cdisplay.c

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////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2009-2026 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// 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
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////
 
#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif
 
#include <stdlib.h>
 
#if defined (OCTAVE_USE_WINDOWS_API)
#  include <windows.h>
#elif defined (HAVE_FRAMEWORK_CARBON)
#  include <Carbon/Carbon.h>
#else
#  if defined (HAVE_X_WINDOWS)
#    include <X11/Xlib.h>
#  endif
#  if defined (HAVE_WAYLAND_CLIENT)
#    include <string.h>
#    include <wayland-client.h>
#  endif
#endif
 
#include "cdisplay.h"
 
// Programming Note: This file exists so that we can hide system
// header files that make heavy use of macros and C-style casts in a C
// language file and avoid warnings about using old-style casts in C++.
// Additionally, on OS X systems, including the Carbon.h header file
// results in the declaration of a "panic" function that conflicts with
// Octave's global panic function, so Carbon.h can't be included in any
// file that also includes Octave's error.h header file.
 
// Please do NOT eliminate this file and move code from here to
// display.cc.
 
#if defined (HAVE_WAYLAND_CLIENT)
 
// struct to store display information
struct s_display_info {
    int ht;
    int wd;
    int ht_mm;
    int wd_mm;
    int scale;
    int avail;
};
 
// set up Wayland output event listener to capture the relevant information
 
static void
oct_wl_geometry (void *data, struct wl_output *output, int x, int y,
                 int physical_width, int physical_height, int subpixel,
                 const char *make, const char *model, int transform)
{
  struct s_display_info *info = data;
  info->ht_mm = physical_height;
  info->wd_mm = physical_width;
 
  octave_unused_parameter (output);
  octave_unused_parameter (x);
  octave_unused_parameter (y);
  octave_unused_parameter (subpixel);
  octave_unused_parameter (make);
  octave_unused_parameter (model);
  octave_unused_parameter (transform);
}
 
static void
oct_wl_mode (void *data, struct wl_output *output, unsigned int flags,
             int width, int height, int refresh)
{
  struct s_display_info *info = data;
 
  if (flags & WL_OUTPUT_MODE_CURRENT)
    {
      info->wd = width;
      info->ht = height;
      info->avail = 1;
    }
 
  octave_unused_parameter (output);
  octave_unused_parameter (refresh);
}
 
static void oct_wl_done (void *data, struct wl_output *output)
{
  octave_unused_parameter (data);
  octave_unused_parameter (output);
}
 
static void
oct_wl_scale (void *data, struct wl_output *output, int32_t factor)
{
  struct s_display_info *info = data;
  info->scale = factor;
 
  octave_unused_parameter (output);
}
 
static const struct wl_output_listener output_listener = {
    .geometry = oct_wl_geometry,
    .mode = oct_wl_mode,
    .done = oct_wl_done,
    .scale = oct_wl_scale
};
 
// register above output listener
 
static void
oct_wl_global (void *data, struct wl_registry *registry, uint32_t name,
               const char *interface, uint32_t version)
{
  struct s_display_info *info = data;
 
  // collect info only for output device
  if (strcmp (interface, wl_output_interface.name) == 0)
    {
      // bind wl_output interface
      struct wl_output *output = wl_registry_bind (registry, name,
                                                   &wl_output_interface, 1);
      // set up event listener
      wl_output_add_listener (output, &output_listener, info);
    }
 
  octave_unused_parameter (version);
}
 
static void
oct_wl_global_remove (void *data, struct wl_registry *registry, uint32_t name)
{
  octave_unused_parameter (data);
  octave_unused_parameter (registry);
  octave_unused_parameter (name);
}
 
static const struct wl_registry_listener registry_listener = {
    .global = oct_wl_global,
    .global_remove = oct_wl_global_remove
};
 
#endif
 
const char *
octave_get_display_info (const char *dpy_name, int *ht, int *wd, int *dp,
                         double *rx, double *ry, int *dpy_avail)
{
  const char *msg = NULL;
 
  *dpy_avail = 0;
 
  double ht_mm = 0.0;
  double wd_mm = 0.0;
 
#if defined (OCTAVE_USE_WINDOWS_API)
 
  octave_unused_parameter (dpy_name);
 
  HDC hdc = GetDC (0);
 
  if (hdc)
    {
      *dp = GetDeviceCaps (hdc, BITSPIXEL);
 
      *ht = GetDeviceCaps (hdc, VERTRES);
      *wd = GetDeviceCaps (hdc, HORZRES);
 
      ht_mm = GetDeviceCaps (hdc, VERTSIZE);
      wd_mm = GetDeviceCaps (hdc, HORZSIZE);
 
      *dpy_avail = 1;
    }
  else
    msg = "no graphical display found";
 
