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
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/doc/i18n.doc:36 -->
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Internationalization with TQt</title>
<style type="text/css"><!--
fn { margin-left: 1cm; text-indent: -1cm; }
a:link { color: #004faf; text-decoration: none }
a:visited { color: #672967; text-decoration: none }
body { background: #ffffff; color: black; }
--></style>
</head>
<body>
<table border="0" cellpadding="0" cellspacing="0" width="100%">
<tr bgcolor="#E5E5E5">
<td valign=center>
<a href="index.html">
<font color="#004faf">Home</font></a>
| <a href="classes.html">
<font color="#004faf">All Classes</font></a>
| <a href="mainclasses.html">
<font color="#004faf">Main Classes</font></a>
| <a href="annotated.html">
<font color="#004faf">Annotated</font></a>
| <a href="groups.html">
<font color="#004faf">Grouped Classes</font></a>
| <a href="functions.html">
<font color="#004faf">Functions</font></a>
</td>
<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>Internationalization with TQt</h1>
<p> <!-- index internationalization --><a name="internationalization"></a><!-- index i18n --><a name="i18n"></a>
<p> The internationalization of an application is the process of making
the application usable by people in countries other than one's own.
<p> <!-- toc -->
<ul>
<li><a href="#1"> Step by Step
</a>
<ul>
<li><a href="#1-1"> Use TQString for all User-visible Text
</a>
<li><a href="#1-2"> Use tr() for all Literal Text
</a>
<li><a href="#1-3"> Use TQKeySequence() for Accelerator Values
</a>
<li><a href="#1-4"> Use TQString::arg() for Dynamic Text
</a>
<li><a href="#1-5"> Produce Translations
</a>
<li><a href="#1-6"> Support for Encodings
</a>
<li><a href="#1-7"> Localize
</a>
</ul>
<li><a href="#2"> Dynamic Translation
</a>
<li><a href="#3"> System Support
</a>
<ul>
<li><a href="#3-1"> Unix/X11
</a>
<li><a href="#3-2"> Windows
</a>
</ul>
<li><a href="#4"> Note about Locales on X11
</a>
<li><a href="#5"> Relevant TQt Classes
</a>
</ul>
<!-- endtoc -->
<p> In some cases internationalization is simple, for example, making a US
application accessible to Australian or British users may require
little more than a few spelling corrections. But to make a US
application usable by Japanese users, or a Korean application usable
by German users, will require that the software operate not only in
different languages, but use different input techniques, character
encodings and presentation conventions.
<p> TQt tries to make internationalization as painless as possible for
developers. All input widgets and text drawing methods in TQt offer
built-in support for all supported languages. The built-in font engine
is capable of correctly and attractively rendering text that contains
characters from a variety of different writing systems at the same
time.
<p> TQt supports most languages in use today, in particular:
<ul>
<li> All East Asian languages (Chinese, Japanese and Korean)
<li> All Western languages (using Latin script)
<li> Arabic
<li> Cyrillic languages (Russian)
<li> Greek
<li> Hebrew
<li> Thai and Lao
<li> All scripts in Unicode 3.2 that do not require special processing
</ul>
<p> On Windows NT/2000/XP and Unix/X11 with Xft (client side font support)
the following languages are also supported:
<ul>
<li> Bengali
<li> Devanagari
<li> Dhivehi (Thaana)
<li> Gujarati
<li> Gurmukhi
<li> Kannada
<li> Khmer
<li> Malayalam (X11 only)
<li> Myanmar (X11 only)
<li> Syriac
<li> Tamil
<li> Telugu
<li> Tibetan (X11 only)
</ul>
<p> Many of these writing systems exhibit special features:
<p> <ul>
<p> <li> <b>Special line breaking behavior.</b> Some of the Asian languages are
written without spaces between words. Line breaking can occur either
after every character (with exceptions) as in Chinese, Japanese and
Korean, or after logical word boundaries as in Thai.
<p> <li> <b>Bidirectional writing.</b> Arabic and Hebrew are written from right to
left, except for numbers and embedded English text which is written
left to right. The exact behavior is defined in the <a href="http://www.unicode.org/unicode/reports/tr9/">Unicode Technical Report
#9</a>.
