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 Can't get value from command chaining ...
  • darongyi

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  I called class on dialog..
  I tried to use setstandardoutputprocess.
  It didnt’t bring data.. Can u give examples?
  I want to improve better..

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  Unsolved How to make the QGraphicsView re sizable by mouse?
  • Mohamed Hatem

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  hi
  Maybe this be good starting point
  http://www.davidwdrell.net/wordpress/?page_id=46

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  Unsolved Qt and Exception Trapping
  • webzoid

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  @kshegunov You are absolutely correct - error checking has been added. Testing now so will see if the outcome is different.

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  Unsolved QCanBus - DLC (Data Length Code) automatically calculated from payload?
  • robro

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  Unsolved Make Window start as compact as possible?
  • PascP

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  @PascP said in Make Window start as compact as possible?:

  I omitted that (replaced those two values with 0) and I still get the same results.

  And you went through your QML file and equally got rid of other large, explicit sizes there like for your QMenuBar, didn't you?

  Or tried setting them all to like 1x1 and see whether Qt auto-sizes everything to smallest?

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  Unsolved How to hide shared memory ?
  • jondoe

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  @jondoe
  Although you should indeed read @Asperamanca's references, be aware there is nothing at all there which would address your query about scanning memory for strings (nor would I expect there to be), it's aimed more at obfuscating your source code, which is quite different.

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  Unsolved updating radio buttons programmatically
  • mzimmers

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  @Pablo-J.-Rogina said in updating radio buttons programmatically:

  @mzimmers said in updating radio buttons programmatically:

  I use a QDataWidgetMapper object in my dialog

  having stated this from the very beginning should have saved time and effort, and allow us to narrow down the issue... :-)

  Sorry -- I thought I had done so here:
  https://forum.qt.io/topic/93723/updating-radio-buttons-programmatically/4

  In any event, it may be time to consider a different approach.

  SGaist: looking at your response, I have a couple questions:

  you mention customizing my address type widget - are you referring to the buttongroup? What do you mean by "the setter"?
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  Unsolved QtBluetooth on Windows not working
  bluetooth windows 10 • • elsa

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  @J.Hilk said in QtBluetooth on Windows not working:

  @sierdzio said in QtBluetooth on Windows not working:

  Well, kind of works because BT support on Windows is very weak.

  What a kind way to phrase that, not what would come to my mind.....

  Heh, yeah, the sentence you read is not the first one I wrote :P Although in my recent experience, Windows itself is also not particularly good with bluetooth, especially Low Energy variety.

  Also, the success of QtBluetooth highly relys on the Windows version, I would recommand upgrading to the lastest one possible.

  Indeed. Different versions of Windows 10 work differently, Windows 8.1 comes with extra bunch of crashes...

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  Unsolved QTextEdit / QLineEdit with tag item
  • dridk2

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  @JonB
  Well a widget +layout + a button for close and
  a QLabel with Qt::TextEditable (TextInteractionFlags)
  should do it.

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  Unsolved QSqlTableModel record performance with QString concat
  • JahJerMar

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  @jsulm
  Hi @jsulm. By now the OP has discovered:

  The real issue is accessing the records from the model actually takes the time... that record.value method is killer.
  It's not the QString append or even the + operators concat of the commas and apostrophes.

  His stuff is just too slow to be a strings issue!

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  Solved QProcess don't send signals.
  • Anton Shelenkov

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  @JonB Thank's you !!

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  Solved trouble using qobject_cast (MOC not seeing Q_OBJECT)
  • devDawg

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  @SGaist Makes total sense.

  Thanks man.

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  Unsolved how do something on a window before the user open that window?
  • davidlabib

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  @davidlabib

  but when the user input admin password correct it will enabled the widgets

  When? Do you re-verify the password as he types each character into the line edit?

  my problem is to make the widgets disabled by default

  Put the disablement into the constructor.

  if i put doAll(false) in the constructor when soneone fill admin password correct it will enable

  It will not enable unless you tell it to.

  but if the user closed editUser and open it again it will be enabled without admin password filling

  That is the bit where @mrjj was suggesting you destroy the dialog after using it, and re-create a new one each time it's wanted. Then there is no "open again" from wherever it got to, you always start afresh in the constructor.

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  Solved QGraphicsRecItem::setRect causing a SIGSEGV error
  • Corny

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  Solved

  Gerd and JonB, you’re absolutely correct. The rectangle was initialized in the header file without using new, so it wouldn’t work.

  Thank you so much.

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  Unsolved Updating the Values in AbstarctListModel in Qt
  • Sanjeev Gudisagar

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  Are you cleaning the contents of entire model & inserting the fresh rows or just updating few rows inside the model ?

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  Unsolved command chaining didn't work and no value
  • darongyi

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  @darongyi This is already third thread with same question! Why?

