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 Different files are generated with cmake and with qmake
  • posktomten  

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  Thanks! I'll have to test that
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  UNSOLVED cmake: "cannot find *.ts file"
  • posktomten  

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  UNSOLVED Building .pro as library - suggestions ?
  • AnneRanch  

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  I think that is a solution. That way I can keep editing the source ans still run the "library" a stand alone project - as long as I keep the "inlcude(s) " happy . . I'll give a go.
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  UNSOLVED External program gives std::bad_alloc()
  • Hollow10  

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  in the linux world this would be explained by child inheriting restricting ulimit values from the parent. In windoze, I have no clue. freeglut is an open source opengl ui library. your Qt project build isn't including the header when you compile internally.
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  UNSOLVED Need an assistence with "bluez" libray errors - sort off repost
  • AnneRanch  

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  UNSOLVED How to Insert checkbox in root of Qtreeview. Treeview is created by using QDOMDocument reading XML file.
  • Aviral 0  

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  @Aviral-0 said in How to Insert checkbox in root of Qtreeview. Treeview is created by using QDOMDocument reading XML file.: @JonB You don't know anything, just arrogant rude. I didn't find any solutions to my problem from you! Just wow! I have made over a dozen posts so far over a week trying to help you solve your issues. Told you at each stage what to do, and at least a couple of times what to do now. Why don't you have a look back up? Thanks for nothing, bro.
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  UNSOLVED Hide border when focused in QTreeWidget/QTableWidget
  • Sabrac  

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  UNSOLVED Does Qt Widgets apply default icc color profiles?
  • stefanwoe  

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  The observation described was caused by a icc profile embedded in the png file used for testing. So this problem is solved.
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  UNSOLVED QMovie not starting
  • Dummie1138  

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  @Dummie1138 said in QMovie not starting: ui->loadingLabel->movie()->start(); qDebug() << "welpMovie " << movie->state(); You are calling state() right after calling start(). This will not work - start() is asynchronous. You need to connect a slot to https://doc.qt.io/qt-6/qmovie.html#stateChanged to get state updates when they occur. And you really should use newer Qt5 connect syntax.
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  UNSOLVED QT Serialport GUI and worker thread
  • Vahid Ajallooeian  

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  @MhM93 As in your other thread on this subject. You should not use or recommend to others the use of a thread to do asynchronous serial port IO. That is just what the other posters are telling the OP here. And you should not have code like your readserialport() which uses waitForReadyRead(), multiple times and in loops.
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  UNSOLVED TableView not updated or refreshed unless column is resized and scroll bar move up and down few times
  qsqltablemodel proxy model sort filter • • VikramSamy  

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  @VikramSamy I don't know, but a couple of observations: You are using a QSqlTableModel, so it should be emitting all the dataChanged() and rowsInnserted() signals itself. I would remove all your emits. HistoryProxyModel->setDynamicSortFilter(false);: try setting this to true, any difference? If you remove your proxy model temporarily does everything work? Try starting from a Qt example with model + proxy model, does that work?
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  UNSOLVED Executing batch file and getting finished signal
  • lukutis222  

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  @lukutis222 As @ChrisW67 has written. Note that to wait for finished you will want to use QProcess::start() and not startDetached(). Also do not try to run the Windows start command, that will prevent waiting for finished on the program it runs.
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  UNSOLVED Help improving drawing function of audio peaks in an waveform widget.
  • marcelnitan  

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  @marcelnitan There is no point in drawing rectangles that are 1/100 of a pixel wide. There is some benefit in subsample drawing for smoothing, but you can get most of that by simply drawing 2 rectangles per horizontal pixel. It looks a bit like what you tried, but you simply "jump" and skip data. Instead, calculate the maximum/minimum for each half pixel by looping through the samples that make up that half-pixel. If your data is in a contiguous memory block (like a QVector or std::vector, or even QList from Qt6 on), then processing these min/max values should be very fast. If need be, that calculation could also be massively parallelized, but I'd measure before doing that.
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  UNSOLVED QPainter Performance
  • inthewind2004  