<p> <li> <b>Non spacing or diacritical marks</b> (accents or umlauts in European
languages). Some languages such as Vietnamese make extensive use of
these marks and some characters can have more than one mark at the
same time to clarify pronunciation.
<p> <li> <b>Ligatures.</b> In special contexts, some pairs of characters get
replaced by a combined glyph forming a ligature. Common examples are
the fl and fi ligatures used in typesetting US and European books.
<p> </ul>
<p> TQt tries to take care of all the special features listed above. You
usually don't have to worry about these features so long as you use
TQt's input widgets (e.g. <a href="ntqlineedit.html">TQLineEdit</a>, <a href="ntqtextedit.html">TQTextEdit</a>, and derived classes)
and TQt's display widgets (e.g. <a href="ntqlabel.html">TQLabel</a>).
<p> Support for these writing systems is transparent to the programmer
and completely encapsulated in TQt's text engine. This means that you
don't need to have any knowledge about the writing system used in a
particular language, except for the following small points:
<ul>
<p> <li> <a href="ntqpainter.html#drawText">TQPainter::drawText</a>( int x, int y, const <a href="ntqstring.html">TQString</a> &str ) will always
draw the string with it's left edge at the position specified with
the x, y parameters. This will usually give you left aligned strings.
Arabic and Hebrew application strings are usually right
aligned, so for these languages use the version of drawText() that
takes a <a href="ntqrect.html">TQRect</a> since this will align in accordance with the language.
<p> <li> When you write your own text input controls, use <a href="ntqfontmetrics.html#charWidth">TQFontMetrics::charWidth</a>() to determine the width of a character in a
string. In some languages (e.g. Arabic or languages from the Indian
subcontinent), the width and shape of a glyph changes depending on the
surrounding characters. Writing input controls usually requires a
certain knowledge of the scripts it is going to be used in. Usually
the easiest way is to subclass <a href="ntqlineedit.html">TQLineEdit</a> or <a href="ntqtextedit.html">TQTextEdit</a>.
<p> </ul>
<p> The following sections give some information on the status
of the internationalization (i18n) support in TQt.
<p> See also the <a href="linguist-manual.html">TQt Linguist</a> manual.
<p> <h2> Step by Step
</h2>
<a name="1"></a><p> Writing multi-platform international software with TQt is a gentle,
incremental process. Your software can become internationalized in
the following stages:
<p> <h3> Use <a href="ntqstring.html">TQString</a> for all User-visible Text
</h3>
<a name="1-1"></a><p> Since TQString uses the Unicode encoding internally, every
language in the world can be processed transparently using
familiar text processing operations. Also, since all TQt
functions that present text to the user take a TQString as a
parameter, there is no char* to TQString conversion overhead.
<p> Strings that are in "programmer space" (such as <a href="ntqobject.html">TQObject</a> names
and file format texts) need not use TQString; the traditional
char* or the <a href="ntqcstring.html">TQCString</a> class will suffice.
<p> You're unlikely to notice that you are using Unicode;
TQString, and <a href="qchar.html">TQChar</a> are just like easier versions of the crude
const char* and char from traditional C.
<p> <h3> Use tr() for all Literal Text
</h3>
<a name="1-2"></a><p> Wherever your program uses <tt>"quoted text"</tt> for text that will
be presented to the user, ensure that it is processed by the <a href="ntqapplication.html#translate">TQApplication::translate</a>() function. Essentially all that is necessary
to achieve this is to use <a href="ntqobject.html#tr">TQObject::tr</a>(). For example, assuming the
<tt>LoginWidget</tt> is a subclass of TQWidget:
<p> <pre>
LoginWidget::LoginWidget()
{
<a href="ntqlabel.html">TQLabel</a> *label = new <a href="ntqlabel.html">TQLabel</a>( tr("Password:"), this );
...
}
</pre>
<p> This accounts for 99% of the user-visible strings you're likely to
write.
