qt_add_lrelease

Add targets to transform Qt Linguist .ts files into .qm files.

The command is defined in the LinguistTools component of the Qt6 package. Load the package with:

find_package(Qt6 REQUIRED COMPONENTS LinguistTools)

This command was introduced in Qt 6.2.

Synopsis

qt_add_lrelease(target TS_FILES file1.ts [file2.ts ...]
                [NO_TARGET_DEPENDENCY]
                [NO_GLOBAL_TARGET]
                [QM_FILES_OUTPUT_VARIABLE variable-name]
                [OPTIONS ...])

If versionless commands are disabled, use qt6_add_lrelease() instead. It supports the same set of arguments as this command.

Description

Creates a target ${target}_lrelease to transform .ts files into .qm files with lrelease.

The parameter target is an existing executable or library target that contains sources with translatable strings.

The .ts files must be specified with the argument TS_FILES.

This function is designed to be used in conjunction with qt_add_lupdate. See also the convenience wrapper qt_add_translations.

Options

You can set additional OPTIONS that should be passed when lrelease is invoked. You can find possible options in the lrelease documentation.

By default, the .qm files will be placed in the current build directory (CMAKE_CURRENT_BINARY_DIR). To change this, you can set OUTPUT_LOCATION as a property of the source .ts file.

For example, with the following code, the .qm files are generated in a translations directory below the current build directory.

set_source_files_properties(app_en.ts app_de.ts
    PROPERTIES OUTPUT_LOCATION "${CMAKE_CURRENT_BINARY_DIR}/translations")

Processing Generated .qm Files

To further process the generated .qm files, for example to create install rules, qt_add_lrelease can store the paths of the .qm files in a variable. Pass QM_FILES_OUTPUT_VARIABLE <variable-name> to the function for that.

Build by Default

By default, the command makes ${target} depend on ${target}_lrelease. This ensures that the .qm files are always up-to-date when ${target} is built. This behavior can be turned off with NO_TARGET_DEPENDENCY. In this case, the user must build the ${target}_lrelease target manually.

Umbrella Target

In addition to the target ${target}_lrelease, an umbrella target release_translations is created. This target will build all ${target}_lrelease targets that were created with qt_add_lrelease.

Pass NO_GLOBAL_TARGET to qt_add_lrelease to prevent this behavior.

The name of this target can be overridden by setting the variable QT_GLOBAL_LRELEASE_TARGET before calling qt_add_lrelease.

Examples

Add the targets myapp_lrelease and update_translations for updating the .ts file of an application myapp. Also, install the generated .qm files.

qt_add_lrelease(myapp
    TS_FILES myapp_de.ts
    QM_FILES_OUTPUT_VARIABLE qm_files)
install(FILES ${qm_files} DESTINATION "translations")