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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  SOLVED Could not load the Qt platform plugin "xcb" in "" even though it was found.
  • JonB  

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  Right, here is the reason/solution to this vexing problem: I have already used pip to install PySide2, which goes into ~/.local/lib/python3.7/site-packages (Linux). I am now trying to use a (supposedly) self-contained, standalone virtual environment (minconda) for a project. All its stuff got put into ~/miniconda3/envs/py37/lib/python3.7/site-packages, that includes (its own) PySide2. When I strace where it decides to pick the libQt5Gui.so.5 mentioned in the error message, I see openat(AT_FDCWD, "/home/jon/.local/lib/python3.7/site-packages/PySide2/libQt5Gui.so.5", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/home/jon/.local/lib/python3.7/site-packages/PySide2/Qt/lib/libQt5Gui.so.5", O_RDONLY|O_CLOEXEC) = 4 so it's picking that up in the other PySide2's area. If I rename so that ~/.local/lib/python3.7/site-packages/PySide2 directory cannot be found, the strace now shows openat(AT_FDCWD, "/home/jon/miniconda3/envs/py37/lib/python3.7/site-packages/PySide2/../../../libQt5Gui.so.5", O_RDONLY|O_CLOEXEC) = 4 so it's picking it up in the desired PySide2's area. Lo & behold, the application finally works!! Which is why, as I have said elsewhere, I just don't think these "virtual environments" are "robust"/"safe"/"clear" enough to feel comfortable with, at least from my experiences. For anyone in a similar situation, I have found that running my python program under the virtual environment requires the -s command-line argument ("Don’t add the user site-packages directory to sys.path.") to prevent it from picking up that libQt5Gui.so.5 file in the ~/.local/lib/python3.7/site-packages area when it should be picking it up from where it is in the virtual environment area itself. Sad and frustrating, but true....
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  UNSOLVED Reading data after submit returns wrong values
  • Mark81  

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  @SGaist Unfortunately I didn't find any criteria. I'm just developing with QtCreator.
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  UNSOLVED Problems launching a QProgressDialog after main window is made visible
  • JCBaraza  

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  @JCBaraza said in Problems launching a QProgressDialog after main window is made visible: progress.setRange(0, 0); progress.setAutoClose(true); progress.setValue(1); This doesn't make sense. You set the range from 0 to 0, then you set a value of 1. Have you read the warning about modal QProgressDialogs? Warning: If the progress dialog is modal (see QProgressDialog::QProgressDialog()), setValue() calls QApplication::processEvents(), so take care that this does not cause undesirable re-entrancy in your code. From https://doc.qt.io/qt-5/qprogressdialog.html#value-prop @JCBaraza said in Problems launching a QProgressDialog after main window is made visible: is it possible to change the aspect of the bar in the QProgressDialog to make its text invisible You mean this (progressBar->setTextVisible(false))? @JCBaraza said in Problems launching a QProgressDialog after main window is made visible: this does not show any motion in the progress bar Check if your "slow tasks" are blocking your GUI thread. If they do so, it would cause the progressBar to wait until the tasks are done and continue afterwards.
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  UNSOLVED configure -prefix
  • Cinexus123  

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  First thing: why do you want to build Qt ? As for the source code, if you have a precise version in mind, you can use the MaintenanceTool to download the version you want. Otherwise, get the code from https://code.qt.io
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  UNSOLVED How do I stop repainting on scroll
  • lansing  

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  @SGaist I'm using Qt 5.13.2 and Windows 10. In my ui file, I created a graphicsView object. mainwindow.cpp scene = new QGraphicsScene(this); myItem = new CustomerGraphicsItem(); scene->addItem(myItem ) ui->graphicsView->setScene(scene) mycustomeitem.cpp void CustomerGraphicsItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) { QBrush blackBrush(Qt::black); painter->fillRect(boundingRect(), blackBrush); painter->drawText(blah blah blah) qDebug() << "printing..."; } The program redraw every time I move the scroll bar or resize my window.
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  UNSOLVED QTemporaryDir reasons for not valid/fail to create?
  • pmh4514  

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  UNSOLVED List of custom widgets in QT
  • Cynical  

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  UNSOLVED Error during uninstalling Qt application from MacOS
  • aliks-os  

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  @SGaist yes, I mean in app container. the rigths on folder is drwxr-xr-x 4 userName staff
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  UNSOLVED How to run all unit-tests on macOS?
  • ntt2899  

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  @ntt2899 But why do you want to deploy unit test executables?! They are usually not deployed, just executed after build.
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  UNSOLVED QTreeView - QStyledItemDelegate question
  • Lati  

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  UNSOLVED Vista style is not loaded
  • mcmigliore  

