Windows QPA: Increase API level to 0x600 (Windows Vista).

- Directly link against dwmapi which should be present on
  Windows Vista and remove duplicated header constants.
- Remove struct QWindowsShell32DL since all required functions
  are present on Windows Vista.
- Remove functions that are no longer needed from QWindowsUser32DLL
  with exception of the clipboard functions which are not present
  in the MinGW stub libraries until v5.

Task-number: QTBUG-51673
Change-Id: Ia4a8a3f1db0f0d02322317d547e61ae39f9008b5
Reviewed-by: Oliver Wolff <oliver.wolff@theqtcompany.com>

src/plugins/platforms/windows/qwindowsbackingstore.cpp

@@ -100,19 +100,15 @@ void QWindowsBackingStore::flush(QWindow *window, const QRegion &region,
         POINT ptDst = {r.x(), r.y()};
         POINT ptSrc = {0, 0};
         BLENDFUNCTION blend = {AC_SRC_OVER, 0, BYTE(qRound(255.0 * rw->opacity())), AC_SRC_ALPHA};
-        if (QWindowsContext::user32dll.updateLayeredWindowIndirect) {
+        RECT dirty = {dirtyRect.x(), dirtyRect.y(),
-            RECT dirty = {dirtyRect.x(), dirtyRect.y(),
+                      dirtyRect.x() + dirtyRect.width(), dirtyRect.y() + dirtyRect.height()};
-                dirtyRect.x() + dirtyRect.width(), dirtyRect.y() + dirtyRect.height()};
+        UPDATELAYEREDWINDOWINFO info = {sizeof(info), NULL, &ptDst, &size, m_image->hdc(), &ptSrc, 0, &blend, ULW_ALPHA, &dirty};
-            UPDATELAYEREDWINDOWINFO info = {sizeof(info), NULL, &ptDst, &size, m_image->hdc(), &ptSrc, 0, &blend, ULW_ALPHA, &dirty};
+        const BOOL result = UpdateLayeredWindowIndirect(rw->handle(), &info);
-            const BOOL result = QWindowsContext::user32dll.updateLayeredWindowIndirect(rw->handle(), &info);
+        if (!result)
-            if (!result)
+            qErrnoWarning("UpdateLayeredWindowIndirect failed for ptDst=(%d, %d),"
-                qErrnoWarning("UpdateLayeredWindowIndirect failed for ptDst=(%d, %d),"
+                          " size=(%dx%d), dirty=(%dx%d %d, %d)", r.x(), r.y(),
-                              " size=(%dx%d), dirty=(%dx%d %d, %d)", r.x(), r.y(),
+                          r.width(), r.height(), dirtyRect.width(), dirtyRect.height(),
-                              r.width(), r.height(), dirtyRect.width(), dirtyRect.height(),
+                          dirtyRect.x(), dirtyRect.y());
-                              dirtyRect.x(), dirtyRect.y());
-        } else {
-            QWindowsContext::user32dll.updateLayeredWindow(rw->handle(), NULL, &ptDst, &size, m_image->hdc(), &ptSrc, 0, &blend, ULW_ALPHA);
-        }
     } else {
         const HDC dc = rw->getDC();
         if (!dc) {

src/plugins/platforms/windows/qwindowsclipboard.cpp

@@ -237,8 +237,7 @@ void QWindowsClipboard::propagateClipboardMessage(UINT message, WPARAM wParam, L
         return;
     // In rare cases, a clipboard viewer can hang (application crashed,
     // suspended by a shell prompt 'Select' or debugger).
-    if (QWindowsContext::user32dll.isHungAppWindow
+    if (IsHungAppWindow(m_nextClipboardViewer)) {
-        && QWindowsContext::user32dll.isHungAppWindow(m_nextClipboardViewer)) {
         qWarning("Cowardly refusing to send clipboard message to hung application...");
         return;
     }

src/plugins/platforms/windows/qwindowscontext.cpp

@@ -97,35 +97,26 @@ int QWindowsContext::verbose = 0;
 #    define LANG_SYRIAC 0x5a
 #endif
 