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  Unsolved [PLEASE HELP] how to make a barcode receiver?
  • davidlabib

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  @davidlabib said in [PLEASE HELP] how to make a barcode receiver?:

  always waiting for input 13 digit --any right barcode in the world contain 13 digit

  Be careful with this assumption, think of EAN 8 for instance...

  Like the UPC code, there is the EAN-13 symbology with 13 digits, and an abbreviated EAN barcode called the EAN-8 with only 8 digits for smaller goods where space is limited.

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  Unsolved compiling in ARMv7h fails
  • saber

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  @saber said in compiling in ARMv7h fails:

  Project ERROR: Unknown module(s) in QT: core gui widgets webengine webenginecore webenginewidgets webchannel

  The cross compiled Qt for armv7h is missing the modules mentioned in this error message...
  "make[1]: Leaving directory '/home/manjaro/corebox/src/build/library'" - also, you should NOT build from the source code directory! Use out of source builds. Else you will end up with build artefacts from previous builds (for other platforms) which will cause troubles.

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  Unsolved QTableView custom styling
  • napajejenunedk0

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  Solved how to pass QFile pointer to the QTextStream object
  • thippu

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  @thippu said in how to pass QFile pointer to the QTextStream object:

  the compiler did not say anything about it?

  It did: "but it says that the invalid use of incomplete type class QTextStream"
  "incomplete type" means that compiler does not know what QTextStream is, which usually means that the include is missing.

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  Unsolved QStackedWidget pages and closeEvent()/eventFilter()
  • JonB

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  Unsolved QDockWidget fokussing problem when undocked
  • gde23

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  Unsolved It's possible to change defaultDropAction during drag?
  qdrag drag drop • • calanor

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  Unsolved start terminal with command by QProcess
  • saber

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  @saber

  in future i will take much time to clear the qustion.

  Thank you :)

  because the htop app has a icon and when it clicked it opes the app in the defult terminal.

  You misunderstand how "launching an app from an icon" works. This does not only apply to htop.

  "Launching from an icon" under Linux is a feature of your Desktop Manager. And you could be using a variety of those under Linux, e.g. Unity, GNOME, I guess you're using XFCE. Almost certainly you have a htop.desktop file somewhere, probably hidden somewhere inside your user area (e.g. try running find ~ -name \*.desktop -print; or it might be in either of /usr/share/applications or ~/.local/share/applications). When the desktop launches from an icon it reads that file and that tells it what to do. And if you look in that file (it's text format) you''ll see something stating its a "console" or "terminal" application (e.g. Terminal=true; also see how there is a Exec=... to specify what exactly it is to execute). So when your desktop launches it the desktop creates the console/terminal window for it to run in automatically. When we do it from within another application, like a Qt one, we need to do that ourselves explicitly, hence what you've been trying.

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  Unsolved Can we create multiple tabs in Central Widget of QT QMain Window
  • Qt Enthusiast

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  Hi
  There is really nothing to it.

  you can just do

  auto tw = new QTabWidget (this); tw->addTab(new QWidget, "first"); setCentralWidget( tw );
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  Unsolved Zoom in the photo in flickable, the part outside the window cannot be dragged back
  • jimfar

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  Unsolved Qt Programming Language
  • Annabelle

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  @Annabelle said in Qt Programming Language:

  Is Cmake built in to the Command Prompt in Windows 7? Or would I have to install it from a download at an external source? I also ask this about Qmake. The reason why I ask is because I tried typing the Qmake code that someone posted earlier on the forum, and it said something along the lines of, "Qmake is not an operable program or a valid internal command". What's up with that, I wonder?

  No, cmake is not installed on Windows by default. You can get it from here: https://cmake.org/files/v3.12/cmake-3.12.1-win64-x64.msi I see some warning about this installer on cmake website (https://cmake.org/download/), but I'm not a regular Windows user so I don't know whether this warning can be ignored or not.

  About qmake: when you install Qt, it will not update the system PATH variable - so qmake won't be available in standard command prompt. There are 2 ways around it:

  open Qt command prompt (it will be installed to Qt directory in start menu) or type full path to qmake in normal Windows command prompt (it will be something like c:\Qt\5.11.1\mingw53_32\bin\qmake.exe)
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  Unsolved Zoom In/Out QTableView with a frozen first column
  qtableview qgraphicsview zoomlevel c++ • • MarKS

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  Hi,

  I am using a QGraphicsRectItem on top of QTableView which acts like a SeekBar (horizontal slider). So i have put QTableView and QGraphicsRectItem in one QGraphicsScene. I posted a question on SOV regarding this . Should give you an idea what i am trying to achieve. I am not sure if this is a good approach but if you can share some ideas would be nice.

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  Solved How can I turn off auto sorting of QTableWidget?
  • Aaron Kim

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  @Aaron-Kim

  Please mark topic as solved :)

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  Solved QGraphicsTextItem alignment char to top-left corner
  qgraphicstextit alignment positioning • • kjnm

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  Thanks everyone for help.
  For me solution is using QGraphicsSimpleTextItem and translate by value calculate by QFontMetricsF::tightBoundingRect / QFontMetricsF::boundingRect.
  