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  @inthewind2004 What is the lifetime of m_id2PointList and mImage? If m_id2PointList just gets longer and longer, no need to wonder about performance issues. QPainter is pretty optimized, but it is single-threaded and doesn't use GPU support. And Bezier lines are not the simplest thing to draw. If you only ever want to add lines, then store the image, and only paint new lines on top of the existing image. That should be pretty fast.
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  UNSOLVED is there any way to integrate two projects one build in qT4.1 and onother one in QT 6.4??
  • odJL  

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  @odJL said in is there any way to integrate two projects one build in qT4.1 and onother one in QT 6.4??: well i didnt understand well i don't know i thought also it depend on the compiler cuz qt6 it works with 64bit s!! If you use a library written with Qt4 and already compiled, there is the problem that you need to use the same compiler version (most likely) for the other project as well. For example, on Windows MSVC 2010, 2013 and 2017 are all not compatible with each other. You cannot link between different compiler versions (this has nothing to do with Qt in particular). I know that 2017 and 2019 are compatible, though. If you use pre-compiled Qt libraries, Qt 4 only exists for older compilers and Qt 6 only for newer compilers (on Windows). Biggest problem: your Qt 4 code needs to link to Qt 4 and your Qt 6 code needs to link to Qt 6. This is not possible, because both Qt versions define the same symbols for the linker. You also cannot pass a QString or a QVector between functions of Qt 4 and Qt 6. The ABIs are not compatible. There is no way to have both Qt 4 and Qt 6 inside the same program. This is the reason why you have to port one project over to use the same Qt version.
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  UNSOLVED Linking .lib file generated with MSVC in Qt Creator that uses gcc
  • AathakA  

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  @SGaist Well, since a C library works one could write a wrapper around the MSVC C++ library (using an MSVC compiler) and then use the C bridge from within GCC. Also, the name mangling (Microsoft calls it 'decorated names') seems to be well documented, so you could call the mangled name by hand/write a bridge class that internally calls the mangled name. It is definitely messy and tedious to use a library compiled for a different compiler. Did find just this: https://gcc-help.gcc.gnu.narkive.com/8ikYYHZN/convert-gcc-under-cygwin-name-mangling-to-vc-name-mangling Besides the name mangling there is additional problems with the C++ ABI. This leaves only a C wrapper to interface between MSVC C++ and GCC C++.
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  UNSOLVED Detect out-of-memory
  • MHermann  

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  @MHermann It happens in Release-Mode and than the application is crashing and then closing smells like uninitialised varibales/pointers
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  UNSOLVED Qt5 C++ application compilation from prompt
  • Robert M.  

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  It might help if you also add Qt dir to path: set PATH=C:\Qt\5.13.2\mingw73_64\bin;%PATH%
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  UNSOLVED Comment out a block of text / lines in .pro file ?
  • AnneRanch  

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  qmake only offers single line comments If we guess you are using Qt Creator to edit this pro file then you can: Select all the lines you wish to comment out Press Ctrl-/ to toggle the comment state
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  SOLVED Delete a QVBoxLayout from the centralWidget
  • Tobias88  

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  @Christian-Ehrlicher Thank you! This helped alot and helped me solve my problem! One more Question.... How do I set my Topic as solved? Edit: Got it by myself.
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  UNSOLVED why program is so laggy after using QGraphicsDropShadowEffect
  • saeid0034  

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  I'm seeing the same issue in a small game running PySide6 on an apple M1 Macbook Pro. 200-300 FPS without drop shadow effect enabled, and 30FPS with. One solution for my use case may be to bake the effect into an image asset and draw that instead. I don't need the functionality of the QGraphicsDropShadowEffect during runtime, just the look.
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  UNSOLVED Unexpected message in Debug log
  • Perdrix  

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  Thank you, I set in the application manifest, so if Qt is also trying to set it than that explains the message.
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  UNSOLVED Makefile "WARNING" but no build...
  • AnneRanch  

