// Image Protect, JavaScript. // For The NEUMES Project website. // Copyright 2004-2006 by Louis W. G. Barton // Do not change the line saying 'copyright notice' /* Filename: imageprotect.js * Copyright Notice: * Copyright 2005-2006, Louis W. G. Barton. * All rights reserved. */ // Version: 5 January 2006 /* * Abstract * ======== * This script should be included in the section of all HTML documents of the * NEUMES website. * The primary purpose is to intercept attempts by users to save images to local disk and * display a copyright notice instead. Image saving mechanisms vary between platforms and * browsers, such as right-click on an image (Windows and Linux), image drag to the desktop * (Mac), image drag to Word (IE), or holding down the Ctrl button while clicking (Mac). * This functionality of this script needs to be supplemented on each page by the meta-tags, (prevents use of links directly to images) * Obviously, the interception does not work if the user has JavaScript turned off; a workaround * is to allow access to sensitive pages only via JavaScript. A further deterent is to stop * local caching of images by: (this, however, slows image access) * and/or, * This script does not work in Opera 5- and Omniweb; therefore, if possible, detect these two * browsers, and disable caching (use JS document.write() of META tag in the HEAD). * * Since it can be relied upon that, this script is in every page of the website, additional * functionality can be added here without having to insert it in pages individually. * Additional functionality: * 1/ Check whether the page is being framed inside a non-NEUMES Project webpage, * in which case the page gets replaced immediately by a violation warning page. * * WARNING: The event handlers registered here for onMouseDown, onMouseUp, and onMouseMove might * conflict with event handlers registered on particular pages of the website; be aware of * potential conflicts, and adjust sourcecode accordingly. (The NEUMEs website makes frequent * use of onMouseOver, onMouseOut, and onClick for hyperlink control.) A solution to conflicts * might be for other scripts defined AFTER this one to add code to a handler by this pattern: function addLoadEvent(func) { var oldonload=window.onload; if (typeof window.onload != 'function') { window.onload=func; } else { window.onload=function() { oldonload(); func(); } } } //end, addLoadEvent() ... addLoadEvent(nameOfSomeFunctionToRunOnPageLoad); * * Limitations * =========== * Does not work in Opera 5- and Omniweb. Does not work in Opera 7.20 because this browser does * not detect right-clicks at all. Detecting whether the user calls up the 'special' menu is * impossible in Internet Explorer on Mac. When the image is also a link, this script is much * less reliable. If the image is inside a link, this script does not work in Netscape 4. * * Usage * ===== * In the section of an HTML document, write: * * Implementation Notes * ==================== * Cases to consider: * 1/ User drags image to desktop or another app * 1.a/ MAC, any browser other than NS4 * 1.b/ MAC, NS4 (events cannot be registered on images) * 1.c/ IE, any ver * 2/ User clicks on image * In JavaScript, names of variables and functions in a script are particular to the document * in which the script is defined. Therefore, each document containing this script will have * its own copies of these names, and no confusion should arise. * In NS4, event handlers can only be registered to layers. viz., a DIV or a similar HTML * element that has position: absolute in the style sheet. * Three event models: * 1) Netscape Navigator 4 (NN4); * 2) Internet Explorer 4 and later for Macintosh and Windows (IE4+); and * 3) W3C DOM, as implemented in Netscape Navigator 6. * There are five binding techniques implemented in various browser versions. * TO DO: * if not top.getFramesState() or top.getFramesState()!