#elif defined (HAVE_FRAMEWORK_CARBON)
 
  octave_unused_parameter (dpy_name);
 
  CGDirectDisplayID display = CGMainDisplayID ();
 
  if (display)
    {
#if defined (HAVE_CARBON_CGDISPLAYBITSPERPIXEL)
 
      *dp = CGDisplayBitsPerPixel (display);
 
#else
 
      /* FIXME: This will only work for MacOS > 10.5.  For earlier versions
         this code is not needed (use CGDisplayBitsPerPixel instead).  */
 
      CGDisplayModeRef mode = CGDisplayCopyDisplayMode (display);
      CFStringRef pixelEncoding = CGDisplayModeCopyPixelEncoding (mode);
 
      if (CFStringCompare (pixelEncoding, CFSTR (IO32BitDirectPixels), 0) == 0)
        *dp = 32;
      else if (CFStringCompare (pixelEncoding,
                                CFSTR (IO16BitDirectPixels), 0) == 0)
        *dp = 16;
      else
        *dp = 8;
 
#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.  */
 
      ht_mm = sz_mm.height;
      wd_mm = sz_mm.width;
 
      *dpy_avail = 1;
    }
  else
    msg = "no graphical display found";
 
#elif defined (HAVE_X_WINDOWS) || defined (HAVE_WAYLAND_CLIENT)
 
#  if defined (HAVE_X_WINDOWS)
 
  /* If dpy_name is NULL, XopenDisplay will look for DISPLAY in the
     environment.  */
 
  Display *display = XOpenDisplay (dpy_name);
 
  if (display)
    {
      Screen *screen = DefaultScreenOfDisplay (display);
 
      if (screen)
        {
          *dp = DefaultDepthOfScreen (screen);
 
          *ht = HeightOfScreen (screen);
          *wd = WidthOfScreen (screen);
 
          int screen_number = XScreenNumberOfScreen (screen);
 
          ht_mm = DisplayHeightMM (display, screen_number);
          wd_mm = DisplayWidthMM (display, screen_number);
 
          *dpy_avail = 1;
        }
#    if ! defined (HAVE_WAYLAND_CLIENT)
      else
        msg = "X11 display has no default screen";
#    endif
 
      XCloseDisplay (display);
    }
#    if ! defined (HAVE_WAYLAND_CLIENT)
  else
    msg = "unable to open X11 DISPLAY";
#    endif
#  endif
 
#  if defined (HAVE_WAYLAND_CLIENT)
  if (*dpy_avail == 0)
    {
      // try to connect to Wayland display
      struct wl_display *wldisplay = wl_display_connect (dpy_name);
 
      if (wldisplay)
        {
         struct s_display_info info = {0};
 
          // set up Wayland registry
          struct wl_registry *registry = wl_display_get_registry (wldisplay);
          // add output listener
          wl_registry_add_listener (registry, &registry_listener, &info);
          // process display events
          // first roundtrip to get registry events
          wl_display_roundtrip (wldisplay);
          // second roundtrip to get output events
          wl_display_roundtrip (wldisplay);
          // disconnect display
          wl_display_disconnect (wldisplay);
 
          if (info.avail)
            {
              // FIXME: There is no easy way to query the pixel depth using
              //        Wayland. The closest might be to query the used buffer
              //        format and to try and defer the pixel depth from that.
              //        But that is not easily done. So, just assume a pixel
              //        depth of 32 bits.
              *dp = 32;
 
              *ht = info.ht;
              *wd = info.wd;
 
              ht_mm = info.ht_mm;
              wd_mm = info.wd_mm;
 
              *dpy_avail = 1;
            }
          else
#    if defined (HAVE_X_WINDOWS)
            msg = "no Wayland or X11 display available";
#    else
            msg = "no Wayland display available";
#    endif
        }
      else
#    if defined (HAVE_X_WINDOWS)
        msg = "unable to open Wayland or X11 display";
#    else
        msg = "unable to open Wayland display";
#    endif
    }
#  endif
 
#else
 
  octave_unused_parameter (dpy_name);
  octave_unused_parameter (ht);
  octave_unused_parameter (wd);
  octave_unused_parameter (dp);
  octave_unused_parameter (rx);
  octave_unused_parameter (ry);
 
  msg = "no graphical display found";
 
#endif
 
  if (*dpy_avail)
    {
      if (wd_mm == 0 || ht_mm == 0)
        {
          msg = "screen width or height reported to be zero";
 
          // Sizes reported as zero have been found on some systems.
          // For example, X/Wayland running inside virtualbox.
 
          // Guess a DPI.
 
          *rx = 96.0;
          *ry = 96.0;
        }
      else
        {
          *rx = *wd * 25.4 / wd_mm;
          *ry = *ht * 25.4 / ht_mm;
        }
    }
 
  return msg;
}