Creating Applications with Mozilla-Chapter 11. Localization-P3

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Creating Applications with Mozilla-Chapter 11. Localization-P3

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Nội dung Text: Creating Applications with Mozilla-Chapter 11. Localization-P3

  1. Chapter 11. Localization-P3 11.4.4. Localizable Resources in HTML As a web application, Mozilla permits seamless integration of web content, both local and remote, in many formats. If you have verbose text that just needs to be displayed somewhere in the framework of your application, HTML or XML content may be ideal for this purpose. Through the use of XUL content widgets, such as and , you have ready-made frames to slot your content into: Therefore, a simple modification of xFly.html with a local language leaves the main application untouched. Some other uses of HTML or XML content include an "About" dialog/page, Help pages, a wizard interface, or a getting started/introduction page. 11.4.5. Localizable Resources in RDF Strings to be converted in RDF content can take more than one form. You can use entities directly in your RDF file or have the text inline in your node descriptions. Whichever method you choose, you must ensure that the file is installed in the right place in the tree and registered correctly for the application to pick up on it. As an XML markup, RDF can handle inline entity definitions. These entity definitions have been covered thoroughly in the chapter so far. Example 11-
  2. 8 looks at localizable strings contained directly in RDF node descriptions. This example is taken from the Help table of contents in the Mozilla tree. Example 11-8. RDF Description node with localizable text The text in the nc:name attribute is the text that will be changed. Note that this issue of text in RDF is separate from the topic of using RDF as the mechanism in the chrome registry to register your locale and set up a switching mechanism. This difference is addressed in the next section. 11.5. The Chrome Registry and Locale
  3. Your application is built and you're ready to upload your shiny new Mozilla program to your server for download. The last piece of the puzzle, locale versions, has been put in place. With the structures that Mozilla has in place, it no longer has to be an afterthought. Once you have the translated files, you need to make the decision about how you want to distribute your language versions, the languages you want to make available to the users, and the level of customization that you want to give to them. In this section, we look at how the Mozilla application suite handles the chrome's locale component. Then you see how to apply these chrome registry structures and utilities on a more generic level for your application. 11.5.1. The Directory Structure A typical application chrome structure looks like the directory structure in Figure 11-2. A folder for each language is under the locale directory. The general format is that each language has a unique identifier based on country code and the region. This conforms to the ISO-639 two-letter code with ISO- 3166 two-letter country code standards. The W3C site has good resources that provide information about the ISO-639 and ISO-3166 standards at HTML-tags.html. For example, the unique identifier for Scots, Great Britain, is Sc-GB. The first code, Sc, is for the Scots (Scottish) dialect, and the second code, GB, is for the country code for Great Britain. This is the standard that Mozilla follows. Figure 11-2. Locale's placement in typical chrome layout
  4. The folder that is registered is the language folder, which is what has to be changed on an install. Thus, the URL chrome://package/locale actually points to package/locale/en-US or whichever language is turned on at the time. The language folder may in turn include subfolders that contain logical units for your application. 11.5.2. Interaction with the Chrome Registry As pointed out in Chapter 6, your packages directories need to be registered as chrome with the chrome registry. The first step is to ensure that the entry for your package component is in the file chrome.rdf in the root chrome directory. A resource:/ URL points to the folder for your files to be picked up and recognized by the chrome mechanism and accessed via chrome:// URLs in your application code. The locale is no exception.
  5. c:baseURL="resource:/chrome/xfly/locale/en- US/"> c:localeVersion="" A built-in versioning system in the chrome registry uses c:localeVersion descriptor, if you plan on distributing multiple language packs for your application. Other descriptors are available if you choose to use them: display name (c:displayName), internal name (c:name), location type (c:locType), and author (c:author). 11.5.3. Distribution Language distribution may not be an issue for you. If, for example, your application were only going to be localized into a finite number of languages, bundling each of them up with the main installer would be most convenient. If, however, the need for new language versions arises at various intervals in the release process, you need to find a way to make them available and install them on top of an existing installation. For example, as more people from various locations in the world are becoming aware of the Mozilla project, they want to customize it into their own language. Here are the steps that you need to take to set up your version. 1. Register as a contributor and set up the resources that you need, if any (web page, mailing list). This will ensure that you are added to the project page on the site.
