General and Desktop

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  How to create the plugin of MYSQL for Qt
  • BlackStar

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  @flydragon

  Do not duplicate posting because you do not get an answer immendiately.

  [edit:koahnig see https://forum.qt.io/topic/82629/why-qsqlquery-exec-exit-failed ]

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  Reporting inappropriate content on the forums
  spam • • Eddy

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  Thank you for the report. I have banned the user, which got rid of the spam posting. Not a loss, as this user did not post any other content on the site. Just deleting this one posting was not possible.

  Thanks for reporting this.

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  Unsolved how to debug Qt sources on mac
  • davecotter

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  @davecotter debug looks fine.

  I poked around in Xcode and found that the source for QCoreApplication for example lived at /Users/qt/work/qt/qtbase/src/corelib/kernel/qcoreapplication.cpp

  So your source mapping looks correct. I added that source mapping in lldb inside Xcode, using

  settings set target.source-map /Users/qt/work/qt /Users/hamish/dev/Qt5.12.4/5.12.4/Src

  and Xcode displayed the Qt source OK.

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  Unsolved Raspberry PI Zero Qt GUI Animation too Slow rendering performance
  • SoheilSabz

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  Unsolved How to send json-file to the address?
  • Mikeeeeee

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  Trying to connect to websocket "wss://ws.binaries.com/websockets/v3?app_id=1089".
  Yesterday, he was connected here, and today is not connected.
  Apparently he works on a certain time.

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  Unsolved using mutex when separate QSortFilterProxyModel and its source model in other thread?
  • NguyenMinh

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  @NguyenMinh said in using mutex when separate QSortFilterProxyModel and its source model in other thread?:

  What do you mean it's not supported?

  It may work but there is no guarantee and you will likely get strange errors.

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  Unsolved Weird warning message, it makes no sense
  • Guerrian

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  @Guerrian You did not answer second question from @SGaist
  Did you debug to see whether really all elements of tr were initialised?

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  Unsolved Audio duration for file manager
  • Nemooo

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  @Nemooo Something like (not really Qt specific):

  auto index = filemodel->index(0, 2); connect(player, &QMediaPlayer::durationChanged, this, [this, index](qint64 dur) { dura = static_cast<double>(dur)/60000.0; qDebug() << "duration = " << dura; filemodel->setData(index, QString().setNum(dura)); });
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  Solved qmake "-spec win32-msvc" for 64 bit?
  • davecotter

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  thanks! yes it was mixing some other dll incorrect bit depth!

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  Unsolved QT5 application crashed after running for some long time.....
  crash bad allocation memory exception • • VikramSamy

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  @aha_1980 said in QT5 application crashed after running for some long time.....:

  Usually you just start the program in the debugger and on an exception, the debugger jumps in.

  Yup this what i expected, but the debugger didnt jump in.... so did i miss any kind of settings or configurations in the debugger??.

  @mpergand said in QT5 application crashed after running for some long time.....:

  I've experiencing same issue on Mac, I solved it by doing two things:

  put a breakpoint according to the exception, here std::bad_alloc::bad_alloc() add _GLIBCXX_DEBUG=1 to the Buid environment variables (unless the stack trace is meaningless)

  Hope it helps.

  HI @mpergand , what u mean by "put a breakpoint according to the exception, here std::bad_alloc::bad_alloc()", and where do i need to put the breakpoint, u mean i can tell in 'debugger configurations' to break the at the exception??? care for more details about what u saying??

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  Unsolved setDotsPerMeterX() function cannot work on my image
  • RayX

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  Unsolved Advice please on application design
  • Tom asso

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  @Tom-asso said in Advice please on application design:

  How best to represent the main window and the map display? Can someone refer me to an example that implements something close to my application?

  Have a look at these examples: https://doc.qt.io/qt-5/datavisualization-examples.html There's a mix of Widgets and Qt Quick (QML) examples there.

