Most voted "qt" questions
Qt is a framework for developing graphical interfaces written in C++ supporting a wide number of platforms. Applications can also be created with QML/Javascript. It is currently developed and maintained by Digia.
Learn more…186 questions
Sort by count of
-
19
votes2
answers1037
viewsHow to use Qt translations directly with Qapplication::tr()
In an application developed in Qt I have a non-visual class (i.e., that is not inherited from a QWidget) but that handles text strings that must be presented to the user. To use the Qt translation…
-
15
votes1
answer205
viewsWaiting for a signal within a Qquickimageprovider
I’m creating an application using QML and the Qt 5.2. In her a ListView displays multiple items, each with an image and associated text. The image is built based on data uploaded from a server by…
-
12
votes2
answers4009
viewsFormat decimal with comma and thousand with dot
How can I format a float for the Brazilian value format(price)? Example: in php number_format($float,2,',','.') separates decimal with comma and unit of thousand with dot.…
-
11
votes1
answer172
viewsDifficulties with selecting items in a Qtreeview
Setting: I have an application that manages a list of images of human faces with prototypical emotional expressions. I created a class inherited from QAbstractListModel to provide the model (model)…
-
11
votes1
answer127
viewsQvideowidget displays nothing
I’m trying to use the classes QMediaPlayer and QVideoWidget to display a video on a system I’m producing. Only these class rays don’t work as expected. The QVideoWidget just doesn’t show up, doesn’t…
-
9
votes2
answers990
viewsHow to verify collision between particles?
I need to know how to make each circle collide with each other along with the part of how I’m going to go in such a direction after this collision. This is the class of the main program window:…
-
9
votes1
answer261
viewsOptimize the collision between particles
I need to optimize as much as possible the algorithm that makes the particles collide, is there anything that can be done to do that? And I also want to add a background image, it’s possible?…
-
8
votes3
answers9428
viewsHow does serial communication work and how do I use C/C++?
I use the Debian 7.1 and need to make serial communication between a computer and a microcontroller using C/C++. I’ve done a lot of research on the subject, but the articles and examples I found are…
-
8
votes1
answer211
viewsQT + Opencv on Mac Os 10.10.3 with error: Symbol(s) not found for Architecture x86_64
I recently installed Qt Creator and Opencv. I was able to easily compile QT and Opencv separately. But I can’t compile both together. My file .pro is like this:…
-
7
votes2
answers4418
viewsWhat does it mean to create an object with that asterisk?
Although I knew programming for a reasonable time, learning C++ with QT, I came across something I hadn’t seen in other languages. I noticed that some objects (not all) need to be created with an…
-
7
votes1
answer711
viewsHow does the class constructor statement in Qt work?
I work with C and a little bit of Assembly, in Atmel AVR microcontrollers. I’m trying to understand how the framework Qt extends C++. I created a new project with Qt Creator (Widgets), and generated…
-
6
votes1
answer197
viewsDisplay a dynamically loaded text/photo pad with QML for Android
I’m writing an app using the newly released Qt 5.2 QML for Android. On one of the screens I need to display an article that is loaded from a server and may change after the launch of the…
-
6
votes1
answer830
viewsERROR: This application is failed to start because it could not find or load the Qt Platform plugin "windows"
I am in error when running a program that was created with Qt , it generates the photo error! This error is generated when running exe, all the dlls indicated in the Walker dependency are in the exe…
-
6
votes2
answers790
viewsLinux-based c++ Qt program to run on Windows
People wanted to know if there is any way and if there is what, to basically create an executable ,of a GUI program made in Qt, for Windows being that I am using Linux.
-
6
votes1
answer1949
viewsWhat is the difference between Debug and Release?
I started having the error: "Microsoft C++ Runtime error library". And I got many problems trying to fix this error. I was using Qt Creator with mingw32 in mode debug, but I realized that this mode…
-
5
votes3
answers457
viewsLock the window zoom
How can I block the window rise QDialog and QWidget? For example, in the Skype login window you cannot enlarge the window.
-
5
votes2
answers592
viewsHow to convert a Std::string to a Qstring?