  Now yellow is QGraphicsSimpleTextItem::boundingRect.

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  Solved Visual Studio 15.8.0 and Qt 5.11.1 does not compile (QRandom/std::aligned_storage)
  visual studio • • sophonet

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  Hello @sophonet ,

  thank you very much for your answer.
  You are right. In the meantime, my problem with Qt 5.9.5 was solved:

  [https://codereview.qt-project.org/#/c/236948/2/src/corelib/tools/qalgorithms.h](link url)

  Many greetings from Germany,
  Matthias

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  Solved Problem with new Visual Studio update 2017 Version 15.8.0 and Qt 5.9.5
  visual studio • • QMatthias

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  I too just upgraded to version 15.8.0 yesterday running Qt 5.10.1 on Windows x86 (32-bit) and ran into the same problem. My solution was to downgrade to 15.7.6.

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  Solved beginner error trying to deploy project
  bbb • • roo_

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  @roo_ said in beginner error trying to deploy project:

  _ZNSt18condition_variable4waitERSt1unique_lockStmutexE could not be located in the dynamic link library path QT5Core.dll.

  Often, this means you accidentally deployed the MSVC version instead of the MinGW version of Qt5Core.dll.

  The recommended way to deploy is to use windeployqt.

  If you want to deploy manually, make sure you copy the correct DLLs (do not take any DLLs from the Qt Creator folder!) See http://wiki.qt.io/Deploy_an_Application_on_Windows for details.

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  Unsolved qt ssl and https
  • Jedd

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  @SGaist Thanks for that suggestion. Depends revealed the openssl I'm includiing has an msvcr dependency. I'm looking for a different solution. Pity I can't just include the openssl DLLs that Qt uses.

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  Unsolved Serializing a widget
  • EL-jos

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  Well, first I'd say:
  General advice is always use prepared statements.
  Prepare: https://stackoverflow.com/questions/5609245/qsqlquery-prepared-statements-proper-usage

  More general advice is figure out the actual query you sent the engine by firing a verbatim copy of the query generated in your application directly @ the engine without the application.

  So, how I see it:

  Determine the actual statement run it at the engine (using with command line or query / db engine tools and see the response - independent from your application anyhow). Witness the engine response as a result of your statement (I'm expecting a syntax error as it seems you are too) This will lead you to the reasons what is not being correctly done in your application. Fix the application statement Try again

  I suspect it would be a parsing error as you're playing with the single quotes but cannot say. I also won't troubleshoot what seems just syntax/parsing... that's for you to determine / observe.

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  Solved Weak QHash per value? what do you think about QHash<MyElement, QWeakPointer<MyElement>> ?
  • mbruel

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  @kshegunov

  It's not hidden it's public:

  QSharedData sharedObj;
  int counter = sharedObj.ref.load();

  well good to know, it could avoid me to re-create a reference count...
  I won't touch it but at least I could know when the reference count is 1 and thus it would mean that the only instance existing is the one in my cache which means nobody else is using it and so I could delete the entry from the cache.
  As you said it isn't documented so I thought it was totally private following the pImpl pattern. This should definitely be documented! it could be really useful in my kind of use case.

  I'd start by doing a very quick test case where I have a real-world example of how much objects of a given type are in use at any one time (not in the future, at one moment) - no caching at all. Could you do that?

  I've done it. Here are the numbers for one simulation :

  [MB_TRACE] Nb elem in cache : 5059084 (reused: 39457190, nb keys: 5047742

  So there is no doubt, I'm factorizing 45 millions distinct copy in just 5 millions in a cache. (this is where the 3GB were coming from if I'm not sharing the map of properties)
  (And a user would keep the app opened and launch several simulation so the sharing factor could be multiplied)

  Those (the instance in the cache) are the "important" instances that I store. The other one that detach are just intermediate steps so they don't matter. I just don't want to bother to make 2 distinct classes and have to copy from the intermediate class to a final (const) one. It is just easier to allow the flexibility of modification and thus to detach from the cache.

  Anyway, if we just go on this kind of implementation, do you see anything wrong or inefficient with the code I've posted? cause at the end, even if I save unique allocation for each instance (going up to 5 millions), I've extra copies with the value version and the perf in my use case are better with the pointer version...

  I don't think that relying on the QSharedData ref count would change anything significant in the implementation of my cache as a QHash as I didn't protect the ref count I've implemented with atomics.

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  Solved How to Add Custom Class to Qt Designer/Edit Layout Outside of Qt Designer
  • pistorinoj

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  That appears to be it.
  Thanks

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  Solved how do something before the user close the window?
  • davidlabib

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  i got it , thanks a lot
  @JonB and again I'm Apologizing about deleting the topic but it had a lot of mistakes
  i thought that deleting it and make a new one is better