Re: [Plplot-general] [Plplot] keeping item sizes during zooming

[<mj...@ga...>]

Lehmann, Eckhard {TR-I~Penzberg} writes:
 > Hi,
 > 
 > I am using the plplotter Tcl/Tk extension on windows. In the application
 > I write, the user should be able to zoom an xy plot of data. This works
 > so far, but I need to label some points in the plot. So I do that with
 > plptex..., maybe adjust the character size via plschr before. I cannot
 > preserve the aspect ratio during the zoom operation.
 > The problem is now, that whenever the user zooms some part of the plot,
 > the labels get zoomed as well - and look abolutely warped. This comes to
 > a stage where they are totally useless.
 > 
 > Is there a way to keep particular items - such as text labels - at
 > original size or resize them different from the rest of the plot? If not
 > - is it a big change to get this working? (When it isn't, I could do it
 > maybe...).

While I haven't used "the plplotter Tcl/Tk extension on windows", I have
plenty of experience with Tcl/TK & zooming under *ix.  So my suggestions
would be, in order of ease:

 - preserve aspect ratio when zooming.  It may take some getting used to, but
for me it's the only way to go now.

 - take control of the zooming process.  There are now hooks in the CVS HEAD
version of plwidget.tcl for the user to set a zoom handler.  Of course this
means you'll be responsible for replotting the data yourself, but the cool
thing is that you can then drop all sorts of stuff "on top" of the zoomed
data, like scales, labels, etc.  Also gets around precision problems that
appear when zooming to fine scales, due to the 16-bit driver data
representation.

-- 
Maurice LeBrun    mj...@ga...