I’m trying to make a simple dialog box display my name. See the code. Pessoa *p = new Pessoa("Ronald Araújo", "[email protected]", 23); QMessageBox msg;…
-
5
votes1
answer214
viewsHow to use qtwebkit-plugins in my project?
Qtwebkit-plugins is a library that provides functionalities for QWebView, as SpellCheck/Corretor ortografico and Notification Web API. Read about in: SpellCheck Notification Web API I tried to…
-
5
votes0
answers180
viewsQcamera Windows "failed to start"
I made an application with QT where I make the instance of a Camera with QT and display it in the window. So far so good, the problem is that when I want to display it in another window (Qdialog) I…
-
5
votes1
answer354
viewsQt calling method in another class
I’m calling a method another class after entering data. But it is returning an Sqlite error: QSqlDatabasePrivate::removeDatabase: connection 'qt_sql_default_connection' is still in use, all queries…
-
5
votes1
answer938
viewsHow to create buttons next and back QUI Pyqt4
Hello, I’m new to Pyqt and I have a question, I need to create a program with several steps, or screens, where the user will do his due processing on each screen and clicking 'forward' to the next…
-
5
votes0
answers116
viewsHow to print an existing PDF using Poppler (Qt5)?
I’m using Poppler for Qt5, but I’ve reviewed the API documentation https://people.freedesktop.org/~aacid/Docs/Qt5/ to read existing PDF documents, I need to put the functionality to send to printer,…
-
4
votes2
answers144
viewsHow to make a constructor equal to Qobject?
When a new question arises from an old question, I want to know how to create a class equal to QObject. Basically, I want to know: How to make a copy constructor that does not accept "assignment…
-
4
votes1
answer1144
viewsResize components when enlarging window
How can I resize the components inside the QWidget when enlarging the window? Example of how it looks:…
-
4
votes2
answers461
viewsQMYSQL driver not Loaded Qtcreator
I am trying to connect to the database with Qtcreator as follows: this->db = QSqlDatabase::addDatabase("QMYSQL"); this->db.setHostName("localhost"); this->db.setDatabaseName("Pessoa");…
-
4
votes1
answer87
viewsQvector to Qimage
I have to turn one QVector 2d in a QImage to display the image on a label. The QVector in the case of an array of integers with a value of 0 to 255 representing an image in PGM or PPM, this vector…
-
4
votes1
answer81
viewsQsharedpointer Definition and Function
From what I understand, the Qsharedpointer is a smart Pointer, ie, a pointer that offers automatic garbage collection. If possible I would like a code that better explains this, including when I…
-
4
votes3
answers880
viewsInteger for String
In QT Creator 5, how do I convert Integer to string? In Visual Studio 2012 there was the command: std::to_string(10); But it doesn’t work on QT. I tried to: #include <QCoreApplication>…
-
4
votes1
answer213
viewsRepaint screen every little time without crashing - C++
I have the following situation: I have to repaint the screen every little while so that objects on the screen move on their own, but this has to occur so that the program does not lock. I tried to…
-
4
votes1
answer151
viewsQt String Encoding Problem
I’m having a problem encoding strings on Qt. By showing something in a QMessageBox or give a drawText in a paintEvent, my strings come out badly formatted, as if they were not in the correct…
-
4
votes3
answers1952
viewsHow to get a text from a Qlineedit in Qt?
For example, I have a LineEdit, when I press a button I want to pick up what I wrote on this LineEdit and store a QString.
-
4
votes1
answer2088
viewsHow to convert int to Qstring?
I started learning Toolkit today QT and in trying to perform a small test I came across a question: How to convert a whole to QString? Is there a function that receives an integer and returns an…
-
4
votes1
answer168
viewsHow to extend the length of Widgets within a Qscrollarea?
