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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