QPointerEvent throws error

[curiosity]

@Christian-Ehrlicher

I am getting a lot of linker errors. probably QApplication is not resolved while compiling. or what is the possible reason

Severity Code Description Project File Line Suppression State
Error LNK2001 unresolved external symbol "protected: virtual void __cdecl QGraphicsItem::keyReleaseEvent(class QKeyEvent *)" (?keyReleaseEvent@QGraphicsItem@@MEAAXPEAVQKeyEvent@@@Z) TouchPadProj C:\Users\source\repos\TouchProj\TouchProj\Touchpad.obj 1

[Christian Ehrlicher]

@curiosity Then you should link against QtGui as shown in the documentation.

[curiosity]

@Christian-Ehrlicher

there are so many such errors

[Christian Ehrlicher]

@curiosity And why don't you do what I told you then? When you want to use a library then you have to link against this library...

[curiosity]

@Christian-Ehrlicher

this is my .pro file

QT += gui // I guess this is how you suggested
QT += widgets

-lQtGui

HEADERS = knob.h
SOURCES = main.cpp knob.cpp

install

target.path = $$[QT_INSTALL_EXAMPLES]/widgets/touch/knobs
INSTALLS += target

this didnt work

[jsulm]

@curiosity said in QPointerEvent throws error:

-lQtGui

What is this?!

[curiosity]

@jsulm
linker flag... even with/ without this it isnt working

[JonB]

@curiosity But what is it doing as you show in the middle of your .pro file? It will likely make it incorrect.

[jsulm]

@curiosity First: this linker flag is not needed. Second: the way you added it is wrong and makes no sense.

[curiosity]

@JonB

I removed it. also #include <QApplication> is not resolved by the compiler. i have to include the entire path/absolute path something like this

#include <C:\Qt\Qt5.12.12\5.12.12\winrt_x64_msvc2017\include\QtWidgets\QApplication> which is not the right way

[jsulm]

@curiosity said in QPointerEvent throws error:

also #include <QApplication> is not resolved by the compiler

Then something is wrong with your project configuration.
Did you rerun qmake after editing the pro file?
It also looks like you're using Visual Studio - I never used it with Qt, but maybe you need to recreate project files after changing pro file?

[curiosity]

@jsulm

I am not sure from where should i run qmake in visual studio. i rebuilt the solution after deleting the build folder.

[curiosity]

@jsulm @JonB

i switched to qt creator.

i have an error here with signals and slots

looks like i have right signals and slots. but not getting about this errorgetting about

[JonB]

@curiosity
Start by showing definition of the two slot functions you use.
Is this an error only in the code completion inside Qt Creator, or do you get these errors when you actually compile?

[jsulm]

@curiosity You probably need to tell the compiler which overload you want to connect, see https://wiki.qt.io/New_Signal_Slot_Syntax#Overload

[curiosity]

@JonB
these are errors in QtCreator. i am yet to compile.

[jsulm]

@curiosity Well, then compile.
Code model can produce false errors in QtCreator.

[curiosity]

@jsulm

i am trying to print the edited text(values entered by the user) onto the console. but still getting this error

[Christian Ehrlicher]

SIGNAL(&QLineEdit::textEdited)

really?

You should read the Qt signals and slot documentation and also re-read the wiki page which @jsulm already pointed you to.

[curiosity]

@Christian-Ehrlicher

connect(echoComboBox, &QComboBox::editTextChanged(echoLineEdit),
        this, [=](const QString &edited){qDebug() << edited;});

i made the above change. but signal is giving error
"call to non static function without an object argument". editTextChanged has qstring . i tried with qsting and qlineEdit as arg. its giving same error with both