gdk: x11: Fill GdkMonitor manufacturer with PNP id from EDID

Previously, the manufacturer property of the GdkMonitor was NULL,
and having at least PNP id at GdkMonitor.manufacturer makes it
possible to distinguish between different monitors programmatically.

diff --git a/gdk/gdkmonitor.c b/gdk/gdkmonitor.c
index 2d27c29972254bef56bc3b3fdbe6e8ca4f4db15a..37e2c872eb0b7c5953c675ab1d56f12550e5fffe 100644 (file)
--- a/gdk/gdkmonitor.c
+++ b/gdk/gdkmonitor.c
@@ -401,7 +401,12 @@ gdk_monitor_get_connector (GdkMonitor *monitor)
  * gdk_monitor_get_manufacturer:
  * @monitor: a #GdkMonitor
  *
- * Gets the name of the monitor's manufacturer, if available.
+ * Gets the name or PNP ID of the monitor's manufacturer, if available.
+ *
+ * Note that this value might also vary depending on actual
+ * display backend.
+ *
+ * PNP ID registry is located at https://uefi.org/pnp_id_list
  *
  * Returns: (transfer none) (nullable): the name of the manufacturer, or %NULL
  */

diff --git a/gdk/x11/gdkscreen-x11.c b/gdk/x11/gdkscreen-x11.c
index cda654f04ed57ab61a03dd7cabda4a61b8263e89..ffba0708f7ab28ae11707e56d5edc011eb5e2fd6 100644 (file)
--- a/gdk/x11/gdkscreen-x11.c
+++ b/gdk/x11/gdkscreen-x11.c
@@ -354,6 +354,7 @@ init_randr15 (GdkX11Screen *x11_screen, gboolean *changed)
       GdkRectangle geometry;
       GdkRectangle newgeo;
       char *name;
+      char *manufacturer = NULL;
       int refresh_rate = 0;
 
       gdk_x11_display_error_trap_push (display);
@@ -405,6 +406,50 @@ init_randr15 (GdkX11Screen *x11_screen, gboolean *changed)
           g_ptr_array_add (x11_display->monitors, monitor);
         }
 
+      /* Fetch minimal manufacturer information (PNP ID) from EDID */
+      {
+        #define EDID_LENGTH 128
+        Atom actual_type, edid_atom;
+        char tmp[3];
+        int actual_format;
+        unsigned char *prop;
+        unsigned long nbytes, bytes_left;
+        Display *disp = GDK_DISPLAY_XDISPLAY (x11_display);
+
+        edid_atom = XInternAtom (disp, RR_PROPERTY_RANDR_EDID, FALSE);
+
+        XRRGetOutputProperty (disp, output,
+                              edid_atom,
+                              0,
+                              EDID_LENGTH,
+                              FALSE,
+                              FALSE,
+                              AnyPropertyType,
+                              &actual_type,
+                              &actual_format,
+                              &nbytes,
+                              &bytes_left,
+                              &prop);
+
+        // Check partial EDID header (whole header: 00 ff ff ff ff ff ff 00)
+        if (nbytes >= EDID_LENGTH && prop[0] == 0x00 && prop[1] == 0xff)
+          {
+            /* decode the Vendor ID from three 5 bit words packed into 2 bytes
+             * /--08--\/--09--\
+             * 7654321076543210
+             * |\---/\---/\---/
+             * R  C1   C2   C3 */
+            tmp[0] = 'A' + ((prop[8] & 0x7c) / 4) - 1;
+            tmp[1] = 'A' + ((prop[8] & 0x3) * 8) + ((prop[9] & 0xe0) / 32) - 1;
+            tmp[2] = 'A' + (prop[9] & 0x1f) - 1;
+
+            manufacturer = g_strndup (tmp, sizeof (tmp));
+          }
+
+        XFree(prop);
+        #undef EDID_LENGTH
+      }
+
       gdk_monitor_get_geometry (GDK_MONITOR (monitor), &geometry);
       name = g_strndup (output_info->name, output_info->nameLen);
 
@@ -433,6 +478,8 @@ init_randr15 (GdkX11Screen *x11_screen, gboolean *changed)
       gdk_monitor_set_scale_factor (GDK_MONITOR (monitor), x11_screen->surface_scale);
       gdk_monitor_set_model (GDK_MONITOR (monitor), name);
       gdk_monitor_set_connector (GDK_MONITOR (monitor), name);
+      gdk_monitor_set_manufacturer (GDK_MONITOR (monitor), manufacturer);
+      g_free (manufacturer);
       g_free (name);
 
       if (rr_monitors[i].primary)