Re: x-display-pixel-width/height inconsistency

[YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>]

>>>>> On Wed, 08 May 2013 20:41:39 +0300, Eli Zaretskii <eliz@gnu.org> said:

>> I also tried implementing a W32 version of multi-monitor support,
>> but I can't test it (I didn't even compile, actually).  Please test
>> it.

> You need more changes to get this to compile, see the patches below
> that should be applied on top of what you sent.

> After that, the code seems to work on my single-monitor system.  (I
> don't have access to any multi-monitor machines.)

> Thanks.

Thanks for testing.  I updated the w32fns.c part below.

> P.S.  Is it possible to use something more elegant to pass a
> parameter to w32_monitor_enum?  The way you did it, by casting a
> Lisp_Object to a LPARAM, will not work when the width of a
> Lisp_Object is different from the width of a pointer.  And even when
> it does work, it feels kludgey.

No.  What is casted to an LPARAM is not a Lisp_Object value but a
*pointer to* a Lisp_Object variable.  That is a standard way of
passing context information to a callback, and I suppose such
callbacks are usually designed so they can get a pointer-sized context
as an argument.

> P.P.S.  Would you mind to also add the necessary documentation
> changes, like NEWS and additions to the ELisp manual?  TIA.

I'm planning to add an NEWS entry saying that (x-)display-pixel-width
and (x-)display-pixel-height functions now behave consistently among
the platforms, once the change for the remaining platform (i.e., NS)
is done.  (Is anyone working on implementing
ns-display-monitor-attributes-list ?).

I don't know how ELisp manual is usually updated.  Is it supposed to
be done by the same person who designed/implemented the new functions?

				     YAMAMOTO Mitsuharu
				mituharu@math.s.chiba-u.ac.jp

=== modified file 'src/w32fns.c'
*** src/w32fns.c	2013-05-04 10:19:13 +0000
--- src/w32fns.c	2013-05-08 23:54:04 +0000
***************
*** 106,111 ****
--- 106,112 ----
  Lisp_Object Qctrl;
  Lisp_Object Qcontrol;
  Lisp_Object Qshift;
+ static Lisp_Object Qgeometry, Qworkarea, Qmm_size, Qframes;
  
  
  /* Prefix for system colors.  */
***************
*** 131,136 ****
--- 132,146 ----
  #ifndef MONITOR_DEFAULT_TO_NEAREST
  #define MONITOR_DEFAULT_TO_NEAREST 2
  #endif
+ #ifndef MONITORINFOF_PRIMARY
+ #define MONITORINFOF_PRIMARY 1
+ #endif
+ #ifndef SM_XVIRTUALSCREEN
+ #define SM_XVIRTUALSCREEN 76
+ #endif
+ #ifndef SM_YVIRTUALSCREEN
+ #define SM_YVIRTUALSCREEN 77
+ #endif
  /* MinGW headers define MONITORINFO unconditionally, but MSVC ones don't.
     To avoid a compile error on one or the other, redefine with a new name.  */
  struct MONITOR_INFO
***************
*** 141,146 ****
--- 151,168 ----
      DWORD   dwFlags;
  };
  
+ #ifndef CCHDEVICENAME
+ #define CCHDEVICENAME 32
+ #endif
+ struct MONITOR_INFO_EX
+ {
+     DWORD   cbSize;
+     RECT    rcMonitor;
+     RECT    rcWork;
+     DWORD   dwFlags;
+     char    szDevice[CCHDEVICENAME];
+ };
+ 
  /* Reportedly, MSVC does not have this in its headers.  */
  #if defined (_MSC_VER) && _WIN32_WINNT < 0x0500
  DECLARE_HANDLE(HMONITOR);
***************
*** 159,164 ****
--- 181,190 ----
    (IN HMONITOR monitor, OUT struct MONITOR_INFO* info);
  typedef HMONITOR (WINAPI * MonitorFromWindow_Proc)
    (IN HWND hwnd, IN DWORD dwFlags);
+ typedef BOOL CALLBACK (* MonitorEnum_Proc)
+   (IN HMONITOR monitor, IN HDC hdc, IN RECT *rcMonitor, IN LPARAM dwData);
+ typedef BOOL (WINAPI * EnumDisplayMonitors_Proc)
+   (IN HDC hdc, IN RECT *rcClip, IN MonitorEnum_Proc fnEnum, IN LPARAM dwData);
  
