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 ```1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 ``` ``````/**************************************************************************** ** ** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies). ** Contact: http://www.qt-project.org/ ** ** This file is part of the documentation of the Qt Toolkit. ** ** \$QT_BEGIN_LICENSE:FDL\$ ** GNU Free Documentation License ** Alternatively, this file may be used under the terms of the GNU Free ** Documentation License version 1.3 as published by the Free Software ** Foundation and appearing in the file included in the packaging of ** this file. ** ** Other Usage ** Alternatively, this file may be used in accordance with the terms ** and conditions contained in a signed written agreement between you ** and Nokia. ** ** ** ** ** ** \$QT_END_LICENSE\$ ** ****************************************************************************/ /*! \example linguist/arrowpad \title Arrow Pad Example This example is a slightly more involved and introduces a key \e {Qt Linguist} concept: "contexts". It also shows how to use two or more languages. \image linguist-arrowpad_en.png We will use two translations, French and Dutch, although there is no effective limit on the number of possible translations that can be used with an application. The relevant lines of \c arrowpad.pro are \snippet examples/linguist/arrowpad/arrowpad.pro 0 \codeline \snippet examples/linguist/arrowpad/arrowpad.pro 1 Run \c lupdate; it should produce two identical message files \c arrowpad_fr.ts and \c arrowpad_nl.ts. These files will contain all the source texts marked for translation with \c tr() calls and their contexts. See the \l{Qt Linguist manual} for more information about translating Qt application. \section1 Line by Line Walkthrough In \c arrowpad.h we define the \c ArrowPad subclass which is a subclass of QWidget. In the screenshot above, the central widget with the four buttons is an \c ArrowPad. \snippet examples/linguist/arrowpad/arrowpad.h 0 \snippet examples/linguist/arrowpad/arrowpad.h 1 \snippet examples/linguist/arrowpad/arrowpad.h 2 When \c lupdate is run it not only extracts the source texts but it also groups them into contexts. A context is the name of the class in which the source text appears. Thus, in this example, "ArrowPad" is a context: it is the context of the texts in the \c ArrowPad class. The \c Q_OBJECT macro defines \c tr(x) in \c ArrowPad like this: \snippet doc/src/snippets/code/doc_src_examples_arrowpad.cpp 0 Knowing which class each source text appears in enables \e {Qt Linguist} to group texts that are logically related together, e.g. all the text in a dialog will have the context of the dialog's class name and will be shown together. This provides useful information for the translator since the context in which text appears may influence how it should be translated. For some translations keyboard accelerators may need to be changed and having all the source texts in a particular context (class) grouped together makes it easier for the translator to perform any accelerator changes without introducing conflicts. In \c arrowpad.cpp we implement the \c ArrowPad class. \snippet examples/linguist/arrowpad/arrowpad.cpp 0 \snippet examples/linguist/arrowpad/arrowpad.cpp 1 \snippet examples/linguist/arrowpad/arrowpad.cpp 2 \snippet examples/linguist/arrowpad/arrowpad.cpp 3 We call \c ArrowPad::tr() for each button's label since the labels are user-visible text. \image linguist-arrowpad_en.png \snippet examples/linguist/arrowpad/mainwindow.h 0 \snippet examples/linguist/arrowpad/mainwindow.h 1 In the screenshot above, the whole window is a \c MainWindow. This is defined in the \c mainwindow.h header file. Here too, we use \c Q_OBJECT, so that \c MainWindow will become a context in \e {Qt Linguist}. \snippet examples/linguist/arrowpad/mainwindow.cpp 0 In the implementation of \c MainWindow, \c mainwindow.cpp, we create an instance of our \c ArrowPad class. \snippet examples/linguist/arrowpad/mainwindow.cpp 1 We also call \c MainWindow::tr() twice, once for the action and once for the shortcut. Note the use of \c tr() to support different keys in other languages. "Ctrl+Q" is a good choice for Quit in English, but a Dutch translator might want to use "Ctrl+A" (for Afsluiten) and a German translator "Strg+E" (for Beenden). When using \c tr() for \uicontrol Ctrl key accelerators, the two argument form should be used with the second argument describing the function that the accelerator performs. Our \c main() function is defined in \c main.cpp as usual. \snippet examples/linguist/arrowpad/main.cpp 2 \snippet examples/linguist/arrowpad/main.cpp 3 We choose which translation to use according to the current locale. QLocale::system() can be influenced by setting the \c LANG environment variable, for example. Notice that the use of a naming convention that incorporates the locale for \c .qm message files, (and TS files), makes it easy to implement choosing the translation file according to locale. If there is no QM message file for the locale chosen the original source text will be used and no error raised. \section1 Translating to French and Dutch We'll begin by translating the example application into French. Start \e {Qt Linguist} with \c arrowpad_fr.ts. You should get the seven source texts ("\&Up", "\&Left", etc.) grouped in two contexts ("ArrowPad" and "MainWindow"). Now, enter the following translations: \list \li \c ArrowPad \list \li \&Up - \&Haut \li \&Left - \&Gauche \li \&Right - \&Droite \li \&Down - \&Bas \endlist \li \c MainWindow \list \li E\&xit - \&Quitter \li Ctrl+Q - Ctrl+Q \li \&File - \&Fichier \endlist \endlist It's quickest to press \uicontrol{Alt+D} (which clicks the \uicontrol {Done \& Next} button) after typing each translation, since this marks the translation as done and moves on to the next source text. Save the file and do the same for Dutch working with \c arrowpad_nl.ts: \list \li \c ArrowPad \list \li \&Up - \&Omhoog \li \&Left - \&Links \li \&Right - \&Rechts \li \&Down - Omlaa\&g \endlist \li \c MainWindow \list \li E\&xit - \&Afsluiten \li Ctrl+Q - Ctrl+A \li File - \&Bestand \endlist \endlist We have to convert the \c tt1_fr.ts and \c tt1_nl.ts translation source files into QM files. We could use \e {Qt Linguist} as we've done before; however using the command line tool \c lrelease ensures that \e all the QM files for the application are created without us having to remember to load and \uicontrol File|Release each one individually from \e {Qt Linguist}. Type \snippet doc/src/snippets/code/doc_src_examples_arrowpad.qdoc 1 This should create both \c arrowpad_fr.qm and \c arrowpad_nl.qm. Set the \c LANG environment variable to \c fr. In Unix, one of the two following commands should work \snippet doc/src/snippets/code/doc_src_examples_arrowpad.qdoc 2 In Windows, either modify \c autoexec.bat or run \snippet doc/src/snippets/code/doc_src_examples_arrowpad.qdoc 3 When you run the program, you should now see the French version: \image linguist-arrowpad_fr.png Try the same with Dutch, by setting \c LANG=nl. Now the Dutch version should appear: \image linguist-arrowpad_nl.png \section1 Exercises Mark one of the translations in \e {Qt Linguist} as not done, i.e. by unchecking the "done" checkbox; run \c lupdate, then \c lrelease, then the example. What effect did this change have? Set \c LANG=fr_CA (French Canada) and run the example program again. Explain why the result is the same as with \c LANG=fr. Change one of the accelerators in the Dutch translation to eliminate the conflict between \e \&Bestand and \e \&Boven. */ ``````