Re: transparent canvas working in gtkextra-2?

	Hi, Adrian:

	Thanks for responding so quickly, I truly do appreciate it.  Let me
describe more of what I'm trying to do.

	I have a situation where I want to display just a plot when the
application is in one operating mode, and optionally display a sheet
"under" the plot when the application is in a second operating mode.  In
the second mode, the user will enter data in the sheet, and I will
update the plot "over" the sheet as new data is entered.

	In the descriptions below, the phrase "sw/sheet" will mean  a GtkSheet
packed in to a ScrolledWindow container.

	I first tried to use the fact that GtkCanvas is a subclass of GtkFixed,
adding the plot as normal and adding the sw/sheet as a child of the
canvas with gtk_fixed_put().  However, this doesn't work, because there
is no way for the sw/sheet to be transparent (there are other side
effects as well, but the fact that the sw/sheet can not be transparent
causes this approach to not be workable for me).

	The next thing I tried, and one that I think would work well if the
canvas could be transparent, is the following (hopefully the ascii art
will come through):

GtkFixed
  |
  |--ScrolledWindow
  |    |
  |    |--GtkSheet
  |
  |--PlotCanvas
       |
       |--Plot

	
	In this solution, I would make the canvas/plot opaque when I did not
want the user to see the sw/sheet, and I would make the canvas/plot
transparent when I did want them to see the sw/sheet.  My tests so far
have indicated this would work well, if only the canvas would become
transparent when instructed to do so.  But, it does not.

	This is why I am wondering how to get a canvas to be transparent, and
if gtk_plot_canvas_set_transparent() works correctly in gtkextra-2?

	I am definitely open to suggestions for other approaches to get the
desired effect.

	Thanks again, Adrian -- and to anybody else with some ideas to try!

Regards,
Al



On Mon, 2004-02-09 at 11:02, Adrian E. Feiguin wrote:
> I still don't understand what you are trying to do, If you want to show 
> other widgets, use the gtkfixed capabilities as I do with the buttons in 
> testgtksheet. That's the only way to show other widgets inside a canvas. 
> If what you want is to do something called MDI of Window in Window, 
> that's not possible with gtk. You can use a notebook to diplay the plot 
> in one tab and the sheets in other tabs. You can show buttons or icons 
> in a canvas and get a sheet to appear on a different window when you 
> click. Those are some ideas. But again, I still don't get it. What are 
> you exactly trying to do?
> Saludos,
> <ADRIAN>
> 
> Al Hooton wrote:
> 
> >	Follow-up on this:
> >
> >	I have now spent pretty much the entire weekend going trying to get a
> >canvas to be transparent in gtkextra-2.  It does not matter if the
> >canvas has no plots, one plot, many plots -- the canvas will never go
> >transparent so I can see what is behind it.
> >
> >	I've stepped through gtkplotcanvas.c, and related code, trying to
> >figure out what is happening, but that has lead to a dead end.  It
> >appears to me the code should work, in that it is not attempting to draw
> >the main rectangle of the canvas when it is marked transparent. 
> >However, it is still being drawn.  If I comment out the calls to
> >gtk_plot_pc_draw_rectangle in gtk_plot_canvas_paint the rectangle is not
> >drawn, but the canvas still appears to have a pixbuf that covers
> >whatever is underneath.  I would have expected this pixbuf to be
> >unrealized if the canvas widget is transparent, but I'm probably missing
> >something in how this is supposed to work.
> >
> >	Has anybody successfully gotten a transparent canvas?  I'd really like
> >to use the gtkextra-2 package for what I'm doing, but if the canvas can
> >not be transparent I may have to abandon this for something else -- not
> >my preference, since I already have so much work done on top of
> >gtkextra-2.
> >
> >	Thanks!
> >
> >-- Al
> >
> >
> >On Sat, 2004-02-07 at 20:20, Al Hooton wrote:
> >  
> >
> >>	Version: gtkextra-2 from CVS as a couple of weeks ago.
> >>
> >>	I have successfully been using multiple plots on a canvas, with all the
> >>plots transparent.  Today for the first time, I tried making the canvas
> >>transparent also, so I could see through the plots and the canvas to
> >>what is below.  However, the canvas is not transparent when I set it
> >>with gtk_plot_canvas_set_transparent().
> >>
> >>	I have tried a small test program that just creates a canvas as a child
> >>of a parent window that has a blue background.  When I set the canvas to
> >>transparent, I still have the while background of the canvas, instead of
> >>seeing the blue background of the parent, so I know the canvas has not
> >>become transparent.
> >>
> >>	Is this a known problem?  Do we have a workaround?
> >>
> >>	Thanks!
> >>
> >>-Al
> >>
> >>    
> >>
> >
> >
> >
> >
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> >  
> >
> 
> 
> 
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