Cross-compiled Qt 5.15.2 cannot find VirtualKeyboard or Multimedia plugins for Raspberry Pi 4.

Fahad-Cattchi · wrote on 17 Dec 2021, 18:49

I cross-compiled Qt 5.15.2 to my Raspberry Pi 4. I have the installation at /usr/local/qt5.15.

I'm getting these errors when I try to run:

using null output device, none available
module "QtQuick.VirtualKeyboard.Plugins" is not installed

I did export QML2_IMPORT_PATH="/usr/local/qt5.15/qml" so Qt can find most of the qml modules, but it still can't find the Multimedia and VirtualKeyboard.

I pretty sure I have them installed, as I can find them when I search for them.

pi@raspberrypi:~ $ find /usr/local/qt5.15 -name "QtMultimedia"
/usr/local/qt5.15/qml/QtMultimedia
/usr/local/qt5.15/include/QtMultimedia
/usr/local/qt5.15/include/QtMultimedia/QtMultimedia
/usr/local/qt5.15/include/QtMultimedia/5.15.2/QtMultimedia
pi@raspberrypi:~ $ find /usr/local/qt5.15 -name "QtVirtualKeyboard"
/usr/local/qt5.15/include/QtVirtualKeyboard
/usr/local/qt5.15/include/QtVirtualKeyboard/5.15.2/QtVirtualKeyboard
/usr/local/qt5.15/include/QtVirtualKeyboard/QtVirtualKeyboard

I also have qputenv("QT_IM_MODULE", QByteArray("qtvirtualkeyboard")); in my code, so the VirtualKeyboard should work.

Is there some other environment variable I have to set?

SGaist · wrote on 17 Dec 2021, 19:07

Hi,

Did you check the configure summary ?
Does it show anything unusual related to multimedia and virtual keyboard.

Fahad-Cattchi · wrote on 17 Dec 2021, 19:21

Here's the multimedia configuration:

Qt Multimedia:
  ALSA ................................... yes
  GStreamer 1.0 .......................... no
  GStreamer 0.10 ......................... no
  Video for Linux ........................ yes
  OpenAL ................................. no
  PulseAudio ............................. yes
  Resource Policy (libresourceqt5) ....... no
  Windows Audio Services ................. no
  DirectShow ............................. no
  Windows Media Foundation ............... no

I can't find anything related to the virtual keyboard.

SGaist · wrote on 17 Dec 2021, 19:22

Did you check the content of the build folder for the related libraries ?

Fahad-Cattchi · wrote on 17 Dec 2021, 19:29

I think I have them. I'm not sure exactly what I'm looking for, but here's the results for some find commands:

pi@raspberrypi:~ $ find /usr/local/qt5.15 -iname "*multimedia*" | grep .so
/usr/local/qt5.15/qml/QtMultimedia/libdeclarative_multimedia.so
/usr/local/qt5.15/lib/libQt5MultimediaWidgets.so.5
/usr/local/qt5.15/lib/libQt5MultimediaQuick.so.5
/usr/local/qt5.15/lib/libQt5MultimediaQuick.so.5.15.2
/usr/local/qt5.15/lib/libQt5Multimedia.so.5.15.2
/usr/local/qt5.15/lib/libQt5MultimediaWidgets.so.5.15
/usr/local/qt5.15/lib/libQt5MultimediaQuick.so
/usr/local/qt5.15/lib/libQt5MultimediaWidgets.so
/usr/local/qt5.15/lib/libQt5Multimedia.so.5
/usr/local/qt5.15/lib/libQt5Multimedia.so
/usr/local/qt5.15/lib/libQt5Multimedia.so.5.15
/usr/local/qt5.15/lib/libQt5MultimediaQuick.so.5.15
/usr/local/qt5.15/lib/libQt5MultimediaWidgets.so.5.15.2
/usr/local/qt5.15/plugins/playlistformats/libqtmultimedia_m3u.so

