Fix no monitors found on VMware Windows guest

Monitor enumeration now switches to adapters if no displays are
connected to active adapters.  This should provide usable monitor
objects on headless and VMware guest systems.

Fixes #441.
Fixes #556.
Fixes #594.

README.md

@@ -101,6 +101,7 @@ does not find Doxygen, the documentation will not be generated.
                    when no windows existed
  - [Win32] Bugfix: Activating or deactivating displays in software did not
                    trigger monitor callback
+ - [Win32] Bugfix: No monitors were listed on headless and VMware guest systems
  - [Cocoa] Removed support for OS X 10.6
  - [Cocoa] Bugfix: Full screen windows on secondary monitors were mispositioned
  - [Cocoa] Bugfix: Connecting a joystick that reports no name would segfault

src/win32_monitor.c

@@ -33,6 +33,59 @@
 #include <malloc.h>
 
 
+// Create monitor from an adapter and (optionally) a display
+//
+static _GLFWmonitor* createMonitor(DISPLAY_DEVICEW* adapter,
+                                   DISPLAY_DEVICEW* display)
+{
+    _GLFWmonitor* monitor;
+    char* name;
+    HDC dc;
+
+    if (display)
+        name = _glfwCreateUTF8FromWideStringWin32(display->DeviceString);
+    else
+        name = _glfwCreateUTF8FromWideStringWin32(adapter->DeviceString);
+    if (!name)
+    {
+        _glfwInputError(GLFW_PLATFORM_ERROR,
+                        "Win32: Failed to convert string to UTF-8");
+        return NULL;
+    }
+
+    dc = CreateDCW(L"DISPLAY", adapter->DeviceName, NULL, NULL);
+
+    monitor = _glfwAllocMonitor(name,
+                                GetDeviceCaps(dc, HORZSIZE),
+                                GetDeviceCaps(dc, VERTSIZE));
+
+    DeleteDC(dc);
+    free(name);
+
+    if (adapter->StateFlags & DISPLAY_DEVICE_MODESPRUNED)
+        monitor->win32.modesPruned = GLFW_TRUE;
+
+    wcscpy(monitor->win32.adapterName, adapter->DeviceName);
+    WideCharToMultiByte(CP_UTF8, 0,
+                        adapter->DeviceName, -1,
+                        monitor->win32.publicAdapterName,
+                        sizeof(monitor->win32.publicAdapterName),
+                        NULL, NULL);
+
+    if (display)
+    {
+        wcscpy(monitor->win32.displayName, display->DeviceName);
+        WideCharToMultiByte(CP_UTF8, 0,
+                            display->DeviceName, -1,
+                            monitor->win32.publicDisplayName,
+                            sizeof(monitor->win32.publicDisplayName),
+                            NULL, NULL);
+    }
+
+    return monitor;
+}
+
+
 //////////////////////////////////////////////////////////////////////////
 //////                       GLFW internal API                      //////
 //////////////////////////////////////////////////////////////////////////
@@ -96,17 +149,18 @@ void _glfwRestoreVideoModeWin32(_GLFWmonitor* monitor)
 _GLFWmonitor** _glfwPlatformGetMonitors(int* count)
 {
     int found = 0;
+    DWORD adapterIndex, displayIndex, primaryIndex = 0;
+    DISPLAY_DEVICEW adapter, display;
+    GLFWbool hasDisplays = GLFW_FALSE;
     _GLFWmonitor** monitors = NULL;
-    DWORD adapterIndex, displayIndex;
 
     *count = 0;
 
+    // HACK: Check if any active adapters have connected displays
+    //       If not, this is a headless system or a VMware guest
+
     for (adapterIndex = 0;  ;  adapterIndex++)
     {
-        DISPLAY_DEVICEW adapter;
-        int widthMM, heightMM;
-        HDC dc;
-
         ZeroMemory(&adapter, sizeof(DISPLAY_DEVICEW));
         adapter.cb = sizeof(DISPLAY_DEVICEW);
 
@@ -116,71 +170,65 @@ _GLFWmonitor** _glfwPlatformGetMonitors(int* count)
         if (!(adapter.StateFlags & DISPLAY_DEVICE_ACTIVE))
             continue;
 