  TrackMouseEvent_Proc track_mouse_event_fn = NULL;
  ImmGetCompositionString_Proc get_composition_string_fn = NULL;
***************
*** 168,173 ****
--- 194,200 ----
  MonitorFromPoint_Proc monitor_from_point_fn = NULL;
  GetMonitorInfo_Proc get_monitor_info_fn = NULL;
  MonitorFromWindow_Proc monitor_from_window_fn = NULL;
+ EnumDisplayMonitors_Proc enum_display_monitors_fn = NULL;
  
  #ifdef NTGUI_UNICODE
  #define unicode_append_menu AppendMenuW
***************
*** 4656,4662 ****
         doc: /* Return the width in pixels of DISPLAY.
  The optional argument DISPLAY specifies which display to ask about.
  DISPLAY should be either a frame or a display name (a string).
! If omitted or nil, that stands for the selected frame's display.  */)
    (Lisp_Object display)
  {
    struct w32_display_info *dpyinfo = check_x_display_info (display);
--- 4683,4693 ----
         doc: /* Return the width in pixels of DISPLAY.
  The optional argument DISPLAY specifies which display to ask about.
  DISPLAY should be either a frame or a display name (a string).
! If omitted or nil, that stands for the selected frame's display.
! 
! On \"multi-monitor\" setups this refers to the pixel width for all
! physical monitors associated with DISPLAY.  To get information for
! each physical monitor, use `display-monitor-attributes-list'.  */)
    (Lisp_Object display)
  {
    struct w32_display_info *dpyinfo = check_x_display_info (display);
***************
*** 4669,4675 ****
         doc: /* Return the height in pixels of DISPLAY.
  The optional argument DISPLAY specifies which display to ask about.
  DISPLAY should be either a frame or a display name (a string).
! If omitted or nil, that stands for the selected frame's display.  */)
    (Lisp_Object display)
  {
    struct w32_display_info *dpyinfo = check_x_display_info (display);
--- 4700,4710 ----
         doc: /* Return the height in pixels of DISPLAY.
  The optional argument DISPLAY specifies which display to ask about.
  DISPLAY should be either a frame or a display name (a string).
! If omitted or nil, that stands for the selected frame's display.
! 
! On \"multi-monitor\" setups this refers to the pixel height for all
! physical monitors associated with DISPLAY.  To get information for
! each physical monitor, use `display-monitor-attributes-list'.  */)
    (Lisp_Object display)
  {
    struct w32_display_info *dpyinfo = check_x_display_info (display);
***************
*** 4761,4801 ****
         doc: /* Return the height in millimeters of DISPLAY.
  The optional argument DISPLAY specifies which display to ask about.
  DISPLAY should be either a frame or a display name (a string).
! If omitted or nil, that stands for the selected frame's display.  */)
    (Lisp_Object display)
  {
    struct w32_display_info *dpyinfo = check_x_display_info (display);
    HDC hdc;
!   int cap;
  
!   hdc = GetDC (dpyinfo->root_window);
  
!   cap = GetDeviceCaps (hdc, VERTSIZE);
! 
!   ReleaseDC (dpyinfo->root_window, hdc);
! 
!   return make_number (cap);
  }
  
  DEFUN ("x-display-mm-width", Fx_display_mm_width, Sx_display_mm_width, 0, 1, 0,
         doc: /* Return the width in millimeters of DISPLAY.
  The optional argument DISPLAY specifies which display to ask about.
  DISPLAY should be either a frame or a display name (a string).
! If omitted or nil, that stands for the selected frame's display.  */)
    (Lisp_Object display)
  {
    struct w32_display_info *dpyinfo = check_x_display_info (display);
- 
    HDC hdc;
!   int cap;
! 
!   hdc = GetDC (dpyinfo->root_window);
  
!   cap = GetDeviceCaps (hdc, HORZSIZE);
  
