kopia lustrzana https://github.com/xdsopl/qsstv
149 wiersze
4.0 KiB
C++
149 wiersze
4.0 KiB
C++
/* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
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* Qwt Widget Library
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* Copyright (C) 1997 Josef Wilgen
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* Copyright (C) 2002 Uwe Rathmann
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the Qwt License, Version 1.0
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*****************************************************************************/
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#ifndef QWT_WIDGET_OVERLAY_H
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#define QWT_WIDGET_OVERLAY_H
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#include "qwt_global.h"
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#include <qwidget.h>
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#include <qregion.h>
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class QPainter;
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/*!
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\brief An overlay for a widget
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The main use case of an widget overlay is to avoid
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heavy repaint operation of the widget below.
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F.e. in combination with the plot canvas an overlay
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avoid replots as the content of the canvas can be restored from
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its backing store.
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QwtWidgetOverlay is an abstract base class. Deriving classes are
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supposed to reimplement the following methods:
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- drawOverlay()
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- maskHint()
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Internally QwtPlotPicker uses overlays for displaying
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the rubber band and the tracker text.
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\sa QwtPlotCanvas::BackingStore
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*/
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class QWT_EXPORT QwtWidgetOverlay: public QWidget
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{
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public:
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/*!
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\brief Mask mode
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When using masks the widget below gets paint events for
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the masked regions of the overlay only. Otherwise
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Qt triggers full repaints. On less powerful hardware
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( f.e embedded systems ) - or when using the raster paint
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engine on a remote desktop - bit blitting is a noticeable
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operation, that needs to be avoided.
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If and how to mask depends on how expensive the calculation
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of the mask is and how many pixels can be excluded by the mask.
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The default setting is MaskHint.
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\sa setMaskMode(), maskMode()
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*/
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enum MaskMode
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{
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//! Don't use a mask.
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NoMask,
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/*!
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\brief Use maskHint() as mask
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For many situations a fast approximation is good enough
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and it is not necessary to build a more detailed mask
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( f.e the bounding rectangle of a text ).
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*/
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MaskHint,
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/*!
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\brief Calculate a mask by checking the alpha values
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Sometimes it is not possible to give a fast approximation
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and the mask needs to be calculated by drawing the overlay
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and testing the result.
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When a valid maskHint() is available
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only pixels inside this approximation are checked.
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*/
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AlphaMask
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};
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/*!
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\brief Render mode
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For calculating the alpha mask the overlay has already
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been painted to a temporary QImage. Instead of rendering
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the overlay twice this buffer can be copied for drawing
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the overlay.
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On graphic systems using the raster paint engine ( QWS, Windows )
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it means usually copying some memory only. On X11 it results in an
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expensive operation building a pixmap and for simple overlays
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it might not be recommended.
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\note The render mode has no effect, when maskMode() != AlphaMask.
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*/
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enum RenderMode
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{
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//! Copy the buffer, when using the raster paint engine.
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AutoRenderMode,
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//! Always copy the buffer
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CopyAlphaMask,
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//! Never copy the buffer
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DrawOverlay
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};
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QwtWidgetOverlay( QWidget* );
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virtual ~QwtWidgetOverlay();
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void setMaskMode( MaskMode );
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MaskMode maskMode() const;
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void setRenderMode( RenderMode );
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RenderMode renderMode() const;
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void updateOverlay();
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virtual bool eventFilter( QObject *, QEvent *);
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protected:
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virtual void paintEvent( QPaintEvent* event );
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virtual void resizeEvent( QResizeEvent* event );
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virtual QRegion maskHint() const;
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/*!
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Draw the widget overlay
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\param painter Painter
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*/
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virtual void drawOverlay( QPainter *painter ) const = 0;
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private:
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void updateMask();
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void draw( QPainter * ) const;
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private:
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class PrivateData;
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PrivateData *d_data;
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};
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#endif
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