General and Desktop

• 

  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 Unable to build QtHttpServer project.
  • R_cts  

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  Which distribution ? The one recommended by Qt ?
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  UNSOLVED Simple REST API receive image and return json
  • RahibeMeryem  

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  What are you going to use for your AI related activities ?
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  UNSOLVED Hi, I would like to add a sound when i push a button, i have this code but it doesn't actually work, the error while compiling: QSoundEffect(qaudio): Error decoding source, How do i fix this please?
  • med12  

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  Hi and welcome to devnet, You are using a relative path so your application will not find the file as it is not located in the same folder. On an unrelated not, please give your thread a meaningful title and put the actual text of your enquiry as the body of the post along with your code.
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  UNSOLVED In MAC system in which path I can see the Makefile executable
  • Sadanand  

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  Hi, Xcode will ask you if you want to install the command line tools the first time you'll try to build something. Or you can do it from within Xcode if memory serves well.
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  UNSOLVED Qt5 hanging/crashing problems when window is not active (on MacOS)
  • aeszym  

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  My question came because I did not notice a big drop so I did not know what I should be watching for. As for the update, repainting will also depend on the hardware you use. You can't get faster than what your graphics card/screen combo allows. And you also have to think that the human eye still works at around 24fps so trying to update your numbers at high speed will not really make them more visible. Triggering meaningful updates will always be better, you'll perform well on a wider range of hardware.
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  UNSOLVED How can I export QTableView to Excel file (*.xlsx)
  • Thank You  

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  @Thank-You Hi It's quite different to export to CSV versus actually printing to a pdf as with CSV file the number of columns doesn't matter but with actual printing, you have the page limits to consider. So do you need actual printing (PDF) or is data export just fine ? ( CSV) With CSV you will get a file which you have to print using excel or other app than can import CSV file.
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  UNSOLVED QObject member variable destruction: deleteLater vs this
  • TauCeti  

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  Hi, One thing that your code does not show is what are the base classes of class A and B. If you want to use them as parent of the members variable, they have to from a suitable base classe.
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  UNSOLVED Qt 5.15.1 - Setup for app deployment
  • ad5xj  

