }
}
init();
}
initialize_sorting();
//Inspired by http://tool-man.org/examples/sorting.html
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