Re: Printing a Gnome canvas (2nd episode)

[Chema Celorio <chema ximian com>]

On Sat, 2002-12-14 at 07:29, Jean Bréfort wrote:
> Hi,
> 
> I have not written much code yet, being very busy thehe times, but I 
> have perhaps found a solution to avoid making libgnomecanvas dependent 
> to libgnomeprint. The drwoback is that it will add a new dependency to 
> libgnomeprint. Here is my idea:
> 
> The only thing I need to print the canvas is a GnomePrintContext. If we 
> have a parent type for GnomePrintContext, say GPrintContext, we just 
> have to make GnomePrintContext a descendant of GPrintContext and put 
> into GPrintContextClass pointers to almost every 
> gnome_print_context_xxx(...). The default corresponding 
> g_print_context_xxx just emit a warning.

I don't understand why having a parent object to GnomePrintContext would
help you print a canvas. The printing-canvas-code should be using
libgnomeprint, not the other way around. I would start of by adding a
print method to the base CanvasItem which given a GnomePrintContext
draws itself into.

Also, libgnomeprint does not depend on the canvas (libgnomeprintui does)
it is a non-gui library. It depends on: libart_lgpl, glib & pango only.

> Where to put this new type? There are et leat three possibilities: a 
> separate library (just for that, it will be very thin), libgnomecanvas 
> or glib. I don't think that the second option is the good one because 
> other types could use the GPrintContext mechanism (may be PangoLayout 
> (would be great in my opinion)). I don't know if the GLib option is 
> acceptable (does GLib have something o do with printing?) so the 
> separate library might be the best solution unless someone has a better 
> idea.

The best place to develop this code is outside of any of the current
libraries, libgnomecanvasprint or something, I don't see a reason to
have it be part of a library while it is being developed, but if it has
to, then it has to be developed on a branch. The code should be somewhat
working before we can consider integrating it as part of any of the
libraries. Long term I think the canvas should depend on libgnomeprint
if printing is a functionality that the canvas maintainers want it to be
part of.

Writing the code is going to clear up a lot of the issues that we have
right now and raise some new interesting ones that we need to solve.

regards,
Chema

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