SL-12971: Add logging of Display Devices -- useful on dual GPU machines

indra/llwindow/llwindowwin32.cpp

@@ -676,6 +676,37 @@ LLWindowWin32::LLWindowWin32(LLWindowCallbacks* callbacks,
 	//		TrackMouseEvent( &track_mouse_event ); 
 	//	}
 
+    // SL-12971 dual GPU display
+    DISPLAY_DEVICEA display_device;
+    int             display_index = -1;
+    DWORD           display_flags = 0; // EDD_GET_DEVICE_INTERFACE_NAME ?
+    const size_t    display_bytes = sizeof(display_device);
+
+    do
+    {
+        if (display_index >= 0)
+        {
+            // CHAR DeviceName  [ 32] Adapter name
+            // CHAR DeviceString[128]
+            CHAR text[256];
+
+            size_t name_len = strlen(display_device.DeviceName  );
+            size_t desc_len = strlen(display_device.DeviceString);
+
+            CHAR *name = name_len ? display_device.DeviceName   : "???";
+            CHAR *desc = desc_len ? display_device.DeviceString : "???";
+
+            sprintf(text, "Display Device %d: %s, %s", display_index, name, desc);
+            LL_INFOS("Window") << text << LL_ENDL;
+        }
+
+        ::ZeroMemory(&display_device,display_bytes);
+        display_device.cb = display_bytes;
+
+        display_index++;
+    }  while( EnumDisplayDevicesA(NULL, display_index, &display_device, display_flags ));
+
+    LL_INFOS("Window") << "Total Display Devices: " << display_index << LL_ENDL;
 
 	//-----------------------------------------------------------------------
 	// Create GL drawing context