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 ]

• 

  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.

• 

  Unsolved How to get non null terminated data out of a QByteArray ?
  • Curtwagner1984

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  @Curtwagner1984 said in How to get non null terminated data out of a QByteArray ?:

  <= **The problem is here**

  No it's not, it's here: memcpy(&receivingStruct, &c, sizeof(receivingStruct)); change &c to c or ba.constData(). &c is of type char**

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  Unsolved Multithreading and sqllite
  • schouwen

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  @schouwen You're using different databases in different threads. Filling tables in one thread will not affect databases in other threads. As far as I know SQLite is NOT thread safe, if this is true it is in general a bad idea to access same database from more than one thread without serialising the queries.

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  Unsolved QApplication not working as expected with 3rd paramaeter(GUIMode)
  • seetharam

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  #include <memory> int main(int argc, char **argv) { bool useGui = false; std::unique_ptr<QCoreApplication> pApp(nullptr); if(useGui) pApp.reset(new QApplication(argc,argv)); else pApp.reset(new QCoreApplication(argc,argv)); return pApp->exec(); }
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  Unsolved 3-dimensional array storage as string
  • jars121

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  You can use regular expressions:

  // QString datasetString = "dataSet1=[1, 5],[2,10],[3,15],[4,20]"; const QRegularExpression pointsRe(R"**([\s*([-+]?\d*\.?\d+)\s*,\s*([-+]?\d*\.?\d+)\s*])**"); auto matchesIter = pointsRe.globalMatch(datasetString); while (matchesIter.hasNext()){ const auto match = matchesIter.next(); qDebug() << QPointF(match.capturedRef(1).toDouble(),match.capturedRef(2).toDouble()); }

  @jsulm said in 3-dimensional array storage as string:

  Why do you need a 3-dimensional vector?

  i share the question

• 

  Unsolved polygon QGraphicsItem shape
  • user4592357

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  @kenchan
  it's really weird. i set background brush to black of my graphics view, and when i add something like

  item = PolygonItem([QPointF(30, 30), QPointF(50, 50), QPointF(100, 100)])

  to the scene, the view becomes white and no item is drawn :(

  here's the scene and view:

  class Scene(QGraphicsScene): def __init__(self, parent=None): super(Scene, self).__init__(parent) class View(QGraphicsView): def __init__(self, parent=None): super(View, self).__init__(parent) self.setRenderHint(QPainter.Antialiasing) self.setRenderHint(QPainter.TextAntialiasing) self.setSceneRect(self.scene().sceneRect()) self.setBackgroundBrush(QBrush(Qt.black))

  this is how i create the scene and view in main window:

  def __create_scene_and_view(self): self.__scene = Scene(self) self.__view = View(self.__scene) self.__layout_view.show() self.setCentralWidget(self.__view)

  some items are drawn correctly, though. for example:

  item = PolygonItem([QPointF(75, -10), QPointF(60, 40), QPointF(110, 10), QPointF(0, 0)])

  i noticed, if i add QPointf(0, 0) to the first (non-working) item, it is drawn too

• 

  Unsolved Problems connecting to a broker with QtMqtt
  • glasen77

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  @glasen77 not that I'm an expert with MQTT protocol, but comparing your client with Qt simpleclient example, it seems that you're not subscribing to any topic at all.
  From this tutorial it looks like even if you connect successfully to the MQTT broker (or server) then you need to register your client to "publish" or "subscribe" for a particular topic.

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  Unsolved How to display selected data from database in QTableView ?
  • Amative_Ashu

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  This has nothing to do with Qt, it's just about SQL

  select top 5 eid,name,surname,salary from employeeInfo order by eid asc selects the top 5 select * from (select top 10 eid,name,surname,salary from employeeInfo order by eid desc) order by eid asc selects the last 10
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  Unsolved multiprocess c/c++ linux
  • s002wjh

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  @s002wjh said in multiprocess c/c++ linux:

  "date qwidget"

  Is this widget going to do some heavy processing on its own? If so, I'd say it shouldn't and you would need to consider such calculations into threads.
  Most of the Qt apps keep all the GUI components in just one thread, the GUI thread.

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  Unsolved Try parse QString to int
  • column

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  Hello,

  You can use QString::toInt() method. Which take an optional boolean pointer as argument, giving the result of the conversion.

