QwtWidgetOverlay Class Reference

An overlay for a widget. More...

#include <qwt_widget_overlay.h>

Inheritance diagram for QwtWidgetOverlay:

Classes
class	PrivateData

Public Types
enum	MaskMode { NoMask , MaskHint , AlphaMask }
	Mask mode. More...
enum	RenderMode { AutoRenderMode , CopyAlphaMask , DrawOverlay }

Public Slots
void	updateOverlay ()
	Recalculate the mask and repaint the overlay .

Public Member Functions
	QwtWidgetOverlay (QWidget *)
	Constructor.
virtual	~QwtWidgetOverlay ()
	Destructor .
void	setMaskMode (MaskMode)
	Specify how to find the mask for the overlay.
MaskMode	maskMode () const
void	setRenderMode (RenderMode)
	Set the render mode.
RenderMode	renderMode () const
virtual bool	eventFilter (QObject *, QEvent *) override
	Event filter.

Protected Member Functions
virtual void	paintEvent (QPaintEvent *) override
	Paint event
virtual void	resizeEvent (QResizeEvent *) override
	Resize event
virtual QRegion	maskHint () const
	Calculate an approximation for the mask.
virtual void	drawOverlay (QPainter *painter) const =0
	Draw the widget overlay

Detailed Description

An overlay for a widget.

Member Enumeration Documentation

MaskMode

enum QwtWidgetOverlay::MaskMode

Mask mode.

Enumerator
NoMask	Don't use a mask. .
MaskHint	Use maskHint() as mask For many situations a fast approximation is good enough and it is not necessary to build a more detailed mask ( f.e the bounding rectangle of a text ).
AlphaMask	Calculate a mask by checking the alpha values Sometimes it is not possible to give a fast approximation and the mask needs to be calculated by drawing the overlay and testing the result. When a valid maskHint() is available only pixels inside this approximation are checked.

RenderMode

enum QwtWidgetOverlay::RenderMode

Render mode

For calculating the alpha mask the overlay has already been painted to a temporary QImage. Instead of rendering the overlay twice this buffer can be copied for drawing the overlay.

On graphic systems using the raster paint engine ( QWS, Windows ) it means usually copying some memory only. On X11 it results in an expensive operation building a pixmap and for simple overlays it might not be recommended.

Note

The render mode has no effect, when maskMode() != AlphaMask.

Enumerator
AutoRenderMode	Copy the buffer, when using the raster paint engine. .
CopyAlphaMask	Always copy the buffer .
DrawOverlay	Never copy the buffer .

Constructor & Destructor Documentation

QwtWidgetOverlay()

QwtWidgetOverlay::QwtWidgetOverlay ( QWidget *  widget )

explicit

Constructor.

~QwtWidgetOverlay()

QwtWidgetOverlay::~QwtWidgetOverlay ( )

virtual

Destructor .

Member Function Documentation

drawOverlay()

virtual void QwtWidgetOverlay::drawOverlay ( QPainter *  painter ) const

protectedpure virtual

Draw the widget overlay

Parameters

painter

Painter

Implemented in QwtFigureWidgetOverlay.

eventFilter()

bool QwtWidgetOverlay::eventFilter ( QObject *  object, QEvent *  event  )

overridevirtual

Event filter.

maskHint()

QRegion QwtWidgetOverlay::maskHint ( ) const

protectedvirtual

Calculate an approximation for the mask.

• MaskHint The hint is used as mask.
• AlphaMask The hint is used to speed up the algorithm for calculating a mask from non transparent pixels
• NoMask The hint is unused.

The default implementation returns an invalid region indicating no hint.

Returns

Hint for the mask

Reimplemented in QwtFigureWidgetOverlay.

maskMode()

QwtWidgetOverlay::MaskMode QwtWidgetOverlay::maskMode

(

)

const

Returns

Mode how to find the mask for the overlay

See also

setMaskMode()

paintEvent()

void QwtWidgetOverlay::paintEvent ( QPaintEvent *  event )

overrideprotectedvirtual

Paint event

Parameters

event

Paint event

See also

drawOverlay()

renderMode()

QwtWidgetOverlay::RenderMode QwtWidgetOverlay::renderMode

(

)

const

Returns

Render mode

See also

RenderMode, setRenderMode()

resizeEvent()

void QwtWidgetOverlay::resizeEvent ( QResizeEvent *  event )

overrideprotectedvirtual

Resize event

Parameters

event

Resize event

setMaskMode()

void QwtWidgetOverlay::setMaskMode

(

MaskMode

mode

)

Specify how to find the mask for the overlay.

setRenderMode()

void QwtWidgetOverlay::setRenderMode

(

RenderMode

mode

)

Set the render mode.

updateOverlay

void QwtWidgetOverlay::updateOverlay ( )

slot

Recalculate the mask and repaint the overlay .

Recalculate the mask and repaint the overlay

.

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The documentation for this class was generated from the following files:

• /home/runner/work/QWT/QWT/src/plot/qwt_widget_overlay.h
• /home/runner/work/QWT/QWT/src/plot/qwt_widget_overlay.cpp