Add OSUtils for platform-specific functionality.

Moves MacUtils into a separate sub folder and adds
WinUtils, NixUtils, and OSUtils for platform-native
code on Windows, Unix-like, and generic/all systems.

12 files changed, 808 insertions, 0 deletions

diff --git a/src/gui/osutils/OSUtils.h b/src/gui/osutils/OSUtils.h
new file mode 100644
index 000000000..dd1bd8cd1
--- /dev/null
+++ b/src/gui/osutils/OSUtils.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2020 KeePassXC Team <team@keepassxc.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 or (at your option)
+ * version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef KEEPASSXC_OSUTILS_H
+#define KEEPASSXC_OSUTILS_H
+
+#include "OSUtilsBase.h"
+#include <QtCore>
+
+#if defined(Q_OS_WIN)
+
+#include "winutils/WinUtils.h"
+#define osUtils static_cast<OSUtilsBase*>(winUtils())
+
+#elif defined(Q_OS_MACOS)
+
+#include "macutils/MacUtils.h"
+#define osUtils static_cast<OSUtilsBase*>(macUtils())
+
+#elif defined(Q_OS_UNIX)
+
+#include "nixutils/NixUtils.h"
+#define osUtils static_cast<OSUtilsBase*>(nixUtils())
+
+#endif
+
+#endif // KEEPASSXC_OSUTILS_H
diff --git a/src/gui/osutils/OSUtilsBase.cpp b/src/gui/osutils/OSUtilsBase.cpp
new file mode 100644
index 000000000..143cb72c1
--- /dev/null
+++ b/src/gui/osutils/OSUtilsBase.cpp
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2020 KeePassXC Team <team@keepassxc.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 or (at your option)
+ * version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "OSUtilsBase.h"
+
+OSUtilsBase::OSUtilsBase(QObject* parent)
+    : QObject(parent)
+{
+}
+
+OSUtilsBase::~OSUtilsBase()
+{
+}
diff --git a/src/gui/osutils/OSUtilsBase.h b/src/gui/osutils/OSUtilsBase.h
new file mode 100644
index 000000000..9467fca09
--- /dev/null
+++ b/src/gui/osutils/OSUtilsBase.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2020 KeePassXC Team <team@keepassxc.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 or (at your option)
+ * version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef KEEPASSXC_OSUTILSBASE_H
+#define KEEPASSXC_OSUTILSBASE_H
+
+#include <QObject>
+#include <QPointer>
+
+/**
+ * Abstract base class for generic OS-specific functionality
+ * which can be reasonably expected to be available on all platforms.
+ */
+class OSUtilsBase : public QObject
+{
+    Q_OBJECT
+
+public:
+    virtual bool isDarkMode() = 0;
+
+protected:
+    explicit OSUtilsBase(QObject* parent = nullptr);
+    virtual ~OSUtilsBase();
+};
+
+#endif // KEEPASSXC_OSUTILSBASE_H
diff --git a/src/gui/osutils/macutils/AppKit.h b/src/gui/osutils/macutils/AppKit.h
new file mode 100644
index 000000000..2bff8f5b3
--- /dev/null
+++ b/src/gui/osutils/macutils/AppKit.h
@@ -0,0 +1,50 @@
+/*
+ *  Copyright (C) 2016 Lennart Glauer <mail@lennart-glauer.de>
+ *  Copyright (C) 2017 KeePassXC Team <team@keepassxc.org>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 2 or (at your option)
+ *  version 3 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef KEEPASSX_APPKIT_H
+#define KEEPASSX_APPKIT_H
+
+#include <QObject>
+#include <unistd.h>
+
+class AppKit : public QObject
+{
+    Q_OBJECT
+
+public:
+    AppKit(QObject* parent = nullptr);
+    ~AppKit();
+
+    pid_t lastActiveProcessId();
+    pid_t activeProcessId();
+    pid_t ownProcessId();
+    bool activateProcess(pid_t pid);
+    bool hideProcess(pid_t pid);
+    bool isHidden(pid_t pid);
+    bool isDarkMode();
+    bool enableAccessibility();