<p> If the quoted text is not in a member function of a
<a href="ntqobject.html">TQObject</a> subclass, use either the tr() function of an
appropriate class, or the <a href="ntqapplication.html#translate">TQApplication::translate</a>() function
directly:
<p> <pre>
void some_global_function( LoginWidget *logwid )
{
<a href="ntqlabel.html">TQLabel</a> *label = new <a href="ntqlabel.html">TQLabel</a>(
LoginWidget::tr("Password:"), logwid );
}
void same_global_function( LoginWidget *logwid )
{
<a href="ntqlabel.html">TQLabel</a> *label = new <a href="ntqlabel.html">TQLabel</a>(
tqApp-><a href="ntqapplication.html#translate">translate</a>("LoginWidget", "Password:"),
logwid );
}
</pre>
<p> If you need to have translatable text completely
outside a function, there are two macros to help: QT_TR_NOOP()
and QT_TRANSLATE_NOOP(). They merely mark the text for
extraction by the <em>lupdate</em> utility described below.
The macros expand to just the text (without the context).
<p> Example of QT_TR_NOOP():
<pre>
TQString FriendlyConversation::greeting( int greet_type )
{
static const char* greeting_strings[] = {
QT_TR_NOOP( "Hello" ),
QT_TR_NOOP( "Goodbye" )
};
return tr( greeting_strings[greet_type] );
}
</pre>
<p> Example of QT_TRANSLATE_NOOP():
<pre>
static const char* greeting_strings[] = {
QT_TRANSLATE_NOOP( "FriendlyConversation", "Hello" ),
QT_TRANSLATE_NOOP( "FriendlyConversation", "Goodbye" )
};
TQString FriendlyConversation::greeting( int greet_type )
{
return tr( greeting_strings[greet_type] );
}
<a href="ntqstring.html">TQString</a> global_greeting( int greet_type )
{
return tqApp-><a href="ntqapplication.html#translate">translate</a>( "FriendlyConversation",
greeting_strings[greet_type] );
}
</pre>
<p> If you disable the const char* to <a href="ntqstring.html">TQString</a> automatic conversion
by compiling your software with the macro QT_NO_CAST_ASCII
defined, you'll be very likely to catch any strings you are
missing. See <a href="ntqstring.html#fromLatin1">TQString::fromLatin1</a>() for more information.
Disabling the conversion can make programming a bit cumbersome.
<p> If your source language uses characters outside Latin-1, you
might find <a href="ntqobject.html#trUtf8">TQObject::trUtf8</a>() more convenient than
<a href="ntqobject.html#tr">TQObject::tr</a>(), as tr() depends on the
<a href="ntqapplication.html#defaultCodec">TQApplication::defaultCodec</a>(), which makes it more fragile than
TQObject::trUtf8().
<p> <h3> Use <a href="ntqkeysequence.html">TQKeySequence</a>() for Accelerator Values
</h3>
<a name="1-3"></a><p> Accelerator values such as Ctrl+Q or Alt+F need to be
translated too. If you hardcode <tt>CTRL+Key_Q</tt> for "Quit" in
your application, translators won't be able to override
it. The correct idiom is
<p> <pre>
<a href="ntqpopupmenu.html">TQPopupMenu</a> *file = new <a href="ntqpopupmenu.html">TQPopupMenu</a>( this );
file-><a href="ntqmenudata.html#insertItem">insertItem</a>( tr("&Quit"), this, SLOT(quit()),
TQKeySequence(tr("Ctrl+Q", "File|Quit")) );
</pre>
<p> <h3> Use <a href="ntqstring.html#arg">TQString::arg</a>() for Dynamic Text
</h3>
<a name="1-4"></a><p> The TQString::arg() functions offer a simple means for substituting
arguments:
<pre>
void FileCopier::showProgress( int done, int total,
const <a href="ntqstring.html">TQString</a>& current_file )
{
label.setText( tr("%1 of %2 files copied.\nCopying: %3")
.arg(done)
.arg(total)
.arg(current_file) );
}
</pre>
<p> In some languages the order of arguments may need to change, and this
can easily be achieved by changing the order of the % arguments. For
example:
<pre>
<a href="ntqstring.html">TQString</a> s1 = "%1 of %2 files copied. Copying: %3";
<a href="ntqstring.html">TQString</a> s2 = "Kopierer nu %3. Av totalt %2 filer er %1 kopiert.";
<a href="ntqapplication.html#qDebug">qDebug</a>( s1.<a href="ntqstring.html#arg">arg</a>(5).arg(10).arg("somefile.txt").ascii() );
<a href="ntqapplication.html#qDebug">qDebug</a>( s2.<a href="ntqstring.html#arg">arg</a>(5).arg(10).arg("somefile.txt").ascii() );
</pre>
<p> produces the correct output in English and Norwegian:
<pre>
5 of 10 files copied. Copying: somefile.txt
Kopierer nu somefile.txt. Av totalt 10 filer er 5 kopiert.