-static inline bool useRTL_Extensions(QSysInfo::WinVersion ver)
+static inline bool useRTL_Extensions()
 {
-    if ((ver & QSysInfo::WV_NT_based) && (ver >= QSysInfo::WV_VISTA)) {
+    // Since the IsValidLanguageGroup/IsValidLocale functions always return true on
-        // Since the IsValidLanguageGroup/IsValidLocale functions always return true on
+    // Vista, check the Keyboard Layouts for enabling RTL.
-        // Vista, check the Keyboard Layouts for enabling RTL.
+    if (const int nLayouts = GetKeyboardLayoutList(0, 0)) {
-        if (const int nLayouts = GetKeyboardLayoutList(0, 0)) {
+        QScopedArrayPointer<HKL> lpList(new HKL[nLayouts]);
-            QScopedArrayPointer<HKL> lpList(new HKL[nLayouts]);
+        GetKeyboardLayoutList(nLayouts, lpList.data());
-            GetKeyboardLayoutList(nLayouts, lpList.data());
+        for (int i = 0; i < nLayouts; ++i) {
-            for (int i = 0; i < nLayouts; ++i) {
+            switch (PRIMARYLANGID((quintptr)lpList[i])) {
-                switch (PRIMARYLANGID((quintptr)lpList[i])) {
+            case LANG_ARABIC:
-                case LANG_ARABIC:
+            case LANG_HEBREW:
-                case LANG_HEBREW:
+            case LANG_FARSI:
-                case LANG_FARSI:
+            case LANG_SYRIAC:
-                case LANG_SYRIAC:
+                return true;
-                    return true;
+            default:
-                default:
+                break;
-                    break;
-                }
             }
         }
-        return false;
+    }
-    } // NT/Vista
+    return false;
-    // Pre-NT: figure out whether a RTL language is installed
-    return IsValidLanguageGroup(LGRPID_ARABIC, LGRPID_INSTALLED)
-                            || IsValidLanguageGroup(LGRPID_HEBREW, LGRPID_INSTALLED)
-                            || IsValidLocale(MAKELCID(MAKELANGID(LANG_ARABIC, SUBLANG_DEFAULT), SORT_DEFAULT), LCID_INSTALLED)
-                            || IsValidLocale(MAKELCID(MAKELANGID(LANG_HEBREW, SUBLANG_DEFAULT), SORT_DEFAULT), LCID_INSTALLED)
-                            || IsValidLocale(MAKELCID(MAKELANGID(LANG_SYRIAC, SUBLANG_DEFAULT), SORT_DEFAULT), LCID_INSTALLED)
-                            || IsValidLocale(MAKELCID(MAKELANGID(LANG_FARSI, SUBLANG_DEFAULT), SORT_DEFAULT), LCID_INSTALLED);
 }
 
 #if !defined(QT_NO_SESSIONMANAGER)
@@ -152,9 +143,7 @@ static inline QWindowsSessionManager *platformSessionManager() {
     \ingroup qt-lighthouse-win
 */
 QWindowsUser32DLL::QWindowsUser32DLL() :
-    setLayeredWindowAttributes(0), updateLayeredWindow(0),
+    isTouchWindow(0),
-    updateLayeredWindowIndirect(0),
-    isHungAppWindow(0), isTouchWindow(0),
     registerTouchWindow(0), unregisterTouchWindow(0),
     getTouchInputInfo(0), closeTouchInputHandle(0), setProcessDPIAware(0),
     addClipboardFormatListener(0), removeClipboardFormatListener(0),
@@ -165,20 +154,11 @@ QWindowsUser32DLL::QWindowsUser32DLL() :
 void QWindowsUser32DLL::init()
 {
     QSystemLibrary library(QStringLiteral("user32"));
-    // MinGW (g++ 3.4.5) accepts only C casts.
-    setLayeredWindowAttributes = (SetLayeredWindowAttributes)(library.resolve("SetLayeredWindowAttributes"));
-    updateLayeredWindow = (UpdateLayeredWindow)(library.resolve("UpdateLayeredWindow"));
-    if (Q_UNLIKELY(!setLayeredWindowAttributes || !updateLayeredWindow))
-        qFatal("This version of Windows is not supported (User32.dll is missing the symbols 'SetLayeredWindowAttributes', 'UpdateLayeredWindow').");
-
-    updateLayeredWindowIndirect = (UpdateLayeredWindowIndirect)(library.resolve("UpdateLayeredWindowIndirect"));
-    isHungAppWindow = (IsHungAppWindow)library.resolve("IsHungAppWindow");
     setProcessDPIAware = (SetProcessDPIAware)library.resolve("SetProcessDPIAware");
 
