Re: Goocanvas in update from Gtk2 to Gtk3

[damonachaplin gmail com]

On Mon, 2021-02-15 at 11:53 +0000, Paul Emsley via goocanvas-list
wrote:
> On 19/01/2021 12:57, damonachaplin gmail com wrote:
> > On Tue, 2021-01-19 at 10:38 +0000, Paul Emsley via goocanvas-list
> > wrote:
> > > Ah, OK. that's interesting. I linked against system goocanvas-2.0 
> > > and
> > > it
> > > just works!
> > >
> > > Hmm... so you are right.
> > >
> > > But... where do we go from here?
> > How did you install your local version of goocanvas-2.0? Did you do
> > a
> > 'make install'?
> >
> > If you just copied the built files that may be the problem.
>
> Hi Damon,
>
> So, for the moment, I am going with the system installation - I can 
> worry about my build another time.
>
> This is a "have you seen this pathology before?" question
>
> I have now removed all GtkCanvas usage and replaced it with GooCanvas
> as 
> I transition to Gtk3. Good. It looks pretty. And dark mode.
>
> So, I have turned my attention to graphs rather than the previous
> plot 
> (the box with the blue spots). And it seems that the canvas behaves
> in a 
> similar way to the way it behaved for me in the plot. I should note
> that 
> I created the dialog using glade-2 and that contained a
> scrolled_window 
> with a viewport. The scrolled window is below a simple GtkLabel. I
> added 
> the goocanvas to the viewport. I also make size requests:
>
>     gtk_widget_set_size_request(GTK_WIDGET(canvas), canvas_usize_x, 
> canvas_usize_y);
>     gtk_widget_set_size_request(dialog, 600, 400);
>
> And that results in the <attached> behaviour. The canvas behaves OK 
> until the dialog is expanded, then it "jumps" to the top left of the 
> dialog (obscuring the GtkLabel (if I hadn't made it semi-opaque)).
> There 
> is no terminal output when this happens. The blocks appear to
> whatever 
> is handling the button_press_event to be below where they are drawn 
> after jumping has occurred (i.e. where they used to be).
>
> If you know how I can fix this, that would be great.
>
> I might be able to fix this by creating the dialog by hand or by
> using a 
> more recent version of glade and builder. But I'd like to try to
> avoid 
> that. It might be a one-line fix.

I think the viewport may be the problem. GooCanvas handles scrolling
itself so doesn't need a viewport - you need to add it directly to a
scrolledwindow.

Damon