Re: Overall approach for coordinate systems and clipping

[<wie...@we...>]

On Sunday 13 November 2005 00:32 Harald Harders wrote:
> Let me conclude what I think now:
>
> 1.) The screen coordinate system should not be changed anymore (with the
>     exception that the clipping has to be fixed to the current 'set size'
>     to canvas size relationship in all terminals.
>
> 2.) Some new coordinate systems should be introduced:
>   - A canvas coordinate system that always runs from 0 to 1 on the canvas
>   - A subcanvas coordinate system that always runs from 0 to 1 on the
>     "single-multiplot-plot canvas"
>   - One or more coordinate systems with absolute sizes, e.g., mm,
>     inch=25.4mm, pt=1/72inch, pixel=(res in dpi)*inch.
>
> 3.) A resolution should be introduced which can be forwarded to the pixel
>     terminals for the output files and be used by the other terminals to
>     be able to calculate between pixel and the other absolute measures.
>
> 4.) The screen coordinate should be marked as 'deprecated'.
>
> 5.) 'set size' and 'set origin' before 'set terminal' should print a
>     warning because they have strange behaviour.
>
> 6.) 'set size' and 'set origin' after 'set terminal' should only affect
>     the plot, not the canvas. Sizes above 1 should be still allowed in
>     case somebody likes to have a half plot on the screen.
>
> 7.) 'set size', 'set origin' and the size measures for the terminals
>     should understand 'screen' coordinates (which size and origin do
>     exclusively, now) and all absolute coordinate systems (mm, inch, pt,
>     pixel, character). Not that character is the only absolute coordinate
>     system we have at the moment. Its measure only depends on the chosen
>     fontsize.
>
> This approach has a couple of advantages:
> - Compatibility to old scripts is maintained
> - In future, we have a much clearer interface and it is possible to say "I
>   want a plot of 5 x 3 inches" (and this for all terminals). What to do
>   with the screen terminals is somehow unclear. But using the X server
>   solution (which should be accessable), even mm, inch, pt should be
>   possible.
>
>
> What do you all think about this approach?

Sounds *very* reasonable.  But I fear I won't be able to help with the
implemtation.  But don't let this suggestion get buried within the
depths of this thread (or its mother thread, depending on the mail
reader)!

But what does "before 'set terminal'" mean (item 5)?  The first
time, the terminal is changed from the default one?  You know: "Nach
dem 'set terminal' ist vor dem 'set terminal'." ;-))

Juergen