2 files changed, 62 insertions, 24 deletions
diff --git a/src/plugins/platforms/windows/qwindowswindowclassdescription.cpp b/src/plugins/platforms/windows/qwindowswindowclassdescription.cpp
index abd6f02fb0b..6962d28e7d0 100644
--- a/src/plugins/platforms/windows/qwindowswindowclassdescription.cpp
+++ b/src/plugins/platforms/windows/qwindowswindowclassdescription.cpp
@@ -41,43 +41,69 @@ QString QWindowsWindowClassDescription::classNameSuffix(Qt::WindowFlags type, un
     return suffix;
 }
 
-QWindowsWindowClassDescription QWindowsWindowClassDescription::fromName(QString name, WNDPROC procedure)
+bool QWindowsWindowClassDescription::computeHasIcon(Qt::WindowFlags flags, Qt::WindowFlags type)
 {
-    return { std::move(name), procedure };
+    bool hasIcon = true;
+
+    switch (type) {
+        case Qt::Tool:
+        case Qt::ToolTip:
+        case Qt::Popup:
+            hasIcon = false;
+            break;
+        case Qt::Dialog:
+            if (!(flags & Qt::WindowSystemMenuHint))
+                hasIcon = false; // QTBUG-2027, dialogs without system menu.
+            break;
+    }
+
+    return hasIcon;
 }
 
-QWindowsWindowClassDescription QWindowsWindowClassDescription::fromWindow(const QWindow *window, WNDPROC procedure)
+unsigned int QWindowsWindowClassDescription::computeWindowStyles(Qt::WindowFlags flags, Qt::WindowFlags type, WindowStyleOptions options)
 {
-    Q_ASSERT(window);
+    unsigned int style = CS_DBLCLKS;
 
-    QWindowsWindowClassDescription description;
-    description.procedure = procedure;
-
-    const Qt::WindowFlags flags = window->flags();
-    const Qt::WindowFlags type = flags & Qt::WindowType_Mask;
-    // Determine style and icon.
-    description.style = CS_DBLCLKS;
-    description.hasIcon = true;
     // The following will not set CS_OWNDC for any widget window, even if it contains a
     // QOpenGLWidget or QQuickWidget later on. That cannot be detected at this stage.
-    if (window->surfaceType() == QSurface::OpenGLSurface || (flags & Qt::MSWindowsOwnDC))
-        description.style |= CS_OWNDC;
-    if (!(flags & Qt::NoDropShadowWindowHint)
-        && (type == Qt::Popup || window->property("_q_windowsDropShadow").toBool())) {
-        description.style |= CS_DROPSHADOW;
-    }
+    if (options.testFlag(WindowStyleOption::GLSurface) || (flags & Qt::MSWindowsOwnDC))
+        style |= CS_OWNDC;
+    if (!(flags & Qt::NoDropShadowWindowHint) && (type == Qt::Popup || options.testFlag(WindowStyleOption::DropShadow)))
+        style |= CS_DROPSHADOW;
+
     switch (type) {
         case Qt::Tool:
         case Qt::ToolTip:
         case Qt::Popup:
-            description.style |= CS_SAVEBITS; // Save/restore background
-            description.hasIcon = false;
-            break;
-        case Qt::Dialog:
-            if (!(flags & Qt::WindowSystemMenuHint))
-                description.hasIcon = false; // QTBUG-2027, dialogs without system menu.
+            style |= CS_SAVEBITS; // Save/restore background
             break;
     }
+
+    return style;
+}
+
+QWindowsWindowClassDescription QWindowsWindowClassDescription::fromName(QString name, WNDPROC procedure)
+{
+    return { std::move(name), procedure };
+}
+
+QWindowsWindowClassDescription QWindowsWindowClassDescription::fromWindow(const QWindow *window, WNDPROC procedure)
+{
+    Q_ASSERT(window);
+
+    const Qt::WindowFlags flags = window->flags();
+    const Qt::WindowFlags type = flags & Qt::WindowType_Mask;
+
+    WindowStyleOptions options = WindowStyleOption::None;
+    if (window->surfaceType() == QSurface::OpenGLSurface)
+        options |= WindowStyleOption::GLSurface;
+    if (window->property("_q_windowsDropShadow").toBool())
+        options |= WindowStyleOption::DropShadow;
+
+    QWindowsWindowClassDescription description;
+    description.procedure = procedure;
+    description.style = computeWindowStyles(flags, type, options);
+    description.hasIcon = computeHasIcon(flags, type);
     description.name = "QWindow"_L1 + classNameSuffix(type, description.style, description.hasIcon);
 
     return description;
diff --git a/src/plugins/platforms/windows/qwindowswindowclassdescription.h b/src/plugins/platforms/windows/qwindowswindowclassdescription.h
index 692bf18e618..f0019f8f3c2 100644
--- a/src/plugins/platforms/windows/qwindowswindowclassdescription.h
+++ b/src/plugins/platforms/windows/qwindowswindowclassdescription.h
@@ -14,6 +14,14 @@ class QWindow;
 
 struct QWindowsWindowClassDescription
 {
+    enum class WindowStyleOption
+    {
+        None = 0x00,
+        GLSurface = 0x01,
+        DropShadow = 0x02
+    };
+    Q_DECLARE_FLAGS(WindowStyleOptions, WindowStyleOption)
+
     static QWindowsWindowClassDescription fromName(QString name, WNDPROC procedure);
     static QWindowsWindowClassDescription fromWindow(const QWindow *window, WNDPROC procedure);
 
@@ -26,10 +34,14 @@ struct QWindowsWindowClassDescription
 
 private:
     static QString classNameSuffix(Qt::WindowFlags type, unsigned int style, bool hasIcon);
+    static bool computeHasIcon(Qt::WindowFlags flags, Qt::WindowFlags type);
+    static unsigned int computeWindowStyles(Qt::WindowFlags flags, Qt::WindowFlags type, WindowStyleOptions options);
 
     friend QDebug operator<<(QDebug dbg, const QWindowsWindowClassDescription &description);
 };
 
+Q_DECLARE_OPERATORS_FOR_FLAGS(QWindowsWindowClassDescription::WindowStyleOptions)
+
 QT_END_NAMESPACE
 
 #endif // QWINDOWSWINDOWCLASSDESCRIPTION_H