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Questions tagged [qt4]

Questions specifically relating to the deprecated version 4.x.x of the Qt C++ GUI library. If your question applies to the current major version of Qt, use the tag [qt].

Qt 4.x is a specific series of releases of the Qt GUI library. Use this tag if your question only applies to Qt 4.x, and not to Qt 3.x or Qt 5.x. If your question applies to Qt in general, use the tag .

Trolltech released Qt 4.0 on June 28, 2005 and introduced five new technologies in the framework:

  • Tulip: A set of template container classes.
  • Interview: A model/view architecture for item views.
  • Arthur: A 2D painting framework.
  • Scribe: A Unicode text renderer with a public API for performing low-level text layout.
  • MainWindow: A modern action-based main window, toolbar, menu, and docking architecture.

The latest official 4.x release is 4.8.6 (April 24, 2014). The major version indicates API compatibility.

It has been noted that, Qt 4.8 is officially supported till "19.12.2015", In order to get official support it is better to port to Qt5

A list of the supported platforms for version 4.8 can be found here

5315 questions
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Qt designer plugin (custom widget) in Eclipse integration

I have made custom widget plugin, which is recognized and visible in Qt designer, but Qt creator and Qt eclipse integration doesn't show it. Does anyone have ideas how to solve this problem?
Mindaugas
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Preventing a resizable parent widget from being resized by child widgets

Is it possible to create a widget in Qt4 whose size can be changed interactively (e.g. by clicking and dragging the edge), but whose size will not change when its children widgets are added, removed, or resized? In other words, as I populate the…
ChrisB
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Unload Plugin in Qt

Issue comes up when i try to unload plugin that is loaded and load a new one. So both plugins are loaded correctly, but when switching them (first is loaded, second is unloaded and viceversa) my app crashes. What can be the problem ? First what i'm…
user704010
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2 answers

Does QTimer keep counting once it's timedout?

I would like to know if a QTimer will keep on counting once it has timed out. For example, let's say I have a QTimer that times out every 500ms. Let's say when this particular QTimer times out, my program happens to be in some function that I have…
Jean-Luc
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How to close already open browser from application in Qt

I am using QDeskTopServices to open a URL in my application in Qt, but if the browser is already open in background, it does not come to the foreground and does nothing on calling on QDeskTopServices. Is there any way to check and close the browser…
abhishek
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2 answers

Errors running CutyCapt on Centos 5.7 without X Server

Having everything installed and compiled successfully, I am getting this lovely output, anyone has an idea? (it's a centos 5.7 without x server, so I am emulating this using the infamous xvfb-run) ./xvfb-run ./CutyCapt Locking assertion failure. …
Nir O.
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reimp.exe does not create .a

When I invoke reimp libmysql.lib it does not generate .a file and it does not show me anything. I am using QT 4.7.2 command prompt. What am I missing here?
gizemdemirel
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QBoxLayout screws up QFormLayout?

Following simplified code snippet: #include int main(int argc, char **argv) { QApplication app(argc, argv); QWidget *window = new QWidget(); QFormLayout *form = new QFormLayout(); // first row form->addRow("First row:", new…
Ancurio
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Problems using HOGDescriptor

I'm fiddling with a bit of c++/opencv. I was looking some of the samples and haven't manage to compile/run peopledetect.cpp which uses HOGDescriptor. I've setup a basic Qt Console Application to test and narrow down the problem and got to this basic…
George Profenza
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QRadioButton Array issue

I create a QRadioButton array and tried to init it with six radioButtons. At the moment when i populate array with object i do not receive any warnings or errors. But when i try to see if radio button is check i get crash for all radio button , but…
develoops
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Custom sorting method of QTableView?

How can I setup custom sorting method for a QTableView , or for the model ? (Which function should I re-implement) The default sorting algorithm are for strings , I want a number sorting method for some specific column. Thanks.
daisy
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Decoding UDP Streams with LibAV: Insufficient Buffer Size

I'm attempting to using the libav libraries with Qt to decode h.264 UDP video streams, but when I use avformat_open_file, I get the following error message: [udp @ 0x102b5bee0] Part of datagram lost due to insufficient buffer size The message…
Colin Ray
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Can't link qwt in Qt

I use LIBS flag to link qwt library to my project. So in .pro of my project i have LIBS += -L/home/Desktop/qwt-6.0.1/lib -lqwt But anyway Qt does not recognize qwt classes. What i'm missing ??
user704010
2
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2 answers

Setting external CSS for QWebView with resource file

I'm trying to set external CSS for QWebView with: ui->webView->settings()->setUserStyleSheetUrl( QUrl::fromLocalFile(":/default.css") ); Which contains only: body { color: red; } But it's not working on any page ( nothing is in red ) Also i double…
daisy
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Qt cant load temporary status message

I have a class class Window: public QMainWindow { // ... private: Ui::MainWindow ui; } Where Ui::MainWindow is the auto generated ui_mainwindow.h for the mainwindow.ui form. In my constructor Window::Window(QWidget *parent): …
Dewsworld
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