1 files changed, 78 insertions, 0 deletions
diff --git a/src/plugins/platforms/windows/qwindowswindowclassdescription.cpp b/src/plugins/platforms/windows/qwindowswindowclassdescription.cpp
new file mode 100644
index 00000000000..63e16260b62
--- /dev/null
+++ b/src/plugins/platforms/windows/qwindowswindowclassdescription.cpp
@@ -0,0 +1,78 @@
+// Copyright (C) 2025 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#include "qwindowswindowclassdescription.h"
+
+#include <QtGui/qwindow.h>
+
+#include "qwindowswindowclassregistry.h"
+
+QT_BEGIN_NAMESPACE
+
+using namespace Qt::StringLiterals;
+
+QWindowsWindowClassDescription QWindowsWindowClassDescription::fromName(QString name, WNDPROC procedure)
+{
+    return { std::move(name), procedure };
+}
+
+QWindowsWindowClassDescription QWindowsWindowClassDescription::fromWindow(const QWindow *window, WNDPROC procedure)
+{
+    Q_ASSERT(window);
+
+    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;
+    }
+    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.
+            break;
+    }
+    // Create a unique name for the flag combination
+    description.name = "QWindow"_L1;
+    switch (type) {
+        case Qt::Tool:
+            description.name += "Tool"_L1;
+            break;
+        case Qt::ToolTip:
+            description.name += "ToolTip"_L1;
+            break;
+        case Qt::Popup:
+            description.name += "Popup"_L1;
+            break;
+        default:
+            break;
+    }
+    if (description.style & CS_DROPSHADOW)
+        description.name += "DropShadow"_L1;
+    if (description.style & CS_SAVEBITS)
+        description.name += "SaveBits"_L1;
+    if (description.style & CS_OWNDC)
+        description.name += "OwnDC"_L1;
+    if (description.hasIcon)
+        description.name += "Icon"_L1;
+
+    return description;
+}
+
+QT_END_NAMESPACE