!   ReleaseDC (dpyinfo->root_window, hdc);
! 
!   return make_number (cap);
  }
  
  DEFUN ("x-display-backing-store", Fx_display_backing_store,
--- 4796,4841 ----
         doc: /* Return the height in millimeters of DISPLAY.
  The optional argument DISPLAY specifies which display to ask about.
  DISPLAY should be either a frame or a display name (a string).
! If omitted or nil, that stands for the selected frame's display.
! 
! On \"multi-monitor\" setups this refers to the height in millimeters for
! all physical monitors associated with DISPLAY.  To get information
! for each physical monitor, use `display-monitor-attributes-list'.  */)
    (Lisp_Object display)
  {
    struct w32_display_info *dpyinfo = check_x_display_info (display);
    HDC hdc;
!   double mm_per_pixel;
  
!   hdc = GetDC (NULL);
!   mm_per_pixel = ((double) GetDeviceCaps (hdc, VERTSIZE)
! 		  / GetDeviceCaps (hdc, VERTRES));
!   ReleaseDC (NULL, hdc);
  
!   return make_number (x_display_pixel_height (dpyinfo) * mm_per_pixel + 0.5);
  }
  
  DEFUN ("x-display-mm-width", Fx_display_mm_width, Sx_display_mm_width, 0, 1, 0,
         doc: /* Return the width in millimeters of DISPLAY.
  The optional argument DISPLAY specifies which display to ask about.
  DISPLAY should be either a frame or a display name (a string).
! If omitted or nil, that stands for the selected frame's display.
! 
! On \"multi-monitor\" setups this refers to the width in millimeters for
! all physical monitors associated with TERMINAL.  To get information
! for each physical monitor, use `display-monitor-attributes-list'.  */)
    (Lisp_Object display)
  {
    struct w32_display_info *dpyinfo = check_x_display_info (display);
    HDC hdc;
!   double mm_per_pixel;
  
!   hdc = GetDC (NULL);
!   mm_per_pixel = ((double) GetDeviceCaps (hdc, HORZSIZE)
! 		  / GetDeviceCaps (hdc, HORZRES));
!   ReleaseDC (NULL, hdc);
  
!   return make_number (x_display_pixel_width (dpyinfo) * mm_per_pixel + 0.5);
  }
  
  DEFUN ("x-display-backing-store", Fx_display_backing_store,
***************
*** 4847,4852 ****
--- 4887,5080 ----
    return Qnil;
  }
  
