Changeset 9383 in ntrip for trunk/BNC/qwt/qwt_plot_rasteritem.h
- Timestamp:
- Mar 19, 2021, 9:15:03 AM (3 years ago)
- File:
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- 1 edited
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trunk/BNC/qwt/qwt_plot_rasteritem.h
r8127 r9383 51 51 /*! 52 52 renderImage() is called, whenever the image cache is not valid, 53 or the scales, or the size of the canvas has changed. 53 or the scales, or the size of the canvas has changed. 54 54 55 This type of cache is useful for improving the performance 56 of hide/show operations or manipulations of the alpha value. 55 This type of cache is useful for improving the performance 56 of hide/show operations or manipulations of the alpha value. 57 57 All other situations are handled by the canvas backing store. 58 58 */ … … 69 69 When the image is rendered according to the data pixels 70 70 ( QwtRasterData::pixelHint() ) it can be expanded to paint 71 device resolution before it is passed to QPainter. 72 The expansion algorithm rounds the pixel borders in the same 71 device resolution before it is passed to QPainter. 72 The expansion algorithm rounds the pixel borders in the same 73 73 way as the axis ticks, what is usually better than the 74 74 scaling algorithm implemented in Qt. 75 Disabling this flag might make sense, to reduce the size of a 75 Disabling this flag might make sense, to reduce the size of a 76 76 document/file. If this is possible for a document format 77 77 depends on the implementation of the specific QPaintEngine. … … 84 84 typedef QFlags<PaintAttribute> PaintAttributes; 85 85 86 explicit QwtPlotRasterItem( const QString& title = QString ::null);86 explicit QwtPlotRasterItem( const QString& title = QString() ); 87 87 explicit QwtPlotRasterItem( const QwtText& title ); 88 88 virtual ~QwtPlotRasterItem(); … … 99 99 void invalidateCache(); 100 100 101 virtual void draw( QPainter * p,101 virtual void draw( QPainter *, 102 102 const QwtScaleMap &xMap, const QwtScaleMap &yMap, 103 const QRectF & rect ) const;103 const QRectF &canvasRect ) const; 104 104 105 105 virtual QRectF pixelHint( const QRectF & ) const; … … 110 110 protected: 111 111 /*! 112 \brief Render an image 112 \brief Render an image 113 113 114 114 An implementation of render() might iterate over all 115 pixels of imageRect. Each pixel has to be translated into 115 pixels of imageRect. Each pixel has to be translated into 116 116 the corresponding position in scale coordinates using the maps. 117 117 This position can be used to look up a value in a implementation … … 122 122 \param area Requested area for the image in scale coordinates 123 123 \param imageSize Requested size of the image 124 124 125 125 \return Rendered image 126 126 */
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