Re: scrolled windows, again

[Havoc Pennington <hp redhat com>]

Paul Davis <pbd op net> writes:
> >> the problem is that the scrolled window(s) are packed into:
> >> 
> >>     a table thats inside
> >>     an hbox thats inside
> >>     an eventbox thats inside
> >>     a vbox thats inside
> >>     a top level window
> >
> >This can be worked around by setting a geometry widget
> >(set_geometry_hints()), if you do that then the default size applies
> >to the geometry widget instead of the whole window.
> 
> can i get any more hints on this ? the reference docs are pretty
> skimpy, and the only suitable example i've found of using is in
> testgtk, which looks good but doesn't totally explain how this
> works. what are the different fields in a GdkGeometry struct? are
> there any requirements for the widget i pass into set_geometry_hints?
> 

The widget you use needs to be a child of the window you're setting
the hints on. For just setting the geometry widget, I think the
GdkGeometry struct can actually be NULL.

Here are some docs I just drafted up.

Havoc


<!-- ##### ENUM GdkWindowHints ##### -->
<para>
Used to indicate which fields of a #GdkGeometry struct should be paid attention
to. Also, the presence/absence of @GDK_HINT_POS, @GDK_HINT_USER_POS, and
@GDK_HINT_USER_SIZE is significant, though they don't directly refer to
#GdkGeometry fields.  @GDK_HINT_USER_POS will be set automatically by #GtkWindow
if you call gtk_window_move(). @GDK_HINT_USER_POS and @GDK_HINT_USER_SIZE 
should be set if the user specified a size/position using a --geometry 
command-line argument; gtk_window_parse_geometry() automatically sets these
flags.
</para>

@GDK_HINT_POS: indicates that the program has positioned the window
@GDK_HINT_MIN_SIZE: min size fields are set
@GDK_HINT_MAX_SIZE: max size fields are set
@GDK_HINT_BASE_SIZE: base size fields are set
@GDK_HINT_ASPECT: aspect ratio fields are set
@GDK_HINT_RESIZE_INC: resize increment fields are set
@GDK_HINT_WIN_GRAVITY: window gravity field is set
@GDK_HINT_USER_POS: indicates that the window's position was explicitly set by the user
@GDK_HINT_USER_SIZE: indicates that the window's size was explicitly set by the user

<!-- ##### STRUCT GdkGeometry ##### -->
<para>
The #GdkGeometry struct gives the window manager information about 
a window's geometry constraints. Normally you would set these on 
the GTK+ level using gtk_window_set_geometry_hints(). #GtkWindow 
then sets the hints on the #GdkWindow it creates.
</para>

<para>
gdk_window_set_geometry_hints() expects the hints to be fully valid already and
simply passes them to the window manager; in contrast,
gtk_window_set_geometry_hints() performs some interpretation. For example,
#GtkWindow will apply the hints to the geometry widget instead of the toplevel
window, if you set a geometry widget. Also, the
min_width/min_height/max_width/max_height fields may be set to -1, and
#GtkWindow will substitute the size request of the window or geometry widget. If
the minimum size hint is not provided, #GtkWindow will use its requisition as
the minimum size.  If the minimum size is provided and a geometry widget is set,
#GtkWindow will take the minimum size as the minimum size of the geometry widget
rather than the entire window. The base size is treated similarly.
</para>

<para>
The canonical use-case for gtk_window_set_geometry_hints() is to get a terminal
widget to resize properly. Here, the terminal text area should be the geometry
widget; #GtkWindow will then automatically set the base size to the size of
other widgets in the terminal window, such as the menubar and scrollbar.  Then,
the width_inc and height_inc fields should be set to the size of one character
in the terminal. Finally, the base size should be set to the size of one
character. The net effect is that the minimum size of the terminal 
will have a 1x1 character terminal area, and only terminal sizes on 
the "character grid" will be allowed.
</para>

<para>
Here's an example of how the terminal example would be implemented, assuming 
a terminal area widget called "terminal" and a toplevel window "toplevel":
<programlisting>
	GdkGeometry hints;

	hints.base_width = terminal->char_width;
        hints.base_height = terminal->char_height;
        hints.min_width = terminal->char_width;
        hints.min_height = terminal->char_height;
        hints.width_inc = terminal->char_width;
        hints.height_inc = terminal->char_height;

	gtk_window_set_geometry_hints (GTK_WINDOW (toplevel),
				       GTK_WIDGET (terminal),
 				       &hints,
				       GDK_HINT_RESIZE_INC |
                                       GDK_HINT_MIN_SIZE |
                                       GDK_HINT_BASE_SIZE);
</programlisting>
</para>

<para>
The other useful fields are the @min_aspect and @max_aspect fields; these
contain a width/height ratio as a floating point number. If a geometry widget is
set, the aspect applies to the geometry widget rather than the entire window.
The most common use of these hints is probably to set @min_aspect and
@max_aspect to the same value, thus forcing the window to keep a constant aspect
ratio.
</para>

@min_width: minimum width of window (or -1 to use requisition, with #GtkWindow only)
@min_height minimum height of window (or -1 to use requisition, with #GtkWindow only)
@max_width: maximum width of window (or -1 to use requisition, with #GtkWindow only)
@max_height: maximum height of window (or -1 to use requisition, with #GtkWindow only)
@base_width: allowed window widths are base_width + width_inc * N where N is any integer (-1 allowed with #GtkWindow)
@base_height: allowed window widths are base_height + height_inc * N where N is any integer (-1 allowed with #GtkWindow)
@width_inc: width resize increment
@height_inc: height resize increment
@min_aspect: minimum width/height ratio
@max_aspect: maximum width/height ratio
@win_gravity: window gravity, see gtk_window_set_gravity()