[8127] | 1 | /* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
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| 2 | * Qwt Widget Library
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| 3 | * Copyright (C) 1997 Josef Wilgen
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| 4 | * Copyright (C) 2002 Uwe Rathmann
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| 5 | *
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| 6 | * This library is free software; you can redistribute it and/or
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| 7 | * modify it under the terms of the Qwt License, Version 1.0
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| 8 | *****************************************************************************/
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| 9 |
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| 10 | #ifndef QWT_WIDGET_OVERLAY_H
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| 11 | #define QWT_WIDGET_OVERLAY_H
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| 12 |
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| 13 | #include "qwt_global.h"
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| 14 | #include <qwidget.h>
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| 15 | #include <qregion.h>
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| 16 |
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| 17 | class QPainter;
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| 18 |
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| 19 | /*!
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| 20 | \brief An overlay for a widget
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| 21 |
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| 22 | The main use case of an widget overlay is to avoid
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| 23 | heavy repaint operation of the widget below.
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| 24 |
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| 25 | F.e. in combination with the plot canvas an overlay
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| 26 | avoid replots as the content of the canvas can be restored from
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| 27 | its backing store.
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| 28 |
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| 29 | QwtWidgetOverlay is an abstract base class. Deriving classes are
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| 30 | supposed to reimplement the following methods:
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| 31 |
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| 32 | - drawOverlay()
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| 33 | - maskHint()
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| 34 |
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| 35 | Internally QwtPlotPicker uses overlays for displaying
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| 36 | the rubber band and the tracker text.
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| 37 |
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| 38 | \sa QwtPlotCanvas::BackingStore
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| 39 | */
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| 40 | class QWT_EXPORT QwtWidgetOverlay: public QWidget
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| 41 | {
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| 42 | public:
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| 43 | /*!
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| 44 | \brief Mask mode
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| 45 |
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| 46 | When using masks the widget below gets paint events for
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| 47 | the masked regions of the overlay only. Otherwise
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| 48 | Qt triggers full repaints. On less powerful hardware
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| 49 | ( f.e embedded systems ) - or when using the raster paint
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| 50 | engine on a remote desktop - bit blitting is a noticeable
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| 51 | operation, that needs to be avoided.
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| 52 |
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| 53 | If and how to mask depends on how expensive the calculation
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| 54 | of the mask is and how many pixels can be excluded by the mask.
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| 55 |
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| 56 | The default setting is MaskHint.
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| 57 |
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| 58 | \sa setMaskMode(), maskMode()
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| 59 | */
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| 60 | enum MaskMode
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| 61 | {
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| 62 | //! Don't use a mask.
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| 63 | NoMask,
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| 64 |
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| 65 | /*!
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| 66 | \brief Use maskHint() as mask
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| 67 |
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| 68 | For many situations a fast approximation is good enough
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| 69 | and it is not necessary to build a more detailed mask
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| 70 | ( f.e the bounding rectangle of a text ).
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| 71 | */
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| 72 | MaskHint,
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| 73 |
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| 74 | /*!
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| 75 | \brief Calculate a mask by checking the alpha values
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| 76 |
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| 77 | Sometimes it is not possible to give a fast approximation
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| 78 | and the mask needs to be calculated by drawing the overlay
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| 79 | and testing the result.
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| 80 |
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| 81 | When a valid maskHint() is available
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| 82 | only pixels inside this approximation are checked.
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| 83 | */
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| 84 | AlphaMask
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| 85 | };
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| 86 |
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| 87 | /*!
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| 88 | \brief Render mode
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| 89 |
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| 90 | For calculating the alpha mask the overlay has already
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| 91 | been painted to a temporary QImage. Instead of rendering
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| 92 | the overlay twice this buffer can be copied for drawing
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| 93 | the overlay.
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| 94 |
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| 95 | On graphic systems using the raster paint engine ( QWS, Windows )
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| 96 | it means usually copying some memory only. On X11 it results in an
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| 97 | expensive operation building a pixmap and for simple overlays
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| 98 | it might not be recommended.
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| 99 |
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| 100 | \note The render mode has no effect, when maskMode() != AlphaMask.
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| 101 | */
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| 102 | enum RenderMode
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| 103 | {
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| 104 | //! Copy the buffer, when using the raster paint engine.
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| 105 | AutoRenderMode,
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| 106 |
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| 107 | //! Always copy the buffer
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| 108 | CopyAlphaMask,
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| 109 |
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| 110 | //! Never copy the buffer
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| 111 | DrawOverlay
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| 112 | };
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| 113 |
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| 114 | QwtWidgetOverlay( QWidget* );
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| 115 | virtual ~QwtWidgetOverlay();
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| 116 |
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| 117 | void setMaskMode( MaskMode );
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| 118 | MaskMode maskMode() const;
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| 119 |
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| 120 | void setRenderMode( RenderMode );
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| 121 | RenderMode renderMode() const;
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| 122 |
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| 123 | void updateOverlay();
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| 124 |
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| 125 | virtual bool eventFilter( QObject *, QEvent *);
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| 126 |
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| 127 | protected:
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| 128 | virtual void paintEvent( QPaintEvent* event );
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| 129 | virtual void resizeEvent( QResizeEvent* event );
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| 130 |
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| 131 | virtual QRegion maskHint() const;
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| 132 |
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| 133 | /*!
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| 134 | Draw the widget overlay
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| 135 | \param painter Painter
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| 136 | */
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| 137 | virtual void drawOverlay( QPainter *painter ) const = 0;
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| 138 |
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| 139 | private:
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| 140 | void updateMask();
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| 141 | void draw( QPainter * ) const;
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| 142 |
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| 143 | private:
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| 144 | class PrivateData;
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| 145 | PrivateData *d_data;
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| 146 | };
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| 147 |
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| 148 | #endif
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