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  Bonnie "But it seems to have some problem after loading libqxcb. How about ldd ./plugins/platforms/libqxcb.so?" All plugins are present in the plugins folder as shown above. The ldd on libxcb.so shows: $ ldd libqxcb.so linux-vdso.so.1 (0x00007ffd1a1ec000) libQt5XcbQpa.so.5 => /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5 (0x00007f85ea50b000) libfontconfig.so.1 => /usr/lib/x86_64-linux-gnu/libfontconfig.so.1 (0x00007f85ea4c4000) libfreetype.so.6 => /usr/lib/x86_64-linux-gnu/libfreetype.so.6 (0x00007f85ea405000) libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f85ea3e9000) libQt5Gui.so.5 => /home/ken/MyBooks2/plugins/platforms/./../../lib/libQt5Gui.so.5 (0x00007f85e9ab8000) libQt5DBus.so.5 => /usr/lib/x86_64-linux-gnu/libQt5DBus.so.5 (0x00007f85e9a1c000) libQt5Core.so.5 => /home/ken/MyBooks2/plugins/platforms/./../../lib/libQt5Core.so.5 (0x00007f85e9224000) libGL.so.1 => /usr/lib/x86_64-linux-gnu/libGL.so.1 (0x00007f85e919c000) libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f85e9179000) libX11-xcb.so.1 => /usr/lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007f85e9174000) libxcb-icccm.so.4 => /usr/lib/x86_64-linux-gnu/libxcb-icccm.so.4 (0x00007f85e916d000) libxcb-image.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-image.so.0 (0x00007f85e8f68000) libxcb-shm.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-shm.so.0 (0x00007f85e8f61000) libxcb-keysyms.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-keysyms.so.1 (0x00007f85e8f5c000) libxcb-randr.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-randr.so.0 (0x00007f85e8f49000) libxcb-render-util.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-render-util.so.0 (0x00007f85e8f42000) libxcb-render.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-render.so.0 (0x00007f85e8f33000) libxcb-shape.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-shape.so.0 (0x00007f85e8f2e000) libxcb-sync.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-sync.so.1 (0x00007f85e8f22000) libxcb-xfixes.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-xfixes.so.0 (0x00007f85e8f18000) libxcb-xinerama.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-xinerama.so.0 (0x00007f85e8f13000) libxcb-xkb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-xkb.so.1 (0x00007f85e8ef5000) libxcb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb.so.1 (0x00007f85e8ecb000) libXext.so.6 => /usr/lib/x86_64-linux-gnu/libXext.so.6 (0x00007f85e8eb6000) libX11.so.6 => /usr/lib/x86_64-linux-gnu/libX11.so.6 (0x00007f85e8d77000) libxkbcommon-x11.so.0 => /usr/lib/x86_64-linux-gnu/libxkbcommon-x11.so.0 (0x00007f85e8d6c000) libxkbcommon.so.0 => /usr/lib/x86_64-linux-gnu/libxkbcommon.so.0 (0x00007f85e8d2a000) libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f85e8d24000) libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f85e8b43000) libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f85e89f4000) libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f85e89d7000) libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f85e87e5000) libxcb-xinput.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-xinput.so.0 (0x00007f85e87c1000) libXrender.so.1 => /usr/lib/x86_64-linux-gnu/libXrender.so.1 (0x00007f85e85b7000) libSM.so.6 => /usr/lib/x86_64-linux-gnu/libSM.so.6 (0x00007f85e85ac000) libICE.so.6 => /usr/lib/x86_64-linux-gnu/libICE.so.6 (0x00007f85e858e000) libglib-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007f85e8463000) libexpat.so.1 => /lib/x86_64-linux-gnu/libexpat.so.1 (0x00007f85e8435000) libuuid.so.1 => /lib/x86_64-linux-gnu/libuuid.so.1 (0x00007f85e842c000) libpng16.so.16 => /usr/lib/x86_64-linux-gnu/libpng16.so.16 (0x00007f85e83f4000) libdbus-1.so.3 => /lib/x86_64-linux-gnu/libdbus-1.so.3 (0x00007f85e83a3000) libicui18n.so.56 => /home/ken/MyBooks2/plugins/platforms/./../../lib/libicui18n.so.56 (0x00007f85e7f08000) libicuuc.so.56 => /home/ken/MyBooks2/plugins/platforms/./../../lib/libicuuc.so.56 (0x00007f85e7b50000) libicudata.so.56 => /home/ken/MyBooks2/plugins/platforms/./../../lib/libicudata.so.56 (0x00007f85e616d000) libgthread-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007f85e6168000) /lib64/ld-linux-x86-64.so.2 (0x00007f85ea8c9000) libGLdispatch.so.0 => /usr/lib/x86_64-linux-gnu/libGLdispatch.so.0 (0x00007f85e60b0000) libGLX.so.0 => /usr/lib/x86_64-linux-gnu/libGLX.so.0 (0x00007f85e607c000) libxcb-util.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-util.so.1 (0x00007f85e5e74000) libXau.so.6 => /usr/lib/x86_64-linux-gnu/libXau.so.6 (0x00007f85e5e6e000) libXdmcp.so.6 => /usr/lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007f85e5e66000) libbsd.so.0 => /usr/lib/x86_64-linux-gnu/libbsd.so.0 (0x00007f85e5e4c000) libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007f85e5dd7000) libsystemd.so.0 => /lib/x86_64-linux-gnu/libsystemd.so.0 (0x00007f85e5d28000) librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f85e5d1d000) liblzma.so.5 => /lib/x86_64-linux-gnu/liblzma.so.5 (0x00007f85e5cf4000) liblz4.so.1 => /usr/lib/x86_64-linux-gnu/liblz4.so.1 (0x00007f85e5cd3000) libgcrypt.so.20 => /usr/lib/x86_64-linux-gnu/libgcrypt.so.20 (0x00007f85e5bb3000) libgpg-error.so.0 => /lib/x86_64-linux-gnu/libgpg-error.so.0 (0x00007f85e5b90000) I think I included the qt.conf before but here it is as it stands now exists in the app folder: description = MyBooks Library Application version = 2.5.12 [Paths] Prefix = /home/ken/MyBooks2 Binaries = bin Libraries = lib Plugins = plugins Given this output, it does not seem to be working as expected.
• 

  UNSOLVED QtCreator loads system Qt5 libraries
  • imironchik  

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  UNSOLVED multiple resize callbacks on QWindow when user drags corner
  • scott_craig  

