@Massimiliano75 There you are then :) I note that on mine that option is not checked, never has been, and I've never changed anything. And never received the message. I'd be surprised if you want it checked. Then again, I told you it may be to do with running script and to try, say, ls instead....

Hi, The minimal example does not contain it as it seems but I think you need to add: project = YourCoolProject in your configuration file.

@ademmler I'm sorry, I don't download code. As I said, the calculation ("measurement device") needs to be its own thread, so that it can block if it wants. That sends signals when it has something to say. The main GUI acts on that and does updates when its thread is running. I would not expect QApplication::processEvents() anywhere. I leave it to you/others now, who perhaps can help you more.

Since you are a beginner, you should take the time to follow one or more of Qt's widgets tutorials in the documentation before going further. You'll get the ropes and avoid pitfalls doing so.

There's a folder which contains all the test results.

@Allon First of all, thank you for your help. Yes, your example may match with what I need, however it's not representative of the issue I face. AFAIK, the idea is to put the three dots component and its 2 buttons overlay in a well bounded cell, or in an Item placed at the end of the row if the tree doesn't contain columns. But in my case, things are different. I have a multi-columns tree, and I need an overlay which overlap several cells, completely or partially, and remain independent of these cells, breaking thus the logical provided by the tree. And a such overlay is incompatible with the standard painting process, unfortunately. I'm aware that creating a multi-columns tree to break the rules and show graphical elements which overlap the cells sounds like a conception issue, and I already reported that to my client. But as he really want the tree working this way, I need to find a solution. I'm also trying another approach, which use a ListView instead of a TableView, but although this may resolve the overlay issue I described above, I need to rewrite manually the whole columns management, and this brings performance issues as described in this post: https://forum.qt.io/topic/118005/listview-how-to-refresh-rows-which-content-changed-without-slowdown

@KroMignon said in connect() new style syntax return result: But I am not sure this is the best idea for checking connect() return value... It is when you don't want to change any lines of code, other than adding one #define :)

Thanks a lot, it works!

@KroMignon no problem, thx for helping me, I really appreciate it

LIBAPP is unset for this particular project, although it works perfectly fine for it's dependency. Solution that I found is to just add it to the system environment in the build settings. I hate everything.

@JonB I trust you and try this out - thx

Hi，dasun： I have encountered the same problem. Have you resolved it? Could you teach me how to do ? Thank you very much!

Hi SGaist, thanks for your anwer. Yes it is. Sorry!

@sierdzio technically you are correct, the exception comes from the list.at() call, but not because it goes out of bounds (AFAICS from the debugger). Both your gut feeling and @JonB intuition confirms what I was fearing, I just wanted to know if I missed something hidden in the docs. I'll cache the field values themselves in the hope to avoid the issue altogether.

hier ein einfaches Beispiel #include <QApplication> #include <QWidget> #include <QtDebug> #include <QCheckBox> #include <QTimer> std::array<QCheckBox *, 4> checkBoxes; void setRig(int i) {qDebug() << "Set rig to" << i << "Timestamp:" << QTime::currentTime().toString("hh:mm:ss");} void onActionTriggered() {qDebug() << "Some other function call";} void bandHopping() { static int startIndex = 0; if(startIndex >= 4) startIndex = 0; int nextStartIndex = startIndex +1; switch (startIndex){ case 0: if(checkBoxes.at(0)->isChecked ()){ setRig(1000); startIndex = nextStartIndex; onActionTriggered(); return; } else { nextStartIndex++; } Q_FALLTHROUGH(); case 1: if(checkBoxes.at(1)->isChecked ()){ setRig(2000); startIndex = nextStartIndex; onActionTriggered(); return; } else { nextStartIndex++; } Q_FALLTHROUGH(); case 2: if(checkBoxes.at(2)->isChecked ()){ setRig(3000); startIndex = nextStartIndex; onActionTriggered(); return; } else { nextStartIndex++; } Q_FALLTHROUGH(); case 3: if(checkBoxes.at(3)->isChecked ()){ setRig(4000); startIndex = nextStartIndex; onActionTriggered(); return; } else { nextStartIndex++; } } } int main(int argc, char *argv[]) { QApplication a(argc, argv); QWidget w; w.resize(200, 200); QVBoxLayout *l(new QVBoxLayout(&w)); for(int i = 0; i < 4; i++){ auto c = new QCheckBox(&w); c->setText(QStringLiteral("Checkbox %1").arg(i)); c->setChecked(i % 2); l->addWidget(c); checkBoxes[i] = c; } w.show(); QTimer t; t.setInterval(6000); // 6 Sekunden QObject::connect(&t, &QTimer::timeout, &bandHopping); t.start(); return a.exec(); } so ?

