I'd be careful just because of my own assumptions / experience, it sounds like you're setting up a landmine for later, I don't know because I just skimmed your issues, I can't tell enough for a proper context but I can recall the bug report that I found when I did. You might find this useful too: https://bugreports.qt.io/browse/QTBUG-43230 Ulf Hermann added a comment - 18 Mar '19 9:19 PM Note that exposing objects that live in a different thread as the QML engine via context properties is dangerous to begin with. You cannot safely access properties or call methods of such objects from QML. I really recommend proxying the signals through a separate object that lives in the engine thread. Ulf Hermann added a comment - 30 Apr '19 10:02 PM The bad idea is not actually the connection. The fact that the connection behaves in the way described here is just the consequence of the fact that you're exposing an object from a different thread. The QML language has no concept of threads (besides WorkerScript, but that is a different beast), so exposing the C++ threading model to it via context properties is a bad idea. The engine does not magically provide thread safety for otherwise unsafe operations and it needs to inspect the objects given to it as context properties. Please make sure everything you expose to a particular engine lives in the same thread. Otherwise all bets are off anyway.

Thanks for the input guys, much appreciated!

@SGaist Thank you.

OK, Finally we found the solution. The tip is to create a Scene3D in the qml file. And to create the camera and ForwaqrdRenderer in the QML too (and not in the C++). Scene3D { id: scene3D anchors.fill: parent anchors.margins: 10 focus: true Root3DEntity { id : root3DEntity renderSettings : RenderSettings { id : renderSettings pickingSettings.pickMethod : pickingSettings.PrimitivePicking activeFrameGraph: ForwardRenderer { id: renderer clearColor: "#4d4d4f" camera: Camera { id: camera projectionType: CameraLens.PerspectiveProjection fieldOfView: 45 nearPlane: 0.1 farPlane: 1000.0 position: Qt.vector3d(0.0, 0.0, 2.0) upVector: Qt.vector3d(0.0, 1.0, 0.0) viewCenter: Qt.vector3d(0.0, 0.0, 0.0) } } } } }

Sorry for the late reply, I actually managed to figure out how to get my intended behaviour, after calling <setFloating(true)> i needed to add <setWindowFlags(Qt::Window | Qt::FramelessWindowHint);> to make it able to take focus.

@mrjj Thank you sir for helping me and direction. I am able to solve this issue by setting the clipping area properly on graph. Use QWidget::update() instead of QWidget::repaint().

@Yash001 Hi, i wish i knew the answer but im fairly sure canvas()->width(); just returns the actual widget size and not the zoomed area as such. Had a look in the help but didnt find the answer on how to get the extent on a zoomed canvas.

Hi, What is that ??? Ui_MainWindow *form = new Ui_MainWindow(); try: connect(ui->startButton, SIGNAL (pressed()), SLOT (handleExecutionButton()));

@Yash001 said in which container (Qvector or QList) is good to use for insert, delete, and access the last element.: I am adding data point at last position of container, and only accessing the last element of container. So which is better container? It's what we call Last In First Out ( LIFO) queue. So QStack seems an obvious candidate. QStack inherits from QVector.

Hi Thank you for sharing. I don't know anything about Pokemon but its cool you used gif so they are animated and the code looks clean and structured.

@Quawetim I don't know which is better. For my comprehension, it is easier to use implicitHeight/implicitWidth of the item to be scrolled. For example, when the item is a ListView, implicitHeight is automatically updated when an element from the ListView is changed/added/removed. Your View item only have to set implicitHeight/implicitWidth and dynamically the ListView will adapt the scollbars limits/positions

@Chris-Kawa Thank you, this solves the problem. As to alternative way to exit, I already have exit action on tray's menu. Have a nice day.

Hi and welcome to devnet, What version of Windows are you using ? Can you run your application from the same command prompt ?

https://www.linkedin.com/in/sujan-d-6a980151/ This is my Linked In profile. Let me know if visa sponsor is available with you ? I am interested but I am Indian, if you sponsor me work visa, I will be able to move.

Hi, One base rule: all GUI manipulation must be done in the main thread (well the one that started the QApplication event loop).

@sgaist The problem was the QGuiApplication in my main.cpp , i turned it to QApplication and it works fine. And lastly what should i do to use my applicationwindow as my videowidget. I want my video to play on my app like normal mediaplayers, not to open another window for it. Thanks for your kind effort.