+ static BOOL CALLBACK
+ w32_monitor_enum (HMONITOR monitor, HDC hdc, RECT *rcMonitor, LPARAM dwData)
+ {
+   Lisp_Object *monitor_list = (Lisp_Object *) dwData;
+ 
+   *monitor_list = Fcons (make_save_pointer (monitor), *monitor_list);
+ 
+   return TRUE;
+ }
+ 
+ static Lisp_Object
+ w32_display_monitor_attributes_list (struct w32_display_info *dpyinfo)
+ {
+   Lisp_Object attributes_list = Qnil, primary_monitor_attributes = Qnil;
+   Lisp_Object monitor_list = Qnil, monitor_frames, rest, frame;
+   int i, n_monitors;
+   HMONITOR *monitors;
+ 
+   if (!(enum_display_monitors_fn && get_monitor_info_fn
+ 	&& monitor_from_window_fn))
+     return Qnil;
+ 
+   if (!enum_display_monitors_fn (NULL, NULL, w32_monitor_enum,
+ 				 (LPARAM) &monitor_list)
+       || NILP (monitor_list))
+     return Qnil;
+ 
+   n_monitors = 0;
+   for (rest = monitor_list; CONSP (rest); rest = XCDR (rest))
+     n_monitors++;
+ 
+   monitors = xmalloc (n_monitors * sizeof (*monitors));
+   for (i = 0; i < n_monitors; i++)
+     {
+       monitors[i] = XSAVE_POINTER (XCAR (monitor_list), 0);
+       monitor_list = XCDR (monitor_list);
+     }
+ 
+   monitor_frames = Fmake_vector (make_number (n_monitors), Qnil);
+   FOR_EACH_FRAME (rest, frame)
+     {
+       struct frame *f = XFRAME (frame);
+ 
+       if (FRAME_W32_P (f) && FRAME_W32_DISPLAY_INFO (f) == dpyinfo
+ 	  && !EQ (frame, tip_frame))
+ 	{
+ 	  HMONITOR monitor =
+ 	    monitor_from_window_fn (FRAME_W32_WINDOW (f),
+ 				    MONITOR_DEFAULT_TO_NEAREST);
+ 
+ 	  for (i = 0; i < n_monitors; i++)
+ 	    if (monitors[i] == monitor)
+ 	      break;
+ 
+ 	  if (i < n_monitors)
+ 	    ASET (monitor_frames, i, Fcons (frame, AREF (monitor_frames, i)));
+ 	}
+     }
+ 
+   for (i = 0; i < n_monitors; i++)
+     {
+       Lisp_Object geometry, workarea, name, attributes = Qnil;
+       HDC hdc;
+       int width_mm, height_mm;
+       struct MONITOR_INFO_EX mi;
+ 
+       attributes = Fcons (Fcons (Qframes, AREF (monitor_frames, i)),
+ 			  attributes);
+ 
+       mi.cbSize = sizeof (mi);
+       get_monitor_info_fn (monitors[i], (struct MONITOR_INFO *) &mi);
+ 
+       name = make_unibyte_string (mi.szDevice, strlen (mi.szDevice));
+       attributes = Fcons (Fcons (Qname, name), attributes);
+ 
+       hdc = CreateDCA ("DISPLAY", mi.szDevice, NULL, NULL);
+       width_mm = GetDeviceCaps (hdc, HORZSIZE);
+       height_mm = GetDeviceCaps (hdc, VERTSIZE);
+       DeleteDC (hdc);
+       attributes = Fcons (Fcons (Qmm_size, list2i (width_mm, height_mm)),
+ 			  attributes);
+ 
+       workarea = list4i (mi.rcWork.left, mi.rcWork.top,
+ 			 mi.rcWork.right - mi.rcWork.left,
+ 			 mi.rcWork.bottom - mi.rcWork.top);
+       attributes = Fcons (Fcons (Qworkarea, workarea), attributes);
+ 
+       geometry = list4i (mi.rcMonitor.left, mi.rcMonitor.top,
+ 			 mi.rcMonitor.right - mi.rcMonitor.left,
+ 			 mi.rcMonitor.bottom - mi.rcMonitor.top);
+       attributes = Fcons (Fcons (Qgeometry, geometry), attributes);
+ 
+       if (mi.dwFlags & MONITORINFOF_PRIMARY)
+ 	primary_monitor_attributes = attributes;
+       else
+ 	attributes_list = Fcons (attributes, attributes_list);
+     }
+ 
+   if (!NILP (primary_monitor_attributes))
+     attributes_list = Fcons (primary_monitor_attributes, attributes_list);
+ 
+   xfree (monitors);
+ 
+   return attributes_list;
+ }
+ 
+ static Lisp_Object
+ w32_display_monitor_attributes_list_fallback (struct w32_display_info *dpyinfo)
+ {
+   Lisp_Object geometry, workarea, frames, rest, frame, attributes = Qnil;
+   HDC hdc;
+   double mm_per_pixel;
+   int pixel_width, pixel_height, width_mm, height_mm;
+   RECT workarea_rect;
+ 
+   /* Fallback: treat (possibly) multiple physical monitors as if they
+      formed a single monitor as a whole.  This should provide a
+      consistent result at least on single monitor environments.  */