  Just a small example with output

  #include <QCoreApplication> #include <QDebug> void test1(); int main(int argc, char *argv[]) { QCoreApplication a(argc, argv); test1(); return 0; } void test1_toInt(const QString &s){ bool ok; int i = s.toInt(&ok, 10); qInfo() << s << " toInt(dec) -> " << i << (ok ? "OK" : "FAILED"); i = s.toInt(&ok, 16); qInfo() << s << " toInt(hex) -> " << i << (ok ? "OK" : "FAILED"); } void test1(){ test1_toInt("123"); test1_toInt("12H"); test1_toInt("H12"); test1_toInt("FF"); test1_toInt("GHI"); }

  Output:

  "123" toInt(dec) -> 123 OK "123" toInt(hex) -> 291 OK "12H" toInt(dec) -> 0 FAILED "12H" toInt(hex) -> 0 FAILED "H12" toInt(dec) -> 0 FAILED "H12" toInt(hex) -> 0 FAILED "FF" toInt(dec) -> 0 FAILED "FF" toInt(hex) -> 255 OK "GHI" toInt(dec) -> 0 FAILED "GHI" toInt(hex) -> 0 FAILED
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  Unsolved Always compile sql drivers as plugins
  • GGenny

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  Unsolved is it possible to using QNetworkAccessManager in subclass of QGraphicsRectItem?
  • FkZsd

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  @FkZsd +1 to the reply from @jsulm but just to better understand your issue, what's your exact error...?

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  Unsolved [Help] QComboBox multiple events
  • Neko

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  I'm using Qt 5.10 - Win10 with the Visual Studio Qt VS Tools Plugin.

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  Unsolved Using Colour Emojis as a substitution font in Windows
  windows 10 color emojis font match • • boring32

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• 

  Unsolved How to make a "global/shared" widget
  • DavidM29

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  @DavidM29 Add a setter method to your other widget to set the date/time:

  class MyWidget... { public: void setDateTime(const QDateTime&); }
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  Unsolved Qt3D C++Read FBO
  • jimfar

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  who could told me how to read the fragment shader mutilply outputs?Many thanks

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  Solved is there any On/off animated widget is there in qt c++?
  • thippu

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  Thank you!

• 

  Solved Remove space between two QLabel
  • Mr Gisa

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  I told you already that I'm in love with you ♥
  Thank you very much @VRonin

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  Unsolved QSettings->setValue , group contains space will save to %20 ?
  • sonichy

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  From http://doc.qt.io/qt-5/qsettings.html#Format-enum:

  The INI file format has severe restrictions on the syntax of a key. Qt works around this by using % as an escape character in keys.

• 

  Unsolved QMediaPlayer / QVideoWidget do not show
  • GGAllin

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  @mrjj doesn't work just on VideoPlayer.cpp
  VideoPlayer.cpp doesn't work on OSx and Win, but on Linux work perfectly after installation of gstreamer0.10-ffmpeg

  here works perfectly

  int main(int argc, char **argv) { QApplication app(argc, argv); QWidget *widget = new QWidget; widget->resize(400, 300); QVBoxLayout *layout = new QVBoxLayout; QMediaPlayer *player = new QMediaPlayer; QVideoWidget *vw = new QVideoWidget; layout->addWidget(vw); widget->setLayout(layout); player->setVideoOutput(vw); player->setMedia(QUrl::fromLocalFile("/Users/me/Desktop/VIDEO_TEST/video.mp4")); player->setVolume(50); player->play(); widget->show(); qDebug() << "mediaStatus: " << player->mediaStatus() << "error: " << player->error(); return app.exec(); }

  @SGaist : i changed from stop to play in my contructor, but nothing's changed
  ps: sorry for my bad english!

• 

  Solved Segmentation fault outside Qt Creator only
  • Texture

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  Hello all!

  Now after some testing days and so on I could finally find that the problem is in libbrcmGLESv2.so
  To solve this issue this file should be copy from

  /usr/lib/arm-linux-gnueabihf/

  Looks like QtCreator anyway takes this file without dependencies and links that should be done to make QtCreator running on Raspbian 9 (Stretch) (i.e. as described here: https://www.raspberrypi.org/forums/viewtopic.php?t=191857).

  This solved my problem of running Qt compiled apps on RasPi outside Qt Creator.