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  Unsolved Qt equivalent for GTK expander
  • 3beezer

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  @3beezer said in Qt equivalent for GTK expander:

  QToolBox is at least close. It appears to provide the same functionality, but the appearance is quite difference. I like the appearance of the widget in Qt Designer better.

  Try customizing the style of a QToolBox first:

  https://doc.qt.io/qt-5/stylesheet-examples.html#customizing-qtoolbox https://doc.qt.io/qt-5/stylesheet-reference.html

  is it possible to get the code?

  Yep. It's the WidgetBox in Qt Designer: https://code.qt.io/cgit/qt/qttools.git/tree/src/designer/src/components/widgetbox

  The WidgetBox reads widgetbox.xml and uses the data to dynamically populate itself. The GUI is mainly in the WidgetBoxTreeWidget

  Here's an interactive code browser, but it only shows the *.h and *.cpp files: https://code.woboq.org/qt5/qttools/src/designer/src/components/widgetbox/

  I suppose I could translate C++ code

  If you don't like styling or the WidgetBox code, there's also the option of using a QTreeView or QTreeWidget.

  It is surprising to me that such a widget is not standard considering how many widgets there are in Qt.

  You could suggest a feature at https://bugreports.qt.io/

  It is also surprising that there seems to be no gallery of all the widgets showing them in action. Such a thing would be very helpful to beginners like me... The documentation sometimes has an image, but not always. Is there an app that displays all the widgets and permits them to be operated?

  You're right, such an example would be useful. Unfortunately, it doesn't exist.

  Here are some alternatives:

  List of all widget classes: https://doc.qt.io/qt-5/widget-classes.html Gallery code for Qt Quick Controls 2: https://doc.qt.io/qt-5/qtquickcontrols-gallery-example.html
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  Unsolved High DPI (@2x) images in HTML based widgets like ToolTips and QLabels
  high dpi font scaling @2x • • Will

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  Unsolved Unit testing with QtTest only in CLI an application that has GUI
  • Kuczmil

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  @Kuczmil in addtion to @SGaist suggestion of making your class/library "GUI-less", i.e. having no widgets at all, you may want to check the xvfb virtual framebuffer X server for X Version 11. From documentation:

  Xvfb is an X server that can run on machines with no display hardware and no physical input devices. It emulates a dumb framebuffer using virtual memory.

  Earlier Qt for Embedded version provided a virtual framebuffer which allow for simulating different displays when no actual hardware was available...
  In

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  Unsolved Error running statically-linked application... Could not find the Qt platform plugin "xcb"
  • Daniel Williams

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  Good, did that solve your build problem ?

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  Unsolved Open with...
  • GRUB_666

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  Hi,

  What OS are you talking about ?
  In any case, it's likely something you'll have to setup at installation time.

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  Unsolved How to connect to websocket ?
  • Mikeeeeee

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  I have no other working websocket except this one. But this one definitely works.
  Do you know why an example might not work? Maybe he needs some libraries?

• 

  Unsolved problem with memory ram
  c++ leaks memory leak memory • • elidrissizak

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  @elidrissizak
  Hi
  Yes, if you don't insert them into a layout.
  You can also just do and see if it makes a difference as it won't fail even if you also use layouts so
  its a safe thing to do.
  QPushButton *recal = new QPushButton(this);

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  Solved Draw a PE_IndicatorBranch in a QLabel
  • oberluz

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  @oberluz
  You can simply calculate a new rect for the beginning of the text line and
  then ask QLabel to center text or similar.
  If you want complete control you should draw both text and PE_IndicatorBranch
  with painter.
  (and not call QLabel::paintEvent(e); )
  However, if you use rich text in Label or mutliple lines it is slightly more complicated.

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  Unsolved QImageIOPlugin doesn't work
  • sandro4912

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  Ok i guess i forgot to rerun it. Now i could generate the debug files.

