Windows QPA: Better disambiguate Window class names

Use a standard prefix for Window class names containing
version, build and namespace which should reduce conflicts.

Task-number: QTBUG-81347
Change-Id: Ia7c20af71d364e362781f791a4e51b77d605c918
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>

5 files changed, 26 insertions, 7 deletions

diff --git a/src/plugins/platforms/windows/qwindowsclipboard.cpp b/src/plugins/platforms/windows/qwindowsclipboard.cpp
index ccd4e50a8b..efcb0b6e6e 100644
--- a/src/plugins/platforms/windows/qwindowsclipboard.cpp
+++ b/src/plugins/platforms/windows/qwindowsclipboard.cpp
@@ -190,7 +190,7 @@ void QWindowsClipboard::releaseIData()
 void QWindowsClipboard::registerViewer()
 {
     m_clipboardViewer = QWindowsContext::instance()->
-        createDummyWindow(QStringLiteral("Qt5ClipboardView"), L"Qt5ClipboardView",
+        createDummyWindow(QStringLiteral("ClipboardView"), L"QtClipboardView",
                           qClipboardViewerWndProc, WS_OVERLAPPED);
 
     // Try format listener API (Vista onwards) first.
diff --git a/src/plugins/platforms/windows/qwindowscontext.cpp b/src/plugins/platforms/windows/qwindowscontext.cpp
index d31352b854..c85d04b816 100644
--- a/src/plugins/platforms/windows/qwindowscontext.cpp
+++ b/src/plugins/platforms/windows/qwindowscontext.cpp
@@ -72,6 +72,7 @@
 
 #include <QtCore/qset.h>
 #include <QtCore/qhash.h>
+#include <QtCore/qlibraryinfo.h>
 #include <QtCore/qstringlist.h>
 #include <QtCore/qdebug.h>
 #include <QtCore/qoperatingsystemversion.h>
@@ -426,7 +427,7 @@ bool QWindowsContext::initPowerNotificationHandler()
     if (d->m_powerNotification)
         return false;
 
-    d->m_powerDummyWindow = createDummyWindow(QStringLiteral("QtPowerDummyWindow"), L"QtPowerDummyWindow", qWindowsPowerWindowProc);
+    d->m_powerDummyWindow = createDummyWindow(QStringLiteral("PowerDummyWindow"), L"QtPowerDummyWindow", qWindowsPowerWindowProc);
     if (!d->m_powerDummyWindow)
         return false;
 
@@ -536,6 +537,23 @@ void QWindowsContext::setKeyGrabber(QWindow *w)
     d->m_keyMapper.setKeyGrabber(w);
 }
 
+QString QWindowsContext::classNamePrefix()
+{
+    static QString result;
+    if (result.isEmpty()) {
+        QTextStream str(&result);
+        str << "Qt" << QT_VERSION_MAJOR << QT_VERSION_MINOR << QT_VERSION_PATCH;
+        if (QLibraryInfo::isDebugBuild())
+            str << 'd';
+#ifdef QT_NAMESPACE
+#  define xstr(s) str(s)
+#  define str(s) #s
+        str << xstr(QT_NAMESPACE);
+#endif
+    }
+    return result;
+}
+
 // Window class registering code (from qapplication_win.cpp)
 
 QString QWindowsContext::registerWindowClass(const QWindow *w)
@@ -567,8 +585,8 @@ QString QWindowsContext::registerWindowClass(const QWindow *w)
         break;
     }
     // Create a unique name for the flag combination
-    QString cname;
-    cname += QLatin1String("Qt5QWindow");
+    QString cname = classNamePrefix();
+    cname += QLatin1String("QWindow");
     switch (type) {
     case Qt::Tool:
         cname += QLatin1String("Tool");
@@ -878,7 +896,7 @@ HWND QWindowsContext::createDummyWindow(const QString &classNameIn,
 {
     if (!wndProc)
         wndProc = DefWindowProc;
-    QString className = registerWindowClass(classNameIn, wndProc);
+    QString className = registerWindowClass(classNamePrefix() + classNameIn, wndProc);
     return CreateWindowEx(0, reinterpret_cast<LPCWSTR>(className.utf16()),
                           windowName, style,
                           CW_USEDEFAULT, CW_USEDEFAULT,
diff --git a/src/plugins/platforms/windows/qwindowscontext.h b/src/plugins/platforms/windows/qwindowscontext.h
index 8027f09389..43ab8416ab 100644
--- a/src/plugins/platforms/windows/qwindowscontext.h
+++ b/src/plugins/platforms/windows/qwindowscontext.h
@@ -180,6 +180,7 @@ public:
 
     int defaultDPI() const;
 
+    static QString classNamePrefix();
     QString registerWindowClass(const QWindow *w);
     QString registerWindowClass(QString cname, WNDPROC proc,
                                 unsigned style = 0, HBRUSH brush = nullptr,
diff --git a/src/plugins/platforms/windows/qwindowsglcontext.cpp b/src/plugins/platforms/windows/qwindowsglcontext.cpp
index f2d31d5783..f5d0a8780a 100644
--- a/src/plugins/platforms/windows/qwindowsglcontext.cpp
+++ b/src/plugins/platforms/windows/qwindowsglcontext.cpp
@@ -802,7 +802,7 @@ static HGLRC createContext(const QOpenGLStaticContext &staticContext,
 static inline HWND createDummyGLWindow()
 {
     return QWindowsContext::instance()->
-        createDummyWindow(QStringLiteral("QtOpenGLDummyWindow"),
+        createDummyWindow(QStringLiteral("OpenGLDummyWindow"),
                           L"OpenGLDummyWindow", nullptr, WS_OVERLAPPED | WS_CLIPCHILDREN | WS_CLIPSIBLINGS);
 }
 
diff --git a/src/plugins/platforms/windows/qwindowssystemtrayicon.cpp b/src/plugins/platforms/windows/qwindowssystemtrayicon.cpp
index 66c558df1e..53562c87dd 100644
--- a/src/plugins/platforms/windows/qwindowssystemtrayicon.cpp
+++ b/src/plugins/platforms/windows/qwindowssystemtrayicon.cpp
@@ -168,7 +168,7 @@ static inline HWND createTrayIconMessageWindow()
         return nullptr;
     // Register window class in the platform plugin.
     const QString className =
-        ctx->registerWindowClass(QStringLiteral("QTrayIconMessageWindowClass"),
+        ctx->registerWindowClass(QWindowsContext::classNamePrefix() + QStringLiteral("TrayIconMessageWindowClass"),
                                  qWindowsTrayIconWndProc);
     const wchar_t windowName[] = L"QTrayIconMessageWindow";
     return CreateWindowEx(0, reinterpret_cast<const wchar_t *>(className.utf16()),