[maemo-developers] How to get a transparent GtkWindow (fremantle)

[From: Luca Donaggio]

Thanks Kimmo, somehow I haven't seen it in the manual page!
But... I found it's not necessary: the thing which was preventing the
transparency effect to work as expected was this instruction:

gdk_window_reparent(myapp->imgparamwin->window,gtk_widget_get_window(GTK_WIDGET
(myapp->mainwin)),offset,offset);

Without it I can get the transparent background just as Conny suggested, BUT
... without it the HildonAppMenu stops working: it shows up and immediately
disappear!

Luca Donaggio

2009/10/30 Kimmo Hämäläinen <kimmo.hamalainen at nokia.com>

> On Fri, 2009-10-30 at 14:36 +0100, ext Luca Donaggio wrote:
> > Thanks Conny and Kimmo,
> >
> > here are my progresses:
> >
> > I'm able to draw to the GtkWindow using Cairo only if I do it in a
> > callback attached to the expose event of the window itself, but I'm
> > still getting no transparency!
> > I'm sure this is the problem with the window manager that Kimmo
> > pointed out, but I don't know how to set the override-redirect flag
> > apart from passing the correct value inside a GdkWindowAttr struct
> > when manually creating a GdkWindow with gdk_window_new(), but I'm not
> > doing this manually, so I'm lost here!
>
> gdk_window_set_override_redirect () sets it. You need to set it after
> realizing (gtk_widget_realize ()) your window but before showing it.
> gtk_widget_get_window () returns GdkWindow of your widget.
>
> -Kimmo
>
> >
> > Luca Donaggio
> >
> > 2009/10/30 Kimmo Hämäläinen <kimmo.hamalainen at nokia.com>
> >         On Thu, 2009-10-29 at 17:29 +0100, ext Luca Donaggio wrote:
> >         > I'm trying to create a transparent, non-decorated popup
> >         GtkWindow on
> >         > top af my app HildonWindow and draw something on its
> >         underlying
> >         > GdkWindow object using cairo.
> >         > All I was able to obtain so far is a black (or whatever is
> >         the
> >         > background colour of the selected theme) rectangle -ie it's
> >         not
> >         > transparent and everything I paint in its GdkWindow with
> >         Cairo is not
> >         > showed at all.
> >
> >
> >         You may hit (at least) this hard-coded limitation:
> >         http://maemo.gitorious.org/fremantle-hildon-
> >         desktop/libmatchbox2/blobs/master/matchbox/core/mb-wm-
> >         client.c#line173
> >
> >         Currently alpha in dialogs and application windows is ignored
> >         because it
> >         allows for optimisations in the compositor. But if you set the
> >         override-
> >         redirect flag for the window, that should go around that
> >         (because the
> >         type of your window would be MBWMClientTypeOverride).
> >
> >         -Kimmo
> >
> >
> >         > Here is the code I'm using:
> >         >
> >         > void create_image_details(GtkWidget *callerobj,app_data_t
> >         *myapp) {
> >         >     PangoLayout *textbuff;
> >         >     cairo_t *cr;
> >         >     gint x0, y0, r, txtwidth, txtheight;
> >         >
> >         >     /* For the widget itself let's use a GtkWindow */
> >         >     if ((myapp->imgparamwin != NULL) & GTK_IS_WINDOW(myapp-
> >         > >imgparamwin)) gtk_widget_destroy(myapp->imgparamwin);
> >         >     myapp->imgparamwin = gtk_window_new(GTK_WINDOW_POPUP);
> >         >     gtk_window_set_decorated(GTK_WINDOW (myapp-
> >         >imgparamwin),FALSE);
> >         >     gtk_window_set_opacity(GTK_WINDOW (myapp-
> >         >imgparamwin),0);
> >         >     gtk_widget_set_app_paintable(myapp->imgparamwin,TRUE);
> >         >     gtk_widget_realize(myapp->imgparamwin);
> >         >     /* gdk_window_set_back_pixmap(myapp->imgparamwin-
> >         > >window,NULL,FALSE); */
> >         >     /* Get the Cairo context */
> >         >     cr = gdk_cairo_create(GDK_DRAWABLE (myapp->imgparamwin-
> >         >window));
> >         >     textbuff = pango_cairo_create_layout(cr);
> >         >     pango_layout_set_markup(textbuff,myapp->imgparam,-1);
> >         >     pango_layout_get_pixel_size
> >         (textbuff,&txtwidth,&txtheight);
> >         >     /* Draw a rounded rectangle */
> >         >
> >         > [cairo stuff is here]
> >         >
> >         >     cairo_destroy(cr);
> >         >     g_object_unref(textbuff);
> >         >     /* Show the widget */
> >         >     gtk_window_resize(GTK_WINDOW (myapp-
> >         >imgparamwin),txtwidth + (r *
> >         > 2),txtheight + (r * 2));
> >         >     gtk_window_move(GTK_WINDOW (myapp->imgparamwin),30,30);
> >         >     gdk_window_reparent(myapp->imgparamwin->window,myapp-
> >         >image-
> >         > >window,30,30);
> >         >     gtk_widget_show_all(myapp->imgparamwin);
> >         > }
> >         >
> >         > The window dimension after the gtk_window_resize() are
> >         correct -ie the
> >         > dimension of the PangoLayout containing the text to be
> >         rendered, so
> >         > something is definitely going on under the hood... but
> >         nothing is
> >         > displayed!
> >         > If I add some widget to the popoup window (for example a
> >         GtkLabel with
> >         > some text in it), it's rendered correctly, but, of course
> >         it's not
> >         > transparent!
> >         >
> >         > Any help, as always, is much appreciated!
> >         >
> >         > Luca Donaggio
> >
> >
> >
>
>
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