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  Hi and welcome to devnet, Does it happen on a deployed application ?
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  UNSOLVED Camera activity check
  • Prawn  

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  Hi and welcome to devnet, I would try with the QCamera::status property.
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  UNSOLVED How to add Sailfish OS SDK to already installed Qt 5.12?
  • bogong  

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  Just sent email to the support of Sailfish OS. Hope will get reply.
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  UNSOLVED General questions about Model in Qt (docs)
  • Xilit  

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  @J-Hilk Still don't work.( But as I've mentioned above I've already found in Woboq code browser. On this link). Interesting. I download Sources to make MySQL work, but it doesn't. Maybe that's why? Because Sqlite does. But I'm not sure what does Target path means.
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  UNSOLVED Voice recognition(Speech to Text) Implementation in Qt
  • Venkatesh V  

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  Hi @SGaist , I have clone the branch wip/speech-recognition in the link you give But I did't know how to what next ? I just know that we need install Flite in window 10 for me, but It still does't work . Can you give a more guide to complete run this speech - to text . Many thanks.
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  UNSOLVED Regarding Projector Programming using QT
  • Prath  

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  @Prath You should check what write() returns and connect a slot to https://doc.qt.io/qt-5/qserialport.html#errorOccurred to see whether you get any errors.
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  UNSOLVED Successfully loaded .qm files, but translator remained empty
  • QTLeearn  

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  @QTLeearn it looks like your .qm file(s) are empty. Even with no translations provided at all (no "LAST CASE") if the .qm file was properly built and loaded, you should see "TEXT_BUTTON_LAST_CASE" as the "translated" string So you need to do the lupdate / translations (Linguist) / lrelease process properly.
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  UNSOLVED configure is not recognized
  • Cinexus123  

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  Isn't this thread more or less the same as this one ?
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  SOLVED Refresh entire form upon pressing a button
  • russjohn834  

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  Thank you @JonB for your feedback
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  UNSOLVED QComboBox item model with ItemIsUserCheckable and ItemIsSelectable
  • Alvein  

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  @Alvein said in QComboBox item model with ItemIsUserCheckable and ItemIsSelectable: So, mixing the two flags, does not show the checkboxes. I will have to take your word for it. But I did find Google examples out there using both flags, and nobody mentioned what you say. When using "native" comboboxes on platforms I don't think they allow checkboxes, I'm used to they just offer a single-label list to single-select from, though I could be wrong. I don't know how that relates to the Qt QComboBox ones.
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  UNSOLVED Connect to multiple Bluetooth Low Energy devices
  • SpaceToon  

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  UNSOLVED Widget required
  • Colins2  

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  Hi For big log files, maybe a ListView+model works better ? QPlainTextEdit is much like MemoPad however, it will copy the text to its internal buffer so it becomes heavy with thousands of lines.
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  UNSOLVED Mainwindow content gets vignetted at border
  • gde23  

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  @gde23 said in Mainwindow content gets vignetted at border: which will automatically generate the layouts It does not, you have to layout your widgets the way you want them to be layd out.
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  UNSOLVED QStackedWidget with layouts
  • hobbyProgrammer  

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  @hobbyProgrammer said in QStackedWidget with layouts: Is there any way I can make my QStackedWidget scalable & responsive? Sure, put it into a layout.
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  UNSOLVED Opening a window behind main window
  windows mainwindow pixmap graphicsview raises window • • hodahle  

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  @hodahle Briefly. Yes, you would need another slot for QTimer. To get it to have access to title & geometryfrom your function you could conveniently use a C++ lambda. That is a whole other topic, which one day you should look up. However, for now it's not relevant, as you have said you can delete all those extra lines and it's still "delayed". I don't know why you get such a "delay". (Is your viewer "big" with "lots of" widgets?) One thing you could try, don't know if it would help/how it would behave, is to move the MainWindow::raise() call into the the viewers QWidget::showEvent slot (for now, while you test, just hack in access to your mainWindow instance because you're not sure how to pass that around).. If that works, it might run earlier, I don't know. Or, if you have to, you could look at the Qt source code (e.g. via woboq) to see what just the raise() has to do.
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  SOLVED Assign value to a string in a struct
  • russjohn834  

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  @russjohn834 Great! Don't forget to use the topic tools to set this topic to solved 😉
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  UNSOLVED is it possible to use QtConcurrent::mapped inside a QThread ?
  • RahibeMeryem  

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  @RahibeMeryem Try to use lambda instead of detecFaceModifyFrames. detecFaceModifyFrames is a non static method and cannot be used without class instance.
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  UNSOLVED Qt3DCore - High CPU Usage
  • webzoid  

