Re: Canvas basics

[John Coppens <john jcoppens com>]

Roger

This sounds very much like a problem I had a few days ago. I changed the
coordinate conversion routines from gnome_canvas_c2w to
gnome_canvas_window_to_world, this last function takes into account the
centering if zooming out.

John

On Thu, 23 Dec 2004 13:45:53 +0000
Roger Leigh <rleigh whinlatter ukfsn org> wrote:

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> Al Hooton <al hootons org> writes:
>
> > On Thu, 2004-12-23 at 00:17 +0000, Roger Leigh wrote:
> >
> > <snip lots of canvas stuff>
> >
> >     Roger, have you looked at the GtkSheet object in the GtkExtra
> >     project?
> >
> >     http://gtkextra.sourceforge.net/
> >
> >     I haven't used the sheet widget very much, but I'm using the
> >     canvas and
> > plot widgets extensively.  From what I've seen, I believe the sheet
> > widget, when placed on a canvas widget, may do everything you're
> > looking for.  It might at least be something to look at as a
> > possibility.
>
> Thanks for the suggestion.  It might work quite well, and I'll have a
> look into it.  However, one reason I want to use the canvas is to
> learn more about it.  I'm using this simple application as an
> experiment.
>
> I've updated the test program I wrote to illustrate what I'm trying to
> achieve.  It's here:
> http://www.whinlatter.ukfsn.org/gtk/cse-0.1.1.tar.gz
> I've also made a screenshot:
> http://www.whinlatter.ukfsn.org/gtk/cse-screenshot.png
>
> As you can see, the row and column headings are quite complex.  When the
> user scrolls the canvas, I'd the parts to the top and left of the red
> lines to stay stuck to the viewable edge of the canvas (but scroll in
> one direction in the same manner as Gnumeric).  Later on, I'd like to
> add column/row/region selection, cut and paste, drag and drop etc.
>
>
> One other problem I've run into is text scaling.  I can use
> gnome_canvas_set_pixels_per_unit to set the canvas scaling factor
> (cse-mainwindow.c, line 73).  If I change this, the text does not
> scale with the other canvas items.  How can I get this to work
> correctly?  At a scaling factor of 1.0, I get an unreadable mess.
>
>
> Regards,
> Roger
>
> - -- 
> Roger Leigh
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