+    bool enableScreenRecording();
+
+signals:
+    void lockDatabases();
+
+private:
+    void* self;
+};
+
+#endif // KEEPASSX_APPKIT_H
diff --git a/src/gui/osutils/macutils/AppKitImpl.h b/src/gui/osutils/macutils/AppKitImpl.h
new file mode 100644
index 000000000..326879766
--- /dev/null
+++ b/src/gui/osutils/macutils/AppKitImpl.h
@@ -0,0 +1,42 @@
+/*
+ *  Copyright (C) 2016 Lennart Glauer <mail@lennart-glauer.de>
+ *  Copyright (C) 2017 KeePassXC Team <team@keepassxc.org>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 2 or (at your option)
+ *  version 3 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#import "AppKit.h"
+
+#import <Foundation/Foundation.h>
+#import <AppKit/NSRunningApplication.h>
+
+@interface AppKitImpl : NSObject
+{
+    AppKit* m_appkit;
+}
+- (id) initWithObject:(AppKit*)appkit;
+
+@property (strong) NSRunningApplication *lastActiveApplication;
+
+- (pid_t) activeProcessId;
+- (pid_t) ownProcessId;
+- (bool) activateProcess:(pid_t) pid;
+- (bool) hideProcess:(pid_t) pid;
+- (bool) isHidden:(pid_t) pid;
+- (bool) isDarkMode;
+- (void) userSwitchHandler:(NSNotification*) notification;
+- (bool) enableAccessibility;
+- (bool) enableScreenRecording;
+
+@end
diff --git a/src/gui/osutils/macutils/AppKitImpl.mm b/src/gui/osutils/macutils/AppKitImpl.mm
new file mode 100644
index 000000000..4a93f963a
--- /dev/null
+++ b/src/gui/osutils/macutils/AppKitImpl.mm
@@ -0,0 +1,217 @@
+/*
+ *  Copyright (C) 2016 Lennart Glauer <mail@lennart-glauer.de>
+ *  Copyright (C) 2017 KeePassXC Team <team@keepassxc.org>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 2 or (at your option)
+ *  version 3 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#import "AppKitImpl.h"
+
+#import <AppKit/NSWorkspace.h>
+#import <CoreVideo/CVPixelBuffer.h>
+
+@implementation AppKitImpl
+
+- (id) initWithObject:(AppKit*)appkit
+{
+    self = [super init];
+    if (self) {
+        m_appkit = appkit;
+        [[[NSWorkspace sharedWorkspace] notificationCenter] addObserver:static_cast<id>(self)
+                                                           selector:@selector(didDeactivateApplicationObserver:)
+                                                               name:NSWorkspaceDidDeactivateApplicationNotification
+                                                             object:nil];
+    
+        [[[NSWorkspace sharedWorkspace] notificationCenter] addObserver:static_cast<id>(self)
+                                                            selector:@selector(userSwitchHandler:)
+                                                                name:NSWorkspaceSessionDidResignActiveNotification
+                                                                object:nil];
+    }
+    return self;
+}
+
+//
+// Update last active application property
+//
+- (void) didDeactivateApplicationObserver:(NSNotification*) notification
+{
+    NSDictionary* userInfo = notification.userInfo;
+    NSRunningApplication* app = userInfo[NSWorkspaceApplicationKey];
+
+    if (app.processIdentifier != [self ownProcessId]) {
+        self.lastActiveApplication = app;
+    }
+}
+
+//
+// Get process id of frontmost application (-> keyboard input)
+//
+- (pid_t) activeProcessId
+{
+    return [NSWorkspace sharedWorkspace].frontmostApplication.processIdentifier;
+}
+
+//
+// Get process id of own process
+//
+- (pid_t) ownProcessId
+{
+    return [NSProcessInfo processInfo].processIdentifier;
+}
+
+//
+// Activate application by process id
