[Qt module] Added translation files compilation method

- Added a new compile_translations method since preprocess was already quite
full and translations compilation is quite different from ui, qrc, cpp files
preprocessing.
- Updated translation.
- Updated test case.

Signed-off-by: Alexis Jeandet <alexis.jeandet@member.fsf.org>

6 files changed, 73 insertions, 3 deletions

diff --git a/docs/markdown/Qt5-module.md b/docs/markdown/Qt5-module.md
index aea2ae1..c7a2578 100644
--- a/docs/markdown/Qt5-module.md
+++ b/docs/markdown/Qt5-module.md
@@ -1,7 +1,7 @@
 # Qt5 module
 
 The Qt5 module provides tools to automatically deal with the various
-tools and steps required for Qt. The module has one method.
+tools and steps required for Qt. The module has two methods.
 
 ## preprocess
 
@@ -12,6 +12,14 @@ This method takes the following keyword arguments:
 
 It returns an opaque object that should be passed to a main build target.
 
+## compile_translations
+
+This method generates the necessary targets to build translation files with lrelease, it takes the following keyword arguments:
+ - `ts_files`, the list of input translation files produced by Qt's lupdate tool.
+ - `install` when true, this target is installed during the install step.
+ - `install_dir` directory to install to
+ - `build_by_default` when set to true, to have this target be built by default, that is, when invoking plain ninja; the default value is false.
+
 A simple example would look like this:
 
 ```meson
@@ -21,6 +29,7 @@ inc = include_directories('includes')
 moc_files = qt5.preprocess(moc_headers : 'myclass.h',
                            moc_extra_arguments: ['-DMAKES_MY_MOC_HEADER_COMPILE'],
                            include_directories: inc)
+translations = qt5.compile_translations(ts_files : 'myTranslation_fr.ts', build_by_default : true)
 executable('myprog', 'main.cpp', 'myclass.cpp', moc_files,
            include_directories: inc,
            dependencies : qt5_dep)
@@ -28,5 +37,4 @@ executable('myprog', 'main.cpp', 'myclass.cpp', moc_files,
 
 
 The 'modules' argument is used to include Qt modules in the project.
-See the Qt documentation for the [list of
-modules](http://doc.qt.io/qt-5/qtmodules.html).
+See the Qt documentation for the [list of modules](http://doc.qt.io/qt-5/qtmodules.html).
diff --git a/mesonbuild/modules/qt.py b/mesonbuild/modules/qt.py
index c07a361..463bf01 100644
--- a/mesonbuild/modules/qt.py
+++ b/mesonbuild/modules/qt.py
@@ -144,3 +144,21 @@ class QtBaseModule:
             moc_output = moc_gen.process_files('Qt{} moc source'.format(self.qt_version), moc_sources, state)
             sources.append(moc_output)
         return ModuleReturnValue(sources, sources)
+
+    @permittedKwargs({'ts_files', 'install', 'install_dir', 'build_by_default', 'method'})
+    def compile_translations(self, state, args, kwargs):
+        ts_files, install_dir = extract_as_list(kwargs, 'ts_files', 'install_dir', pop=True)
+        self._detect_tools(state.environment, kwargs.get('method', 'auto'))
+        translations = []
+        for ts in ts_files:
+            cmd = [self.lrelease, '@INPUT@', '-qm', '@OUTPUT@']
+            lrelease_kwargs = {'output': '@BASENAME@.qm',
+                               'input': ts,
+                               'install': kwargs.get('install', False),
+                               'build_by_default': kwargs.get('build_by_default', False),
+                               'command': cmd}
+            if install_dir is not None:
+                lrelease_kwargs['install_dir'] = install_dir
+            lrelease_target = build.CustomTarget('qt{}-compile-{}'.format(self.qt_version, ts), state.subdir, state.subproject, lrelease_kwargs)
+            translations.append(lrelease_target)
+        return ModuleReturnValue(translations, translations)
diff --git a/test cases/frameworks/4 qt/meson.build b/test cases/frameworks/4 qt/meson.build
index 374707a..7c33268 100644
--- a/test cases/frameworks/4 qt/meson.build
+++ b/test cases/frameworks/4 qt/meson.build
@@ -59,6 +59,8 @@ foreach qt : ['qt4', 'qt5']
     # We need a console test application because some test environments
     # do not have an X server.
 
+    translations = qtmodule.compile_translations(ts_files : qt+'core_fr.ts', build_by_default : true)
+
     qtcore = dependency(qt, modules : 'Core', method : get_option('method'))
 
     qtcoreapp = executable(qt + 'core', 'q5core.cpp',
diff --git a/test cases/frameworks/4 qt/q5core.cpp b/test cases/frameworks/4 qt/q5core.cpp
index 706e4dc..25b80b8 100644
--- a/test cases/frameworks/4 qt/q5core.cpp
+++ b/test cases/frameworks/4 qt/q5core.cpp
@@ -1,8 +1,26 @@
 #include <QCoreApplication>
+#include <QtGlobal>
+#include <QString>
+#include <QTranslator>
+#include <QLocale>
+#include <QLibraryInfo>
+#include <QDebug>
 
 int main(int argc, char **argv) {
   QCoreApplication app(argc, argv);
 
+  QTranslator qtTranslator;
+  qtTranslator.load("qt_" + QLocale::system().name(),
+                  QLibraryInfo::location(QLibraryInfo::TranslationsPath));
+  app.installTranslator(&qtTranslator);
+
+  QTranslator myappTranslator;
+  if(!myappTranslator.load("qt5core_fr") )
+    return 1;
+
+  app.installTranslator(&myappTranslator);
+
+  qDebug() << QObject::tr("Translate me!");
   // Don't actually start the main loop so this
   // can be run as a unit test.
   //return app.exec();
diff --git a/test cases/frameworks/4 qt/qt4core_fr.ts b/test cases/frameworks/4 qt/qt4core_fr.ts
new file mode 100644
index 0000000..0638bd5
--- /dev/null
+++ b/test cases/frameworks/4 qt/qt4core_fr.ts
@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!DOCTYPE TS>
+<TS version="2.0" language="fr_FR">
+<context>
+    <name>QObject</name>
+    <message>
+        <location filename="q5core.cpp" line="23"/>
+        <source>Translate me!</source>
+        <translation>Traduisez moi!</translation>
+    </message>
+</context>
+</TS>
diff --git a/test cases/frameworks/4 qt/qt5core_fr.ts b/test cases/frameworks/4 qt/qt5core_fr.ts
new file mode 100644
index 0000000..4e3116b
--- /dev/null
+++ b/test cases/frameworks/4 qt/qt5core_fr.ts
@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!DOCTYPE TS>
+<TS version="2.1" language="fr_FR">
+<context>
+    <name>QObject</name>
+    <message>
+        <location filename="q5core.cpp" line="23"/>
+        <source>Translate me!</source>
+        <translation>Traduisez moi!</translation>
+    </message>
+</context>
+</TS>