@TravisLedo This is only a guess: ui->listWidget->takeItem(ui->listWidget->currentRow()); You have taken out the "current row". I wonder what has happened to the current row now? I wonder if that is relevant to the next click? Certainly, if we ignore the remove and just do two Add Items in a row I would not expect any funny behaviour. Are you claiming that does not work right? If so i would suspect other code somewhere; try to reproduce that in a minimal application.

@Please_Help_me_D I'm not sure what you're asking here. You are mapping the whole of the file. As you begin to access data in the mapped area it gets brought into memory, and that takes up space. If you have limited memory, this is not a good idea. I haven't used memory mapping myself, but presumably if you want to keep memory usage down you have to do something like only map partial areas of the file at a time (arguments to map()), and release previously mapped areas (unmap()). You'd have to test whether that actually results in less memory usage. If you are limited in memory compared to the size of the file, perhaps you shouldn't be using memory mapping at all. File seeking to desired data won't have a memory overhead. In the code you show you are reading the data just once, so there may not be much difference. Have you actually measured performance with file versus memory-map access?

Hi, I know this is 7 years old but I wanted to share this little shortcut anyway. So, by looking at the QML source code of CheckBox there seems to be a property that is bound to the text color: control.palette.windowText contentItem: CheckLabel { leftPadding: control.indicator && !control.mirrored ? control.indicator.width + control.spacing : 0 rightPadding: control.indicator && control.mirrored ? control.indicator.width + control.spacing : 0 text: control.text font: control.font color: control.palette.windowText } It seems to work quite well though I have done no extensive research on the effects of changing the value of that property. Cheers.

@ndkt is there a way I can generate a new label each time a button is pressed. Yes. In your slot (just like anywhere else) you can create widgets dynamically by newLabel = QLabel() or similar, and then add the new widget wherever appropriate somewhere in your widget hierarchy. Or is there another way that doesn't use text label that I should use? You could represent these via individual QLabels, and add those onto, say, a QVerticalLayout. However, there are many other ways, perhaps better suited. You could, say, add them onto a QTableWidget via QTableWidgetItem(const QString &text), or use a QGridLayout which allows the adding of rows/columns, or you might pick a QListWidget to store/show them as a list in a single widget, which would be my first inclination. Especially if there are going to be a large number of items, you don't want to create a large number of individual QLabels, speed & memory.

@Shane00 said in OpenCV library in QT Creator: Not quite sure why that made it happen but its working now. Thanks anyways that added opencv to the environment path, and generally a bad idea, especially if you don't know what you're doing 😉 My company asked me to use it because of cross platform portability. Qt is generally known, for cross platform GUI framework, opencv is generally know for its image processing. You can combine these, do the processing in opencv do the Gui in Qt. And it's probably what your company want you to do ;)

@rp123 wherein i don't know the column names or the number of columns In https://wiki.qt.io/Handling_Microsoft_Excel_file_format, the very first example I look at using select * from [" + QString("Sheet1") + "$] clearly works where you don't know anything about the number, names or types of the columns, just as you ask for. You will also have noted it states and discusses there: By default OBDC uses the first row as names for the columns And similarly if you use @J-Hilk's Use QFile to open the file and read the context and split(';') That doesn't need to know number or names of columns either.

@sierdzio said in Is child coordinates (x, y, z) associated with visual parent, or object parent?: (in fact, I have never seen it used in any actual project). Like I always, I'm the one who does the fringe stuff I have a custom Popup component, that has to have a Rectangle as the root element and not a Window(so it can't be Popup itself). But I create instances of it deep inside the item hierarchy for that reason I internally reassign the parent to the top most Item, on creation 😬 that said, @lawrence-emke Window has a component that can and does function as parent, the parent of ccb exists, so you could do the following: Window { visible: true width: 640 height: 480 title: qsTr("Hello World") color: "green" id: win Rectangle { id: ccb x: 87 y: 190 width: 100 height: 100 Component.onCompleted: { console.log("number: " + ccb.children.length ) } Rectangle { id: rect1 color: "yellow" parent: ccb.parent x: 49 z:1 width: 30 height: 30 } Rectangle { parent: ccb.parent id: rect2 color: "red" x: 200 z:2 width: 12 height: 40 } } } and it should behave as expected