+//
+- (bool) activateProcess:(pid_t) pid
+{
+    NSRunningApplication* app = [NSRunningApplication runningApplicationWithProcessIdentifier:pid];
+    return [app activateWithOptions:NSApplicationActivateIgnoringOtherApps];
+}
+
+//
+// Hide application by process id
+//
+- (bool) hideProcess:(pid_t) pid
+{
+    NSRunningApplication* app = [NSRunningApplication runningApplicationWithProcessIdentifier:pid];
+    return [app hide];
+}
+
+//
+// Get application hidden state by process id
+//
+- (bool) isHidden:(pid_t) pid
+{
+    NSRunningApplication* app = [NSRunningApplication runningApplicationWithProcessIdentifier:pid];
+    return [app isHidden];
+}
+
+//
+// Get state of macOS Dark Mode color scheme
+//
+- (bool) isDarkMode
+{
+    NSDictionary* dict = [[NSUserDefaults standardUserDefaults] persistentDomainForName:NSGlobalDomain];
+    id style = [dict objectForKey:@"AppleInterfaceStyle"];
+    return ( style && [style isKindOfClass:[NSString class]]
+             && NSOrderedSame == [style caseInsensitiveCompare:@"dark"] );
+}
+
+//
+// Notification for user switch
+//
+- (void) userSwitchHandler:(NSNotification*) notification
+{
+    if ([[notification name] isEqualToString:NSWorkspaceSessionDidResignActiveNotification] && m_appkit)
+    {
+        emit m_appkit->lockDatabases();
+    }
+}
+
+//
+// Check if accessibility is enabled, may show an popup asking for permissions
+//
+- (bool) enableAccessibility
+{
+    // Request accessibility permissions for Auto-Type type on behalf of the user
+    NSDictionary* opts = @{static_cast<id>(kAXTrustedCheckOptionPrompt): @YES};
+    return AXIsProcessTrustedWithOptions(static_cast<CFDictionaryRef>(opts));
+}
+
+//
+// Check if screen recording is enabled, may show an popup asking for permissions
+//
+- (bool) enableScreenRecording
+{
+    if (@available(macOS 10.15, *)) {
+        // Request screen recording permission on macOS 10.15+
+        // This is necessary to get the current window title
+        CGDisplayStreamRef stream = CGDisplayStreamCreate(CGMainDisplayID(), 1, 1, kCVPixelFormatType_32BGRA, nil,
+                                                          ^(CGDisplayStreamFrameStatus status, uint64_t displayTime, 
+                                                                  IOSurfaceRef frameSurface, CGDisplayStreamUpdateRef updateRef) {
+                                                              Q_UNUSED(status);
+                                                              Q_UNUSED(displayTime);
+                                                              Q_UNUSED(frameSurface);
+                                                              Q_UNUSED(updateRef);
+                                                          });
+        if (stream) {
+            CFRelease(stream);
+        } else {
+            return NO;
+        }
+    }
+    return YES;
+}
+
+@end
+
+//
+// ------------------------- C++ Trampolines -------------------------
+//
+
+AppKit::AppKit(QObject* parent) : QObject(parent)
+{
+    self = [[AppKitImpl alloc] initWithObject:this];
+}
+
+AppKit::~AppKit()
+{
+    [[[NSWorkspace sharedWorkspace] notificationCenter] removeObserver:static_cast<id>(self)];
+    [static_cast<id>(self) dealloc];
+}
+
+pid_t AppKit::lastActiveProcessId()
+{
+    return [static_cast<id>(self) lastActiveApplication].processIdentifier;
+}
+
+pid_t AppKit::activeProcessId()
+{
+    return [static_cast<id>(self) activeProcessId];
+}