</pre>
<p> <h3> Produce Translations
</h3>
<a name="1-5"></a><p> Once you are using tr() throughout an application, you can start
producing translations of the user-visible text in your program.
<p> <a href="linguist-manual.html">TQt Linguist</a>'s manual provides
further information about TQt's translation tools, <em>TQt Linguist</em>, <em>lupdate</em> and <em>lrelease</em>.
<p> Translation of a TQt application is a three-step process:
<p> <ol type=1>
<p> <li> Run <em>lupdate</em> to extract translatable text from the C++ source
code of the TQt application, resulting in a message file for
translators (a <tt>.ts</tt> file). The utility recognizes the tr() construct
and the QT_*_NOOP macros described above and produces <tt>.ts</tt> files
(usually one per language).
<p> <li> Provide translations for the source texts in the <tt>.ts</tt> file, using
<em>TQt Linguist</em>. Since <tt>.ts</tt> files are in XML format, you can also
edit them by hand.
<p> <li> Run <em>lrelease</em> to obtain a light-weight message file (a <tt>.qm</tt>
file) from the <tt>.ts</tt> file, suitable only for end use. Think of the <tt>.ts</tt> files as "source files", and <tt>.qm</tt> files as "object files". The
translator edits the <tt>.ts</tt> files, but the users of your application
only need the <tt>.qm</tt> files. Both kinds of files are platform and
locale independent.
<p> </ol>
<p> Typically, you will repeat these steps for every release of your
application. The <em>lupdate</em> utility does its best to reuse the
translations from previous releases.
<p> Before you run <em>lupdate</em>, you should prepare a project file. Here's
an example project file (<tt>.pro</tt> file):
<p> <pre>
HEADERS = funnydialog.h \
wackywidget.h
SOURCES = funnydialog.cpp \
main.cpp \
wackywidget.cpp
FORMS = fancybox.ui
TRANSLATIONS = superapp_dk.ts \
superapp_fi.ts \
superapp_no.ts \
superapp_se.ts
</pre>
<p> When you run <em>lupdate</em> or <em>lrelease</em>, you must give the name of the
project file as a command-line argument.
<p> In this example, four exotic languages are supported: Danish, Finnish,
Norwegian and Swedish. If you use <a href="qmake-manual.html">qmake</a>, you usually don't need an extra project
file for <em>lupdate</em>; your <tt>qmake</tt> project file will work fine once
you add the <tt>TRANSLATIONS</tt> entry.
<p> In your application, you must <a href="ntqtranslator.html#load">TQTranslator::load</a>() the translation
files appropriate for the user's language, and install them using <a href="ntqapplication.html#installTranslator">TQApplication::installTranslator</a>().
<p> If you have been using the old TQt tools (<tt>findtr</tt>, <tt>msg2qm</tt> and <tt>mergetr</tt>), you can use <em>qm2ts</em> to convert your old <tt>.qm</tt> files.
<p> <em>linguist</em>, <em>lupdate</em> and <em>lrelease</em> are installed in the <tt>bin</tt>
subdirectory of the base directory TQt is installed into. Click Help|Manual
in <em>TQt Linguist</em> to access the user's manual; it contains a tutorial
to get you started.