-    if (QSysInfo::windowsVersion() >= QSysInfo::WV_VISTA) {
+    addClipboardFormatListener = (AddClipboardFormatListener)library.resolve("AddClipboardFormatListener");
-        addClipboardFormatListener = (AddClipboardFormatListener)library.resolve("AddClipboardFormatListener");
+    removeClipboardFormatListener = (RemoveClipboardFormatListener)library.resolve("RemoveClipboardFormatListener");
-        removeClipboardFormatListener = (RemoveClipboardFormatListener)library.resolve("RemoveClipboardFormatListener");
+
-    }
     getDisplayAutoRotationPreferences = (GetDisplayAutoRotationPreferences)library.resolve("GetDisplayAutoRotationPreferences");
     setDisplayAutoRotationPreferences = (SetDisplayAutoRotationPreferences)library.resolve("SetDisplayAutoRotationPreferences");
 }
@@ -196,38 +176,6 @@ bool QWindowsUser32DLL::initTouch()
     return isTouchWindow && registerTouchWindow && unregisterTouchWindow && getTouchInputInfo && closeTouchInputHandle;
 }
 
-/*!
-    \class QWindowsShell32DLL
-    \brief Struct that contains dynamically resolved symbols of Shell32.dll.
-
-    The stub libraries shipped with the MinGW compiler miss some of the
-    functions. They need to be retrieved dynamically.
-
-    \sa QWindowsUser32DLL
-
-    \internal
-    \ingroup qt-lighthouse-win
-*/
-
-QWindowsShell32DLL::QWindowsShell32DLL()
-    : sHCreateItemFromParsingName(0)
-    , sHGetKnownFolderIDList(0)
-    , sHGetStockIconInfo(0)
-    , sHGetImageList(0)
-    , sHCreateItemFromIDList(0)
-{
-}
-
-void QWindowsShell32DLL::init()
-{
-    QSystemLibrary library(QStringLiteral("shell32"));
-    sHCreateItemFromParsingName = (SHCreateItemFromParsingName)(library.resolve("SHCreateItemFromParsingName"));
-    sHGetKnownFolderIDList = (SHGetKnownFolderIDList)(library.resolve("SHGetKnownFolderIDList"));
-    sHGetStockIconInfo = (SHGetStockIconInfo)library.resolve("SHGetStockIconInfo");
-    sHGetImageList = (SHGetImageList)library.resolve("SHGetImageList");
-    sHCreateItemFromIDList = (SHCreateItemFromIDList)library.resolve("SHCreateItemFromIDList");
-}
-
 QWindowsShcoreDLL::QWindowsShcoreDLL()
     : getProcessDpiAwareness(0)
     , setProcessDpiAwareness(0)
@@ -246,7 +194,6 @@ void QWindowsShcoreDLL::init()
 }
 
 QWindowsUser32DLL QWindowsContext::user32dll;
-QWindowsShell32DLL QWindowsContext::shell32dll;
 QWindowsShcoreDLL QWindowsContext::shcoredll;
 
