QBackingStore 类

QBackingStore class provides a drawing area for QWindow . 更多...

Header:	#include <QBackingStore>
qmake:	QT += gui
Since:	Qt 5.0

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公共函数

	QBackingStore (QWindow * window )
	~QBackingStore ()
void	beginPaint (const QRegion & region )
void	endPaint ()
void	flush (const QRegion & region , QWindow * window = nullptr, const QPoint & offset = QPoint())
QPlatformBackingStore *	handle () const
bool	hasStaticContents () const
QPaintDevice *	paintDevice ()
void	resize (const QSize & size )
bool	scroll (const QRegion & area , int dx , int dy )
void	setStaticContents (const QRegion & region )
QSize	size () const
QRegion	staticContents () const
QWindow *	window () const

详细描述

QBackingStore class provides a drawing area for QWindow .

QBackingStore enables the use of QPainter to paint on a QWindow with type RasterSurface. The other way of rendering to a QWindow is through the use of OpenGL with QOpenGLContext .

A QBackingStore contains a buffered representation of the window contents, and thus supports partial updates by using QPainter to only update a sub region of the window contents.

QBackingStore might be used by an application that wants to use QPainter without OpenGL acceleration and without the extra overhead of using the QWidget or QGraphicsView UI stacks. For an example of how to use QBackingStore see the 光栅窗口范例 .

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QBackingStore:: QBackingStore ( QWindow * window )

Constructs an empty surface for the given top-level window .

QBackingStore:: ~QBackingStore ()

销毁此表面。

void QBackingStore:: beginPaint (const QRegion & region )

Begins painting on the backing store surface in the given region .

You should call this function before using the paintDevice () to paint.

另请参阅 endPaint () 和 paintDevice ().

void QBackingStore:: endPaint ()

Ends painting.

You should call this function after painting with the paintDevice () has ended.

另请参阅 beginPaint () 和 paintDevice ().

void QBackingStore:: flush (const QRegion & region , QWindow * window = nullptr, const QPoint & offset = QPoint())

Flushes the given region from the specified window onto the screen.

window must either be the top level window represented by this backingstore, or a non-transient child of that window. Passing nullptr falls back to using the backingstore's top level window.

若 window is a child window, the region should be in child window coordinates, and the offset should be the child window's offset in relation to the backingstore's top level window.

You should call this function after ending painting with endPaint ().

另请参阅 QWindow::transientParent ().

QPlatformBackingStore *QBackingStore:: handle () const

Returns a pointer to the QPlatformBackingStore implementation

bool QBackingStore:: hasStaticContents () const

Returns a boolean indicating if this window has static contents or not.

QPaintDevice *QBackingStore:: paintDevice ()

Returns the paint device for this surface.

警告： The device is only valid between calls to beginPaint () 和 endPaint (). You should not cache the returned value.

void QBackingStore:: resize (const QSize & size )

Sets the size of the window surface to size .

另请参阅 size ().

bool QBackingStore:: scroll (const QRegion & area , int dx , int dy )

Scrolls the given area dx pixels to the right and dy downward; both dx and dy may be negative.

返回 true if the area was scrolled successfully; false otherwise.

void QBackingStore:: setStaticContents (const QRegion & region )

Set region as the static contents of this window.

另请参阅 staticContents ().

QSize QBackingStore:: size () const

Returns the current size of the window surface.

QRegion QBackingStore:: staticContents () const

返回 QRegion representing the area of the window that has static contents.

另请参阅 setStaticContents ().

QWindow *QBackingStore:: window () const

Returns a pointer to the top-level window associated with this surface.