QApplication ¶

概要 ¶

详细描述 ¶

QApplication specializes QGuiApplication with some functionality needed for QWidget -based applications. It handles widget specific initialization, finalization.

For any GUI application using Qt, there is precisely one QApplication object, no matter whether the application has 0, 1, 2 or more windows at any given time. For non- QWidget based Qt applications, use QGuiApplication instead, as it does not depend on the QtWidgets 库。

Some GUI applications provide a special batch mode ie. provide command line arguments for executing tasks without manual intervention. In such non-GUI mode, it is often sufficient to instantiate a plain QCoreApplication to avoid unnecessarily initializing resources needed for a graphical user interface. The following example shows how to dynamically create an appropriate type of application instance:

def main():
    useGUI = not '-no-gui' in sys.argv
    app = QApplication(sys.argv) if useGUI else QCoreApplication(sys.argv)
    ...
    return app.exec_()
											

QApplication object is accessible through the instance() function that returns a pointer equivalent to the global qApp 指针。

QApplication ‘s main areas of responsibility are:

• It initializes the application with the user’s desktop settings such as palette() , font() and doubleClickInterval() . It keeps track of these properties in case the user changes the desktop globally, for example through some kind of control panel.

• It performs event handling, meaning that it receives events from the underlying window system and dispatches them to the relevant widgets. By using sendEvent() and postEvent() you can send your own events to widgets.

• It parses common command line arguments and sets its internal state accordingly. See the 构造函数 文档编制 below for more details.

• It defines the application’s look and feel, which is encapsulated in a QStyle object. This can be changed at runtime with setStyle() .

• It provides localization of strings that are visible to the user via translate() .

• It provides some magical objects like the desktop() 和 clipboard() .

• It knows about the application’s windows. You can ask which widget is at a certain position using widgetAt() , get a list of topLevelWidgets() and closeAllWindows() ，等。

• It manages the application’s mouse cursor handling, see setOverrideCursor()

由于 QApplication object does so much initialization, it must be created before any other objects related to the user interface are created. QApplication also deals with common command line arguments. Hence, it is usually a good idea to create it before any interpretation or modification of argv is done in the application itself.

函数组
系统设置	desktopSettingsAware() , setDesktopSettingsAware() , cursorFlashTime() , setCursorFlashTime() , doubleClickInterval() , setDoubleClickInterval() , setKeyboardInputInterval() , wheelScrollLines() , setWheelScrollLines() , palette() , setPalette() , font() , setFont() , fontMetrics() .
事件处理	exec() , processEvents() , exit() , quit() . sendEvent() , postEvent() , sendPostedEvents() , removePostedEvents() , hasPendingEvents() , notify() .
GUI 样式	style() , setStyle() .
文本处理	installTranslator() , removeTranslator() translate() .
Widgets	allWidgets() , topLevelWidgets() , desktop() , activePopupWidget() , activeModalWidget() , clipboard() , focusWidget() , activeWindow() , widgetAt() .
高级光标处理	overrideCursor() , setOverrideCursor() , restoreOverrideCursor() .
杂项	closeAllWindows() , startingUp() , closingDown() .

另请参阅

QCoreApplication QAbstractEventDispatcher QEventLoop QSettings

class QApplication ¶

QApplication(arg__1)

参数

arg__1 – 字符串列表

PySide2.QtWidgets.QApplication. ColorSpec ¶

常量	描述
QApplication.NormalColor	the default color allocation policy
QApplication.CustomColor	the same as for X11; allocates colors to a palette on demand under Windows
QApplication.ManyColor	the right choice for applications that use thousands of colors

见 setColorSpec() for full details.

static PySide2.QtWidgets.QApplication. aboutQt ( ) ¶

Displays a simple message box about Qt. The message includes the version number of Qt being used by the application.

This is useful for inclusion in the Help menu of an application, as shown in the 菜单 范例。

This function is a convenience slot for aboutQt() .

static PySide2.QtWidgets.QApplication. activeModalWidget ( ) ¶

返回类型

QWidget

Returns the active modal widget.

A modal widget is a special top-level widget which is a subclass of QDialog that specifies the modal parameter of the constructor as true. A modal widget must be closed before the user can continue with other parts of the program.

Modal widgets are organized in a stack. This function returns the active modal widget at the top of the stack.

另请参阅

activePopupWidget() topLevelWidgets()

static PySide2.QtWidgets.QApplication. activePopupWidget ( ) ¶

返回类型

QWidget

Returns the active popup widget.

A popup widget is a special top-level widget that sets the Qt::WType_Popup widget flag, e.g. the QMenu widget. When the application opens a popup widget, all events are sent to the popup. Normal widgets and modal widgets cannot be accessed before the popup widget is closed.