• 

  Unsolved How to make ViewPort expand with QGraphicsView
  layout graphics view viewport • • ProstoNekitos

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  Solved Application change following the windows session username?
  • filipdns

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  @mrjj great thank you!

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  Unsolved Increment a QDateTime -- but stop it from being an endless loop
  • ShylerC

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  hi
  @ShylerC said in Increment a QDateTime -- but stop it from being an endless loop:

  Team,

  I used to += -- but with ... startdate.addDays -- Super Confused! How to increment until condition is met?

  So in 'ol C++ regular I would do this -

  while (startdate < enddate) {
  startdate += days }

  //Would see my startdate increment until it met condition.

  Option 1.

  while (startdate < enddate){ QDateTime NewTime; NewTime=startdate.addDays(days); qDebug() << NewTime; }

  in QT ... I get an endless loop... Any ideas?

  add Days returns a new QDateTime, but you don't do anything with it in your code example therefore startdate never changes.

  while (startdate < enddate){ startdate = startdate.addDays(); }
• 

  Unsolved qtlite size any new progress?
  • RIVOPICO

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  @RIVOPICO This is user forum. It would make more sense to ask actual developers of Qt on the mailing list.

• 

  Unsolved QOpenGLWidget and QPainter
  • Qt_crazyer

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  @Qt_crazyer

  You seem to be on the right path. But if you're using QPainter::fillRect() to paint the background, you'd want to do it BEFORE your OpenGL 3D painting code, not after. Otherwise fillRect() would wipe out all your 3D painting.

  It's OK to mix QPainter and OpenGL painting in QOpenGLWidget::paintGL() in any order, as long as OpenGL parts are enclosed by beginNativePainting() and endNativePainting(). You can do 1) QPainter::fillRect() background 2) OpenGL 3D 3) more QPainter painting for other 2D objects over the background.

• 

  Unsolved Setting style on QTreeWidget root items (PyQT)
  • jspeirs

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• 

  Unsolved make an application as plugin
  • miladm31

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  thanks for reply. but i don't get it. the major application that i talk about is digital instrument cluster and there will be some other application inside that like player app , navigation etc.
  those applications have their own c++ back logic and qml design in front. how we put them together in plugin or what will be the structure of it. is this possible at all?
  i read about qtplugin for c++ shared object and QQmlExtensionPlugin but those are not suitable for this kind of imaginary plugin i think :))

• 

  Unsolved show widget on custom widget mouseMoveEvent
  • Mr Gisa

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  @SGaist You mean the paint or the mouse move event?

  void Sidebar::mouseMoveEvent(QMouseEvent *event) { int index = at(event->pos()); if (! isValidIndex(index)) { if (mTooltip.isVisible()) { mTooltip.hide(); } mHoveredIndex = -1; update(); return; } SidebarItem item = mItemList.at(index); QRect itemRect = mRectList.at(index); QPoint global = mapToGlobal(QPoint(0, 0)); int xpos = global.x() + itemRect.width(); int ypos = global.y() + itemRect.y() + 25; // 25 is hard coded here for testing purpose mTooltip.setText(item.text()); mTooltip.move(xpos, ypos); if (! mTooltip.isVisible()) { // SGaist suggestion QMetaObject::invokeMethod(&mTooltip, "show", Qt::QueuedConnection); } if (mCurrentIndex == index) { mHoveredIndex = -1; update(); return; } if (mHoveredIndex == index) { return; } mHoveredIndex = index; update(); } void Sidebar::paintEvent(QPaintEvent *event) { QPainter painter(this); painter.setRenderHint(QPainter::Antialiasing); // paint the background painter.fillRect(rect(), mBackgroundColor); int itemHeight = 0; for (int i = 0; i < count(); ++i) { SidebarItem item = mItemList.at(i); // get the current item rect QRect itemRect(0, itemHeight, event->rect().width(), mItemHeight); // save that rect so I can use later for the tooltip mRectList.insert(i, itemRect); // paint the hovered item if (mHoveredIndex == i) { painter.fillRect(itemRect, mHoveredItemColor); } // paint the current item if (mCurrentIndex == i) { painter.fillRect(itemRect, mCurrentItemColor); } itemHeight += itemRect.height(); } }

  mTooltip is: Tooltip mTooltip; in the private section of the header file.

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  Solved Error in toolchain.prf when building new project
  • glarson

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  Glad you found out and thanks for sharing !