+   attributes = Fcons (Fcons (Qname, build_string ("combined screen")),
+ 		      attributes);
+ 
+   frames = Qnil;
+   FOR_EACH_FRAME (rest, frame)
+     {
+       struct frame *f = XFRAME (frame);
+ 
+       if (FRAME_W32_P (f) && FRAME_W32_DISPLAY_INFO (f) == dpyinfo
+ 	  && !EQ (frame, tip_frame))
+ 	frames = Fcons (frame, frames);
+     }
+   attributes = Fcons (Fcons (Qframes, frames), attributes);
+ 
+   pixel_width = x_display_pixel_width (dpyinfo);
+   pixel_height = x_display_pixel_height (dpyinfo);
+ 
+   hdc = GetDC (NULL);
+   mm_per_pixel = ((double) GetDeviceCaps (hdc, HORZSIZE)
+ 		  / GetDeviceCaps (hdc, HORZRES));
+   width_mm = pixel_width * mm_per_pixel + 0.5;
+   mm_per_pixel = ((double) GetDeviceCaps (hdc, VERTSIZE)
+ 		  / GetDeviceCaps (hdc, VERTRES));
+   height_mm = pixel_height * mm_per_pixel + 0.5;
+   ReleaseDC (NULL, hdc);
+   attributes = Fcons (Fcons (Qmm_size, list2i (width_mm, height_mm)),
+ 		      attributes);
+ 
+   /* GetSystemMetrics below may return 0 for Windows 95 or NT 4.0, but
+      we don't care.  */
+   geometry = list4i (GetSystemMetrics (SM_XVIRTUALSCREEN),
+ 		     GetSystemMetrics (SM_YVIRTUALSCREEN),
+ 		     pixel_width, pixel_height);
+   if (SystemParametersInfo (SPI_GETWORKAREA, 0, &workarea_rect, 0))
+     workarea = list4i (workarea_rect.left, workarea_rect.top,
+ 		       workarea_rect.right - workarea_rect.left,
+ 		       workarea_rect.bottom - workarea_rect.top);
+   else
+     workarea = geometry;
+   attributes = Fcons (Fcons (Qworkarea, workarea), attributes);
+ 
+   attributes = Fcons (Fcons (Qgeometry, geometry), attributes);
+ 
+   return list1 (attributes);
+ }
+ 
+ DEFUN ("w32-display-monitor-attributes-list", Fw32_display_monitor_attributes_list,
+        Sw32_display_monitor_attributes_list,
+        0, 1, 0,
+        doc: /* Return a list of physical monitor attributes on the W32 display DISPLAY.
+ 
+ The optional argument DISPLAY specifies which display to ask about.
+ DISPLAY should be either a frame or a display name (a string).
+ If omitted or nil, that stands for the selected frame's display.
+ 
+ Internal use only, use `display-monitor-attributes-list' instead.  */)
+   (Lisp_Object display)
+ {
+   struct w32_display_info *dpyinfo = check_x_display_info (display);
+   Lisp_Object attributes_list;
+ 
+   block_input ();
+   attributes_list = w32_display_monitor_attributes_list (dpyinfo);
+   if (NILP (attributes_list))
+     attributes_list = w32_display_monitor_attributes_list_fallback (dpyinfo);
+   unblock_input ();
+ 
+   return attributes_list;
+ }
+ 
  DEFUN ("set-message-beep", Fset_message_beep, Sset_message_beep, 1, 1, 0,
         doc: /* Set the sound generated when the bell is rung.
  SOUND is 'asterisk, 'exclamation, 'hand, 'question, 'ok, or 'silent
***************
*** 7339,7344 ****
--- 7567,7576 ----
    DEFSYM (Qcontrol, "control");
    DEFSYM (Qshift, "shift");
    DEFSYM (Qfont_param, "font-parameter");
+   DEFSYM (Qgeometry, "geometry");
+   DEFSYM (Qworkarea, "workarea");
+   DEFSYM (Qmm_size, "mm-size");
+   DEFSYM (Qframes, "frames");
    /* This is the end of symbol initialization.  */
  
  
***************
*** 7617,7622 ****
--- 7849,7855 ----
    defsubr (&Sx_display_visual_class);
    defsubr (&Sx_display_backing_store);
    defsubr (&Sx_display_save_under);
+   defsubr (&Sw32_display_monitor_attributes_list);
    defsubr (&Sx_create_frame);
    defsubr (&Sx_open_connection);
    defsubr (&Sx_close_connection);
***************
*** 7689,7694 ****
--- 7922,7929 ----
      GetProcAddress (user32_lib, "GetMonitorInfoA");
    monitor_from_window_fn = (MonitorFromWindow_Proc)
      GetProcAddress (user32_lib, "MonitorFromWindow");
+   enum_display_monitors_fn = (EnumDisplayMonitors_Proc)
+     GetProcAddress (user32_lib, "EnumDisplayMonitors");
  
    {
      HMODULE imm32_lib = GetModuleHandle ("imm32.dll");