  When running my testprogram with debug it stills fails but the message is different

  Got keys from plugin meta data () QFactoryLoader::QFactoryLoader() checking directory path "E:/Cpp_Projekte/QT/Foundations_of_QT/CH11_image_plugin/read/build-read-Desktop_Qt_5_12_2_MSVC2017_32bit-Debug/debug/imageformats" ... loaded library "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qgifd.dll" loaded library "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qicnsd.dll" loaded library "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qicod.dll" loaded library "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qjpegd.dll" loaded library "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qsvgd.dll" loaded library "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qtgad.dll" loaded library "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qtiffd.dll" loaded library "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qwbmpd.dll" loaded library "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qwebpd.dll" "bmp" "cur" "gif" "icns" "ico" "jpeg" "jpg" "pbm" "pgm" "png" "ppm" "svg" "svgz" "tga" "tif" "tiff" "wbmp" "webp" "xbm" "xpm" Failed to load. QLibraryPrivate::unload succeeded on "E:/Qt/5.12.2/msvc2017/plugins/styles/qwindowsvistastyled.dll" QLibraryPrivate::unload succeeded on "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qgifd.dll" QLibraryPrivate::unload succeeded on "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qicnsd.dll" QLibraryPrivate::unload succeeded on "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qicod.dll" QLibraryPrivate::unload succeeded on "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qjpegd.dll" QLibraryPrivate::unload succeeded on "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qsvgd.dll" QLibraryPrivate::unload succeeded on "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qtgad.dll" QLibraryPrivate::unload succeeded on "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qtiffd.dll" QLibraryPrivate::unload succeeded on "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qwbmpd.dll" QLibraryPrivate::unload succeeded on "E:/Qt/5.12.2/msvc2017/plugins/imageformats/qwebpd.dll" QLibraryPrivate::unload succeeded on "E:/Qt/5.12.2/msvc2017/plugins/platforms/qwindowsd.dll"
• 

  Unsolved Auto-Renewable Subscription for iOS/Android.
  • bogong

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  I've published example of subscription handling written on Swift (i's from one of my projects). It's not full featured but it's showing of how it works. Before building it in XCode define Subscription Product in iTunes Connect. Soon after I am going to publish examples written on Objective-C and Objective-CPP that might be used in Qt Project. Working on adopting Swift for Qt through Objective-CPP.

  I am still seeking anyone who will help me write something like published for Google Play Store. Is anyone here? Or everyone is awaiting when someone will do it? If anyone here contact me please.

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  Unsolved Qt Tools and Versions & MSVC 2019
  • Pradeep P N

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  @Cobra91151
  Thanks.
  Jup, shifted to MSVC 2017.

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  Solved QBuffer is deprecated, what to use now for vertex buffers?
  • KoenD

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  Ok, great! Thanks!

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  Unsolved Debug Build Error on 5.12 - ASSERT: "xs == xData.data() + xData.size()"
  • EatonCode

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  Correction...

  The fix was on 5.12.3

  Looks like it's broke on 5.12.4 again.. for some reason it looks like this.

  https://www.eatoncode.com/resources/shareit/qtbug_73742_2019-06-24_07.18.28.png

  https://www.eatoncode.com/resources/shareit/Desktop_2019-06-24_07.28.31.mp4

  At least there is not a fatal error, it's just NOT displaying correctly according to the docs

  Buttons works on
  5.6.X - 5.11.X
  5.12.0 - 5.12.2 - Broke with Error listed above.
  5.12.3 - Buttons work perfectly again
  5.12.4 - No Error But Example has display issues with 4 square backgrounds. (See above screenshot and movie clip)
  5.13.0 - Has same fatal error as 5.12.2

  @Christian-Ehrlicher - Ok, I will be checking out 5.13.1 once it comes out. Thanks for the help.

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  Unsolved How to determine QObject* is empty or not?
  • clementNg

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  @clementNg said in How to determine QObject* is empty or not?:

  I dun know how to check the event too

  If event is a pointer then you do it like you do for object...