<p> While these utilities offer a convenient way to create <tt>.qm</tt> files,
any system that writes <tt>.qm</tt> files is sufficient. You could make an
application that adds translations to a <a href="ntqtranslator.html">TQTranslator</a> with
<a href="ntqtranslator.html#insert">TQTranslator::insert</a>() and then writes a <tt>.qm</tt> file with
<a href="ntqtranslator.html#save">TQTranslator::save</a>(). This way the translations can come from any
source you choose.
<p> <a name="qt-itself"></a>
TQt itself contains over 400 strings that will also need to be
translated into the languages that you are targeting. You will find
translation files for French and German in <tt>$QTDIR/translations</tt> as
well as a template for translating to other languages. (This directory
also contains some additional unsupported translations which may be
useful.)
<p> Typically, your application's main() function will look like this:
<pre>
int main( int argc, char **argv )
{
<a href="ntqapplication.html">TQApplication</a> app( argc, argv );
// translation file for TQt
<a href="ntqtranslator.html">TQTranslator</a> qt( 0 );
qt.<a href="ntqtranslator.html#load">load</a>( TQString( "qt_" ) + TQTextCodec::locale(), "." );
app.<a href="ntqapplication.html#installTranslator">installTranslator</a>( &qt );
// translation file for application strings
<a href="ntqtranslator.html">TQTranslator</a> myapp( 0 );
myapp.<a href="ntqtranslator.html#load">load</a>( TQString( "myapp_" ) + TQTextCodec::locale(), "." );
app.<a href="ntqapplication.html#installTranslator">installTranslator</a>( &myapp );
...
return app.<a href="ntqapplication.html#exec">exec</a>();
}
</pre>
<p> <h3> Support for Encodings
</h3>
<a name="1-6"></a><p> The <a href="ntqtextcodec.html">TQTextCodec</a> class and the facilities in <a href="ntqtextstream.html">TQTextStream</a> make it easy to
support many input and output encodings for your users' data. When an
application starts, the locale of the machine will determine the 8-bit
encoding used when dealing with 8-bit data: such as for font
selection, text display, 8-bit text I/O and character input.
<p> The application may occasionally require encodings other than the
default local 8-bit encoding. For example, an application in a
Cyrillic KOI8-R locale (the de-facto standard locale in Russia) might
need to output Cyrillic in the ISO 8859-5 encoding. Code for this
would be:
<p> <pre>
<a href="ntqstring.html">TQString</a> string = ...; // some Unicode text
<a href="ntqtextcodec.html">TQTextCodec</a>* codec = TQTextCodec::<a href="ntqtextcodec.html#codecForName">codecForName</a>( "ISO 8859-5" );
<a href="ntqcstring.html">TQCString</a> encoded_string = codec-><a href="ntqtextcodec.html#fromUnicode">fromUnicode</a>( string );
...; // use encoded_string in 8-bit operations
</pre>
<p> For converting Unicode to local 8-bit encodings, a shortcut is
available: the <a href="ntqstring.html#local8Bit">local8Bit</a>() method
of <a href="ntqstring.html">TQString</a> returns such 8-bit data. Another useful shortcut is the
<a href="ntqstring.html#utf8">utf8</a>() method, which returns text in the
8-bit UTF-8 encoding: this perfectly preserves Unicode information
while looking like plain US-ASCII if the text is wholly US-ASCII.
<p> For converting the other way, there are the <a href="ntqstring.html#fromUtf8">TQString::fromUtf8</a>() and
<a href="ntqstring.html#fromLocal8Bit">TQString::fromLocal8Bit</a>() convenience functions, or the general code,
demonstrated by this conversion from ISO 8859-5 Cyrillic to Unicode
conversion:
<p> <pre>
<a href="ntqcstring.html">TQCString</a> encoded_string = ...; // Some ISO 8859-5 encoded text.
<a href="ntqtextcodec.html">TQTextCodec</a>* codec = TQTextCodec::<a href="ntqtextcodec.html#codecForName">codecForName</a>("ISO 8859-5");
<a href="ntqstring.html">TQString</a> string = codec-><a href="ntqtextcodec.html#toUnicode">toUnicode</a>(encoded_string);
...; // Use string in all of TQt's TQString operations.