@MNix Good that you are getting the hang of signals/slots, from Python. You will need it all the time for Qt programming. I don't know where you got those QtCore.SLOT("setText(str(int))") from(?). First, I haven't seen PySide2 or PyQt5 actually using it in practice, all code I've seen uses the sender.signal.connect(receiver.slot) syntax (which you will not see in C++ examples you look at). And secondly, you wouldn't be able to write what you are trying to do there for converting the parameter in the string argument, hence the error message. Now that you are an expert! You have successfully used the simple way of declaring the slot to match the signal exactly, and then doing any work on the parameter in the slot code. This is the simplest, use it whenever you can. However, you ask me, how would I do what I tried to do, now that I am a confident user? And I would answer: via Python lambda: self.lcdSlider.slider.valueChanged.connect(lambda intValue: num.valueChanged(str(intValue))) This effectively defines an "anonymous" method which takes a parameter, intValue, which we know to be an int, and calls num.valueChanged() passing the str() value of the int, so the slot would receive a str. So we can call methods with different types/order/numbers of parameters than the exact-matching slot would have. Here I would stick to your original method, the slot taking the int, and therefore no need for a lambda. It makes sense that the slot for a slider value change would receive a number; the fact that you want to use the string of that number inside the slot for some purpose fits better into the slot code than the slot declaration. But over time you will find uses for these lambdas. Here endeth the first lesson....

@Crag_Hack Yes, close() when it is that you're done. Either your program has a close down where you shut any open resources, or you could do it just before exiting. Whenever you are done with doing SQL stuff. You don't need to do anything after you have done INSERT/UPDATE/DELETEs. setDatabaseName() is a one-off operation. You do it just before open()ing, like you would for a file. https://doc.qt.io/qt-5/qsqldatabase.html#setDatabaseName: QSqlDatabase db = QSqlDatabase::addDatabase("QODBC"); db.setDatabaseName("DRIVER={Microsoft Access Driver (*.mdb, *.accdb)};FIL={MS Access};DBQ=myaccessfile.mdb"); if (db.open()) { // success! }

Thank you all guys. Your suggestions and expert opinion helped a lot with solving the problem. QT forum is always so helpful. After trying many things here is the conclusion and code is now working perfectly fine I removed the tic toc part time(&start); timer = double(getTickCount()); tic(); It was working but crashing then just to make sure that QImage is not NULL I removed the img = QImage(); // releasing memory with if(!img.isNull()) img = QImage(); Its working perfectly fine now.

@GREYON Thanks after going through Qsql documentation,the problem has been resolved

@Chris-Kawa this is what i came up with: int findSimularchars(vector<string> arr) { std::map<char, int> values; char alpha[] = "abcdefghijklmnopqrstuvwxyz"; for (long unsigned int i = 0; i < strlen(alpha); i++) { values.insert(std::make_pair(alpha[i], 0)); } for(auto ii : arr){ for(long unsigned int j = 0; j < strlen(alpha); j++){ std::size_t found=ii.find(alpha[j]); if (found!=std::string::npos){ std::map<char, int>::iterator it = values.find(alpha[j]); if (it != values.end()) it->second = it->second + 1; } } } int counter = 0; for(auto& x : values) { if(x.second == arr.size()){ counter++; } } return counter; } works perfect.

@mirro Hi As far as i know its not used at all. Qt web components use chrome engine. But you can load it via ActiveX/Qt tps://doc.qt.io/qt-5.9/activeqt-activeqt-webbrowser-example.html

@Christian-Ehrlicher said in qtcpsocket with qthread QObject: Cannot create children for a parent that is in a different thread: You have to create the socket in the run() function as only there the new thread is running. See https://doc.qt.io/qt-5/qthread.html#details its solved , i have tried to create socket in run() function void UpdataServerThread::run() { updata_socket = new QTcpSocket(); if (!updata_socket->setSocketDescriptor(socketDescriptor)) { emit error(updata_socket->error()); return; } connect(updata_socket,SIGNAL(readyRead()),this,SLOT(readyRead()),Qt::QueuedConnection); connect(updata_socket,SIGNAL(disconnected()),this,SLOT(disconnected()),Qt::DirectConnection); connected_client_socket.insert(updata_socket->peerAddress(),updata_socket); qDebug()<<"creating socket ptr"; updata_socket->write("Welecome Message"); exec(); } Thanks alot sir ,, i got new another problem with sending/write data on socket maybe i shoud make new topic for this

@lansing Depending on how complicated it will be. If you only want to draw like "press, drag, release, done", then you may use QWidget + QPainter. But you need to save the lines you draw as member variables (the Scribble example save them to a QImage). If you want move or do other transform operations to the drawn lines, you need to use QGraphicsScene + QGraphicsView. You may also look at this example: Diagram Scene Example It have some line drawing thing in a QGraphicsScene (but in this example the line will be deleted when releasing the mouse)

Thanks christian but i think i found my way around like so : QString dir = QString::fromLatin1("dirección");

@Charles-Cai I know this thread is very old but do you got any solution? I am stuck in same problem. I want to load HTML page containing java applet using QWebEngineView. Can't find any way out. Your input can help me. Thanks