Re: pngcairo: suggestion for additional option

[Allin C. <cot...@wf...>]

On Wed, 21 Nov 2007, Hans-Bernhard Bröker wrote:

> Allin Cottrell wrote:
> > I'll float this by the list first and submit a tracker item if there's any
> > support.
> 
> No need to.  There's been an item open for ages about this...

OK, but then nothing has happened about this.  I'm now proposing 
what seems to me a minimalistic solution that shouldn't disturb 
the existing codebase.

> More abstractly speaking, what these requests are about is a 
> very rough approximation of on aspect of mouse interaction: 
> coordinate mapping back to data values for static bitmap 
> terminal drivers.

Why would it be a "very rough approximation", if you know the 
pixel bounds of the actual plot area in the bitmap graphic, and 
the data bounds of the plot?  Pixels are discrete, of course, but 
the approximation should be pretty good if we have hundreds of 
pixels in both dimensions.

> Version 4.2.2 has quite a lot of this already your finger tips, 
> by way of gnuplot-defined variables GPVAL_X_MIN etc.  Adding 
> GRAPH_XLEFT etc. shouldn't pose a major problem.

Sorry, I don't really understand.  There's no difficulty at all 
calculating/retrieving this information inside gnuplot.  The issue 
is how to make it available to the outside world -- that is, to 
another program that has called gnuplot to make a plot file, and 
wants to know some internal properties of the file.

Allin Cottrell