Re: Print preview widget

[Behdad Esfahbod <behdad behdad org>]

On Thu, 2008-04-17 at 18:07 +0100, Gustavo J. A. M. Carneiro wrote:
> > 
> > +1 too.  Though opening the actual generated PDF in evince is always
> > going to be a more reliable preview than rendering to a widget.  There
> > always will be bugs here and there, you know...
> 
> _If_ gtk+ printing has to go through a cairo layer, I don't see why this
> would be so.  Cairo should render the same content to screen as it does
> to a PS/PDF file.  By explicit goal of the Cairo project, this _must
> work_.

Because as I said, "There always will be bugs here and there".  For
example, pango keeps glyph extents in a 22.10 fixed format.  Cairo keeps
as double in device space.  There will be rounding bugs here and there.
They may add up and change your text layout.  I do have plans to fix
this properly.  That has just not happened yet.

> You could claim quite the reverse.  If print preview does not go through
> App->Cairo->PDF->Cairo->Screen layers (would be only
> App->Cairo->Screen), then users will not catch PDF/PS generation bugs so
> soon, they only see the bugs appear on paper, and then it will be
> convoluted by printer driver bugs, etc.

That's what I meant.  One way around it would be to "print" to a cairo
PDF surface, then paint that surface to the actual widget surface.  This
would avoid the issues I mentioned above, at the cost of being heavier
on memory and processor.

> Anyway, +1 from me too.
> 
-- 
behdad
http://behdad.org/

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