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  Solved Is it possible to force update everything for a QWidget without actually show it on the screen ?
  • stronger1234

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  Hmm... it may be a workaround for my case. However, the show() and hide() operations are not totally invisible for the user. When I debug the code and step over the first pushButton->show(), taking a break before the pushButton->hide(), I still see a not painted tool window showing there. I guess there might be a very short flash while running on some low performace machines. I'm wondering whether there is something better like ensureReparented(), which is similar to ensurePolished() for getting geometry, font, palette, ... before the widget is shown.
  Anyway, your workaround is acceptable for me at present. Thank you!

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  Unsolved QTableView Model FontRole Error.
  • Pada_

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  @Pada_ Maybe QTableView::setFont() ?

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  Unsolved QMYSQL Driver not loaded in Ubuntu
  qmysql c++ • • Double A

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  @Double-A said in QMYSQL Driver not loaded in Ubuntu:

  libmysqlclient.so.18

  As the error says it can't find libmysqlclient.so.18
  Also don't forget that on UNIX/Linux it is not enough to put the lib in same directory like on Windows.

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  Unsolved QGraphicsScene save to file, and read the file to reload ?
  • sonichy

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  Hi
  @Pl45m4 solution will allow you to make bitmap images of the scene/items and edit on other programs.

  However, if you mean to save the scene as a file and later load the same scene, you will need to save it differently for that to be possible.

  see here for a sample saving the items.
  https://stackoverflow.com/questions/30678877/save-load-items-from-a-qgraphicsscene

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  Unsolved Draggable ItemWidget in treeWidget
  • clementNg

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  @Pl45m4
  oh sorry. Changed to be a shorter name

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  Unsolved QReadWriteLock finding out whether it's write locked on same thread
  • Pavel Celba

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  I have decided, I'll write my own mutex meeting my requirements.

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  Solved Are Qt/QML apps native or hybrid
  • qcoderpro

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  @mrjj
  Thanks. :)

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  Solved Want App, but Qt is creating a DLL instead
  • harveyab

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  @harveyab said in Want App, but Qt is creating a DLL instead:

  CONFIG -= app_bundle

  You can also remove this line. It is only relevant on macOS, while you are targetting Windows only.

• 

  This topic is deleted!
  • harveyab

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  Unsolved Arduino & Qt
  • NotYourFan

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  @NotYourFan @SGaist already suggested to use readyRead() signal to read from the serial port - did you try? What exactly is the problem?

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  Solved Loading images or draw them?? witch one is faster?
  • arsinte_andrei

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  @arsinte_andrei said in Loading images or draw them?? witch one is faster?:

  hmm... that is bed news for me... I do prefer to design things in Krita or Inkscape... but to draw them in C++... that is another story.. how can I draw a moon?? what to use to do it?? just a normal white moon-shape

  It sounds like there may have been a miscommunication if you feel that you've gotten bad news. The act of taking an image loaded into memory and putting it on screen is called "painting" and you use QPainter to do it. Regardless of whether you are drawing lines and circles using the API, or copying a buffer from a pixmap that started out as a PNG image.

  As for the fastest way to do it... Just start with the simplest way, and see if that's fast enough. Only worry about solving the problems you have. A Raspberry Pi is obviously a lot slower than a desktop system so you are more likely to run into performance problems there. But it makes more sense to start with a simple prototype, and profile what the slow parts are, rather than worry about things you imagine could potentially be slow and spend your time working on stuff that may not actually have been a problem.

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  Solved Qt suddenly claims it can't find QSqlDatabase
  • Stokestack

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  @SGaist Just came back to say to say thanks again for thinking to add this remark. I was indeed pointlessly storing the DB connection in member variables and complicating my task.

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  Unsolved Export to wasm from a developed animating software using Qt5.12
  qt5.12 wasm c++ qt5 • • alizadeh91

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  Unsolved How to provide C callbacks in a library
  • Stokestack

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  @aha_1980 Thanks. I don't know why I was thinking this wouldn't work in a lib.