QML Conditional Based on Kit

Dane 0

I would like to specify a custom gstreamer pipeline for my MediaPlayer when running on embedded Linux (but not when running on desktop Linux). I can't use Qt.platform.os as this is "linux" for both. How can I detect the Kit (or any other parameter making it possible to detect the embedded Linux target) in QML?

sierdzio

@Dane-0 I think you need to get that information in C++ and then pass it to QML.

Dane 0

@sierdzio Thanks! How would I do that? I'm currently trying to get a define added under the CMake configuration using something like
-DQMAKE_CXXFLAGS:STRING='-DEMBEDDED'
or
-DCMAKE_CXXFLAGS:STRING='-DEMBEDDED'
however I haven't been able to get this to work as yet.

sierdzio

@Dane-0 there are many ways to do it, personally I'd probably go with something like this:

In some CMakeLists.txt:

option(IS_EMBEDDED "Enable embedded mode" OFF)

if (IS_EMBEDDED)
    message("Building embedded")
    add_definitions(-DEMBEDDED)
endif()

You can call cmake with cmake -DIS_EMBEDDED=ON or just select that option in Qt Creator's Project->Build settings.

Then, in C++ you can do this:

engine->rootContext()->setContextProperty("isEmbedded", 
#ifdef EMBEDDED
    true
#else
    false
#endif
);

Lastly, in QML:

Text {
    text: isEmbedded ? "Embedded!" : "Desktop :-("
}

Dane 0

@sierdzio Thanks again! :-)
I am new to this so please excuse me if these questions are "silly":

In some CMakeLists.txt:

There is not currently any CMakeLists.txt in the project. Must I add this manually? Or do I add something to the .pro file? What about under Kits -> CMake Configuration?

You can call cmake with cmake -DIS_EMBEDDED=ON or just select that option in Qt Creator's Project->Build settings.

Where would this option be selected? I'm looking under "Projects" (mode selected on the left), but don't immediately see "options" to be selected.

I follow with everything after that, just struggling to get the actual #define implemented.

sierdzio

@Dane-0 said in QML Conditional Based on Kit:

@sierdzio Thanks again! :-)
I am new to this so please excuse me if these questions are "silly":

In some CMakeLists.txt:

There is not currently any CMakeLists.txt in the project. Must I add this manually? Or do I add something to the .pro file? What about under Kits -> CMake Configuration?

If you have a .pro file then you are NOT using cmake but qmake.

So, with qmake this will be a bit different. In your .pro:

is-embedded {
  DEFINES += EMBEDDED
}

Then call qmake with:

qmake CONFIG+=is-embedded

C++ and QML stay the same.

Dane 0

Brilliant, that works, thanks! :-)

I ended up with:

is_embedded {
  DEFINES += IS_EMBEDDED
}

in the .pro

and then

CONFIG+=is_embedded

under Projects -> Build (for relevant kit) -> Build Steps -> Additional arguments.

Thanks again @sierdzio !