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  Don't redraw on a resize event but use a QTimer so you repaint only when e.g. the size did not change for 50ms or so.
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  UNSOLVED Connect to internet
  • cludic  

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  Thanks a lot for the suggestions, I will look in to them! I am still not sure how the QTcpServer works exactly. Is it only listening on the local network when using QHostAddress::AnyIPv4? Is it "safe" to use a QTcpServer that is listening for QHostAddress::AnyIPv4? I mean, if it is possible for computers outside the local network, is there any risks using it? After reading your posts, it sounds like it will take some time to make it possible to play over internet, so I think I will stick to the local network while I try to learn more. Do you have any other suggestions when using QTcpServer for a local network?
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  SOLVED Find exact match for substring in a QString using QRegularExpression
  • MarKS  

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  @KroMignon Indeed!
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  UNSOLVED Creating custom model for QTableView
  qtableview qt 5.12 • • Thank You  

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  @Thank-You If you want to add columns/rows beyond what the SQL returns (and don't want to manipulate the query to returns these extras, which is a different possibility), you need to interpose some some kind of QAbstractProxyModel between the SQL model and the QTableView.
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  UNSOLVED Export QTableView to Excel file
  • lincoln  

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  @lincoln Did you get the way to do it ? Can you share your code if you have done it
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  UNSOLVED QThread parent issues
  • raketmus  

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  @JKSH Here is the output of the debugging it. SocketThread(0x1d02b90b3d0) QThread(0x1d02b870250) QThread(0x1d02b870250) It would see they all have the same id. You don't usually need a thread for a socket. Just leave the socket in the GUI thread. Qt socket classes and other communications classes are asynchronous. i am running a server and i would like to use blocking since that is how i set my sockets up. but i am not sure how you want me to call it if not like i am doing right now.
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  UNSOLVED thanks
  • yoser  

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  SOLVED Cant compile project
  • Mothershadowninja  

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  After a new install from Qt and MinGW it works. Thanks for the help everyone
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  UNSOLVED How to change audio plot for read from file instead of sound card?
  • zhmh  

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  SOLVED Font size on a 125% display
  • duarna  

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  Thank you all, I'll deal with it !
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  UNSOLVED Controls with listboxes differ between "vista" and "fusion" style?
  • mireiner  

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  @mireiner Fusion style has different height for those two controls. Use a custom style or QProxyStyle if you don't like it.
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  UNSOLVED printing: Why have you disabeled "reverse order" in "QTextDocument::print" ?
  • Drure  

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  Thank you all. and The application is responsible for reading the page order and printing accordingly. Not all developers of QT programs are aware of this. Many of them think something like: "My program has no control over the print process. It only calls Qt's print dialog; the rest is done by Qt (and CUPS)." See here: https://github.com/tsujan/FeatherPad/issues/455#issuecomment-731603828
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  UNSOLVED Listening and receiving data from a socket.
  • SPlatten  

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  @jsulm , whilst I try to resolve it myself, granted I could also be reading the documentation.
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  UNSOLVED How to move Qt from C:\ to another drive?
  move qt • • BenCheung0422  

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  You should reinstall Qt to make sure everything works correctly. Some of the Qt tools - especially qmake - have the installation path baked in. They will not work right away when copied to a different directory. I believe there is a way to fix the paths. However, I cannot remember and I don't know which tools need fixing. To be safe: reinstall Qt in the proper location. It's way easier.
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  UNSOLVED QCamera focus over some area, suggestions.
  • upallay  

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  @SGaist , I'm running in ubuntu 18, but I tried in windows as well, and the results is the same. I'm thinking to convert the data from the camera to image, cut, rotate and set them over a QLabel, but I don't know if this method is going to be the best way, because I would like to capture 15 fps at less.
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  UNSOLVED QFuture<void> Thread is not Starting
  • Ketan__Patel__0011  

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  @Ketan__Patel__0011 said in QFuture<void> Thread is not Starting: try to start and stop both function again and again As written in documentation, to start a new function there must be an available thread in the used thread pool: Runs function in a separate thread. The thread is taken from the global QThreadPool. Note that function may not run immediately; function will only be run once a thread becomes available. You could check before starting function how many thread are already used: qDebug() << "Allowed thread:" << pool.maxThreadCount() <<"/ threads in use:" << pool.activeThreadCount() << "/ available threads:" << (pool.maxThreadCount() - pool.activeThreadCount());
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  SOLVED How to save QMap
  • naax  