pi@raspberrypi:~ $ find /usr/local/qt5.15 -iname "*keyboard*" | grep .so
/usr/local/qt5.15/qml/QtQuick/VirtualKeyboard/libqtquickvirtualkeyboardplugin.so
/usr/local/qt5.15/qml/QtQuick/VirtualKeyboard/Styles/libqtquickvirtualkeyboardstylesplugin.so
/usr/local/qt5.15/qml/QtQuick/VirtualKeyboard/Settings/libqtquickvirtualkeyboardsettingsplugin.so
/usr/local/qt5.15/lib/libQt5VirtualKeyboard.so.5.15.2
/usr/local/qt5.15/lib/libQt5VirtualKeyboard.so.5.15
/usr/local/qt5.15/lib/libQt5VirtualKeyboard.so.5
/usr/local/qt5.15/lib/libQt5VirtualKeyboard.so
/usr/local/qt5.15/plugins/generic/libqevdevkeyboardplugin.so
/usr/local/qt5.15/plugins/virtualkeyboard/libqtvirtualkeyboard_pinyin.so
/usr/local/qt5.15/plugins/virtualkeyboard/libqtvirtualkeyboard_hangul.so
/usr/local/qt5.15/plugins/virtualkeyboard/libqtvirtualkeyboard_openwnn.so
/usr/local/qt5.15/plugins/virtualkeyboard/libqtvirtualkeyboard_tcime.so
/usr/local/qt5.15/plugins/virtualkeyboard/libqtvirtualkeyboard_thai.so
/usr/local/qt5.15/plugins/platforminputcontexts/libqtvirtualkeyboardplugin.so

SGaist · wrote on 17 Dec 2021, 19:55

That looks good...
Maybe a silly question but are you sure you are using the correct qmake to build your application ?

Fahad-Cattchi · wrote on 17 Dec 2021, 20:39

I think it's the correct qmake. I'm using CMake to build.

In my Raspberry Pi kit in QtCreator I have a manual Qt version defined that's using the path: ~/pi/qt5.15/bin/qmake which is what I expect since my local cross-compile install directory is ~/pi/qt5.15.

SGaist · wrote on 17 Dec 2021, 20:43

Something is not completely clear.

Are you cross-compiling from your desktop to your Pi or directly on the Pi ?

Usually, when cross-compiling, the Qt build shall be copied to the target in the some folder tree.

Fahad-Cattchi · wrote on 17 Dec 2021, 21:12

My cross-compiled Qt5.15.2 was built on my host machine against the Raspberry Pi libraries, and then copied over from host: ~/pi/qt5.15/ to Pi: /usr/local/qt5.15/. Both paths have the same content & folder structure.

I'm now trying to build my program with QtCreator on my host machine, and then deploy it over to the Pi. Which is generally working. The main window shows up correctly at least.

SGaist · wrote on 19 Dec 2021, 19:39

You should have these files in the same folder on your Pi.

Fahad-Cattchi · wrote on 20 Dec 2021, 18:30

I have the exact same files in those 2 locations. If I ls -l on each machine:

fahad@fahad-ThinkPad-T490:~$ ls -l ~/pi/qt5.15/
total 68
drwxrwxr-x  2 fahad fahad  4096 Dec 14 10:56 bin
drwxrwxr-x  4 fahad fahad  4096 Dec 14 10:52 doc
drwxrwxr-x 91 fahad fahad  4096 Dec 14 10:56 include
drwxrwxr-x  5 fahad fahad 28672 Dec 14 10:56 lib
drwxrwxr-x 77 fahad fahad  4096 Dec 14 10:52 mkspecs
drwxrwxr-x 29 fahad fahad  4096 Dec 14 10:55 plugins
drwxrwxr-x 25 fahad fahad  4096 Dec 14 10:56 qml
drwxrwxr-x  2 fahad fahad 12288 Dec 14 10:56 translations

pi@raspberrypi:~ $ ls -l /usr/local/qt5.15/
total 68
drwxrwxr-x  2 pi pi  4096 Dec 14 10:56 bin
drwxrwxr-x  4 pi pi  4096 Dec 14 10:52 doc
drwxrwxr-x 91 pi pi  4096 Dec 14 10:56 include
drwxrwxr-x  5 pi pi 28672 Dec 14 10:56 lib
drwxrwxr-x 77 pi pi  4096 Dec 14 10:52 mkspecs
drwxrwxr-x 29 pi pi  4096 Dec 14 10:55 plugins
drwxrwxr-x 25 pi pi  4096 Dec 14 10:56 qml
drwxrwxr-x  2 pi pi 12288 Dec 14 10:56 translations

Or are you saying I need to exact same folder structure down to root? Like, if my files are at /usr/local/qt5.15/ on the Pi then they also need to be at /usr/local/qt5.15/ on my host?

SGaist · wrote on 20 Dec 2021, 18:44

The second choice, same folder structure.