Only other popup widgets may be opened when a popup widget is shown. The popup widgets are organized in a stack. This function returns the active popup widget at the top of the stack.

另请参阅

activeModalWidget() topLevelWidgets()

static PySide2.QtWidgets.QApplication. activeWindow ( ) ¶

返回类型

QWidget

返回拥有键盘输入聚焦的应用程序顶层窗口，或 None if no application window has the focus. There might be an even if there is no focusWidget() , for example if no widget in that window accepts key events.

另请参阅

setActiveWindow() setFocus() hasFocus() focusWidget()

static PySide2.QtWidgets.QApplication. alert ( widget [ , duration=0 ] ) ¶

参数

• widget – QWidget

• duration – int

Causes an alert to be shown for widget if the window is not the active window. The alert is shown for msec miliseconds. If msec is zero (the default), then the alert is shown indefinitely until the window becomes active again.

Currently this function does nothing on Qt for Embedded Linux.

On macOS, this works more at the application level and will cause the application icon to bounce in the dock.

On Windows, this causes the window’s taskbar entry to flash for a time. If msec is zero, the flashing will stop and the taskbar entry will turn a different color (currently orange).

On X11, this will cause the window to be marked as “demands attention”, the window must not be hidden (i.e. not have hide() called on it, but be visible in some sort of way) in order for this to work.

static PySide2.QtWidgets.QApplication. allWidgets ( ) ¶

返回类型

返回应用程序的所有 Widget 的列表。

列表是空的 ( isEmpty() ) if there are no widgets.

注意

某些 Widget 可能被隐藏。

范例：

def updateAllWidgets():
    for widget in QApplication.allWidgets()
        widget.update()
											

另请参阅

topLevelWidgets() isVisible()

PySide2.QtWidgets.QApplication. autoSipEnabled ( ) ¶

返回类型

bool

另请参阅

setAutoSipEnabled()

static PySide2.QtWidgets.QApplication. beep ( ) ¶

响铃声，使用默认音量和声音。函数 not 可用于 Qt for Embedded Linux。

static PySide2.QtWidgets.QApplication. closeAllWindows ( ) ¶

关闭所有顶层窗口。

This function is particularly useful for applications with many top-level windows. It could, for example, be connected to a Exit entry in the File menu:

exitAct = QAction(tr("E&xit"), self)
exitAct.setShortcut(tr("Ctrl+Q"))
exitAct.setStatusTip(tr("Exit the application"))
exitAct.triggered.connect(qApp.closeAllWindows)
											

The windows are closed in random order, until one window does not accept the close event. The application quits when the last window was successfully closed; this can be turned off by setting quitOnLastWindowClosed 为 false。

另请参阅

quitOnLastWindowClosed lastWindowClosed() close() closeEvent() lastWindowClosed() quit() topLevelWidgets() isWindow()

static PySide2.QtWidgets.QApplication. colorSpec ( ) ¶

返回类型

int

注意

此函数被弃用。

Returns the color specification.

另请参阅

setColorSpec()

static PySide2.QtWidgets.QApplication. cursorFlashTime ( ) ¶

返回类型

int

另请参阅

setCursorFlashTime()

static PySide2.QtWidgets.QApplication. desktop ( ) ¶

返回类型

QDesktopWidget

返回桌面 Widget (也称根窗口)。

桌面可能由多个屏幕组成，因此它将是不正确的，例如：试图 center some widget in the desktop’s geometry. QDesktopWidget has various functions for obtaining useful geometries upon the desktop, such as screenGeometry() and availableGeometry() .

static PySide2.QtWidgets.QApplication. doubleClickInterval ( ) ¶

返回类型

int

另请参阅

setDoubleClickInterval()

PySide2.QtWidgets.QApplication. focusChanged ( old , now ) ¶

参数

• old – QWidget

• now – QWidget

static PySide2.QtWidgets.QApplication. focusWidget ( ) ¶

返回类型

QWidget

返回拥有键盘输入聚焦的应用程序 Widget，或 None 若此应用程序的 Widget 不拥有聚焦。

另请参阅

setFocus() hasFocus() activeWindow() focusChanged()

static PySide2.QtWidgets.QApplication. font ( arg__1 ) ¶

参数

arg__1 – QWidget

返回类型

QFont

这是重载函数。

返回默认字体，为 widget .

另请参阅

fontMetrics() setFont()

static PySide2.QtWidgets.QApplication. font ( className ) ¶

参数

className – str

返回类型

QFont

这是重载函数。

返回 Widget 字体为给定 className .

