bug#460: 23.0.60; x-display-color-cells returns 20 on w32 remote desktop

[John Paul Wallington]

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:
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