 QWindowsContext *QWindowsContext::m_instance = 0;
@@ -292,16 +239,14 @@ QWindowsContextPrivate::QWindowsContextPrivate()
     , m_eventType(QByteArrayLiteral("windows_generic_MSG"))
     , m_lastActiveWindow(0), m_asyncExpose(0)
 {
-    const QSysInfo::WinVersion ver = QSysInfo::windowsVersion();
     QWindowsContext::user32dll.init();
-    QWindowsContext::shell32dll.init();
     QWindowsContext::shcoredll.init();
 
     if (m_mouseHandler.touchDevice() && QWindowsContext::user32dll.initTouch())
         m_systemInfo |= QWindowsContext::SI_SupportsTouch;
     m_displayContext = GetDC(0);
     m_defaultDPI = GetDeviceCaps(m_displayContext, LOGPIXELSY);
-    if (useRTL_Extensions(ver)) {
+    if (useRTL_Extensions()) {
         m_systemInfo |= QWindowsContext::SI_RTL_Extensions;
         m_keyMapper.setUseRTLExtensions(true);
     }

src/plugins/platforms/windows/qwindowscontext.h

@@ -85,31 +85,17 @@ struct QWindowsUser32DLL
     inline void init();
     inline bool initTouch();
 
-    typedef BOOL (WINAPI *IsTouchWindow)(HWND, PULONG);
+    typedef BOOL (WINAPI *IsTouchWindow)(HWND, PULONG); // Windows 7
     typedef BOOL (WINAPI *RegisterTouchWindow)(HWND, ULONG);
     typedef BOOL (WINAPI *UnregisterTouchWindow)(HWND);
     typedef BOOL (WINAPI *GetTouchInputInfo)(HANDLE, UINT, PVOID, int);
     typedef BOOL (WINAPI *CloseTouchInputHandle)(HANDLE);
-    typedef BOOL (WINAPI *SetLayeredWindowAttributes)(HWND, COLORREF, BYTE, DWORD);
-    typedef BOOL (WINAPI *UpdateLayeredWindow)(HWND, HDC , const POINT *,
-                 const SIZE *, HDC, const POINT *, COLORREF,
-                 const BLENDFUNCTION *, DWORD);
-    typedef BOOL (WINAPI *UpdateLayeredWindowIndirect)(HWND, const UPDATELAYEREDWINDOWINFO *);
-    typedef BOOL (WINAPI *IsHungAppWindow)(HWND);
     typedef BOOL (WINAPI *SetProcessDPIAware)();
     typedef BOOL (WINAPI *AddClipboardFormatListener)(HWND);
     typedef BOOL (WINAPI *RemoveClipboardFormatListener)(HWND);
     typedef BOOL (WINAPI *GetDisplayAutoRotationPreferences)(DWORD *);
     typedef BOOL (WINAPI *SetDisplayAutoRotationPreferences)(DWORD);
 
-    // Functions missing in Q_CC_GNU stub libraries.
-    SetLayeredWindowAttributes setLayeredWindowAttributes;
-    UpdateLayeredWindow updateLayeredWindow;
-
-    // Functions missing in older versions of Windows
-    UpdateLayeredWindowIndirect updateLayeredWindowIndirect;
-    IsHungAppWindow isHungAppWindow;
-
     // Touch functions from Windows 7 onwards (also for use with Q_CC_MSVC).
     IsTouchWindow isTouchWindow;
     RegisterTouchWindow registerTouchWindow;
@@ -120,7 +106,8 @@ struct QWindowsUser32DLL
     // Windows Vista onwards
     SetProcessDPIAware setProcessDPIAware;
 
-    // Clipboard listeners, Windows Vista onwards
+    // Clipboard listeners are present on Windows Vista onwards
+    // but missing in MinGW 4.9 stub libs. Can be removed in MinGW 5.
     AddClipboardFormatListener addClipboardFormatListener;
     RemoveClipboardFormatListener removeClipboardFormatListener;
 
@@ -129,24 +116,6 @@ struct QWindowsUser32DLL
     SetDisplayAutoRotationPreferences setDisplayAutoRotationPreferences;
 };
 
