this component is very useful for my circle of tasks
but I need to change something and don't know how to do that exactly.

1. we have z-(color)-scale with gradient
z-color-scale.jpg
I have 4 colors.
in my case it's very necessary to have only clear colors without smooth gradient between each color.
can I achieve it with this component? and how... may be try another alternative?


2. Also got it from example - possibility of hint
coordinates.jpg

code:
Qt Code: 
  1. class MyZoomer: public QwtPlotZoomer {
  2.  
  3. public:
  4.     MyZoomer( QwtPlotCanvas *canvas ):
  5.         QwtPlotZoomer(canvas) {
  6.         setTrackerMode(AlwaysOn);
  7.     }
  8.  
  9.     virtual QwtText trackerTextF(const QPointF &pos) const {
  10.         QColor bg(Qt::white);
  11.         bg.setAlpha(200);
  12.  
  13.         QwtText text = QwtPlotZoomer::trackerTextF(pos);
  14.         text.setBackgroundBrush(QBrush(bg));
  15.         return text;
  16.     }
  17. };
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hereby we have coordinates in the hint near cursor (x, y)
how to add here the third value of z axis?


3. How to disable zooming out below a certain value (for example when the pic fit to width)?
example:
here in the picture good variant
zoom_out_ok.jpg

and here - not appropriate
zoom_out_not_ok.jpg


thanks a lot!