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  @JKSH Yes, I will happily report this as a bug. Given that it can be recreated with one of the examples then I shouldn't need to add too much extra detail. Thanks for your help.
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  UNSOLVED qml use same rectangle component for multiple objects
  • Mandeep.Chaudhary  

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  The nearest i go was using component and loader. but problem is declaring path is again a problem. ``` Component { id: redSquare Rectangle { id: temperature x: 8 y: 11 width: 351 height: 329 color: "#ffffff" radius: 10 property string path: "/root/temp" property string val: "" Text{ id: textFieldtemp text :qsTr("") y:50 font.family: "Helvetica" font.pointSize: 24 anchors.horizontalCenter: parent.horizontalCenter } Connections { target: myModel onSensorValueChanged:{ // path = "/root/temp" val = value if (addr === path) { textFieldtemp.text = "Temperature " + val + "*C" } } } } } Loader { sourceComponent: redSquare } // Loader { sourceComponent: redSquare ; x:369; path:"/root/moist"}
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  UNSOLVED stop a loop in object that has been moved to a QThread?
  qthread loop movetothread stop • • pauledd  

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  @pauledd I would recommend using the build-in QThread mechanism to interrupt a thread: public slots: void doWork() { forever() { ... if ( QThread::currentThread()->isInterruptionRequested() ) { return; } ... } } You can add this check to your SPI loop multiple times but avoid to call it too often, according to the dokumentation. Add something like this to your MainWindow-Instance: public slots: void cancel() { if( thread.isRunning()) { thread.requestInterruption(); } } and connect this Slot to some Cancel-Button.
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  UNSOLVED Styling a QCheckBox on demand
  • donquibeats  

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  Hi, There's nothing fundamentally different between the C++ and Python with regard to the stylesheet handling. See the Customizing QCheckBox part of the stylesheet examples.
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  [solved] setStyleSheet to QPushButton - rounded corners
  • never_ever  

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  Try this and also check this https://doc.qt.io/qt-5/stylesheet-examples.html and https://doc.qt.io/qt-5/stylesheet-reference.html QPushButton { color: #333; border: 2px solid #555; border-radius: 20px; border-style: outset; background: qradialgradient( cx: 0.3, cy: -0.4, fx: 0.3, fy: -0.4, radius: 1.35, stop: 0 #fff, stop: 1 #888 ); padding: 5px; } QPushButton:hover { background: qradialgradient( cx: 0.3, cy: -0.4, fx: 0.3, fy: -0.4, radius: 1.35, stop: 0 #fff, stop: 1 #bbb ); } QPushButton:pressed { border-style: inset; background: qradialgradient( cx: 0.4, cy: -0.1, fx: 0.4, fy: -0.1, radius: 1.35, stop: 0 #fff, stop: 1 #ddd ); }
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  UNSOLVED Changing QCursor dynamically between @1x and @2x
  • Sivan  

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  UNSOLVED How to load the Gif in transparent
  • sankarapandiyan  

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  UNSOLVED how to upload images taken from QTapp to Cloud Server
  qcamera api google drive • • vinaygopal  

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  @vinaygopal Is your Google storage mounted as a drive? If so you can access it as any other drive. If not then you probably will need to use Google API for uploading.
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  UNSOLVED QSerialPort on Linux with high baudrate
  • Texture  

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  @kuzulis Thank you for your reply. I have spent a time to get some experiment results before answering. Some answers and notices are below: As external device for testing I have STM32F4 Discovery and its UART connected with PC via CH340 serial converter. First simple case (500k baudrate) is perfectly working on Linux with CuteCom terminal emulator (unfortunately, it doesn't support 1kk baudrate). I have created pure simple console application with two approaches (singleton and dynamic QSerialPort handler classes), everything is working well with 500k and 1kk baudrate. I have tried to put my serial port handler class to other thread in my program, but nothing changed. Very weird and not obvious effect for me: if I programmatically generate answer array in STM32 (e.g. fill in for-loop with for index), my program is working without any problem. If I use ADC in STM32 to fill my array (as it supposed for my embedded device) I get issues described above. I am so confused with so many factors that affect on serial port reading and don't know, what should I try to fix at first...
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  UNSOLVED Trying to implement QChart, get error undefined reference to 'qt_version_tag@Qt_5.9'
  qchart qtversiontag • • markd  

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  @markd Do you have another Qt version installed on your system (in /usr for example)? Check the linker call when building your app with QChart to see what it links.
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  SOLVED How we can disable the close [X] button in the top right corner of GUI?
  • Mijaz  

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  @J-Hilk Now I have removed the title bar. and its working on board also. setWindowFlags(Qt::Dialog | Qt::FramelessWindowHint | Qt::WindowTitleHint);