</pre>
<p> Ideally Unicode I/O should be used as this maximizes the portability
of documents between users around the world, but in reality it is
useful to support all the appropriate encodings that your users will
need to process existing documents. In general, Unicode (UTF-16 or
UTF-8) is best for information transferred between arbitrary people,
while within a language or national group, a local standard is often
more appropriate. The most important encoding to support is the one
returned by <a href="ntqtextcodec.html#codecForLocale">TQTextCodec::codecForLocale</a>(), as this is the one the user
is most likely to need for communicating with other people and
applications (this is the codec used by local8Bit()).
<p> TQt supports most of the more frequently used encodings natively. For a
complete list of supported encodings see the <a href="ntqtextcodec.html">TQTextCodec</a>
documentation.
<p> In some cases and for less frequently used encodings it may be
necessary to write your own <a href="ntqtextcodec.html">TQTextCodec</a> subclass. Depending on the
urgency, it may be useful to contact Trolltech technical support or
ask on the <tt>qt-interest</tt> mailing list to see if someone else is
already working on supporting the encoding. A useful interim measure
can be to use the <a href="ntqtextcodec.html#loadCharmapFile">TQTextCodec::loadCharmapFile</a>() function to build a
data-driven codec, although this approach has a memory and speed
penalty, especially with dynamically loaded libraries. For details of
writing your own TQTextCodec, see the main TQTextCodec class
documentation.
<p> <!-- index localization --><a name="localization"></a>
<p> <h3> Localize
</h3>
<a name="1-7"></a><p> Localization is the process of adapting to local conventions, for
example presenting dates and times using the locally preferred
formats. Such localizations can be accomplished using appropriate tr()
strings.
<p> <pre>
void Clock::setTime(const <a href="qtime.html">TQTime</a>& t)
{
if ( tr("AMPM") == "AMPM" ) {
// 12-hour clock
} else {
// 24-hour clock
}
}
</pre>
<p> In the example, for the US we would leave the translation of "AMPM" as
it is and thereby use the 12-hour clock branch; but in Europe we would
translate it as something else (anything else, e.g. "EU") and this
will make the code use the 24-hour clock branch.
<p> Localizing images is not recommended. Choose clear icons that are
appropriate for all localities, rather than relying on local puns or
stretched metaphors.
<p> <h2> Dynamic Translation
</h2>
<a name="2"></a><p> Some applications, such as TQt Linguist, must be able to support changes
to the user's language settings while they are still running. To make
widgets aware of changes to the system language, implement a public
slot called <tt>languageChange()</tt> in each widget that needs to be notified.
In this slot, you should update the text displayed by widgets using the
<a href="ntqobject.html#tr">TQObject::tr</a>(){tr()} function in the usual way; for example:
<p> <pre>
void MyWidget::languageChange()
{
titleLabel->setText(tr("Document Title"));
...
okPushButton->setText(tr("&OK"));
}
</pre>
<p> The default event handler for <a href="ntqwidget.html">TQWidget</a> subclasses responds to the
<a href="ntqevent.html#Type-enum">LanguageChange</a> event, and will call this slot
when necessary; other application components can also connect signals
to this slot to force widgets to update themselves.
<p> <h2> System Support
</h2>
<a name="3"></a><p> Some of the operating systems and windowing systems that TQt runs on
only have limited support for Unicode. The level of support available
in the underlying system has some influence on the support that TQt can
provide on those platforms, although in general TQt applications need
not be too concerned with platform-specific limitations.
<p> <h3> Unix/X11
</h3>
<a name="3-1"></a><p> <ul>
<li> Locale-oriented fonts and input methods. TQt hides these and
provides Unicode input and output.
<li> Filesystem conventions such as
<a href="http://www.ietf.org/rfc/rfc2279.txt">UTF-8</a>
are under development
in some Unix variants. All TQt file functions allow Unicode,
but convert filenames to the local 8-bit encoding, as
this is the Unix convention
(see <a href="ntqfile.html#setEncodingFunction">TQFile::setEncodingFunction</a>()
to explore alternative encodings).