I decided to ask this question specifically in a separate post, just in case a JS memory manager expert might not have found the title of this post interesting. Here's the other post: https://forum.qt.io/topic/106655/does-qjsvalue-protect-its-value-from-garbage-collection

Hi, I am interested in your project. My CV: https://drive.google.com/open?id=1uJUxifF2F4JbWM5GL6bw_H1SDdUWjOH09bN9gnSvKqo GitHub: https://github.com/amsantosr

@alexey_golubev said in Предупреждения в процессе сборки qcustomplot.h: Вроде да. Хорошо. А какая версия qt? Просто я пока не могу перейти на новую версию IDE так как у меня поддержка программы ещё на Qt 5.10, а Qt 5.11 уже не подходит. Там некоторые библиотеки перелопачены

@oblivioncth said in Why does the const Object returned by QList::at() block access to instance methods?: Hey, going above and beyond! Thanks again. You're most welcome! I'm not completely ignorant in the ways of C++ though, I'm not 100% certain, but fairly confident that: Const 1) Ensures the returned value can't be modified, Yep. the use cases of which I'll admit I'm not really privy to. Use case 1: Allow the caller to read the data without creating a copy, AND Make sure the data is read-only If the returned reference is non-const, the caller will be able to directly modify the object's internal memory. This breaks encapsulation. Use case 2: Allow the function to be called in another const function. There's a const and a non-const version of QList::operator[](int): T & operator[](int i) const T & operator[](int i) const Version #1 allows the caller to modify the QList element. However, it cannot be called in a const function -- it will cause the error in your original post. Thus, version #2 is required for use in const functions. I know that its only really useful when dealing with user defined classes and returning by value reference (which is the case in your example) to prevent memory modification if desired. (Acknowledging your typo) Why would it be "only really useful when dealing with user defined classes"? Notice that QList::at() returns a const reference. I do remember seeing something about this being somewhat obsolete in C++ 11 (or was it 17) and forward, though I'm not sure why. Returning const references is defintiely not obsolete. You might be remembering move semantics, which is said to make passing parameters by const-reference obsolete: https://stackoverflow.com/questions/10231349/are-the-days-of-passing-const-stdstring-as-a-parameter-over Qt will not be making this change anytime soon though; this is too disruptive. Const 2) The pointer argument "arg" in that class is for the type "const MyOtherClass", i.e. a pointer to a constant value (value cannot) Yep, myfunc() cannot modify the MyOtherClass object. (In other words, it can only call const methods of the object) Const 3) Marks the pointer "arg" itself as pointer, so that the pointer itself also cannot be modified) Yep. This is not very useful IMHO, but it's part of the language. Const 4) Thanks to you, I now understand this means that the function does not modify the object instance that the function is being called on/from (i.e. cannot manipulate member variables). Great! Next, start thinking about the difference between logical const-ness and physical const-ness: https://isocpp.org/wiki/faq/const-correctness#logical-vs-physical-state Btw I do like a lot of the explanations on that site as they provide a lot of detail and examples, and I had never read the article for const. Agreed

@kromignon Since Android is based on Linux you could put the libs in /usr/lib and see whether it works.

@Mayankjain C is plain better (IMHO) :) But for your career, C++ is definitely more advisable!

https://i.redd.it/1fl5yi6bbpzz.png

@alizadeh91 I don't have a solution for you, only a warning. If you intend to parse arbitrary C++ files from anywhere, rather than some terribly cut-down subset whose layout you know intimately, you're going to find this very hard to do. Very, very hard! Heck, you can't even write a grammar for parsing C++ source files because of the pre-processor, e.g. http://trevorjim.com/c-and-cplusplus-are-not-context-free/ To parse C and C++, you start by using a very powerful preprocessor. These preprocessors are inevitably written by hand (they are not based on a theoretic foundation like regular expressions or context-free grammars). As far as I am aware, there is no open source which will produce a standalone parse tree for you. The consensus (search the web) is that you really need to try to leverage an existing C++ compiler to do such a job. You could look at gcc, or perhaps more likely clang. I still don't think you'll get what you want out of them. If all you want to do is some hacky approximation which just extracts #include statements so that you can follow them then you could do something with QRegularExpressions. Correctly locating & extracting the definition of functions in .cpp/.h files will be harder --- you'll probably end up making all sorts of assumptions as to where definitions start & end more on a line-by-line basis than via regular expressions or proper parsing. It may do you for your purposes, provided you are happy with some vague approximation which is not robust. Sorry, but good luck!