  6. 2. Get a copy of Mozilla to test either via a binary distribution or by downloading and building your own source (see Appendix A for more information). 3. Translate the files. 4. Package your new files for distribution. 5. Test and submit your work. Step 4, the packaging of the new language pack, is discussed next. Mozilla's Cross-Platform Install (XPI) is the ideal candidate for achieving this packaging. This method is discussed extensively in Chapter 6. This distribution method provides great flexibility and has the benefit of being native to Mozilla, thus bypassing the search for external install technologies for your application. The anatomy of an install script Example 11-9 presents a script that is based on the Mozilla process that distributes localized language packs. It presumes that there is a single JAR file for the language that is installed and registered in the Mozilla binary's chrome root. The XPI archive consists of the JAR file in a bin/chrome directory and the install.js file, together in a compressed archive with an .xpi extension. Simply clicking on a web page link to this file invokes the Mozilla software installation service and installs your language. For convenience, inline comments in Example 11-9 explain what is happening. Example 11-9. The locale XPI install script, install.js function verifyDiskSpace(dirPath, spaceRequired)
  7. { var spaceAvailable; spaceAvailable = fileGetDiskSpaceAvailable(dirPath); spaceAvailable = parseInt(spaceAvailable / 1024); if(spaceAvailable < spaceRequired) { logComment("Insufficient disk space: " + dirPath); logComment(" required : " + spaceRequired + " K"); logComment(" available: " + spaceAvailable + " K"); return(false); } return(true); } // platform detection function getPlatform( ) { var platformStr; var platformNode; if('platform' in Install) { platformStr = new String(Install.platform);
  8. if (!^Macintosh/)) platformNode = 'mac'; else if (!^Win/)) platformNode = 'win'; else platformNode = 'unix'; } else { var fOSMac = getFolder("Mac System"); var fOSWin = getFolder("Win System"); logComment("fOSMac: " + fOSMac); logComment("fOSWin: " + fOSWin); if(fOSMac != null) platformNode = 'mac'; else if(fOSWin != null) platformNode = 'win'; else platformNode = 'unix'; } return platformNode; } // Size in KB of JAR file
  9. var srDest = 500; var err; var fProgram; var platformNode; platformNode = getPlatform( ); // -- - LOCALIZATION NOTE: translate only these - - - // These fields are changeable in this generic script var prettyName = "Irish"; var langcode = "ie"; var regioncode = "GA"; var chromeNode = langcode + "-" + regioncode; // -- - END LOCALIZABLE RESOURCES -- - // build the paths and file names for registry and chrome:// url access var regName = "locales/mozilla/" + chromeNode; var chromeName = chromeNode + ".jar"; var regionFile = regioncode + ".jar"; var platformName = langcode + "-" + platformNode + ".jar"; var localeName = "locale/" + chromeNode + "/"; // Start the installation
  10. err = initInstall(prettyName, regName, ""); logComment("initInstall: " + err); fProgram = getFolder("Program"); logComment("fProgram: " + fProgram); // Check disk space using utility function at the start of the script if (verifyDiskSpace(fProgram, srDest)) { err = addDirectory("", "bin", fProgram, ""); logComment("addDirectory( ) returned: " + err); // register chrome var cf = getFolder(fProgram, "chrome/"+chromeName); var pf = getFolder(fProgram, "chrome/"+platformName); var rf = getFolder(fProgram, "chrome/"+regionFile); var chromeType = LOCALE | DELAYED_CHROME; registerChrome(chromeType, cf, localeName + "global/");
  11. registerChrome(chromeType, cf, localeName + "communicator/"); registerChrome(chromeType, cf, localeName + "content-packs/"); registerChrome(chromeType, cf, localeName + "cookie/"); registerChrome(chromeType, cf, localeName + "editor/"); registerChrome(chromeType, cf, localeName + "forms/"); registerChrome(chromeType, cf, localeName + "help/"); registerChrome(chromeType, cf, localeName + "messenger/"); registerChrome(chromeType, cf, localeName + "messenger-smime/"); registerChrome(chromeType, cf, localeName + "mozldap/"); registerChrome(chromeType, cf, localeName + "navigator/"); registerChrome(chromeType, cf, localeName + "necko/"); registerChrome(chromeType, cf, localeName + "pipnss/");
  12. registerChrome(chromeType, cf, localeName + "pippki/"); registerChrome(chromeType, cf, localeName + "wallet/"); registerChrome(chromeType, pf, localeName + "global-platform/"); registerChrome(chromeType, pf, localeName + "communicator-platform/"); registerChrome(chromeType, pf, localeName + "navigator-platform/"); if (platformNode == "win") { registerChrome(chromeType, pf, localeName + "messenger-mapi/"); } registerChrome(chromeType, rf, regionName + "global-region/"); registerChrome(chromeType, rf, regionName + "communicator-region/"); registerChrome(chromeType, rf, regionName + "editor-region/"); registerChrome(chromeType, rf, regionName + "messenger-region/"); registerChrome(chromeType, rf, regionName + "navigator-region/");
  13. if (err == SUCCESS) { // complete the installation err = performInstall( ); logComment("performInstall( ) returned: " + err); } else { // cancel the installation cancelInstall(err); logComment("cancelInstall due to error: " + err); } } else { // if we enter this section, // there is not enough disk space for installation cancelInstall(INSUFFICIENT_DISK_SPACE); }
  14. By changing some values of the changeable fields, you can tailor this script to handle the install in any directory in the chrome (cf) that you want and register the chrome URL (localeName) for use. The rest is handled by the built-in functionality in XPI provided by such functions as initInstall and performInstall. Switching languages The mechanism for switching languages can take many forms. Mozilla switches languages by updating an RDF datasource when a language pack is installed. The UI for switching languages in Mozilla is in the main Preferences (Edit > Preferences). Within the preferences area, the language/content panel (Appearance > Languages/Content) interacts with the chrome registry when loaded, reading in the installed language packs and populating a selectable list with the available language identifier. Selecting one language and restarting Mozilla changes the interface for the user. Example 11-10 is a simple script for switching locales. Example 11-10. Locale-switching script function switchLocale(langcode) { try { var chromeRegistry = Components.classes[" registry;1"].getService(Components.interfaces.nsICh romeRegistry); chromeRegistry.selectLocale(langcode, true);