  Happy coding :)

• 

  Unsolved Correctly stop QTimer after its QThread has already quit?
  • TheLoneMilkMan

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  The first thing that is fishy is that you dereference obj1. QObject based classes cannot be copied.

  What I was suggesting is just to create your QTimer member on the heap in your TestClass` constructor.

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  Unsolved audiooutput
  • Leopold

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  The you have to build your stereo data accordingly.

  Start your QTimer when you want to start sending data or rather after you sent your first data to QAudioOutput.

  app.exec() will return either when you close the last window of your application or call QApplication::quit from e.g. a menu action.

• 

  Unsolved Have dynamic combo box based on selections from another combo box
  • te777

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  @te777 if your issue is solved, please don't forget to mark your post as such. Thanks.

• 

  Unsolved How to encode/decode and write and read binary data?
  • Curtwagner1984

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  Take the "Header Checksum" for example they are already stored as qint8 numerals inside QByteArray, if you want to convert those 2 bytes in a 4 bytes int then it becomes a problem. If you just want to access the values you can use constData().operator[]

  const QByteArray checksum= ba.mid(1,2); qDebug() << "First Byte in decimal" << static_cast<qint16>(checksum.constData()[0]); //the cast is necessary otherwise qDebug() will try to print an ascii value qDebug() << "Full Values in hexadecimal" << checksum.toHex();
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  Solved qtCUrl How to add (--data) option?
  • Guapo

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  Yes @Pablo-J-Rogina , these brackets aren´t necessary for one id...I tried with and without brackets.

  Now I´m using another function ( without QtCUrl ).

  CURL *curl; CURLcode res; QString autorizacao; autorizacao=QString("Authorization: bearer %1").arg(token); curl_global_init(CURL_GLOBAL_ALL); std::string jsonstr = qPrintable(str); /* get a curl handle */ curl = curl_easy_init(); if(curl) { /* First set the URL that is about to receive our POST. This URL can just as well be a https:// URL if that is what should receive the data. */ struct curl_slist *headers = NULL; headers = curl_slist_append(headers, qPrintable(autorizacao)); headers = curl_slist_append(headers, "Cache-Control: no-cache"); headers = curl_slist_append(headers, "Content-Type: application/json"); curl_easy_setopt(curl, CURLOPT_POSTFIELDS, jsonstr.c_str()); curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE,jsonstr.size()); curl_easy_setopt(curl, CURLOPT_URL, "https://pos-api.ifood.com.br/v1.0/events/acknowledgment"); curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers); /* Now specify the POST data */ /* Perform the request, res will get the return code */ res = curl_easy_perform(curl); /* Check for errors */ if(res != CURLE_OK) fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res)); /* always cleanup */ curl_easy_cleanup(curl); } curl_global_cleanup(); return 0;

  This code fixed my problem.

  I don´t know wireshark....I´ll install here to debug my first function.

  After posting yesterday, I noticed the bullshit I wrote about the double quotes... : )

  Thank you very much!!!

• 

  Solved model populated signal
  • user4592357

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  @VRonin
  my bad, right...

  how didn't i realize? thanks

• 

  Unsolved How to test workstation OpenGL version with QSurfaceFormat?
  qglformat qsurfaceformat • • Alchete

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  QSurfaceFormat fmt(this->format()); cout << fmt.majorVersion() << "." << fmt.minorVersion() << endl;
• 

  uchar* QImage::bits() returned '\0'...(nullptr)
  • shtomik

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  @mranger90 @VRonin @mrjj

  Thank you guys... I found a couple of mistakes in my code, but the main mistake was in trust to the debugger, sometimes it was 0x0 or 0 or '\0' value for pointer to uchar that was 0.

• 

  Solved How to join 2 QList and filter by QString ?
  • sonichy

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  QFileInfoList listSearch; QDir dir1(path1); QFileInfoList list1 = dir1.entryInfoList(); QDir dir2(path2); QFileInfoList list1 = dir2.entryInfoList(); QFileInfoList list3 = list1 + list2; void MainWindow::search(QString text) { listSearch.clear(); for (int i=0; i<list3.size(); i++) { QFileInfo fileInfo = list3.at(i); if (fileInfo.fileName().contains(text,Qt::CaseInsensitive)) { listSearch.append(fileInfo); } } }