gfse: add missing file sort.js to the repository

src/www/gfse/sort.js

@@ -0,0 +1,122 @@
+
+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