I have created and instantiated some qml components and I have a button that takes the dynamically created objects, passes them to a C++ function, converts them to qml code and writes it into a file.

I have managed to get the name of the object (Rectangle, Text, etc.) and all its children and to write it to a file as qml valid code. The difficult part is the properties. I would like to write just the properties that are different from the default object, so that I don't write all of them. My solution was to create a default instance of the same class and then iterate through all the properties in the metaObject of the class, compare them, and write them to the file only if the value is not the same.
I wasn't able to create the default instance.

I will share some of my code for the conversion. I must say, I have used a lot of string operations instead of object operations, which in my experience, is a sign that I am not doing it right.

QString ProjectManager::convertObjectToQml(const QObject *content, int indentLevel = 0) { if (!content) return ""; QString qmlCode; QString indent(indentLevel * 4, ' '); // Indentation for readability // Iterate over children (skip rendering the root Item itself) for (QObject *component : content->children()) { if (!component) continue; // Extract class name const QMetaObject *superMeta = component->metaObject()->superClass(); if (!superMeta) { qDebug() << "No superMeta class found."; } QString className = superMeta->className(); className = className.split("_").first(); className = className.split("QQuick").last(); qmlCode += "\n" + indent + className + " {\n"; // // Check for modified properties // const QMetaObject *metaObject = component->metaObject(); // QObject *defaultObject = metaObject->newInstance(); // Create a default instance for comparison // if (defaultObject) { // for (int i = 0; i < metaObject->propertyCount(); ++i) { // QMetaProperty property = metaObject->property(i); // QVariant value = component->property(property.name()); // QVariant defaultValue = defaultObject->property(property.name()); // // Only add properties that differ from the default // if (value.isValid() && value != defaultValue) { // qmlCode += indent + " " + QString(property.name()) + ": " + value.toString() + "\n"; // } // } // delete defaultObject; // } else { // qWarning() << "Could not create default instance for" << className; // } // Recursively process children qmlCode += convertObjectToQml(component, indentLevel + 1); qmlCode += indent + "}\n"; } return qmlCode; }

Here I have attempted to create a new instance of the same class, but it doesn't return any object, and the documentation says this method is deprecated.

const QMetaObject *metaObject = component->metaObject(); QObject *defaultObject = metaObject->newInstance();

I have seen this method of instantiating a component from C++, but it requires a file with a custom component:

QQmlEngine engine; QQmlComponent component(&engine, "MyItem.qml"); QObject *object = component.create();

when i run qt quick simple example using qt 6.8 i am getting below error:

":-1: error: CMakeFiles/appRectangle.dir/main.cpp.o: undefined reference to symbol '_ZdlPvm@@CXXABI_1.3.9'
:-1: error: /usr/lib64/libstdc++.so.6: error adding symbols: DSO missing from command line
:-1: error: collect2: error: ld returned 1 exit status
:-1: error: [CMakeFiles/appRectangle.dir/build.make:266: appRectangle] Error 1"

Solution: adding stdc++ in below code

target_link_libraries(appRectangle PRIVATE Qt6::Quick stdc++ )

why compile out put generate this many lines :

CCACHE_NODISABLE=true DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus DEBUGINFOD_URLS=https://debuginfod.fedoraproject.org/ DESKTOP_SESSION=gnome DISPLAY=:0 EDITOR=/usr/bin/nano EMSDK=/home/ma/WebAssembly/emsdk EMSDK_NODE=/home/ma/WebAssembly/emsdk/node/16.20.0_64bit/bin/node EM_CACHE=/home/ma/WebAssembly/emsdk/upstream/emscripten/cache EM_CONFIG=/home/ma/WebAssembly/emsdk/.emscripten GDMSESSION=gnome GDM_LANG=en_US.UTF-8 GIO_LAUNCHED_DESKTOP_FILE=/home/ma/.local/share/applications/org.qt-project.qtcreator.desktop GIO_LAUNCHED_DESKTOP_FILE_PID=4957 GITHUB_TOKEN=ghp_YDxEGA24MePZ5 GJS_DEBUG_OUTPUT=stderr GJS_DEBUG_TOPICS=JS ERROR;JS LOG GNOME_SETUP_DISPLAY=:1 HISTCONTROL=ignoredups HISTSIZE=1000 HOME=/home/ma HOSTNAME=fedora INVOCATION_ID=ea7079b8c6 JFROG_API_KEY=AKCpM JFROG_USERNAME=ma JOURNAL_STREAM=8:16781 LANG=en_US.UTF-8 LD_LIBRARY_PATH=/home/ma/Qt6.8.3/6.8.3/gcc_64/lib:/usr/lib::/usr/local/lib LESSOPEN=||/usr/bin/lesspipe.sh %s LOCAL_DEV_MACHINE=true LOGNAME=ma MAIL=/var/spool/mail/ma MANAGERPID=2085 MOZ_GMP_PATH=/usr/lib64/mozilla/plugins/gmp-gmpopenh264/system-installed PATH=/home/ma/WebAssembly/emsdk:/home/ma/WebAssembly/emsdk/upstream/emscripten:/home/ma/WebAssembly/emsdk/node/16.20.0_64bit/bin:/home/ma/.local/bin:/home/ma/bin:/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/var/lib/snapd/snap/bin PWD=/home/ma QTDIR=/home/ma/Qt6.8.3/6.8.3/gcc_64 QT_IM_MODULE=ibus QT_QPA_PLATFORM=xcb SESSION_MANAGER=local/unix:@/tmp/.ICE-unix/2268,unix/unix:/tmp/.ICE-unix/2268 SHELL=/bin/bash SHLVL=0 SSH_AUTH_SOCK=/run/user/1000/keyring/ssh SYSTEMD_EXEC_PID=2329 USER=ma USERNAME=ma WAYLAND_DISPLAY=wayland-0 XAUTHORITY=/run/user/1000/.mutter-Xwaylandauth.C1SZ32 XDG_CURRENT_DESKTOP=GNOME XDG_DATA_DIRS=/home/ma/.local/share/flatpak/exports/share:/var/lib/flatpak/exports/share:/usr/local/share/:/usr/share/:/var/lib/snapd/desktop XDG_MENU_PREFIX=gnome- XDG_RUNTIME_DIR=/run/user/1000 XDG_SESSION_CLASS=user XDG_SESSION_DESKTOP=gnome XDG_SESSION_TYPE=wayland XMODIFIERS=@im=ibus _QTC_LD_LIBRARY_PATH=/home/ma/Qt6.8.3/6.8.3/gcc_64/lib

