virtual keyboard in QT Application

[StrikeByte]

It's a while ago that I made InputDeviceV3.zip, but didn't have a need to build a new one up until now,
now I needed a virtual input for Qt5.3 so I made the InputDevice working again.
I didn't do any major changes (only the name), it still only works for QLineEdits
Here is the download:
VirtualInput.zip

How to use:

• Build the library
• copy the library to platforminputcontexts in your application or to plugins/platforminputcontexts in your QtDir
• Add a custom property named "keyboard" (without the quotes) of the type bool to the QLineEdit and set it to enabled
• For text you can set the maxLength property
• For values you can add a QIntValidator to the QLineEdit

[srm]

Hi, thanks for the update.
I'm pretty new to Qt (and to C++) and I'm having trouble using your project. Running Qt-Creator 3.3.0 and Qt5.4.
I can open your project, but compiling it yields errors.

numpad.cpp:166:18: error: taking the address of a temporary object of type 'QVariant' [-Waddress-of-temporary]
emit dataSet(&QVariant(ui->edValue->text()));
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
numpad.cpp:189:33: error: non-const lvalue reference to type 'QString' cannot bind to a temporary of type 'QString'
if (validator->validate(ui->edValue->text(),pos) == QValidator::Acceptable)
^~~~~~~~~~~~~~~~~~~
/Users/srm/Development/Qt/5.4/clang_64/lib/QtGui.framework/Headers/qvalidator.h:67:37: note: passing argument to parameter here
virtual State validate(QString &, int &) const = 0;
^

This was running qmake && make in the project dir.
What am I doing wrong? Do you need any more information?

EDIT: running on OSX 10.10.2

[StrikeByte]

I made the project on a windows machine and a visual studio compiler. It looks like the compiler you are using won't allow temp variables in function calls
I don't have a mac to try it on.
Mabe you can find more when googling the error description (QString' cannot bind to a temporary of type 'QString) or start a thread in the newbe section of the forum.

[anda_skoa]

Instead of taking the address of a temporary QVariant, make it a local variable and take its address.

In the second error, you are required to pass a reference to a QString. You are trying to pass the return value of a function, which is also a temporary.
Again, make a local variable, initialiize it with the result of the function and then pass the variable to the validate method.

Cheers,
_

[srm]

Thanks for the pointers. I was able to fix the error messages as per your suggestion.
For example

emit dataSet(&QVariant(ui->edValue->text()));

became

QVariant qv = QVariant(ui->edValue->text());
emit dataSet(&qv);

But now I'm stuck on how to actually use it. I have absolutely no clue on how to incorporate that into my own app. I did a make install but neither do I know how to activate it, nor how to ensure cross platform functionality.

So I moved over to give http://qt-apps.org/content/show.php/...content=107388 a try, which was mentioned in earlier in this thread.

Would be great if you could explain/give a sample app on how to actually use such an extra inputcontext, for the total noobs

[StrikeByte]

There is a howto on the first page of this thread

[kiran prabhu]

hi,thanks for the virtual keyboard

[clutch12]

This looks very useful. I've been trying out the latest VIInputContext class. Any chance you can add some clarification on usage with a mainwindow widget?
I put this in my mainwindow.h
VIInputContext inputdevice;
and in the constructor I do this
ui->lineEdit->setProperty("keyboard",true);


But, I must be missing something as when I click in the lineEdit box nothing happens.

[kovis]

Hi, thanks for the update.
I'm pretty new to Qt (and to C++) and I'm having trouble using your project. Running Qt-Creator 3.3.0 and Qt5.4.
I can open your project, but compiling it yields errors.

This was running qmake && make in the project dir.
What am I doing wrong? Do you need any more information?

EDIT: running on OSX 10.10.2

Looks like signatures changed here and there in Qt 5.4,
your problem can get around easily as
QString editedText = ui->edValue->text();
if (validator->validate(editedText, pos) == QValidator::Acceptable)

I also changes dataSet(QVariant*) to plain value call dataSet(QVariant)

but my problem is that I never got the virtual keyboard working on Linux/X11/Qt 5.4.1

I compiled the library, did sudo make install so it got copied into the right plugin directory
I set the proper spellword "keyboard" property, hell, I even removed all property checks in the plugin to be sure this is not the problem.

But on my test application the virtual keyboard never appeared.
Actually I wonder how "magically" it could appear - currently I am missing some plugin activation on QLineEdit.

I attach my test project if anyone could see what is the reason of virtual keyboard not showing up...
Many thanks in advance

Jan Struhar

[Robb]

Hi @ all.

I've tried to use the keyboard in Qt 4. I included the InputDevice.h in my main file and created an intance of the InputDevice like you've posted it.
But every time I want to build by project it says "undefined reference to 'InputDevice::InputDevice()'".

Have I need to link something else or include on another place?

Thanks in advance.

[natile]

Hi all
I hava the same problem
I cant compile my test app, it is fail in <include "inputdevice.h">
Does anyone actually succeeded to run it ??

[mvly]

I am using this in on an embedded arm and the compiler is telling me they cannot find <QtDesigner/QDesignerExportWidget>.

Any way either not to use this or where I can find this file?

Thanks

[StrikeByte]

kovis did you try to add the plugin to your application build directory?
what to do:
* create a folder named platforminputcontexts in next to your executable
* place the plugin in this directory
* start the application

Also important is that the plugin is build in the sameway as your application (debug/release)

[HenrikSkott]

Hi StrikeByte,

I really appreciate the work you've done with the virtual keyboard, but I notice you haven't added a license to the code. I hope this can be placed in the public doman (so anyone can use it for anything, even relicensing) or LGPL, so it can be used in projects using a LGPL licensed Qt.

Thanks,

Henrik

[StrikeByte]

Hey HenrikSkott,

You can do with it whatever you want.

I havn't used this keyboard for a while, but it seems Qt has changed something in the platforminputcontext loader

if you want to use it you need to add this to your main
qputenv("QT_IM_MODULE", QByteArray("virtualinput"));

[JasonMa]

I just created a project on github based on StrikeByte's code. https://github.com/mazj/VirtualInput