Opera Style Link Drag

OperaStyle_linkDragSelection.uc.js

// ==UserScript==
// @name     Opera Style Link Drag
// @author   Griever satyr
// @include  main
// @include  chrome://global/content/viewSource.xul
// @include  chrome://global/content/viewPartialSource.xul
// @version  0.0.1.20100421
// ==/UserScript==
Array.forEach(document.querySelectorAll('tabbrowser, browser'), function(b){
  b.addEventListener('mousedown', this, true);
}, function OSLD_down(e){
  if(e.button !== 0 || e.altKey || e.metaKey ||
     e.explicitOriginalTarget.nodeType !== document.TEXT_NODE) return;

  var link = e.target;
  do if(link instanceof HTMLAnchorElement) break;
  while(link = link.parentNode);
  if(!link) return;

  e.stopPropagation();

  var {screenX: x, screenY: y} = e, sleep = true;

  listen1(this, 'mousemove', function OSLD_move(e){
    // cancel drag if moving horizontally (30 degree > elevation angle)
    if(Math.tan(Math.PI/6) > Math.abs((e.screenY - y) / (e.screenX - x)))
      link.setAttribute('draggable', false);
    sleep = false;
  }, true);

  listen1(this, 'mouseup', function OSLD_up(e){
    sleep = false;
    link.removeAttribute('draggable');
    // cancel click if still on same link and selected
    var sel = e.view.getSelection();
    if(sel.isCollapsed) return;
    var {target} = e;
    do if(target === link) break; while(target = target.parentNode);
    if(!target) return;
    var node = e.explicitOriginalTarget;
    for(let i = sel.rangeCount; i--;) let(rng = sel.getRangeAt(i)){
      if(rng.startContainer !== node && rng.endContainer !== node) continue;
      listen1(this, 'click', function OSLD_click(e){
        e.preventDefault();
        e.stopPropagation();
      }, true);
      return;
    }
  }, true);

  setTimeout(function(){ sleep = false; }, 8e3); // safety net

  // hold mousedown
  var thread = Cc['@mozilla.org/thread-manager;1'].getService().currentThread;
  while(sleep) thread.processNextEvent(true);

  function listen1(target, type, listener, capture){
    target.addEventListener(type, function listener1(event){
      target.removeEventListener(type, listener1, capture);
      listener.call(this, event);
    }, capture);
  }
});