另请参阅

setFont() font()

static PySide2.QtWidgets.QApplication. fontMetrics ( ) ¶

返回类型

QFontMetrics

返回用于应用程序字体的显示 (屏幕) 字体规格。

另请参阅

font() setFont() fontMetrics() fontMetrics()

static PySide2.QtWidgets.QApplication. globalStrut ( ) ¶

返回类型

QSize

另请参阅

setGlobalStrut()

static PySide2.QtWidgets.QApplication. isEffectEnabled ( arg__1 ) ¶

参数

arg__1 – UIEffect

返回类型

bool

返回 true if effect 被启用；否则返回 false .

By default, Qt will try to use the desktop settings. To prevent this, call setDesktopSettingsAware (false).

注意

All effects are disabled on screens running at less than 16-bit color depth.

另请参阅

setEffectEnabled() UIEffect

static PySide2.QtWidgets.QApplication. keyboardInputInterval ( ) ¶

返回类型

int

另请参阅

setKeyboardInputInterval()

static PySide2.QtWidgets.QApplication. palette ( arg__1 ) ¶

参数

arg__1 – QWidget

返回类型

QPalette

若 widget is passed, the default palette for the widget’s class is returned. This may or may not be the application palette. In most cases there is no special palette for certain types of widgets, but one notable exception is the popup menu under Windows, if the user has defined a special background color for menus in the display settings.

另请参阅

setPalette() palette()

static PySide2.QtWidgets.QApplication. palette ( className ) ¶

参数

className – str

返回类型

QPalette

这是重载函数。

Returns the palette for widgets of the given className .

另请参阅

setPalette() palette()

static PySide2.QtWidgets.QApplication. setActiveWindow ( act ) ¶

参数

act – QWidget

Sets the active window to the active widget in response to a system event. The function is called from the platform specific event handlers.

警告

This function does not set the keyboard focus to the active widget. Call activateWindow() 代替。

It sets the activeWindow() and focusWidget() attributes and sends proper WindowActivate / WindowDeactivate and FocusIn / FocusOut events to all appropriate widgets. The window will then be painted in active state (e.g. cursors in line edits will blink), and it will have tool tips enabled.

另请参阅

activeWindow() activateWindow()

PySide2.QtWidgets.QApplication. setAutoSipEnabled ( enabled ) ¶

参数

enabled – bool

另请参阅

autoSipEnabled()

static PySide2.QtWidgets.QApplication. setColorSpec ( arg__1 ) ¶

参数

arg__1 – int

注意

此函数被弃用。

Sets the color specification for the application to spec .

This call has no effect.

The color specification controls how the application allocates colors when run on a display with a limited amount of colors, e.g. 8 bit / 256 color displays.

The color specification must be set before you create the QApplication 对象。

The options are:

Be aware that the CustomColor and ManyColor choices may lead to colormap flashing: The foreground application gets (most) of the available colors, while the background windows will look less attractive.

范例：

def main():
    QApplication.setColorSpec(QApplication.ManyColor)
    QApplication app(sys.argv)
    ...
    return app.exec_()
											

另请参阅

colorSpec()

static PySide2.QtWidgets.QApplication. setCursorFlashTime ( arg__1 ) ¶

参数

arg__1 – int

另请参阅

cursorFlashTime()

static PySide2.QtWidgets.QApplication. setDoubleClickInterval ( arg__1 ) ¶

参数

arg__1 – int

另请参阅

doubleClickInterval()

static PySide2.QtWidgets.QApplication. setEffectEnabled ( arg__1 [ , enable=true ] ) ¶

参数

• arg__1 – UIEffect

• enable – bool

Enables the UI effect effect if enable is true, otherwise the effect will not be used.

注意

All effects are disabled on screens running at less than 16-bit color depth.

另请参阅

isEffectEnabled() UIEffect setDesktopSettingsAware()

static PySide2.QtWidgets.QApplication. setFont ( arg__1 [ , className=None ] ) ¶

参数

• arg__1 – QFont

• className – str

把默认应用程序字体改为 font 。若 className is passed, the change applies only to classes that inherit className (as reported by inherits() ).

On application start-up, the default font depends on the window system. It can vary depending on both the window system version and the locale. This function lets you override the default font; but overriding may be a bad idea because, for example, some locales need extra large fonts to support their special characters.

