Changeset 9383 in ntrip for trunk/BNC/qwt/qwt_widget_overlay.h
- Timestamp:
- Mar 19, 2021, 9:15:03 AM (3 years ago)
- File:
-
- 1 edited
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trunk/BNC/qwt/qwt_widget_overlay.h
r8127 r9383 23 23 heavy repaint operation of the widget below. 24 24 25 F.e. in combination with the plot canvas an overlay 26 avoid replots as the content of the canvas can be restored from 25 F.e. in combination with the plot canvas an overlay 26 avoid replots as the content of the canvas can be restored from 27 27 its backing store. 28 28 … … 33 33 - maskHint() 34 34 35 Internally QwtPlotPicker uses overlays for displaying 35 Internally QwtPlotPicker uses overlays for displaying 36 36 the rubber band and the tracker text. 37 37 … … 47 47 the masked regions of the overlay only. Otherwise 48 48 Qt triggers full repaints. On less powerful hardware 49 ( f.e embedded systems ) - or when using the raster paint 49 ( f.e embedded systems ) - or when using the raster paint 50 50 engine on a remote desktop - bit blitting is a noticeable 51 51 operation, that needs to be avoided. 52 53 If and how to mask depends on how expensive the calculation 52 53 If and how to mask depends on how expensive the calculation 54 54 of the mask is and how many pixels can be excluded by the mask. 55 55 … … 66 66 \brief Use maskHint() as mask 67 67 68 For many situations a fast approximation is good enough 68 For many situations a fast approximation is good enough 69 69 and it is not necessary to build a more detailed mask 70 70 ( f.e the bounding rectangle of a text ). … … 78 78 and the mask needs to be calculated by drawing the overlay 79 79 and testing the result. 80 80 81 81 When a valid maskHint() is available 82 82 only pixels inside this approximation are checked.
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