zotero/chrome/content/zotero/xpcom/file.js

/*
    ***** BEGIN LICENSE BLOCK *****
    
    Copyright (c) 2006  Center for History and New Media
                        George Mason University, Fairfax, Virginia, USA
                        http://chnm.gmu.edu
    
    Licensed under the Educational Community License, Version 1.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at
    
    http://www.opensource.org/licenses/ecl1.php
    
    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
    
    ***** END LICENSE BLOCK *****
*/

Zotero.File = new function(){
	this.getExtension = getExtension;
	this.getSample = getSample;
	this.getContents = getContents;
	this.getCharsetFromFile = getCharsetFromFile;
	this.addCharsetListener = addCharsetListener;
	
	
	function getExtension(file){
		var pos = file.leafName.lastIndexOf('.');
		return pos==-1 ? '' : file.leafName.substr(pos+1);
	}
	
	
	/*
	 * Get the first 128 bytes of the file as a string (multibyte-safe)
	 */
	function getSample(file){
		var fis = Components.classes["@mozilla.org/network/file-input-stream;1"].
			createInstance(Components.interfaces.nsIFileInputStream);
		fis.init(file, false, false, false);
		
		const replacementChar
			= Components.interfaces.nsIConverterInputStream.DEFAULT_REPLACEMENT_CHARACTER;
		var is = Components.classes["@mozilla.org/intl/converter-input-stream;1"]
			.createInstance(Components.interfaces.nsIConverterInputStream);
		is.init(fis, "UTF-8", 128, replacementChar);
		var str = {};
		var numChars = is.readString(512, str);
		is.close();
		
		return str.value;
	}
	
	
	function getContents(file, charset){
		var fis = Components.classes["@mozilla.org/network/file-input-stream;1"].
			createInstance(Components.interfaces.nsIFileInputStream);
		fis.init(file, false, false, false);
		
		if (charset){
			charset = Zotero.CharacterSets.getName(charset);
		}
		
		if (!charset){
			charset = "UTF-8";
		}
		
		const replacementChar
			= Components.interfaces.nsIConverterInputStream.DEFAULT_REPLACEMENT_CHARACTER;
		var is = Components.classes["@mozilla.org/intl/converter-input-stream;1"]
			.createInstance(Components.interfaces.nsIConverterInputStream);
		is.init(fis, charset, 1024, replacementChar);
		
		var contents = [], str = {};
		while (is.readString(4096, str) != 0) {
			contents.push(str.value);
		}
		
		is.close();
		
		return contents.join();
	}
	
	
	/*
	 * Not implemented, but it'd sure be great if it were
	 */
	function getCharsetFromString(str){
		
	}
	
	
	/*
	 * An extraordinarily inelegant way of getting the character set of a
	 * text file using a hidden browser
	 *
	 * I'm quite sure there's a better way
	 *
	 * Note: This is for text files -- don't run on other files
	 *
	 * 'callback' is the function to pass the charset (and, if provided, 'args')
	 * to after detection is complete
	 */
	function getCharsetFromFile(file, mimeType, callback, args){
		if (!file || !file.exists()){
			return false;
		}
		
		if (mimeType.substr(0, 5)!='text/' ||
			!Zotero.MIME.hasInternalHandler(mimeType, this.getExtension(file))){
			return false;
		}
		
		var browser = Zotero.Browser.createHiddenBrowser();
		
		var url = Components.classes["@mozilla.org/network/protocol;1?name=file"]
				.getService(Components.interfaces.nsIFileProtocolHandler)
				.getURLSpecFromFile(file);
		
		this.addCharsetListener(browser, callback, args);
		
		browser.loadURI(url);
	}
	
	
	/*
	 * Attach a load listener to a browser object to perform charset detection
	 *
	 * We make sure the universal character set detector is set to the
	 * universal_charset_detector (temporarily changing it if not--shhhh)
	 *
	 * 'callback' is the function to pass the charset (and, if provided, 'args')
	 * to after detection is complete
	 */
	function addCharsetListener(browser, callback, args){
		var prefService = Components.classes["@mozilla.org/preferences-service;1"]
							.getService(Components.interfaces.nsIPrefBranch);
		var oldPref = prefService.getCharPref('intl.charset.detector');
		var newPref = 'universal_charset_detector';
		//Zotero.debug("Default character detector is " + (oldPref ? oldPref : '(none)'));
		
		if (oldPref != newPref){
			//Zotero.debug('Setting character detector to universal_charset_detector');
			prefService.setCharPref('intl.charset.detector', 'universal_charset_detector');
		}
		
		browser.addEventListener("pageshow", function(){
			var charset = browser.contentDocument.characterSet;
			Zotero.debug("Detected character set '" + charset + "'");
			
			//Zotero.debug('Resetting character detector to ' + (oldPref ? oldPref : '(none)'));
			prefService.setCharPref('intl.charset.detector', oldPref);
			
			callback(charset, args);
			
			Zotero.Browser.deleteHiddenBrowser(browser);
		}, false);
	}
}