Changeset 72011 in vbox for trunk/src

Timestamp:

Apr 25, 2018 12:21:09 PM (7 years ago)

Author:

vboxsync

Message:

UIDesktopWidgetWatchdog.cpp: Only resolve EnumDisplayMonitors once, and make sure to perfectly match the function pointer with the SDK headers.

File:

• trunk/src/VBox/Frontends/VirtualBox/src/globals/UIDesktopWidgetWatchdog.cpp (modified) (2 diffs)

trunk/src/VBox/Frontends/VirtualBox/src/globals/UIDesktopWidgetWatchdog.cpp

@@ -59 +59 @@
 } MONITOR_DPI_TYPE;
 
-bool MonitorEnumProcF(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lpClipRect, LPARAM dwData)
+static BOOL CALLBACK MonitorEnumProcF(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lpClipRect, LPARAM dwData)
 {
     /* These required for clipped screens only: */
@@ -432 +432 @@
 
 #ifdef VBOX_WS_WIN
-
-    /* Dynamically access User32.dll: */
-    QLibrary user32("User32.dll", NULL);
-
-    /* Enumerate available monitors through EnumDisplayMonitors (available since Windows 2k): */
-    typedef bool (*MonitorEnumProcFP)(HMONITOR hMonitor, HDC hdcMonitor, LPRECT lpClipRect, LPARAM dwData);
-    typedef bool (*EnumDisplayMonitorsFP)(HDC hdc, LPCRECT lprcRect, MonitorEnumProcFP lpfnEnum, LPARAM dwData);
-    EnumDisplayMonitorsFP EnumDisplayMonitorsF = (EnumDisplayMonitorsFP)user32.resolve("EnumDisplayMonitors");
-    if (EnumDisplayMonitorsF)
+    /* Dynamically resolve EnumDisplayMonitors (available since Windows 2k) first time through: */
+    static bool volatile                  s_fResolved = false;
+    static decltype(EnumDisplayMonitors) *s_pfnEnumDisplayMonitors = NULL;
+    decltype(EnumDisplayMonitors)        *pfnEnumDisplayMonitors;
+    if (s_fResolved)
+        pfnEnumDisplayMonitors = s_pfnEnumDisplayMonitors;
+    else
+    {
+        pfnEnumDisplayMonitors = (decltype(EnumDisplayMonitors) *)GetProcAddress(GetModuleHandleW(L"USER32.DLL"),
+                                                                                 "EnumDisplayMonitors");
+        s_pfnEnumDisplayMonitors = pfnEnumDisplayMonitors;
+        s_fResolved = true;
+    }
+
+    /* Enumerate available monitors through EnumDisplayMonitors if available: */
+    if (pfnEnumDisplayMonitors)
     {
         QList<QPair<int, int> > listOfScreenDPI;
-        EnumDisplayMonitorsF(0, 0, MonitorEnumProcF, (LPARAM)&listOfScreenDPI);
+        pfnEnumDisplayMonitors(0, 0, MonitorEnumProcF, (LPARAM)&listOfScreenDPI);
         if (iHostScreenIndex >= 0 && iHostScreenIndex < listOfScreenDPI.size())
         {