display.cc

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/*

Copyright (C) 2009-2013 John W. Eaton

This file is part of Octave.

Octave is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3 of the License, or (at your
option) any later version.

Octave is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with Octave; see the file COPYING.  If not, see
<http://www.gnu.org/licenses/>.

*/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <cstdlib>

#if defined (OCTAVE_USE_WINDOWS_API)
#include <windows.h>
#elif defined (HAVE_FRAMEWORK_CARBON)
#include <Carbon/Carbon.h>
#elif defined (HAVE_X_WINDOWS)
#include <X11/Xlib.h>
#endif

#include "singleton-cleanup.h"

#include "display.h"
#include "error.h"

display_info *display_info::instance = 0;

#if defined (HAVE_FRAMEWORK_CARBON) && ! defined (HAVE_CARBON_CGDISPLAYBITSPERPIXEL)
// FIXME: This will only work for MacOS > 10.5. For earlier versions
// this code is not needed (use CGDisplayBitsPerPixel instead).
size_t DisplayBitsPerPixel (CGDirectDisplayID display)
{
  CGDisplayModeRef mode = CGDisplayCopyDisplayMode (display);
  CFStringRef pixelEncoding = CGDisplayModeCopyPixelEncoding (mode);

  if (CFStringCompare (pixelEncoding, CFSTR (IO32BitDirectPixels), 0) == 0)
    return 32;
  else if (CFStringCompare (pixelEncoding, CFSTR (IO16BitDirectPixels), 0) == 0)
    return 16;
  else
    return 8;
}
#endif

void
display_info::init (bool query)
{
  if (query)
    {
#if defined (OCTAVE_USE_WINDOWS_API)

      HDC hdc = GetDC (0);

      if (hdc)
        {
          dp = GetDeviceCaps (hdc, BITSPIXEL);

          ht = GetDeviceCaps (hdc, VERTRES);
          wd = GetDeviceCaps (hdc, HORZRES);

          double ht_mm = GetDeviceCaps (hdc, VERTSIZE);
          double wd_mm = GetDeviceCaps (hdc, HORZSIZE);

          rx = wd * 25.4 / wd_mm;
          ry = ht * 25.4 / ht_mm;

          dpy_avail = true;
        }
      else
        err_msg = "no graphical display found";

#elif defined (HAVE_FRAMEWORK_CARBON)

      CGDirectDisplayID display = CGMainDisplayID ();

      if (display)
        {
#  if defined (HAVE_CARBON_CGDISPLAYBITSPERPIXEL)
          // For MacOS < 10.7 use the line below
          dp = CGDisplayBitsPerPixel (display);
#  else
          // For MacOS > 10.5 use the line below
          dp = DisplayBitsPerPixel (display);
#  endif

          ht = CGDisplayPixelsHigh (display);
          wd = CGDisplayPixelsWide (display);

          CGSize sz_mm = CGDisplayScreenSize (display);
          // For MacOS >= 10.6, CGSize is a struct keeping 2 CGFloat values,
          // but the CGFloat typedef is not present on older systems,
          // so use double instead.
          double ht_mm = sz_mm.height;
          double wd_mm = sz_mm.width;

          rx = wd * 25.4 / wd_mm;
          ry = ht * 25.4 / ht_mm;

          dpy_avail = true;
        }
      else
        err_msg = "no graphical display found";

#elif defined (HAVE_X_WINDOWS)

      const char *display_name = getenv ("DISPLAY");

      if (display_name && *display_name)
        {
          Display *display = XOpenDisplay (display_name);

          if (display)
            {
              Screen *screen = DefaultScreenOfDisplay (display);

              if (screen)
                {
                  dp = DefaultDepthOfScreen (screen);

                  ht = HeightOfScreen (screen);
                  wd = WidthOfScreen (screen);

                  int screen_number = XScreenNumberOfScreen (screen);

                  double ht_mm = DisplayHeightMM (display, screen_number);
                  double wd_mm = DisplayWidthMM (display, screen_number);

                  rx = wd * 25.4 / wd_mm;
                  ry = ht * 25.4 / ht_mm;
                }
              else
                err_msg = "X11 display has no default screen";

              XCloseDisplay (display);

              dpy_avail = true;
            }
          else
            err_msg = "unable to open X11 DISPLAY";
        }
      else
        err_msg = "X11 DISPLAY environment variable not set";
#else

      err_msg = "no graphical display found";

#endif
    }
}

bool
display_info::instance_ok (bool query)
{
  bool retval = true;

  if (! instance)
    {
      instance = new display_info (query);

      if (instance)
        singleton_cleanup_list::add (cleanup_instance);
    }

  if (! instance)
    {
      ::error ("unable to create display_info object!");

      retval = false;
    }

  return retval;
}