1 files changed, 79 insertions, 0 deletions
diff --git a/src/gui/platform/windows/qwindowsthemecache.cpp b/src/gui/platform/windows/qwindowsthemecache.cpp
new file mode 100644
index 0000000000..3bb92e67ca
--- /dev/null
+++ b/src/gui/platform/windows/qwindowsthemecache.cpp
@@ -0,0 +1,79 @@
+// Copyright (C) 2023 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 "qwindowsthemecache_p.h"
+#include <QtCore/qdebug.h>
+#include <QtCore/qhash.h>
+
+QT_BEGIN_NAMESPACE
+
+// Theme names matching the QWindowsVistaStylePrivate::Theme enumeration.
+constexpr const wchar_t *themeNames[] = {
+    L"BUTTON",   L"COMBOBOX",   L"EDIT",    L"HEADER",    L"LISTVIEW",
+    L"MENU",     L"PROGRESS",   L"REBAR",   L"SCROLLBAR", L"SPIN",
+    L"TAB",      L"TASKDIALOG", L"TOOLBAR", L"TOOLTIP",   L"TRACKBAR",
+    L"WINDOW",   L"STATUS",     L"TREEVIEW"
+};
+
+typedef std::array<HTHEME, std::size(themeNames)> ThemeArray;
+typedef QHash<HWND, ThemeArray> ThemesCache;
+Q_GLOBAL_STATIC(ThemesCache, themesCache);
+
+QString QWindowsThemeCache::themeName(int theme)
+{
+    return theme >= 0 && theme < int(std::size(themeNames))
+        ? QString::fromWCharArray(themeNames[theme]) : QString();
+}
+
+HTHEME QWindowsThemeCache::createTheme(int theme, HWND hwnd)
+{
+    if (Q_UNLIKELY(theme < 0 || theme >= int(std::size(themeNames)) || !hwnd)) {
+        qWarning("Invalid parameters #%d, %p", theme, hwnd);
+        return nullptr;
+    }
+
+    // Get or create themes array for this window.
+    ThemesCache *cache = themesCache();
+    auto it = cache->find(hwnd);
+    if (it == cache->end())
+        it = cache->insert(hwnd, ThemeArray {});
+
+    // Get or create theme data
+    ThemeArray &themes = *it;
+    if (!themes[theme]) {
+        const wchar_t *name = themeNames[theme];
+        themes[theme] = OpenThemeData(hwnd, name);
+        if (Q_UNLIKELY(!themes[theme]))
+            qErrnoWarning("OpenThemeData() failed for theme %d (%s).",
+                          theme, qPrintable(themeName(theme)));
+    }
+    return themes[theme];
+}
+
+static void clearThemes(ThemeArray &themes)
+{
+    for (auto &theme : themes) {
+        if (theme) {
+            CloseThemeData(theme);
+            theme = nullptr;
+        }
+    }
+}
+
+void QWindowsThemeCache::clearThemeCache(HWND hwnd)
+{
+    ThemesCache *cache = themesCache();
+    auto it = cache->find(hwnd);
+    if (it == cache->end())
+        return;
+    clearThemes(*it);
+}
+
+void QWindowsThemeCache::clearAllThemeCaches()
+{
+    ThemesCache *cache = themesCache();
+    for (auto &themeArray : *cache)
+        clearThemes(themeArray);
+}
+
+QT_END_NAMESPACE