Re: Scale color using Qwt::

[Gerard V. <gve...@gr...>]

On Sat, 13 Mar 2004 15:17:50 -0800 (PST)
qw...@ds... wrote:

> The program I am working on needs to be able to draw
> a QwtPlot subclass widget onto a QPixmap to be able
> to double-buffer and draw things onto the graph.  I have
> about 252 of these plots to draw and use.
> 
> I determined that the following code placed in this plotter
> class would print onto a QPainter:
> 
>    print (painter, plotRect);
> 
> (I did read in the mailing list of the Qpixmap::grabWidget()
> way of doing this, but it turned out to be really slow.)
> 
> The problem I faced with this approach (print method)
> is that the background I chose is black and the routine
> printScales() that print() calls also paints the scales
> in black by default with this code (qwt_plot_print.cpp):
> 
> #if 1
>     painter->setPen(Qt::black); // acisColor ????
> #endif
> 
> That_s from 4.2rc1.  So I checked the CVS and the only
> change was in the comment.
> 
> It would be nice if we had control over the color that the
> scales are printed somehow.  I imagine this would not
> be terribly difficult to implement as part of
> the QwtScale class, using a call similar to setTitleColor(),
> maybe setScaleColor() or setPen() -- this, in my mind,
> includes the tick marks, and major tick labels).
> 
> What do you think?
>
This problem has been recently reported and is supposed to be
fixed in CVS.  Printing of the widget background color can
be enabled by passing a suitable QwtPrintFilter.  I quote
from a list of changes sent to me by Uwe:

- QwtPlotPrintFilter::PrintWidgetBackground introduced,
  QwtPlotPrintFilter::PrintBackground renamed to
  QwtPlotPrintFilter::PrintCanvasBackground

If you set the print filter options so that widget background
printing is enabled, it should work (it is implemented but I did
not test it).

A workaround for people who do not want to use CVS is to
fill the pixmap with for instance a white color before
passing it to a print() function.  

Gerard