How to use CuteKeyboard (Free virtual keyboard) in Qt 6.8

I want to use the following Virtual Keyboard library in a Qt QML application.

https://github.com/amarula/cutekeyboard/

The plugin and application builds successfully, but when I start the application I get the following error:

QQmlApplicationEngine failed to load component
qrc:/qt/qml/qml_test/Main.qml:4:1: Module loaded for URI 'QtQuick.CuteKeyboard' does not implement QQmlEngineExtensionInterface

How do I build a project to use the above plugins in Qt 6.8?

I'm a beginner with Qt.

The environment is as follows. OS: Ubuntu 24.04 Qt: 6.8.3 Qt Creator: 17.0.2 Cmake: 3.28.3

I have tried the following

build and install cutekeyboard

~$ git clone https://github.com/amarula/cutekeyboard.git
~/cutekeyboard$ cmake -S . -B build -GNinja
~/cutekeyboard$ cmake --build build --target all
~/cutekeyboard/build$ sudo cmake --install .

-- Install configuration: ""
-- Installing: /usr/lib/x86_64-linux-gnu/cmake/Qt6/../../../plugins/platforminputcontexts/libcutekeyboardplugin.so
-- Set non-toolchain portion of runtime path of "/usr/lib/x86_64-linux-gnu/cmake/Qt6/../../../plugins/platforminputcontexts/libcutekeyboardplugin.so" to "$ORIGIN/../../../lib"

copy the build files to the Qt directory

sudo cp -r cutekeyboard/build/src/QtQuick/CuteKeyboard /opt/Qt/6.8.3/gcc_64/qml/QtQuick

create qml project

Create a QML Application Project in Qt Creator.

Add the following to the source.

main.cpp

qputenv("QT_IM_MODULE", QByteArray("cutekeyboard"));

Main.qml

import QtQuick.CuteKeyboard 1.0

Errors while reading typeinfo files: File "/opt/Qt/6.8.3/gcc_64/qml/QtQuick/CuteKeyboard/cutekeyboardplugin.qmltypes" does not exist.

When I run the application, the following error occurs:

16:29:58: Starting /home/.../qml_test/build/Desktop_Qt_6_8_3-Debug/appqml_test...
QML debugging is enabled. Only use this in a safe environment.
QQmlApplicationEngine failed to load component
qrc:/qt/qml/qml_test/Main.qml:4:1: Module loaded for URI 'QtQuick.CuteKeyboard' does not implement QQmlEngineExtensionInterface
16:29:58: The command "/home/.../qml_test/build/Desktop_Qt_6_8_3-Debug/appqml_test" terminated with exit code 255.

Update #1

When I run the cmake command with BUILD_EXAMPLES turned ON to build the cutekeyboard example, the following error occurs:

~/cutekeyboard$ cmake -S . -B build -GNinja -DBUILD_EXAMPLES=ON

...
CMake Error at /usr/lib/x86_64-linux-gnu/cmake/Qt6Core/Qt6CoreMacros.cmake:2428 (message):
  Unexpected arguments: OUTPUT_SCRIPT;deploy_script
Call Stack (most recent call first):
  /usr/lib/x86_64-linux-gnu/cmake/Qt6Core/Qt6CoreMacros.cmake:2503 (qt6_generate_deploy_app_script)
  example/CMakeLists.txt:15 (qt_generate_deploy_app_script)

Update #2

After specifying the options as follows, the example project also built successfully.

cmake -S . -B build -GNinja -DBUILD_EXAMPLES=ON -DCMAKE_PREFIX_PATH=/opt/Qt/6.5.3/gcc_64 -DQT_DIR=/opt/Qt/6.5.3/gcc_64/lib/cmake/Qt6

The example project built successfully, but when launched, the following is output to the terminal and the GUI does not appear.

qt.qpa.plugin: Could not find the Qt platform plugin "wayland" in ""
QQmlApplicationEngine failed to load component
qrc:/main.qml:5:1: module "QtQuick.Window" is not installed
qrc:/main.qml:4:1: module "QtQuick.Layouts" is not installed
qrc:/main.qml:3:1: module "QtQuick.CuteKeyboard" is not installed
qrc:/main.qml:2:1: module "QtQuick.Controls" is not installed

When I launched my own project, the following error occurred.

QQmlApplicationEngine failed to load component
qrc:/qt/qml/ck_test_65/Main.qml:3:1: Namespace 'QtQuick.CuteKeyboard' has already been used for type registration