QApplication Class

 QCoreApplication* createApplication(int &argc, char *argv[])
 {
     for (int i = 1; i < argc; ++i) {
         if (!qstrcmp(argv[i], "-no-gui"))
             return new QCoreApplication(argc, argv);
     }
     return new QApplication(argc, argv);
 }

 int main(int argc, char* argv[])
 {
     QScopedPointer<QCoreApplication> app(createApplication(argc, argv));

     if (qobject_cast<QApplication *>(app.data())) {
        // start GUI version...
     } else {
        // start non-GUI version...
     }

     return app->exec();
 }

Property Documentation

autoSipEnabled : bool

toggles automatic SIP (software input panel) visibility

Set this property to true to automatically display the SIP when entering widgets that accept keyboard input. This property only affects widgets with the WA_InputMethodEnabled attribute set, and is typically used to launch a virtual keyboard on devices which have very few or no keys.

The property only has an effect on platforms that use software input panels.

The default is platform dependent.

This property was introduced in Qt 4.5.

Access functions:

cursorFlashTime : int

This property holds the text cursor's flash (blink) time in milliseconds

The flash time is the time required to display, invert and restore the caret display. Usually the text cursor is displayed for half the cursor flash time, then hidden for the same amount of time, but this may vary.

The default value on X11 is 1000 milliseconds. On Windows, the Control Panel value is used and setting this property sets the cursor flash time for all applications.

We recommend that widgets do not cache this value as it may change at any time if the user changes the global desktop settings.

Access functions:

doubleClickInterval : int

This property holds the time limit in milliseconds that distinguishes a double click from two consecutive mouse clicks

The default value on X11 is 400 milliseconds. On Windows and Mac OS, the operating system's value is used.

Access functions:

keyboardInputInterval : int

This property holds the time limit in milliseconds that distinguishes a key press from two consecutive key presses

The default value on X11 is 400 milliseconds. On Windows and Mac OS, the operating system's value is used.

This property was introduced in Qt 4.2.

Access functions:

startDragDistance : int

If you support drag and drop in your application, and want to start a drag and drop operation after the user has moved the cursor a certain distance with a button held down, you should use this property's value as the minimum distance required.

For example, if the mouse position of the click is stored in startPos and the current position (e.g. in the mouse move event) is currentPos, you can find out if a drag should be started with code like this:

 if ((startPos - currentPos).manhattanLength() >=
         QApplication::startDragDistance())
     startTheDrag();

Qt uses this value internally, e.g. in QFileDialog.

The default value (if the platform doesn't provide a different default) is 10 pixels.

Access functions:

See also startDragTime(), QPoint::manhattanLength(), and Drag and Drop.

startDragTime : int

This property holds the time in milliseconds that a mouse button must be held down before a drag and drop operation will begin

If you support drag and drop in your application, and want to start a drag and drop operation after the user has held down a mouse button for a certain amount of time, you should use this property's value as the delay.

Qt also uses this delay internally, e.g. in QTextEdit and QLineEdit, for starting a drag.

The default value is 500 ms.

Access functions:

See also startDragDistance() and Drag and Drop.

styleSheet : QString

This property holds the application style sheet

By default, this property returns an empty string unless the user specifies the -stylesheet option on the command line when running the application.

This property was introduced in Qt 4.2.

Access functions:

See also QWidget::setStyle() and Qt Style Sheets.

wheelScrollLines : int

This property holds the number of lines to scroll a widget, when the mouse wheel is rotated.

If the value exceeds the widget's number of visible lines, the widget should interpret the scroll operation as a single page up or page down. If the widget is an item view class, then the result of scrolling one line depends on the setting of the widget's scroll mode. Scroll one line can mean scroll one item or scroll one pixel.

By default, this property has a value of 3.

Access functions:

See also QStyleHints::wheelScrollLines().

windowIcon : QIcon

This property holds the default window icon

Access functions:

See also QWidget::setWindowIcon() and Setting the Application Icon.