[89] | 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_PLOT_RASTERITEM_H
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| 11 | #define QWT_PLOT_RASTERITEM_H
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| 12 |
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| 13 | #include <qglobal.h>
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| 14 | #include <qstring.h>
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| 15 | #include <qimage.h>
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| 16 |
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| 17 | #include "qwt_plot_item.h"
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| 18 |
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| 19 | /*!
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| 20 | \brief A class, which displays raster data
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| 21 |
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| 22 | Raster data is a grid of pixel values, that can be represented
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| 23 | as a QImage. It is used for many types of information like
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| 24 | spectrograms, cartograms, geographical maps ...
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| 25 |
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| 26 | Often a plot has several types of raster data organized in layers.
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| 27 | ( f.e a geographical map, with weather statistics ).
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| 28 | Using setAlpha() raster items can be stacked easily.
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| 29 |
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| 30 | QwtPlotRasterItem is only implemented for images of the following formats:
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| 31 | QImage::Format_Indexed8, QImage::Format_ARGB32.
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| 32 |
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| 33 | \sa QwtPlotSpectrogram
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| 34 | */
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| 35 |
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| 36 | class QWT_EXPORT QwtPlotRasterItem: public QwtPlotItem
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| 37 | {
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| 38 | public:
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| 39 | /*!
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| 40 | - NoCache\n
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| 41 | renderImage() is called, whenever the item has to be repainted
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| 42 | - PaintCache\n
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| 43 | renderImage() is called, whenever the image cache is not valid,
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| 44 | or the scales, or the size of the canvas has changed. This type
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| 45 | of cache is only useful for improving the performance of hide/show
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| 46 | operations. All other situations are already handled by the
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| 47 | plot canvas cache.
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| 48 | - ScreenCache\n
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| 49 | The screen cache is an image in size of the screen. As long as
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| 50 | the scales don't change the target image is scaled from the cache.
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| 51 | This might improve the performance
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| 52 | when resizing the plot widget, but suffers from scaling effects.
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| 53 |
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| 54 | The default policy is NoCache
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| 55 | */
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| 56 | enum CachePolicy
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| 57 | {
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| 58 | NoCache,
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| 59 | PaintCache,
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| 60 | ScreenCache
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| 61 | };
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| 62 |
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| 63 | explicit QwtPlotRasterItem(const QString& title = QString::null);
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| 64 | explicit QwtPlotRasterItem(const QwtText& title);
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| 65 | virtual ~QwtPlotRasterItem();
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| 66 |
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| 67 | void setAlpha(int alpha);
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| 68 | int alpha() const;
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| 69 |
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| 70 | void setCachePolicy(CachePolicy);
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| 71 | CachePolicy cachePolicy() const;
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| 72 |
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| 73 | void invalidateCache();
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| 74 |
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| 75 | virtual void draw(QPainter *p,
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| 76 | const QwtScaleMap &xMap, const QwtScaleMap &yMap,
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| 77 | const QRect &rect) const;
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| 78 |
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| 79 | virtual QSize rasterHint(const QwtDoubleRect &) const;
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| 80 |
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| 81 | protected:
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| 82 |
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| 83 | /*!
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| 84 | Renders an image for an area
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| 85 |
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| 86 | The format of the image must be QImage::Format_Indexed8,
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| 87 | QImage::Format_RGB32 or QImage::Format_ARGB32
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| 88 |
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| 89 | \param xMap Maps x-values into pixel coordinates.
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| 90 | \param yMap Maps y-values into pixel coordinates.
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| 91 | \param area Requested area for the image in scale coordinates
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| 92 | */
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| 93 | virtual QImage renderImage(const QwtScaleMap &xMap,
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| 94 | const QwtScaleMap &yMap, const QwtDoubleRect &area
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| 95 | ) const = 0;
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| 96 |
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| 97 | private:
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| 98 | QwtPlotRasterItem( const QwtPlotRasterItem & );
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| 99 | QwtPlotRasterItem &operator=( const QwtPlotRasterItem & );
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| 100 |
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| 101 | void init();
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| 102 |
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| 103 | class PrivateData;
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| 104 | PrivateData *d_data;
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| 105 | };
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| 106 |
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| 107 | #endif
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