-struct QWindowsShell32DLL
-{
-    QWindowsShell32DLL();
-    inline void init();
-
-    typedef HRESULT (WINAPI *SHCreateItemFromParsingName)(PCWSTR, IBindCtx *, const GUID&, void **);
-    typedef HRESULT (WINAPI *SHGetKnownFolderIDList)(const GUID &, DWORD, HANDLE, PIDLIST_ABSOLUTE *);
-    typedef HRESULT (WINAPI *SHGetStockIconInfo)(int , int , _SHSTOCKICONINFO *);
-    typedef HRESULT (WINAPI *SHGetImageList)(int, REFIID , void **);
-    typedef HRESULT (WINAPI *SHCreateItemFromIDList)(PCIDLIST_ABSOLUTE, REFIID, void **);
-
-    SHCreateItemFromParsingName sHCreateItemFromParsingName;
-    SHGetKnownFolderIDList sHGetKnownFolderIDList;
-    SHGetStockIconInfo sHGetStockIconInfo;
-    SHGetImageList sHGetImageList;
-    SHCreateItemFromIDList sHCreateItemFromIDList;
-};
-
 // Shell scaling library (Windows 8.1 onwards)
 struct QWindowsShcoreDLL {
     QWindowsShcoreDLL();
@@ -235,7 +204,6 @@ public:
     QWindowsTabletSupport *tabletSupport() const;
 
     static QWindowsUser32DLL user32dll;
-    static QWindowsShell32DLL shell32dll;
     static QWindowsShcoreDLL shcoredll;
 
     static QByteArray comErrorString(HRESULT hr);

src/plugins/platforms/windows/qwindowsdialoghelpers.cpp

@@ -988,22 +988,18 @@ void QWindowsNativeFileDialogBase::setWindowTitle(const QString &title)
 IShellItem *QWindowsNativeFileDialogBase::shellItem(const QUrl &url)
 {
     if (url.isLocalFile()) {
-        if (!QWindowsContext::shell32dll.sHCreateItemFromParsingName)
-            return Q_NULLPTR;
         IShellItem *result = Q_NULLPTR;
         const QString native = QDir::toNativeSeparators(url.toLocalFile());
         const HRESULT hr =
-                QWindowsContext::shell32dll.sHCreateItemFromParsingName(reinterpret_cast<const wchar_t *>(native.utf16()),
+                SHCreateItemFromParsingName(reinterpret_cast<const wchar_t *>(native.utf16()),
-                                                                        NULL, IID_IShellItem,
+                                            NULL, IID_IShellItem,
-                                                                        reinterpret_cast<void **>(&result));
+                                            reinterpret_cast<void **>(&result));
         if (FAILED(hr)) {
             qErrnoWarning("%s: SHCreateItemFromParsingName(%s)) failed", __FUNCTION__, qPrintable(url.toString()));
             return Q_NULLPTR;
         }
         return result;
     } else if (url.scheme() == QLatin1String("clsid")) {
-        if (!QWindowsContext::shell32dll.sHGetKnownFolderIDList || !QWindowsContext::shell32dll.sHCreateItemFromIDList)
-            return Q_NULLPTR;
         // Support for virtual folders via GUID
         // (see https://msdn.microsoft.com/en-us/library/windows/desktop/dd378457(v=vs.85).aspx)
         // specified as "clsid:<GUID>" (without '{', '}').
@@ -1014,12 +1010,12 @@ IShellItem *QWindowsNativeFileDialogBase::shellItem(const QUrl &url)
             return Q_NULLPTR;
         }
         PIDLIST_ABSOLUTE idList;
-        HRESULT hr = QWindowsContext::shell32dll.sHGetKnownFolderIDList(uuid, 0, 0, &idList);
+        HRESULT hr = SHGetKnownFolderIDList(uuid, 0, 0, &idList);
         if (FAILED(hr)) {
             qErrnoWarning("%s: SHGetKnownFolderIDList(%s)) failed", __FUNCTION__, qPrintable(url.toString()));
             return Q_NULLPTR;
         }
-        hr = QWindowsContext::shell32dll.sHCreateItemFromIDList(idList, IID_IShellItem, reinterpret_cast<void **>(&result));
+        hr = SHCreateItemFromIDList(idList, IID_IShellItem, reinterpret_cast<void **>(&result));
         CoTaskMemFree(idList);
         if (FAILED(hr)) {
             qErrnoWarning("%s: SHCreateItemFromIDList(%s)) failed", __FUNCTION__, qPrintable(url.toString()));

