Re: Partial width struts

[Rob Adams <robadams ucla edu>]

> 	Actually, now that I think about it. That's going to be 9 zeros in any
> case I can think of, which is a bit of jump in wasted space. How about
> something like this:
> 
>   _NET_WM_STRUT, border, width, start, end, CARDINAL[4]/32
>   
>     #define _NET_WM_STRUT_BORDER_LEFT   0
>     #define _NET_WM_STRUT_BORDER_RIGHT  1
>     #define _NET_WM_STRUT_BORDER_TOP    2
>     #define _NET_WM_STRUT_BORDER_BOTTOM 3
> 
> 
> 	So that the property only specifies a single strut. I think that makes
> sense - are there any use cases for more than one strut ?
> 

Well I could imagine some weird shaped window in the corner maybe
setting multiple struts, but I agree that's pretty unlikely.  The
existing proposal is ever-so-slightly more general, but what do people
think?  Would you rather use the mostly-zero length 12 list or the magic
number length 4 list?

Using the length 12 list does have the advantage that it makes it very
easy for applications setting the partial-width strut to set the
full-width one as well, but that's a pretty minor point.

> "
> The purpose of struts is to reserve space at the borders of the
> desktop.  This is very useful for a docking area, a taskbar or a panel,
> for instance. The Window Manager should take this reserved area into
> account when constraining window positions - maximized windows, for
> example, should not cover that area.
> 
> The start and end values associated with each strut allow areas to be
> reserved which do not span the entire width or height of the screen.
> Struts MUST be specified relative to the edges of the logical screen,
> and not to the edges of any view port or Xinerama monitor.
> "

OK sure.  Attached is another revision of the spec.  If people indicate
they like the length 4 list I'll go ahead and update it; otherwise I
think I'll stick with the length 12 list.

-Rob

Index: wm-spec.sgml
===================================================================
RCS file: /freedesktop/web/content/standards/wm-spec/1.3/wm-spec.sgml,v
retrieving revision 1.2
diff -u -r1.2 wm-spec.sgml
--- wm-spec.sgml	3 Jan 2003 20:31:14 -0000	1.2
+++ wm-spec.sgml	11 Jun 2003 21:22:37 -0000
@@ -446,7 +446,11 @@
  Work area SHOULD be used by desktop applications to place desktop icons appropriately.
 	</para>
 	<para>
-	The Window Manager SHOULD calculate this space by taking the current page minus space occupied by dock and panel windows, as indicated by the <link linkend="NETWMSTRUT">_NET_WM_STRUT</link> property set on client windows.
+The Window Manager SHOULD calculate this space by taking the current
+page minus space occupied by dock and panel windows, as indicated by
+the <link linkend="NETWMSTRUT">_NET_WM_STRUT</link> or <link
+linkend="NETWMSTRUTPARTIAL">_NET_WM_STRUT_PARTIAL</link> property set on
+client windows.
 	</para>
 	</sect2>
 	<sect2>
@@ -1119,19 +1123,66 @@
 _NET_WM_STRUT, left, right, top, bottom, CARDINAL[4]/32
 ]]></programlisting>
 	<para>
-This property MUST be set by the Client if the window is to reserve space at
-the edge of the screen.  The property contains 4 cardinals specifying the
-width of the reserved area at each border of the screen.  
-The order of the borders is left, right, top, bottom.
-The client MAY change this property at any time, therefore the Window Manager MUST
-watch out for property notify events.  
+This property is a shortcut for the use case for _NET_WM_STRUT_PARTIAL
+where all start values are 0 and all end values are height or width of
+the logical screen.  Clients MAY set this property in addition to
+_NET_WM_STRUT_PARTIAL using just the first four values of the
+_NET_WM_STRUT_PARTIAL property to ensure backward compatibility with
+Window Managers supporting older versions of the Specification.
 	</para>
-	<para>
-The purpose of struts is to reserve space at the borders of the desktop.  This
-is very useful for a docking area, a taskbar or a panel, for instance. The  
-Window Manager should know about this reserved space in order to be able to
-preserve the space. Also maximized windows should not cover that reserved
-space.
+</sect2>
+<sect2><title>_NET_WM_STRUT_PARTIAL</title>
+	<programlisting id="NETWMSTRUTPARTIAL"><![CDATA[
+_NET_WM_STRUT_PARTIAL, left, right, top, bottom, left_start_y, left_end_y,
+right_start_y, right_end_y, top_start_x, top_end_x, bottom_start_x,
+bottom_end_x,CARDINAL[12]/32
+]]></programlisting>
+	<para>
+This property MUST be set by the Client if the window is to reserve
+space at the edge of the screen.  The property contains 4 cardinals
+specifying the width of the reserved area at each border of the
+screen, and an additional 8 cardinals specifying the beginning and end
+coordinated for each of the four struts.  The order of the values is
+left, right, top, bottom, left_start_y, left_end_y, right_start_y,
+right_end_y, top_start_x, top_end_x, bottom_start_x, bottom_end_x The
+client MAY change this property at any time, therefore the Window
+Manager MUST watch out for property notify events if the Window
+Manager uses this property to assign special semantics to the window.
+	</para>
+	<para>
+If both this property and the _NET_WM_STRUT property are set, the
+Window Manager MUST ignore the _NET_WM_STRUT property values and use
+instead the values for this property.  This will ensure that Clients
+can safely set both properties without giving up the improved
+semantics of the new property.
+	</para>
+	<para>
+The purpose of struts is to reserve space at the borders of the
+desktop.  This is very useful for a docking area, a taskbar or a panel,
+for instance. The Window Manager should take this reserved area into
+account when constraining window positions - maximized windows, for
+example, should not cover that area.
+	</para>
+	<para> 
+The start and end values associated with each strut allow areas to be
+reserved which do not span the entire width or height of the screen.
+Struts MUST be specified relative to the edges of the logical screen,
+and not to the edges of any view port or Xinerama monitor.
+The purpose of struts is to reserve space at the borders of the
+	</para>
+	<para>
+For example, for a panel-style Client appearing at the bottom of the
+screen, 50 pixels tall, and occupying the space from 200-600 pixels
+from the left of the screen edge would set a bottom strut of 50, and
+set bottom_start_x to 200 and bottom_end_x to 600.  Another example is
+a panel on a screen using the Xinerama extension.  Assume that the set
+up uses two monitors, one running at 1280x1024 and the other to the
+right running at 1024x768, with the top edge of the two physical
+displays aligned.  If the panel wants to fill the entire bottom edge
+of the smaller display with a panel 50 pixels tall, it should set a
+bottom strut of 306, with bottom_start_x of 1280, and bottom_end_x of
+2303.  Note that the strut is relative to the screen edge, and not the
+edge of the xinerama.
 	</para>
 	<para>
 Rationale: A simple "do not cover" hint is not enough for dealing with e.g.
@@ -1142,7 +1193,8 @@
 A "corner" panel that does not extend for the full length of a screen border
 SHOULD only set one strut.
 	</para>
-	</sect2><sect2><title>_NET_WM_ICON_GEOMETRY</title>
+</sect2>
+<sect2><title>_NET_WM_ICON_GEOMETRY</title>
 <programlisting><![CDATA[
 _NET_WM_ICON_GEOMETRY, x, y, width, height, CARDINAL[4]/32
 ]]></programlisting>