/usr/include/qwt/qwt_widget_overlay.h is in libqwt-headers 6.1.3-1.
This file is owned by root:root, with mode 0o644.
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* Qwt Widget Library
* Copyright (C) 1997 Josef Wilgen
* Copyright (C) 2002 Uwe Rathmann
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the Qwt License, Version 1.0
*****************************************************************************/
#ifndef QWT_WIDGET_OVERLAY_H
#define QWT_WIDGET_OVERLAY_H
#include "qwt_global.h"
#include <qwidget.h>
#include <qregion.h>
class QPainter;
/*!
\brief An overlay for a widget
The main use case of an widget overlay is to avoid
heavy repaint operation of the widget below.
F.e. in combination with the plot canvas an overlay
avoid replots as the content of the canvas can be restored from
its backing store.
QwtWidgetOverlay is an abstract base class. Deriving classes are
supposed to reimplement the following methods:
- drawOverlay()
- maskHint()
Internally QwtPlotPicker uses overlays for displaying
the rubber band and the tracker text.
\sa QwtPlotCanvas::BackingStore
*/
class QWT_EXPORT QwtWidgetOverlay: public QWidget
{
public:
/*!
\brief Mask mode
When using masks the widget below gets paint events for
the masked regions of the overlay only. Otherwise
Qt triggers full repaints. On less powerful hardware
( f.e embedded systems ) - or when using the raster paint
engine on a remote desktop - bit blitting is a noticeable
operation, that needs to be avoided.
If and how to mask depends on how expensive the calculation
of the mask is and how many pixels can be excluded by the mask.
The default setting is MaskHint.
\sa setMaskMode(), maskMode()
*/
enum MaskMode
{
//! Don't use a mask.
NoMask,
/*!
\brief 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 ).
*/
MaskHint,
/*!
\brief 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.
*/
AlphaMask
};
/*!
\brief 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.
*/
enum RenderMode
{
//! Copy the buffer, when using the raster paint engine.
AutoRenderMode,
//! Always copy the buffer
CopyAlphaMask,
//! Never copy the buffer
DrawOverlay
};
QwtWidgetOverlay( QWidget* );
virtual ~QwtWidgetOverlay();
void setMaskMode( MaskMode );
MaskMode maskMode() const;
void setRenderMode( RenderMode );
RenderMode renderMode() const;
void updateOverlay();
virtual bool eventFilter( QObject *, QEvent *);
protected:
virtual void paintEvent( QPaintEvent* event );
virtual void resizeEvent( QResizeEvent* event );
virtual QRegion maskHint() const;
/*!
Draw the widget overlay
\param painter Painter
*/
virtual void drawOverlay( QPainter *painter ) const = 0;
private:
void updateMask();
void draw( QPainter * ) const;
private:
class PrivateData;
PrivateData *d_data;
};
#endif
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