src/plugins/platforms/windows/qwindowstheme.cpp

@@ -490,7 +490,7 @@ QPixmap QWindowsTheme::standardPixmap(StandardPixmap sp, const QSizeF &size) con
     const int scaleFactor = primaryScreen ? qRound(QHighDpiScaling::factor(primaryScreen)) : 1;
     const QSizeF pixmapSize = size * scaleFactor;
     int resourceId = -1;
-    int stockId = SIID_INVALID;
+    SHSTOCKICONID stockId = SIID_INVALID;
     UINT stockFlags = 0;
     LPCTSTR iconName = 0;
     switch (sp) {
@@ -577,20 +577,16 @@ QPixmap QWindowsTheme::standardPixmap(StandardPixmap sp, const QSizeF &size) con
     }
 
     if (stockId != SIID_INVALID) {
-        if (QSysInfo::WindowsVersion >= QSysInfo::WV_VISTA
+        QPixmap pixmap;
-            && (QSysInfo::WindowsVersion & QSysInfo::WV_NT_based)
+        SHSTOCKICONINFO iconInfo;
-            && QWindowsContext::shell32dll.sHGetStockIconInfo) {
+        memset(&iconInfo, 0, sizeof(iconInfo));
-            QPixmap pixmap;
+        iconInfo.cbSize = sizeof(iconInfo);
-            SHSTOCKICONINFO iconInfo;
+        stockFlags |= (pixmapSize.width() > 16 ? SHGFI_LARGEICON : SHGFI_SMALLICON);
-            memset(&iconInfo, 0, sizeof(iconInfo));
+        if (SHGetStockIconInfo(stockId, SHGFI_ICON | stockFlags, &iconInfo) == S_OK) {
-            iconInfo.cbSize = sizeof(iconInfo);
+            pixmap = qt_pixmapFromWinHICON(iconInfo.hIcon);
-            stockFlags |= (pixmapSize.width() > 16 ? SHGFI_LARGEICON : SHGFI_SMALLICON);
+            pixmap.setDevicePixelRatio(scaleFactor);
-            if (QWindowsContext::shell32dll.sHGetStockIconInfo(stockId, SHGFI_ICON | stockFlags, &iconInfo) == S_OK) {
+            DestroyIcon(iconInfo.hIcon);
-                pixmap = qt_pixmapFromWinHICON(iconInfo.hIcon);
+            return pixmap;
-                pixmap.setDevicePixelRatio(scaleFactor);
-                DestroyIcon(iconInfo.hIcon);
-                return pixmap;
-            }
         }
     }
 
@@ -669,14 +665,8 @@ static QPixmap pixmapFromShellImageList(int iImageList, const SHFILEINFO &info)
     // For MinGW:
     static const IID iID_IImageList = {0x46eb5926, 0x582e, 0x4017, {0x9f, 0xdf, 0xe8, 0x99, 0x8d, 0xaa, 0x9, 0x50}};
 
-    if (!QWindowsContext::shell32dll.sHGetImageList)
-        return result;
-    if (iImageList == sHIL_JUMBO && QSysInfo::WindowsVersion < QSysInfo::WV_VISTA)
-        return result;
-
     IImageList *imageList = 0;
-    HRESULT hr = QWindowsContext::shell32dll.sHGetImageList(iImageList, iID_IImageList,
+    HRESULT hr = SHGetImageList(iImageList, iID_IImageList, reinterpret_cast<void **>(&imageList));
-                                                            reinterpret_cast<void **>(&imageList));
     if (hr != S_OK)
         return result;
     HICON hIcon;

src/plugins/platforms/windows/qwindowswindow.cpp

@@ -62,6 +62,8 @@
 
 #include <QtCore/QDebug>
 
+#include <dwmapi.h>
+
 QT_BEGIN_NAMESPACE
 
 enum {
@@ -258,55 +260,22 @@ static inline bool windowIsOpenGL(const QWindow *w)
 