@VinayBalajiRajputh said in Busy indicator in QML: I have tried adding log messages and it seems only after the function open file is finished all the messages are logged IMHO that's the expected behavior as you are not using thread and make everything in a function the events are blocked until execution is finished. What you can do if to provide a property from TestClass whic indicates if thread is running, and then bind this property with the BusyIndicator. But just a warning about the thread part, as I'm not an expert I reused your code with some modification for creating and starting the thread. But I don't think this is the correct way to use threads. I recommend that you read carefully QThread documentation, there is a nice example of how to use worker objects by moving them to the thread using QObject::moveToThread(). There are also other ways like QThreadPool and QRunnable or QtConcurrent. There are also plenty of post on this forum and many others about how to use QThread import QtQuick 2.10 import QtQuick.Window 2.10 //Post: https://forum.qt.io/topic/104906/busy-indicator-in-qml/3 import QtQuick 2.4 import QtQuick.Controls 1.3 import QtQuick.Window 2.2 import QtQuick.Dialogs 1.2 ApplicationWindow { title: qsTr("Hello World") width: 640 height: 480 visible: true Connections{ target: obj onIsRunningChanged: console.log("Running: " + obj.isRunning) } BusyIndicator { id: indicator running: obj.isRunning anchors.centerIn: parent } Button { text: "start" anchors.top: parent.top anchors.horizontalCenter: parent.horizontalCenter onClicked: obj.runWorkerFuntion() } } c++ //testclass.h #ifndef TESTCLASS_H #define TESTCLASS_H #include <QObject> class TestClass : public QObject { Q_OBJECT Q_PROPERTY(bool isRunning READ isRunning NOTIFY isRunningChanged) bool m_isRunning = false; void workerFunction(); public: explicit TestClass(QObject *parent = nullptr); bool isRunning() const; public slots: void runWorkerFuntion(); signals: void isRunningChanged(bool isRunning); protected slots: void setIsRunning(bool isRunning); void threadStarted(); void threadFinished(); }; #endif // TESTCLASS_H testclass.cpp #include "testclass.h" #include <QThread> #include <QDebug> TestClass::TestClass(QObject *parent) : QObject(parent) {} bool TestClass::isRunning() const { return m_isRunning; } void TestClass::runWorkerFuntion() { qDebug() << "runWorkerFuntion() from main thread: " << QThread::currentThreadId(); // /!\ THIS IS NOT A GOOD WAY TO USE THREAD QThread* thread = QThread::create([this](){ workerFunction(); }); connect(thread, &QThread::started, this, &TestClass::threadStarted); connect(thread, &QThread::finished, this, &TestClass::threadFinished); connect(thread, &QThread::finished, thread, &QObject::deleteLater); thread->start(); } void TestClass::workerFunction() { qDebug() << "workerFunction() from thread: " << QThread::currentThreadId(); QThread::sleep(1); } void TestClass::setIsRunning(bool isRunning) { if (m_isRunning == isRunning) return; m_isRunning = isRunning; emit isRunningChanged(m_isRunning); } void TestClass::threadStarted() { setIsRunning(true); } void TestClass::threadFinished() { setIsRunning(false); } console output: runWorkerFuntion() from main thread: 0x4228 workerFunction() from thread: 0x15a4 qml: Running: true qml: Running: false

Hi @Sebastien-Leon and welcome to devnet, Can you post the link to the bug report / gerrit review you made ?

breaks SOLID It doesn't. In fact, if it worked as you expected it would break SOLID it's definitely a serious design flaw Sorry to be brutal: No, it's not a flaw, you just didn't understand the design of model/views. To help you get a better idea of what is going on, try use the same model with 2 different treeviews. In only one of the view call setRootIndex, and then trigger the filtering.

@Double-A said in QMYSQL Driver not loaded in Ubuntu: libmysqlclient.so.18 As the error says it can't find libmysqlclient.so.18 Also don't forget that on UNIX/Linux it is not enough to put the lib in same directory like on Windows.

@alizadeh91 Basically, your question is the same as "How do I make a standalone executable that is compiled to native code that plays my animation." You need to either write or use a compiler and toolchain that builds software for the target. In this case, your target is webassembly rather than something like Win64 or OS-X. It's unclear if that's really what you want to do, but there's no real support for emitting webassembly from Qt, any more than there is for emitting Windows .exe's. Qt depends on the system's native compiler and toolchain to make compiled executables. It isn't a compiler in itself. If you are able to export your animations to a (de facto) standard format like Lottie : https://airbnb.io/lottie/ you can find off the shelf player tools which may be useful to you.

Simply don't use the waitForFoo() functions to make sure you're running the eventloop. Use signals/slots instead.

ok, I must leave Qt3D and use opneGL...sigh!

@J.Hilk Thank you for your input! I will give it a try and come back on this forum if stuck ;) Cheers,

Why do you want to "display it in my map using one MapQuickItem only"? You will need to create multiple MapQuickItem instances to display multiple markers on map at once. You can create them statically (if their number is known in advance) or dynamically (if not).

@wraitii Thanks for information! You've probably meant libstdc++ and libc++, because libc is kinda different thing