I’m looking to build a question form in Qt. As there are several questions to be answered, it is necessary to allow the scrolling of the form, and so I used a QScrollArea. Questions are all answered…
-
4
votes1
answer91
viewsfind_package failed to generate project (in Qt) with Cmake
I’m trying to generate the build configuration of a simple Qt example using Cmake. The code of the example is this: #include <QApplication> #include <QTextEdit> int main(int argc, char**…
-
4
votes1
answer68
viewsProblems to remove vector node
I have two classes: class CAlbum { private: QString Nome; /**< Nome do Álbum */ QString Descricao; /**< Descrição do Álbum */ QString Diretoria; /**< Diretoria onde se encontra o Álbum */…
-
4
votes1
answer560
viewsC++ - Sort particular points of a rectangle in a vector?
I have a project in c++ where I should map regions of an image using the mouse click. The point is that I should get the mapping points in a specific storage order, as in the image below: my problem…
-
4
votes3
answers220
viewsAttributeerror: 'Qstring' Object has no attribute 'strip'
I’m making a small application in Pyqt4 to understand how it works. In a certain part, I’m using a callback function to display in a QLabel the text that is typed in QtextEdit. This text should be…
-
4
votes2
answers78
viewsDynamic/stochastic object allocation in QML
I am currently trying to do the following in QML, simultaneously: do dynamic loading of Objects previously created a separate file; by doing what is described above, select objects stochastically…
-
3
votes1
answer203
viewsHow to treat screen orientation in QML?
I usually develop focused to vertical orientation, but when I turn the device screen to horizontal, the elements are resized in an unwanted way, leaving some smaller than they really should be. For…
-
3
votes1
answer4156
viewsCommand to exit the scope of a function (`break`equivalent)
How can I create an algorithm in C++ (using Qt) to abort code processing? I have to validate many different entries and I don’t want to keep creating if else if else. The code is ugly. Example, but…
-
3
votes1
answer171
viewsPrint Tableview Data with Qprinter
How can I get the data from a TableView add to layout html and print with QPrinter? Code: QString html; html = "<div>Titulo</div>" "<div>etc</div>"…
-
3
votes1
answer70
viewsFilter month on Qsqltablemodel
How do I filter the month on QSqlTableModel? I’m doing like this: model = new QSqlTableModel(this); model->setTable("tabela"); // db sqlite model->setFilter("strftime('%m',…
-
3
votes2
answers155
viewsConvert Qvector<Qstring> to int in C++
I have a Qvector and I want to convert it so I can make comparisons to find out which one is bigger. I tried to do this but it doesn’t work: QVector<QString> vector; std::atoi(vector.value…
-
3
votes1
answer857
viewsHow to make a window transparent using Qt?
I’m developing a college job in Qt. I would like to make the background of my application transparent. I did some research and the function I found was: this->setWindowOpacity(0); Meanwhile, the…
-
3
votes1
answer196
viewsHow to use Qvector<Qvector <double> as matrix?
In the mainwindow.h have: private: QVector<QVector<double> > numbers; //Variável que será minha matriz public slot: void realizar_calcs(QVector<QVector<double> >…
-
3
votes2
answers1327
viewsQmake - Independent executable
How do I compile a Qt Creator program(.pro) with "static link"? I compiled by QT Creator, but I need to copy about 6 dlls to the executable folder, some of them are more than 100mb. I read in the…
-
3
votes1
answer103
viewsHow to install Qt for MSVC without the Microsoft IDE?
You can install Qt and the MSVC compiler without installing the Microsoft IDE? I downloaded this version of Qt 5.4.0 for Windows 32-bit (VS 2013, Opengl, 694 MB) and installed, but I do not have…
-
3
votes1
answer534
viewsHow to call a Python script in a C++ code in Qt Creator?
How do I call a Python script in a C++ code in Qt Creator?
-
3
votes1
answer73
viewsQt return during release
When I compile my project as debug, it works normally, but when I try to compile in release appears the following message in the Output Compile: cc1plus: error: argument to '-O' should be a…
-
3
votes2
answers1296
viewsHow to get operating system time in nanoseconds or milliseconds using Qt Creator?
How can I get system time in nanoseconds or milliseconds in C++ using the Qt Creator? For example, in Java use: long tempoInicial = System.nanoTime(); treinaRNAEpocas(10000); long tempoFinal =…