 static bool applyBlurBehindWindow(HWND hwnd)
 {
-    enum { dwmBbEnable = 0x1, dwmBbBlurRegion = 0x2 };
-
-    struct DwmBlurBehind {
-        DWORD dwFlags;
-        BOOL  fEnable;
-        HRGN  hRgnBlur;
-        BOOL  fTransitionOnMaximized;
-    };
-
-    typedef HRESULT (WINAPI *PtrDwmEnableBlurBehindWindow)(HWND, const DwmBlurBehind*);
-    typedef HRESULT (WINAPI *PtrDwmIsCompositionEnabled)(BOOL *);
-
-    // DWM API is available only from Windows Vista
-    if (QSysInfo::windowsVersion() < QSysInfo::WV_VISTA)
-        return false;
-
-    static bool functionPointersResolved = false;
-    static PtrDwmEnableBlurBehindWindow dwmBlurBehind = 0;
-    static PtrDwmIsCompositionEnabled dwmIsCompositionEnabled = 0;
-
-    if (Q_UNLIKELY(!functionPointersResolved)) {
-        QSystemLibrary library(QStringLiteral("dwmapi"));
-        if (library.load()) {
-            dwmBlurBehind = (PtrDwmEnableBlurBehindWindow)(library.resolve("DwmEnableBlurBehindWindow"));
-            dwmIsCompositionEnabled = (PtrDwmIsCompositionEnabled)(library.resolve("DwmIsCompositionEnabled"));
-        }
-
-        functionPointersResolved = true;
-    }
-
-    if (Q_UNLIKELY(!dwmBlurBehind || !dwmIsCompositionEnabled))
-        return false;
-
     BOOL compositionEnabled;
-    if (dwmIsCompositionEnabled(&compositionEnabled) != S_OK)
+    if (DwmIsCompositionEnabled(&compositionEnabled) != S_OK)
         return false;
 
-    DwmBlurBehind blurBehind = {0, 0, 0, 0};
+    DWM_BLURBEHIND blurBehind = {0, 0, 0, 0};
 
     if (compositionEnabled) {
-        blurBehind.dwFlags = dwmBbEnable | dwmBbBlurRegion;
+        blurBehind.dwFlags = DWM_BB_ENABLE | DWM_BB_BLURREGION;
         blurBehind.fEnable = TRUE;
         blurBehind.hRgnBlur = CreateRectRgn(0, 0, -1, -1);
     } else {
-        blurBehind.dwFlags = dwmBbEnable;
+        blurBehind.dwFlags = DWM_BB_ENABLE;
         blurBehind.fEnable = FALSE;
     }
 
-    const bool result = dwmBlurBehind(hwnd, &blurBehind) == S_OK;
+    const bool result = DwmEnableBlurBehindWindow(hwnd, &blurBehind) == S_OK;
 
     if (blurBehind.hRgnBlur)
         DeleteObject(blurBehind.hRgnBlur);
@@ -351,9 +320,9 @@ static void setWindowOpacity(HWND hwnd, Qt::WindowFlags flags, bool hasAlpha, bo
         if (hasAlpha && !openGL && (flags & Qt::FramelessWindowHint)) {
             // Non-GL windows with alpha: Use blend function to update.
             BLENDFUNCTION blend = {AC_SRC_OVER, 0, alpha, AC_SRC_ALPHA};
-            QWindowsContext::user32dll.updateLayeredWindow(hwnd, NULL, NULL, NULL, NULL, NULL, 0, &blend, ULW_ALPHA);
+            UpdateLayeredWindow(hwnd, NULL, NULL, NULL, NULL, NULL, 0, &blend, ULW_ALPHA);
         } else {
-            QWindowsContext::user32dll.setLayeredWindowAttributes(hwnd, 0, alpha, LWA_ALPHA);
+            SetLayeredWindowAttributes(hwnd, 0, alpha, LWA_ALPHA);
         }
     } else if (IsWindowVisible(hwnd)) { // Repaint when switching from layered.
         InvalidateRect(hwnd, NULL, TRUE);

src/plugins/platforms/windows/windows.pro

@@ -4,7 +4,7 @@ QT *= core-private
 QT *= gui-private
 QT *= platformsupport-private
 
-LIBS += -lgdi32
+LIBS += -lgdi32 -ldwmapi
 
 include(windows.pri)