='no' then reopen this page in frames. * * Semantic Designs Obfuscator Notes: * String literals should get encrypted. * Callback fns must be added to reserved-names list. * RegExp for copyright notice (at bottom of file) is added to Comment Filter in the GUI * (blanks and punctuation escaped). * * * oncontextmenu: supported by IE5+ only: The right mouse button (or its equivalent keyboard * sequence) has been activated for an element. * onselectstart: supported by IE4+ only. Content selection has begun. * ondragstart: supported by IE4+ only. Notifies the source element when a drag operation begins. */ /* ************************** *** GLOBAL VARIABLES *** ************************** */ var img_prot_initialized=false; // whether mousedown events have been registered for images var img_prot_drag=false; // sense drag: set true when OnMouseDown; clear false when OnMouseUp var img_prot_ckLoadedTimer=null; // timer for periodic check of whether document has loaded var img_prot_msg1='Please do not copy images or other intellectual property from this website.' + '\n\nAll content of this website is protected by one or more of ' + 'the following copyrights, or by other copyrights on particular pages.\n' + 'Copyright 2005-2006, The University of Oxford.\n' + 'Copyright 2003-2005 by Louis W. G. Barton.\n'; var img_prot_msg2='Copyright 2002-2003 by The President and Fellows of Harvard College;\n' + 'contains software or other intellectual property licensed from Louis W. G. Barton,\n' + 'copyright 1995-2001 by Louis W. G. Barton.'; var img_prot_msg3='\n\nExcept where otherwise stated, the content is provided only as ' + 'reference material for educational, cultural, and non-commercial purposes.'; /* ******************* *** FUNCTIONS *** ******************* */ /* FN: SET MOUSE DRAG * * This flag gets set OnMouseDown. * This must be done regardless of whether event registration is on images or on the document. */ function img_prot_mousedown() { img_prot_drag=true; } //end, img_prot_mousedown() /* FN: CLEAR MOUSE DRAG * * This flag gets cleared OnMouseUp. * This must be done regardless of whether event registration is on images or on the document, * because MouseUp might trigger outside an image. */ function img_prot_mouseup() { img_prot_drag=false; } //end, img_prot_mouseup() /* TEMP DUMMY: */ function img_prot_register() { } /* Initially, register OnMouseDown, check whether events have been registered for images in this document. * The document.onmousedown event is supported by (all): * IE 5 and 6 (Windows); IE 5.2 Mac; Mozilla 1.75; Safari 1.3; Opera 8; and Netscape 4. * Remark that Netscape 4 requires captureEvents() to be registered on the window. * MouseDown is the most useful event because almost all properties that should work with * all events actually work with MouseDown only. Use it instead of onClick. */ if (document.getElementsByTagName) { // Level 1 DOM document.onmousedown=img_prot_register; } else if (document.all) { // IE4 document.onmousedown=img_prot_register; } else if (document.layers) { // NS4 document.onmousedown=img_prot_register; window.captureEvents(Event.MOUSEDOWN); // required, case-sensitive } //end, if/else /* FN: MOUSE MOVE * * Invoke by OnMouseDown event. Check whether image events have been registered for this window. * If not registered yet, then call img_prot_init(). * Remark: it would be preferable to just register image events after the document is loaded, * but that would entail adding code to every page in the website; by triggering image-event * registration upon the first OnMouseDown event, website maintenance is simplified. */ function img_prot_mouseMove() { if (true == self.img_prot_initialized) { return true; // mouse event not handled (continue) } else { self.img_prot_init(); // initialize event handling on images self.img_prot_initialized=true; // set flag = has been done return true; // mouse event not handled (continue) } //end, if/else } //end, img_prot_mouseMove() // To-do: onunload, remove event handlers in order to avoid memory leak. /* FN: CHECK FOR DOCUMENT LOADED * * Check whether the document has loaded, viz., that the BODY node exists. * If not, then wait for a time and try this again. * If loaded, then call initialization function. * Remarks: * It might be preferable to invoke this function by the onload event, but doing so would * involve maintenance on many files of the website. An advantage of this method is that, * it will run when the BODY node is created, which is sooner than onload, which (at least, * in principle) runs when all images, Java Applets, etc., have been loaded. * The advantage of using item() instead of directly referencing the slot in the collection is * that