-        dc = CreateDCW(L"DISPLAY", adapter.DeviceName, NULL, NULL);
-        widthMM  = GetDeviceCaps(dc, HORZSIZE);
-        heightMM = GetDeviceCaps(dc, VERTSIZE);
-        DeleteDC(dc);
+        ZeroMemory(&display, sizeof(DISPLAY_DEVICEW));
+        display.cb = sizeof(DISPLAY_DEVICEW);
 
-        for (displayIndex = 0;  ;  displayIndex++)
+        if (EnumDisplayDevicesW(adapter.DeviceName, 0, &display, 0))
         {
-            DISPLAY_DEVICEW display;
-            _GLFWmonitor* monitor;
-            char* name;
-
-            ZeroMemory(&display, sizeof(DISPLAY_DEVICEW));
-            display.cb = sizeof(DISPLAY_DEVICEW);
-
-            if (!EnumDisplayDevicesW(adapter.DeviceName, displayIndex, &display, 0))
-                break;
+            hasDisplays = GLFW_TRUE;
+            break;
+        }
+    }
 
-            name = _glfwCreateUTF8FromWideStringWin32(display.DeviceString);
-            if (!name)
-            {
-                _glfwInputError(GLFW_PLATFORM_ERROR,
-                                "Win32: Failed to convert string to UTF-8");
-                continue;
-            }
+    for (adapterIndex = 0;  ;  adapterIndex++)
+    {
+        ZeroMemory(&adapter, sizeof(DISPLAY_DEVICEW));
+        adapter.cb = sizeof(DISPLAY_DEVICEW);
 
-            monitor = _glfwAllocMonitor(name, widthMM, heightMM);
-            free(name);
+        if (!EnumDisplayDevicesW(NULL, adapterIndex, &adapter, 0))
+            break;
 
-            if (adapter.StateFlags & DISPLAY_DEVICE_MODESPRUNED)
-                monitor->win32.modesPruned = GLFW_TRUE;
+        if (!(adapter.StateFlags & DISPLAY_DEVICE_ACTIVE))
+            continue;
 
-            wcscpy(monitor->win32.adapterName, adapter.DeviceName);
-            wcscpy(monitor->win32.displayName, display.DeviceName);
+        if (adapter.StateFlags & DISPLAY_DEVICE_PRIMARY_DEVICE)
+            primaryIndex = found;
 
-            WideCharToMultiByte(CP_UTF8, 0,
-                                adapter.DeviceName, -1,
-                                monitor->win32.publicAdapterName,
-                                sizeof(monitor->win32.publicAdapterName),
-                                NULL, NULL);
+        if (hasDisplays)
+        {
+            for (displayIndex = 0;  ;  displayIndex++)
+            {
+                ZeroMemory(&display, sizeof(DISPLAY_DEVICEW));
+                display.cb = sizeof(DISPLAY_DEVICEW);
 
-            WideCharToMultiByte(CP_UTF8, 0,
-                                display.DeviceName, -1,
-                                monitor->win32.publicDisplayName,
-                                sizeof(monitor->win32.publicDisplayName),
-                                NULL, NULL);
+                if (!EnumDisplayDevicesW(adapter.DeviceName, displayIndex, &display, 0))
+                    break;
 
+                found++;
+                monitors = realloc(monitors, sizeof(_GLFWmonitor*) * found);
+                monitors[found - 1] = createMonitor(&adapter, &display);
+            }
+        }
+        else
+        {
             found++;
             monitors = realloc(monitors, sizeof(_GLFWmonitor*) * found);
-            monitors[found - 1] = monitor;
-
-            if (adapter.StateFlags & DISPLAY_DEVICE_PRIMARY_DEVICE &&
-                displayIndex == 0)
-            {
-                _GLFW_SWAP_POINTERS(monitors[0], monitors[found - 1]);
-            }
+            monitors[found - 1] = createMonitor(&adapter, NULL);
         }
     }
 
+    _GLFW_SWAP_POINTERS(monitors[0], monitors[primaryIndex]);
+
     *count = found;
     return monitors;
 }
 
 GLFWbool _glfwPlatformIsSameMonitor(_GLFWmonitor* first, _GLFWmonitor* second)
 {
-    return wcscmp(first->win32.displayName, second->win32.displayName) == 0;
+    if (wcslen(first->win32.displayName))
+        return wcscmp(first->win32.displayName, second->win32.displayName) == 0;
+    else
+        return wcscmp(first->win32.adapterName, second->win32.adapterName) == 0;
 }
 
 void _glfwPlatformGetMonitorPos(_GLFWmonitor* monitor, int* xpos, int* ypos)