matplotlib-devel

[matplotlib-devel] more questions about the PS backend

[Jochen V. <vo...@se...>]

Hello,

the current way the PostScript backend works is as follows:

  1) FigureCanvasPS.print_figure() uses StringIO to make a string look like
     a file.

  2) The RendererPS class writes the PostScript file (except for the header=
s)
     into this string, using file operations.  This is done via call to
     Figure.draw()

  3) FigureCanvasPS.print_figure() writes the resulting string into the
     output file.

Is there a reason for storing the PostScript data in a string first?
Otherwise I could just pass the real file handle to RendererPS and it
would write all the stuff directly into the output file.

All the best,
Jochen
--=20
http://seehuhn.de/

Re: [matplotlib-devel] more questions about the PS backend

[John H. <jdh...@ac...>]

>>>>> "Jochen" == Jochen Voss <vo...@se...> writes:


    Jochen> Is there a reason for storing the PostScript data in a
    Jochen> string first?  Otherwise I could just pass the real file
    Jochen> handle to RendererPS and it would write all the stuff
    Jochen> directly into the output file.

The reason I did it (I think) was for efficiency, (wrongly) thinking
it would be faster to write to StringIO than to a file object.  Of
course, file objects buffer their output, so this is not a real
consideration.  I think its fine to make the change you suggested -
while you're in there, I suggest supporting writing to a file object
as well as a filename, as agg does now.  All backends should support
this.

JDH

Re: [matplotlib-devel] more questions about the PS backend

[Jochen V. <vo...@se...>]

Hello John,

On Tue, Nov 02, 2004 at 12:41:03PM -0600, John Hunter wrote:
> I think its fine to make the change you suggested -
> while you're in there, I suggest supporting writing to a file object
> as well as a filename, as agg does now.  All backends should support
> this.
Done!

All the best,
Jochen
--=20
http://seehuhn.de/

Re: [matplotlib-devel] more questions about the PS backend

[Jochen V. <vo...@se...>]

Hello,

On Tue, Nov 02, 2004 at 12:41:03PM -0600, John Hunter wrote:
> >>>>> "Jochen" =3D=3D Jochen Voss <vo...@se...> writes:
>     Jochen> Is there a reason for storing the PostScript data in a
>     Jochen> string first?  Otherwise I could just pass the real file
>     Jochen> handle to RendererPS and it would write all the stuff
>     Jochen> directly into the output file.
>=20
> The reason I did it (I think) was for efficiency, (wrongly) thinking
> it would be faster to write to StringIO than to a file object.  Of
> course, file objects buffer their output, so this is not a real
> consideration.  I think its fine to make the change you suggested -
I found a good reason for storing the PS in a string first:
we have to process all of the figure before we write the PostScript
prologue.  Otherwise there is no good way to know which fonts
to include in the PostScript file :-(
I reverted my change for now, we are back to storing the PostScript
data temporarily in a string.

All the best,
Jochen
--=20
http://seehuhn.de/