item() returns a null value if the index supplied is invalid or the element in question * is not within the collection. This is often more desirable than the error message you might * get when referencing a nonexistent slot in the collection. */ function img_prot_ckLoaded() { var bodyNodeArr=null; // array, element bodyNodeArr[0] will be the BODY node if (!document.getElementsByTagName) { // pre-NS4 browser, can't handle it return false; } bodyNodeArr=document.getElementsByTagName('body'); if (null == bodyNodeArr.item(0)) { // Wait a second, then try again: img_prot_ckLoadedTimer=setTimeout('img_prot_ckLoaded();', 1000); return true; } else { clearTimeout(img_prot_ckLoadedTimer); // help avoid memory leak img_prot_init(); return false; } } //end, img_prot_ckLoaded() /* FN: IMAGE PROTECT INITIALIZE * * Capture event on images (for NS4, events on images are not supported; capture events on entire document.) * The core of this function executes just once per document after the document has loaded. * Remarks: */ function img_prot_init() { // If we get here, then BODY node should have been parsed. var imgs=null; // array of image objects if (!(document.getElementById || document.all || document.layers)) { return; } // overkill document.onmousedown=img_prot_mousedown; // register event handler document.onmouseup=img_prot_mouseup; // register event handler if(document.getElementsByTagName) { // Level 1 DOM imgs=document.getElementsByTagName('img'); } else if(document.all) { // IE4 imgs=document.all.tags('img'); } else { // NS4 document.captureEvents(Event.MOUSEMOVE); document.onmousedown=img_prot_register; window.captureEvents(Event.MOUSEDOWN); // required, case-sensitive return true; // event not handled (continue); shouldn't get here } for (var i=0; i < imgs.length; i++) { if(navigator.appName == 'Netscape') { // do this only once imgs[i].captureEvents(Event.MOUSEDOWN); // is this necessary? } imgs[i].onmousedown=img_prot_click; } img_prot_initialized=true; // set flag = has been done return false; } //end, img_prot_init() /* FN: IMAGE PROTECT CLICK * * If right-click on image, then issue an alert and stop; else continue. */ function img_prot_click(e) { var img_prot_msg=img_prot_msg1 + img_prot_msg2 + img_prot_msg3; if(navigator.appName == 'Netscape' && (e.which == 2 || e.which == 3)) { alert(img_prot_msg); return(false); } else if(navigator.appName == 'Microsoft Internet Explorer' && (event.button == 2 || event.button == 3)) { alert(img_prot_msg); return(false); } return false; // event handled (stop) } //end, img_prot_click() /* ********************* *** INLINE CODE *** ********************* */ /* If the page is being framed inside a non-NEUMES Project webpage, then replace * the page by a violation warning page. */ if (top.location.hostname != self.location.hostname) { window.location.replace('http://purl.oclc.org/SCRIBE/NEUMES/violation.htm'); } //end, if /* After half second from now, check whether document is loaded: * [position this after img_prot_ckLoaded() has been defined] */ img_prot_ckLoadedTimer=setTimeout('img_prot_ckLoaded();', 500); //window.onmousedown=right; //=== // With few exceptions, event handlers can only be registered to layers. // In this context a layer is a DIV or a similar HTML element that has position: absolute in the // style sheet. //window.captureEvents() //layer.captureEvents() //document.captureEvents() // click doesn't work on Linux /* Detecting which key has been pressed is not (yet) possible in Konqueror/Safari, iCab and * Opera 5 on Mac. * Remark: Only one event handler can be registered per event. Registering a second handler on * an event over-rides the first handler. * Never EVER use a browser detect. This is the fastest way to hell. Any script that uses * navigator.userAgent for event model detection is worse than useless. */ /* FN: ENCRYPT STRING LITERALS * * This function is required by Thicket(r) obfuscator for string encryption. * This function must be positioned at the end of the sourcecode. */ function Ol(O2) /* Ol Copyright (C) 2003 Semantic Designs; All Rights Reserved SD ECMAScript Obfuscator customers may use this provided copyright text retained in unobfuscated source */ { var l2="",O3=9; for ( var l1=0; l1>0)+O4; } return l2; } //end, Ol() /*[end, imageprotect.js]*/