

Raster data is a grid of pixel values, that can be represented as a QImage. It is used for many types of information like spectrograms, cartograms, geographical maps ...
Often a plot has several types of raster data organized in layers. ( f.e a geographical map, with weather statistics ). Using setAlpha() raster items can be stacked easily.
QwtPlotRasterItem is only implemented for images of the following formats: QImage::Format_Indexed8, QImage::Format_ARGB32.
Definition at line 36 of file qwt_plot_rasteritem.h.
| Public Types | |
| enum | CachePolicy { NoCache, PaintCache, ScreenCache } | 
| Public Member Functions | |
| QwtPlotRasterItem (const QString &title=QString::null) | |
| QwtPlotRasterItem (const QwtText &title) | |
| virtual | ~QwtPlotRasterItem () | 
| void | setAlpha (int alpha) | 
| int | alpha () const | 
| void | setCachePolicy (CachePolicy) | 
| CachePolicy | cachePolicy () const | 
| void | invalidateCache () | 
| virtual void | draw (QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRect &rect) const | 
| virtual QSize | rasterHint (const QwtDoubleRect &) const | 
| Protected Member Functions | |
| virtual QImage | renderImage (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QwtDoubleRect &area) const =0 | 
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 The default policy is NoCache Definition at line 56 of file qwt_plot_rasteritem.h. | 
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| Constructor. 
 Definition at line 91 of file qwt_plot_rasteritem.cpp. | 
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| Constructor. 
 Definition at line 98 of file qwt_plot_rasteritem.cpp. | 
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| Destructor. 
 Definition at line 105 of file qwt_plot_rasteritem.cpp. | 
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 Definition at line 163 of file qwt_plot_rasteritem.cpp. | 
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 Definition at line 192 of file qwt_plot_rasteritem.cpp. | 
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| Draw the raster data. 
 
 Implements QwtPlotItem. Reimplemented in QwtPlotSpectrogram. Definition at line 229 of file qwt_plot_rasteritem.cpp. References QwtPlotItem::boundingRect(), QwtPlotItem::invTransform(), QwtPlotItem::paintRect(), and QwtPlotItem::transform(). Referenced by QwtPlotSpectrogram::draw(). | 
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| Invalidate the paint cache 
 Definition at line 201 of file qwt_plot_rasteritem.cpp. Referenced by setCachePolicy(), QwtPlotSpectrogram::setColorMap(), and QwtPlotSpectrogram::setData(). | 
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| Returns the recommended raster for a given rect. F.e the raster hint can be used to limit the resolution of the image that is rendered. The default implementation returns an invalid size (QSize()), what means: no hint. Reimplemented in QwtPlotSpectrogram. Definition at line 217 of file qwt_plot_rasteritem.cpp. | 
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| Renders an image for an area The format of the image must be QImage::Format_Indexed8, QImage::Format_RGB32 or QImage::Format_ARGB32 
 
 Implemented in QwtPlotSpectrogram. | 
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| Set an alpha value for the raster data. Often a plot has several types of raster data organized in layers. ( f.e a geographical map, with weather statistics ). Using setAlpha() raster items can be stacked easily. The alpha value is a value [0, 255] to control the transparency of the image. 0 represents a fully transparent color, while 255 represents a fully opaque color. 
 
 
 The default alpha value is -1. 
 
 Definition at line 143 of file qwt_plot_rasteritem.cpp. References QwtPlotItem::itemChanged(). | 
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| Change the cache policy The default policy is NoCache 
 
 
 Definition at line 176 of file qwt_plot_rasteritem.cpp. References invalidateCache(), and QwtPlotItem::itemChanged(). | 
 1.4.6
 1.4.6