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  As you can see the error is in mdi.pro, line 31.
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  UNSOLVED QVector of QPair<int, QString> does not sort the elements C++
  c++ qvector sort algorithms qpair • • MEsc  

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  No sort problem but a basic c(++) problem - you pass the parameters to unzip() by value instead by reference so how should the those variables be updated outside?
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  UNSOLVED Can HTML tags be used in QPushButton:setText ?
  • edmh  

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  @edmh said in Can HTML tags be used in QPushButton:setText ?: Moderator - please mark this topic as 'resolved' Thanks. You can do it yourself either using the "Topic Tools" button or the three dotted menu beside the answer you deem correct.
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  SOLVED Can't write on Arduino from Qt
  • Jasmin Quinn  

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  ESPRIT student ?
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  UNSOLVED QWebsocket->valid()
  qwebsocket • • RickF  

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  Hi, Good question ! Behind your back ? Likely not. Based on the documentation it represent a non-ready for communication state.
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  UNSOLVED How to exclude QGraphicsDropShadowEffect from a desired widget side?
  • Karine  

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  This topic is deleted!
  • morte  

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  UNSOLVED Managing Qt event loop in a Python binding created from C++ library
  • glamis  

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  SOLVED QTreeView: hide box in the corner
  qtreeview qtdesigner • • Fire Cube  

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  Many Thanks That worked great.
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  UNSOLVED QRegularExpression to replace match
  • Roberrt  

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  @Roberrt Your regular expression in itself is fine at matching all the way to the first /, as regex101 shows you. Your problem is in the replacement: you replace all of that match with your 12ff00, hence the final result of 12ff00**/. You would want to preserve much more of the original string. There are many ways of doing this, depending on exactly what you want. Reading your original requirement: I'm trying to replace just the value between # and ; in this case a4002c let's do just that? auto re = QRegularExpression("#[^;]*"); str = str.replace(re, "#12ff00")); "Replace a # followed by any number of non-; characters by #12ff00. The rest of the string (before and after the match) remains as-is. As I say, there are many other possibilities depending on exactly what your requirement is. Maybe you will say "but I must only do this if there is border there" or "fine, but I'd like to make my original regular expression work". P.S. I don't think you noticed that at regex101 in the left-hand pane under FUNCTION you had the default of Match. You can test by changing that to Substitution. I have done so for your original expression at https://regex101.com/r/ZgjhKI/1 , so you can see.
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  SOLVED How do I create a directory which can only be accessed and manipulate by the application
  c++11 windows10 directory security • • Deepak Dinesh  

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  @JonB thanks
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  SOLVED How to round the corners of a QImage?
  • n34rt  

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  @n34rt painter.setRenderHint(QPainter::Antialiasing);
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  SOLVED qbytearray find two similar values
  • fadu  

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  @JonB that's it thanks a lot the problem is solved and this is the new code QFile file("test.qcn"); file.open(QIODevice::ReadOnly); QByteArray data = file.readAll(); file.close(); QByteArray patch_data1 = QByteArray::fromHex("8800010026020000"); int64_t index = data.indexOf(patch_data1); int64_t index2 = data.indexOf(patch_data1,index+patch_data1.size()); qInfo() <<data.mid(index,17).toHex()<<index<< data.mid(index2,17).toHex() << index2;
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  UNSOLVED How to handle when an QLineEdit widget is selected and no longer selected
  • Karine  

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  @Karine said in How to handle when an QLineEdit widget is selected and no longer selected: background-color: rgba(0, 0, 0, 190); Removing the alpha from the background, the caret is now visible, could it also be a bug?
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  This topic is deleted!
  • Sabrac  

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  UNSOLVED Static struct member declaration
  • lukutis222  

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  @mpergand said in Static struct member declaration: C++ is stupid enough that you have to declare static vars two times :) No, you have to declare it once and also define it once. static pod members can be declared and defined in one place nowadays.