警告

Do not use this function in conjunction with Qt 样式表 . The font of an application can be customized using the “font” style sheet property. To set a bold font for all QPushButtons, set the application styleSheet() as ” QPushButton { font: bold }”

另请参阅

font() fontMetrics() setFont()

static PySide2.QtWidgets.QApplication. setGlobalStrut ( arg__1 ) ¶

参数

arg__1 – QSize

另请参阅

globalStrut()

static PySide2.QtWidgets.QApplication. setKeyboardInputInterval ( arg__1 ) ¶

参数

arg__1 – int

另请参阅

keyboardInputInterval()

static PySide2.QtWidgets.QApplication. setPalette ( arg__1 [ , className=None ] ) ¶

参数

• arg__1 – QPalette

• className – str

将应用程序调色板更改为 palette .

若 className is passed, the change applies only to widgets that inherit className (as reported by inherits() )。若 className is left 0, the change affects all widgets, thus overriding any previously set class specific palettes.

The palette may be changed according to the current GUI style in polish() .

警告

Do not use this function in conjunction with Qt 样式表 . When using style sheets, the palette of a widget can be customized using the “color”, “background-color”, “selection-color”, “selection-background-color” and “alternate-background-color”.

注意

Some styles do not use the palette for all drawing, for instance, if they make use of native theme engines. This is the case for the Windows Vista and macOS styles.

另请参阅

setPalette() palette() polish()

static PySide2.QtWidgets.QApplication. setStartDragDistance ( l ) ¶

参数

l – int

另请参阅

startDragDistance()

static PySide2.QtWidgets.QApplication. setStartDragTime ( ms ) ¶

参数

ms – int

另请参阅

startDragTime()

static PySide2.QtWidgets.QApplication. setStyle ( arg__1 ) ¶

参数

arg__1 – QStyle

Sets the application’s GUI style to style . Ownership of the style object is transferred to QApplication ，因此 QApplication will delete the style object on application exit or when a new style is set and the old style is still the parent of the application object.

用法范例：

QApplication.setStyle(QWindowsStyle())
											

When switching application styles, the color palette is set back to the initial colors or the system defaults. This is necessary since certain styles have to adapt the color palette to be fully style-guide compliant.

Setting the style before a palette has been set, i.e., before creating QApplication , will cause the application to use standardPalette() for the palette.

警告

Qt style sheets are currently not supported for custom QStyle subclasses. We plan to address this in some future release.

另请参阅

style() QStyle setPalette() desktopSettingsAware()

static PySide2.QtWidgets.QApplication. setStyle ( arg__1 ) ¶

参数

arg__1 – unicode

返回类型

QStyle

PySide2.QtWidgets.QApplication. setStyleSheet ( sheet ) ¶

参数

sheet – unicode

另请参阅

styleSheet()

static PySide2.QtWidgets.QApplication. setWheelScrollLines ( arg__1 ) ¶

参数

arg__1 – int

另请参阅

wheelScrollLines()

static PySide2.QtWidgets.QApplication. startDragDistance ( ) ¶

返回类型

int

另请参阅

setStartDragDistance()

static PySide2.QtWidgets.QApplication. startDragTime ( ) ¶

返回类型

int

另请参阅

setStartDragTime()

static PySide2.QtWidgets.QApplication. style ( ) ¶

返回类型

QStyle

Returns the application’s style object.

另请参阅

setStyle() QStyle

PySide2.QtWidgets.QApplication. styleSheet ( ) ¶

返回类型

unicode

另请参阅

setStyleSheet()

static PySide2.QtWidgets.QApplication. topLevelAt ( x , y ) ¶

参数

• x – int

• y – int

返回类型

QWidget

这是重载函数。

返回的顶层 Widget 在 point ( x , y )；返回 0 若没有这种 Widget。

static PySide2.QtWidgets.QApplication. topLevelWidgets ( ) ¶

返回类型

返回应用程序顶层 Widget (窗口) 的列表。

注意

某些顶层 Widget 可能被隐藏，例如：工具提示，若目前未展示工具提示。

范例：

def showAllHiddenTopLevelWidgets():
    for widget in QApplication.topLevelWidgets():
        if widget.isHidden():
            widget.show()
											

另请参阅

allWidgets() isWindow() isHidden()

static PySide2.QtWidgets.QApplication. wheelScrollLines ( ) ¶

返回类型

int

另请参阅

setWheelScrollLines()

static PySide2.QtWidgets.QApplication. widgetAt ( p ) ¶

参数

p – QPoint

返回类型

QWidget

返回 Widget，在全局屏幕位置 point ，或 None 若那里没有 Qt Widget。

此函数可能很慢。

另请参阅

pos() grabMouse() grabKeyboard()

static PySide2.QtWidgets.QApplication. widgetAt ( x , y ) ¶

参数

• x – int

• y – int

返回类型

QWidget

这是重载函数。

返回 Widget，在全局屏幕位置 ( x , y )，或 None 若那里没有 Qt Widget。