why in older version it works fine without adding it? what is correct solution for it on linux?

question 2: why cmake modules in qt creator get invisible in latest version qt 6.8?

The Blend effect in QtGraphicalEffects was removed in Qt6, so how can I choose a blend mode for texture images?

@jagadish Thank you

@NeilParker-Qt Hey Neil, Thank you for sharing your challenge from the Intro to QML course!

I like the animation you added to bring up the additional details on the business card, and the icons add a lot to the design. The resizing whilst maintaining the aspect ratio was also a nice touch! Overall, with the headshot as the background, it looks like a very professional business card!

I think some basic theming to the details button so the font and style match the rest of the design would finish off the application.

Great job

When you want to include some headers of a library you also must pass the include path to the compiler.
If you use cmake, use target_include_directories() and add the desired include paths there. Later when you use this library (aka you link them with target_link_libraries()), cmake will automatically add the paths specified.

@JoeCFD Try the following

Qt3DCore::QEntity* createTorusWithGradient(Qt3DCore::QEntity* rootEntity) { Qt3DCore::QEntity* torusEntity = new Qt3DCore::QEntity(rootEntity); // Torus mesh Qt3DExtras::QTorusMesh* torusMesh = new Qt3DExtras::QTorusMesh(torusEntity); torusMesh->setRadius(5.0f); torusMesh->setMinorRadius(1.0f); torusMesh->setRings(100); torusMesh->setSlices(20); torusEntity->addComponent(torusMesh); // Transform Qt3DCore::QTransform* transform = new Qt3DCore::QTransform(torusEntity); transform->setScale3D(QVector3D(1.5f, 1.5f, 1.5f)); // Fixed typo transform->setRotation(QQuaternion::fromAxisAndAngle(QVector3D(1, 0, 0), 60.0f)); torusEntity->addComponent(transform); // Custom material setup Qt3DRender::QMaterial* material = new Qt3DRender::QMaterial(torusEntity); // Effect, technique, render pass, and shader Qt3DRender::QEffect* effect = new Qt3DRender::QEffect(); Qt3DRender::QTechnique* gl3Technique = new Qt3DRender::QTechnique(); Qt3DRender::QRenderPass* gl3Pass = new Qt3DRender::QRenderPass(); Qt3DRender::QShaderProgram* glShader = new Qt3DRender::QShaderProgram(); // Simple vertex shader const QByteArray vertexShaderCode = R"( #version 330 core in vec3 vertexPosition; in vec3 vertexNormal; uniform mat4 modelViewProjection; out vec3 fragPosition; void main() { fragPosition = vertexPosition; gl_Position = modelViewProjection * vec4(vertexPosition, 1.0); } )"; // Simple fragment shader with color parameter const QByteArray fragmentShaderCode = R"( #version 330 core in vec3 fragPosition; out vec4 fragColor; uniform vec4 color; void main() { fragColor = color; // Use the color parameter directly } )"; // Set shader code glShader->setVertexShaderCode(vertexShaderCode); glShader->setFragmentShaderCode(fragmentShaderCode); // Connect shader program to render pass gl3Pass->setShaderProgram(glShader); gl3Technique->addRenderPass(gl3Pass); // Set OpenGL 3.3 Core profile gl3Technique->graphicsApiFilter()->setApi(Qt3DRender::QGraphicsApiFilter::OpenGL); gl3Technique->graphicsApiFilter()->setMajorVersion(3); gl3Technique->graphicsApiFilter()->setMinorVersion(3); gl3Technique->graphicsApiFilter()->setProfile(Qt3DRender::QGraphicsApiFilter::CoreProfile); // Add technique to effect effect->addTechnique(gl3Technique); material->setEffect(effect); // Add a color parameter material->addParameter(new Qt3DRender::QParameter("color", QColor::fromRgbF(0.0f, 1.0f, 0.0f, 1.0f))); // Add material to entity torusEntity->addComponent(material); // Debug shader compilation errors QObject::connect(glShader, &Qt3DRender::QShaderProgram::statusChanged, [=](Qt3DRender::QShaderProgram::Status status) { if (status == Qt3DRender::QShaderProgram::Error) { qDebug() << "Shader Error:" << glShader->log(); } }); return torusEntity; }

@exactchange
First: stop insulting others! Read and follow https://forum.qt.io/topic/113070/qt-code-of-conduct Unless you want to be banned from here.
Second: this is user forum, most people here are not from QtCompany and don't spam you - why are you insulting them?

If you want to be constructive you should at least mention what kind of mails you get, so that somebody can figure out from where it is coming and how to stop it.