  15. var observerService = Components.classes[";1"]. getService(Components.interfaces.nsIObserverService ); observerService.notifyObservers(null, "locale- selected", null); var prefUtilBundle = srGetStrBundle ("chrome://communicator/locale/pref/prefutilities.p roperties"); var brandBundle = srGetStrBundle ("chrome://global/locale/"); var alertText = prefUtilBundle.GetStringFromName("languageAlert"); var titleText = prefUtilBundle.GetStringFromName("languageTitle"); alertText = alertText.replace(/%brand%/g, brandBundle.GetStringFromName("brandShortName")); var promptService = Components.classes[" service;1"].getService( );
  16. promptService = promptService.QueryInterface (Components.interfaces.nsIPromptService) promptService.alert(window, titleText, alertText); } catch(e) { return false; } return true; } The language code is passed in as a parameter to the switchLocale JavaScript method in Example 11-10. The locale is set via the nsIChromeRegistry component, which uses a method named selectLocale. This locale selection is located in the first few lines, and the rest of the code prepares and shows a prompt to the user. This prompt reminds you to restart Mozilla to ensure that the new locale takes effect. 11.6. Localization Issues This section aims to dig a little deeper into the issues of UI aesthetics and principles, in order to provide some background into the underlying encoding of documents in the XPFE framework. The main portion is taken up by a discussion of Unicode. There is some background to what Unicode is, how Mozilla uses it, and some practical conversion utilities to ensure that your files are in the correct encoding. 11.6.1. XPFE and Unicode
  17. Unicode is a broad topic and we cannot hope to give you anywhere near a full understanding of what it is. However, a brief introduction will highlight its importance in the software world and show how it is used as one of the internationalization cornerstones in the Mozilla project. For more in-depth information, refer to the book The Unicode Standard, Version 3.0 by the Unicode Consortium, published by Addison Wesley Longman. Another useful reference is Unicode: A Primer by Tony Graham, published by M&T Books. Unicode is an encoding system used to represent every character with a unique number. It is a standard that came about when multiple encoding systems were merged. It became clear that keeping separate systems was hindering global communication, and applications were not able to exchange information with one another successfully. Now all major systems and applications are standardizing on Unicode. Most major operating systems, such as Windows, AIX, Solaris, and Mac OS, have already adopted it. The latest browsers, including Mozilla, support it. This quote from the Unicode Consortium ( sums it up the best: Unicode enables a single software significant cost savings over the use of legacy character sets. Unicode enables a single software product or a single web site to be targeted across multiple platforms, languages and countries without re-engineering. It allows data to be transported through many different systems without corruption.
  18. There are seven character-encoding schemes in Unicode: UTF-8, UTF-16, UTF-16BE, UTF-16LE, UTF-32, UTF-32BE, and UTF-32LE. UTF is an abbreviation for Unicode Transformation Format. The size of the character's internal representation can range from 8 bits (UTF-8) to 32 bits (UTF-32). One of Unicode's core principles is that it be able to handle any character set and that clients supporting it provide the tools necessary to convert. This conversation can be from Unicode to native character sets and vice versa. The number of native character sets is extensive and ranges from Central European (ISO-8859-2) to Thai (TIS-620). The default encoding of XUL, XML, and RDF documents in Mozilla is UTF-8. If no encoding is specified in the text declaration, this is the encoding that is used. In the Mozilla tree, you will usually see no encoding specified in this instance and UTF-8 is the default. To use a different encoding, you need to change the XML text declaration at the top of your file. To change your encoding to Central European, include: 11.6.2. Language Quirks The size and proportion of your windows can come into play when you know your application will be localized into more than one language. In some languages, it takes more words or characters, hence more physical space, to bring meaning to some text. This is especially the case in widgets that contain more text, such as when you want to provide usage guidelines in a panel. One solution that Mozilla uses in at least one place is to make the actual size of the window or make the widget into a localizable entity.
  19. The translator or developer can anticipate the size based on the number of words or preview their changes in the displayed UI. If there is an overflow, they can overflow or do the reverse in the case of empty space. As you begin to localize your application, especially if it is a web-related application, you will encounter words and phrases that have universal meaning and may not require translation. If you translate the whole Mozilla application, for example, you'll find that some words or phrases remain untouched. These items include terms that are used for branding, or universal web browsing terms, such as Bookmarks, Tasks, and Tools. In some instances, the choice to translate some of these terms is purely subjective.
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