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  The more general term for this is object serialization: translating the object into a well defined format that can be saved to disk or transfered across a network. I'd advise that instead of reinventing and coming up with a custom format. You should review existing formats like XML or JSON, and if appropriate, then acquire or write translators to go between native format and the "serialized" format. Qt already has some serialization capabilities but I don't use them so I'm not sure what specifically exists.
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  UNSOLVED Postgresql driver is not found
  • alxdef  

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  @SGaist \sqldrivers\qsqlpsql.dll \platforms\qwindows.dll \vcruntime140.dll \Qt5Sql.dll \Qt5Core.dll \msvcrt.dll \libstdc++-6.dll \libssl-1_1-x64.dll \libpq.dll \libintl-8.dll \libiconv-2.dll \libcrypto-1_1-x64.dll
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  UNSOLVED One more basic C++ question
  • AnneRanch  

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  @AnneRanch connect(ui->list, &QListWidget::itemClicked , ui->list_2, &QListWidget::addItem); https://doc.qt.io/qt-5/signalsandslots.html If using overloaded signals see https://stackoverflow.com/questions/16794695/connecting-overloaded-signals-and-slots-in-qt-5
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  UNSOLVED How to size QPushButtons to width of text and pack left?
  • johnby  

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  ???What are you doing? Setting size in a layout is meaningless, they will be resized by the layout in anytime. You should use layout functions to control their size, instead of calculating by yourself. auto *button1 = new QPushButton(QLatin1String("b1"), parent); button1->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed); auto *button2 = new QPushButton(QLatin1String("b2"), parent); button2->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed); QVBoxLayout *renderLayout = new QVBoxLayout; renderLayout->addWidget(button1, 0, Qt::AlignLeft); renderLayout->addWidget(button2, 0, Qt::AlignLeft); Here's the problem, by default QPushButton has a minimum size hint of about (80, 20) in all kinds of styles. So if your text is not long enough, it will probably use 80 as the width. If you need it to be shorter, I prefer using QToolButton instead, it doesn't have such minimum value.
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  UNSOLVED How can I get value of inout parameter from PostgreSQL procedure call?
  postgresql • • OpenGL  

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  Prepare/bind does not work with postgres procedures, so I have to do it some other way. And I have no idea how.
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  UNSOLVED How to switch SQL Database at runtime with model.
  • sandro4912  

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  The problem is I also use this model in qml. So that means in QML ever time I change the database I have to create a new model? I was thinking about swapping the new model with Loader in QML. Also in reality it is not directly QSQLModel. It is a class derived from it defining already a specific format for the tables. So setQuery is not an option in this case-
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  UNSOLVED QFileSystemWatch -checking the possibility
  • meganathan  

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  @meganathan If you must call it from a python script, call exit(your_process_exit_code) at the end of the script; passing along the exit code of your process.
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  UNSOLVED Multiple pro file project with QTests
  • Creatorczyk  

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  SOLVED Camera class in QThread
  • Creatorczyk  

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  @stryga42 @Christian-Ehrlicher @jsulm Thanks, I fixed it!
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  UNSOLVED MacOS : QOpenGLWindow + QOpenGLWidget in MainWindow + QPainter causes repaint bug
  qpainter macos qopenglwindow • • Karpi  

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  Thanks for the code ! You can use the Q_OS_XXX macros to ifdef your code.
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  UNSOLVED Installing Qt 4.8.7 on Mojave
  • Seyda  

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  Hi, One of the main issue is: 4.8.7 has reached end of life before Mojave was released. You may have better luck checking with macports or brew if they still provide it.
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  UNSOLVED BackgroundRole color change not taking effect in QTableView with stylesheet
  • cdemuru  

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  @cdemuru said in BackgroundRole color change not taking effect in QTableView with stylesheet: It works fine except when I apply a stylesheet. As described in the documentation: "Note: If Qt Style Sheets are used on the same widget as functions that set the appearance of widgets, such as QWidget::setFont() or QTreeWidgetItem::setBackground(), style sheets will take precedence if the settings conflict." Use a custom QStyledItemDelegate.
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  UNSOLVED How to force a thread waiting for signal
  • dual  

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  @Christian-Ehrlicher your answer totally solved my problem. Thank you so much.