1 files changed, 29 insertions, 25 deletions
diff --git a/src/plugins/platforms/windows/qwindowswindowclassregistry.cpp b/src/plugins/platforms/windows/qwindowswindowclassregistry.cpp
index c330720a09c..8bf2fb887f1 100644
--- a/src/plugins/platforms/windows/qwindowswindowclassregistry.cpp
+++ b/src/plugins/platforms/windows/qwindowswindowclassregistry.cpp
@@ -18,8 +18,8 @@ Q_LOGGING_CATEGORY(lcQpaWindowClass, "qt.qpa.windowclass")
 
 QWindowsWindowClassRegistry *QWindowsWindowClassRegistry::m_instance = nullptr;
 
-QWindowsWindowClassRegistry::QWindowsWindowClassRegistry(WNDPROC proc)
-    : m_proc(proc)
+QWindowsWindowClassRegistry::QWindowsWindowClassRegistry(WNDPROC defaultProcedure)
+    : m_defaultProcedure(defaultProcedure)
 {
     m_instance = this;
 }
@@ -69,25 +69,19 @@ QString QWindowsWindowClassRegistry::registerWindowClass(const QWindowsWindowCla
     // add a UUID. The check needs to be performed for each name
     // in case new message windows are added (QTBUG-81347).
     // Note: GetClassInfo() returns != 0 when a class exists.
-    const auto appInstance = static_cast<HINSTANCE>(GetModuleHandle(nullptr));
-    WNDCLASS wcinfo;
-    const bool classExists = GetClassInfo(appInstance, reinterpret_cast<LPCWSTR>(className.utf16()), &wcinfo) != FALSE
-        && wcinfo.lpfnWndProc != description.procedure;
-
-    if (classExists)
+    if (shouldDecorateWindowClassName(description))
         className += QUuid::createUuid().toString();
 
     if (m_registeredWindowClassNames.contains(className))        // already registered in our list
         return className;
 
-    WNDCLASSEX wc;
+    const auto appInstance = static_cast<HINSTANCE>(GetModuleHandle(nullptr));
+
+    WNDCLASSEX wc{};
     wc.cbSize = sizeof(WNDCLASSEX);
     wc.style = description.style;
     wc.lpfnWndProc = description.procedure;
-    wc.cbClsExtra = 0;
-    wc.cbWndExtra = 0;
     wc.hInstance = appInstance;
-    wc.hCursor = nullptr;
     wc.hbrBackground = description.brush;
     if (description.hasIcon) {
         wc.hIcon = static_cast<HICON>(LoadImage(appInstance, L"IDI_ICON1", IMAGE_ICON, 0, 0, LR_DEFAULTSIZE));
@@ -98,31 +92,25 @@ QString QWindowsWindowClassRegistry::registerWindowClass(const QWindowsWindowCla
         }
         else {
             wc.hIcon = static_cast<HICON>(LoadImage(nullptr, IDI_APPLICATION, IMAGE_ICON, 0, 0, LR_DEFAULTSIZE | LR_SHARED));
-            wc.hIconSm = nullptr;
         }
     }
-    else {
-        wc.hIcon = nullptr;
-        wc.hIconSm = nullptr;
-    }
 
-    wc.lpszMenuName = nullptr;
     wc.lpszClassName = reinterpret_cast<LPCWSTR>(className.utf16());
     ATOM atom = RegisterClassEx(&wc);
     if (!atom)
-        qErrnoWarning("QApplication::regClass: Registering window class '%s' failed.",
-            qPrintable(className));
+        qCWarning(lcQpaWindowClass) << "Failed to register window class" << className
+            << "(" << qt_error_string(-1) << ")";
 
     m_registeredWindowClassNames.insert(className);
-    qCDebug(lcQpaWindowClass).nospace() << __FUNCTION__ << ' ' << className
-        << " style=0x" << Qt::hex << description.style << Qt::dec
-        << " brush=" << description.brush << " icon=" << description.hasIcon << " atom=" << atom;
+
+    qCDebug(lcQpaWindowClass).nospace() << __FUNCTION__ << ' ' << className << ' ' << description << " atom=" << atom;
+
     return className;
 }
 
 QString QWindowsWindowClassRegistry::registerWindowClass(const QWindow *window)
 {
-    return registerWindowClass(QWindowsWindowClassDescription::fromWindow(window, m_proc));
+    return registerWindowClass(QWindowsWindowClassDescription::fromWindow(window, m_defaultProcedure));
 }
 
 QString QWindowsWindowClassRegistry::registerWindowClass(QString name, WNDPROC procedure)
@@ -130,13 +118,29 @@ QString QWindowsWindowClassRegistry::registerWindowClass(QString name, WNDPROC p
     return registerWindowClass(QWindowsWindowClassDescription::fromName(name, procedure));
 }
 
+bool QWindowsWindowClassRegistry::shouldDecorateWindowClassName(const QWindowsWindowClassDescription &description) const
+{
+    return shouldDecorateWindowClassName(description.name, description.procedure);
+}
+
+bool QWindowsWindowClassRegistry::shouldDecorateWindowClassName(const QString &name, WNDPROC procedure) const
+{
+    const auto appInstance = static_cast<HINSTANCE>(GetModuleHandle(nullptr));
+
+    WNDCLASS wc{};
+
+    return GetClassInfo(appInstance, reinterpret_cast<LPCWSTR>(name.utf16()), &wc) != FALSE
+        && wc.lpfnWndProc != procedure;
+}
+
 void QWindowsWindowClassRegistry::unregisterWindowClasses()
 {
     const auto appInstance = static_cast<HINSTANCE>(GetModuleHandle(nullptr));
 
     for (const QString &name : std::as_const(m_registeredWindowClassNames)) {
         if (!UnregisterClass(reinterpret_cast<LPCWSTR>(name.utf16()), appInstance) && QWindowsContext::verbose)
-            qErrnoWarning("UnregisterClass failed for '%s'", qPrintable(name));
+            qCWarning(lcQpaWindowClass) << "Failed to unregister window class" << name
+                << "(" << qt_error_string(-1) << ")";
     }
     m_registeredWindowClassNames.clear();
 }