<li> File I/O defaults to the local 8-bit encoding,
with Unicode options in <a href="ntqtextstream.html">TQTextStream</a>.
</ul>
<p> <h3> Windows
</h3>
<a name="3-2"></a><p> <ul>
<li> TQt provides full Unicode support, including input methods, fonts,
clipboard, drag-and-drop and file names.
<li> File I/O defaults to Latin-1, with Unicode options in TQTextStream.
Note that some Windows programs do not understand big-endian
Unicode text files even though that is the order prescribed by
the Unicode Standard in the absence of higher-level protocols.
<li> Unlike programs written with MFC or plain winlib, TQt programs
are portable between Windows 95/98 and Windows NT.
<em>You do not need different binaries to support Unicode.</em>
</ul>
<p> <h2> Note about Locales on X11
</h2>
<a name="4"></a><p> Many Unix distributions contain only partial support for some locales.
For example, if you have a <tt>/usr/share/locale/ja_JP.EUC</tt> directory,
this does not necessarily mean you can display Japanese text; you also
need JIS encoded fonts (or Unicode fonts), and the <tt>/usr/share/locale/ja_JP.EUC</tt> directory needs to be complete. For best
results, use complete locales from your system vendor.
<p> <h2> Relevant TQt Classes
</h2>
<a name="5"></a><p> These classes are relevant to internationalizing TQt applications.
<p><table width="100%">
<tr bgcolor=#f0f0f0><td><b><a href="ntqbig5codec.html">TQBig5Codec</a></b><td>Conversion to and from the Big5 encoding
<tr bgcolor=#f0f0f0><td><b><a href="ntqeucjpcodec.html">TQEucJpCodec</a></b><td>Conversion to and from EUC-JP character sets
<tr bgcolor=#f0f0f0><td><b><a href="ntqeuckrcodec.html">TQEucKrCodec</a></b><td>Conversion to and from EUC-KR character sets
<tr bgcolor=#f0f0f0><td><b><a href="ntqgb18030codec.html">TQGb18030Codec</a></b><td>Conversion to and from the Chinese GB18030/GBK/GB2312 encoding
<tr bgcolor=#f0f0f0><td><b><a href="qgb2312codec.html">TQGb2312Codec</a></b><td>Conversion to and from the Chinese GB2312 encoding
<tr bgcolor=#f0f0f0><td><b><a href="ntqgbkcodec.html">TQGbkCodec</a></b><td>Conversion to and from the Chinese GBK encoding
<tr bgcolor=#f0f0f0><td><b><a href="qhebrewcodec.html">TQHebrewCodec</a></b><td>Conversion to and from visually ordered Hebrew
<tr bgcolor=#f0f0f0><td><b><a href="ntqjiscodec.html">TQJisCodec</a></b><td>Conversion to and from JIS character sets
<tr bgcolor=#f0f0f0><td><b><a href="ntqsjiscodec.html">TQSjisCodec</a></b><td>Conversion to and from Shift-JIS
<tr bgcolor=#f0f0f0><td><b><a href="ntqtextcodec.html">TQTextCodec</a></b><td>Conversion between text encodings
<tr bgcolor=#f0f0f0><td><b><a href="qtextdecoder.html">TQTextDecoder</a></b><td>State-based decoder
<tr bgcolor=#f0f0f0><td><b><a href="qtextencoder.html">TQTextEncoder</a></b><td>State-based encoder
<tr bgcolor=#f0f0f0><td><b><a href="ntqtranslator.html">TQTranslator</a></b><td>Internationalization support for text output
<tr bgcolor=#f0f0f0><td><b><a href="qtranslatormessage.html">TQTranslatorMessage</a></b><td>Translator message and its properties
<tr bgcolor=#f0f0f0><td><b><a href="ntqtsciicodec.html">TQTsciiCodec</a></b><td>Conversion to and from the Tamil TSCII encoding
</table>
<!-- eof -->
<p><address><hr><div align=center>
<table width=100% cellspacing=0 border=0><tr>
<td>Copyright © 2007
<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
<td align=right><div align=right>TQt 3.3.8</div>
</table></div></address></body>
</html>
|
