bug#460: marked as done (23.0.60; x-display-color-cells returns 20 on w32 remote desktop)

[owner@emacsbugs.donarmstrong.com (Emacs bug Tracking System)]

[-- Attachment #1: Type: text/plain, Size: 901 bytes --]


Your message dated Thu, 19 Feb 2009 21:23:21 +0800
with message-id <499D5D49.50405@gnu.org>
and subject line 23.0.60; x-display-color-cells returns 20 on w32 remote desktop
has caused the Emacs bug report #460,
regarding 23.0.60; x-display-color-cells returns 20 on w32 remote desktop
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what this
message is talking about, this may indicate a serious mail system
misconfiguration somewhere. Please contact owner@emacsbugs.donarmstrong.com
immediately.)


-- 
460: http://emacsbugs.donarmstrong.com/cgi-bin/bugreport.cgi?bug=460
Emacs Bug Tracking System
Contact owner@emacsbugs.donarmstrong.com with problems

[-- Attachment #2: Type: message/rfc822, Size: 4573 bytes --]

From: jpw@pobox.com (John Paul Wallington)
To: emacs-pretest-bug@gnu.org
Subject: 23.0.60; x-display-color-cells returns 20 on w32 remote desktop
Date: Sat, 21 Jun 2008 22:27:50 +0100
Message-ID: <841w2qwka1.fsf@pobox.com>

When I run Emacs on my Windows machine and look at it with Remote
Desktop Connection on my Mac the modeline faces are black and white.
This is because the `mode-line' face is defined as inverse-video for
displays with less than 88 colors, and `x-display-color-cells' returns
20 when using RDC.

Here's a hacky patch that I installed locally.  It probably needs more
work before it's suitable for inclusion.  I first tried just checking
whether `cap' was less than 21 rather than checking for a negative
value, but then the function would return the wrong number of colors.
I had to use GetDeviceCaps to work out the color depth.


*** w32fns.c.~1.331.~ Wed Jun 18 2008 07:05:15 PM
--- w32fns.c Tue Jun 17 2008 05:59:23 PM
***************
*** 6711,6719 ****
  
    /* We force 24+ bit depths to 24-bit, both to prevent an overflow
       and because probably is more meaningful on Windows anyway */
!   if (cap < 0)
!     cap = 1 << min (dpyinfo->n_planes * dpyinfo->n_cbits, 24);
! 
--- 6710,6721 ----
      cap = GetDeviceCaps (hdc, NUMCOLORS);
  
    /* We force 24+ bit depths to 24-bit, both to prevent an overflow
       and because probably is more meaningful on Windows anyway */
!   /* Remote Desktop often returns 20 for NUMCOLORS device capability
!      when it can display more */
!   if (cap < 21)
!     cap = 1 << min (GetDeviceCaps (hdc, BITSPIXEL)
! 		    * GetDeviceCaps (hdc, PLANES), 24);
    ReleaseDC (dpyinfo->root_window, hdc);
  
    return make_number (cap);


In GNU Emacs 23.0.60.1 (i386-mingw-nt5.1.2600)
 of 2008-06-21 on GOLDEN
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4)'

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: ENG
  value of $XMODIFIERS: nil
  locale-coding-system: cp1252
  default-enable-multibyte-characters: t

Major mode: Text

Minor modes in effect:
  delete-selection-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
[elided]

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
65536 [2 times]
Quit
Mark set



[-- Attachment #3: Type: message/rfc822, Size: 3310 bytes --]

From: Jason Rumney <jasonr@gnu.org>
To: 460-done@emacsbugs.donarmstrong.com
Subject: 23.0.60; x-display-color-cells returns 20 on w32 remote desktop
Date: Thu, 19 Feb 2009 21:23:21 +0800
Message-ID: <499D5D49.50405@gnu.org>

Looking into the code surrounding this, I found that we were getting the 
depth and other display properties explicitly from the desktop window. 
The docs suggest using NULL for the window handle when you don't have a 
window to explicitly use, so I've changed the code to do that, which 
might fix the bug if the cause is that the desktop window is set 
deliberately to use a 20 color palette even though the rest of the 
remote session supports more colors.

It is possible though that the remote desktop session is setting a low 
color palette to save bandwidth, but letting non-palette-aware 
applications draw in full color, since once the full color data has been 
transferred it makes no sense to artificially reduce it. If this is the 
case, then Emacs is doing the right thing by honoring the request to use 
a palette.