+
+pid_t AppKit::ownProcessId()
+{
+    return [static_cast<id>(self) ownProcessId];
+}
+
+bool AppKit::activateProcess(pid_t pid)
+{
+    return [static_cast<id>(self) activateProcess:pid];
+}
+
+bool AppKit::hideProcess(pid_t pid)
+{
+    return [static_cast<id>(self) hideProcess:pid];
+}
+
+bool AppKit::isHidden(pid_t pid)
+{
+    return [static_cast<id>(self) isHidden:pid];
+}
+
+bool AppKit::isDarkMode()
+{
+    return [static_cast<id>(self) isDarkMode];
+}
+
+bool AppKit::enableAccessibility()
+{
+    return [static_cast<id>(self) enableAccessibility];
+}
+
+bool AppKit::enableScreenRecording()
+{
+    return [static_cast<id>(self) enableScreenRecording];
+}
diff --git a/src/gui/osutils/macutils/MacUtils.cpp b/src/gui/osutils/macutils/MacUtils.cpp
new file mode 100644
index 000000000..498325868
--- /dev/null
+++ b/src/gui/osutils/macutils/MacUtils.cpp
@@ -0,0 +1,87 @@
+/*
+ *  Copyright (C) 2012 Felix Geyer <debfx@fobos.de>
+ *  Copyright (C) 2018 KeePassXC Team <team@keepassxc.org>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 2 or (at your option)
+ *  version 3 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "MacUtils.h"
+#include <QApplication>
+
+QPointer<MacUtils> MacUtils::m_instance = nullptr;
+
+MacUtils::MacUtils(QObject* parent)
+    : OSUtils(parent)
+    , m_appkit(new AppKit())
+{
+    connect(m_appkit.data(), SIGNAL(lockDatabases()), SIGNAL(lockDatabases()));
+}
+
+MacUtils::~MacUtils()
+{
+}
+
+MacUtils* MacUtils::instance()
+{
+    if (!m_instance) {
+        m_instance = new MacUtils(qApp);
+    }
+
+    return m_instance;
+}
+
+WId MacUtils::activeWindow()
+{
+    return m_appkit->activeProcessId();
+}
+
+bool MacUtils::raiseWindow(WId pid)
+{
+    return m_appkit->activateProcess(pid);
+}
+
+bool MacUtils::raiseOwnWindow()
+{
+    return m_appkit->activateProcess(m_appkit->ownProcessId());
+}
+
+bool MacUtils::raiseLastActiveWindow()
+{
+    return m_appkit->activateProcess(m_appkit->lastActiveProcessId());
+}
+
+bool MacUtils::hideOwnWindow()
+{
+    return m_appkit->hideProcess(m_appkit->ownProcessId());
+}
+
+bool MacUtils::isHidden()
+{
+    return m_appkit->isHidden(m_appkit->ownProcessId());
+}
+
+bool MacUtils::isDarkMode()
+{
+    return m_appkit->isDarkMode();
+}
+
+bool MacUtils::enableAccessibility()
+{
+    return m_appkit->enableAccessibility();
+}
+
+bool MacUtils::enableScreenRecording()
+{
+    return m_appkit->enableScreenRecording();
+}
diff --git a/src/gui/osutils/macutils/MacUtils.h b/src/gui/osutils/macutils/MacUtils.h
new file mode 100644
index 000000000..427c7230a
--- /dev/null
+++ b/src/gui/osutils/macutils/MacUtils.h
@@ -0,0 +1,62 @@
+/*
+ *  Copyright (C) 2012 Felix Geyer <debfx@fobos.de>
+ *  Copyright (C) 2017 KeePassXC Team <team@keepassxc.org>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 2 or (at your option)
+ *  version 3 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef KEEPASSXC_MACUTILS_H
+#define KEEPASSXC_MACUTILS_H
+
+#include "gui/osutils/OSUtilsBase.h"
+#include "AppKit.h"
+#include <QPointer>
+
+class MacUtils : public OSUtils
+{
+    Q_OBJECT
+
+public:
+    static MacUtils* instance();
+
+    WId activeWindow();
+    bool raiseWindow(WId pid);
+    bool raiseLastActiveWindow();
+    bool raiseOwnWindow();
+    bool hideOwnWindow();
+    bool isHidden();
+    bool isDarkMode() override;
+    bool enableAccessibility();
+    bool enableScreenRecording();
+
+signals:
+    void lockDatabases();
+
+protected:
+    explicit MacUtils(QObject* parent = nullptr);
+    ~MacUtils() override;
+
+private:
+    QScopedPointer<AppKit> m_appkit;
+    static QPointer<MacUtils> m_instance;
+
+    Q_DISABLE_COPY(MacUtils)
+};
+
+inline MacUtils* macUtils()
+{
+    return MacUtils::instance();
+}
+
+#endif // KEEPASSXC_MACUTILS_H
diff --git a/src/gui/osutils/nixutils/NixUtils.cpp b/src/gui/osutils/nixutils/NixUtils.cpp
new file mode 100644
index 000000000..229d6b519
--- /dev/null
+++ b/src/gui/osutils/nixutils/NixUtils.cpp
@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2020 KeePassXC Team <team@keepassxc.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 or (at your option)
+ * version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "NixUtils.h"
+#include <QApplication>
+#include <QColor>
+#include <QPalette>
+#include <QStyle>
+
+QPointer<NixUtils> NixUtils::m_instance = nullptr;
+
+NixUtils* NixUtils::instance()
+{
+    if (!m_instance) {
+        m_instance = new NixUtils(qApp);
+    }
+
+    return m_instance;
+}
+
+NixUtils::NixUtils(QObject* parent)
+    : OSUtilsBase(parent)
+{
+}
+
+NixUtils::~NixUtils()
+{
+}
+
+bool NixUtils::isDarkMode()
+{
+    if (!qApp || !qApp->style()) {
+        return false;
+    }
+    return qApp->style()->standardPalette().color(QPalette::Window).toHsl().lightness() < 110;
+}
diff --git a/src/gui/osutils/nixutils/NixUtils.h b/src/gui/osutils/nixutils/NixUtils.h
new file mode 100644
index 000000000..bf236cdc3
--- /dev/null
+++ b/src/gui/osutils/nixutils/NixUtils.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2020 KeePassXC Team <team@keepassxc.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 or (at your option)
+ * version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef KEEPASSXC_NIXUTILS_H
+#define KEEPASSXC_NIXUTILS_H
+
+#include "gui/osutils/OSUtilsBase.h"
+#include <QPointer>
+
+class NixUtils : public OSUtilsBase
+{
+    Q_OBJECT
+
+public:
+    static NixUtils* instance();
+
+    bool isDarkMode() override;
+
+private:
+    explicit NixUtils(QObject* parent = nullptr);
+    ~NixUtils() override;
+
+private:
+    static QPointer<NixUtils> m_instance;
+
+    Q_DISABLE_COPY(NixUtils)
+};
+
+inline NixUtils* nixUtils()
+{
+    return NixUtils::instance();
+}
+
+#endif // KEEPASSXC_NIXUTILS_H
diff --git a/src/gui/osutils/winutils/WinUtils.cpp b/src/gui/osutils/winutils/WinUtils.cpp
new file mode 100644
index 000000000..f92192f18
--- /dev/null
+++ b/src/gui/osutils/winutils/WinUtils.cpp
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2020 KeePassXC Team <team@keepassxc.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 or (at your option)
+ * version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "WinUtils.h"
+#include <QAbstractNativeEventFilter>
+#include <QApplication>
+#include <QSettings>
+
+#include <windows.h>
+
+QPointer<WinUtils> WinUtils::m_instance = nullptr;
+QScopedPointer<WinUtils::DWMEventFilter> WinUtils::m_eventFilter;
+
+WinUtils* WinUtils::instance()
+{
+    if (!m_instance) {
+        m_instance = new WinUtils(qApp);
+    }
+
+    return m_instance;
+}
+
+WinUtils::WinUtils(QObject* parent)
+    : OSUtilsBase(parent)
+{
+}
+
+WinUtils::~WinUtils()
+{
+}
+
+/**
+ * Register event filters to handle native platform events such as theme changes.
+ */
+void WinUtils::registerEventFilters()
+{
+    if (!m_eventFilter) {
+        m_eventFilter.reset(new DWMEventFilter);
+        qApp->installNativeEventFilter(m_eventFilter.data());
+    }
+}
+
+bool WinUtils::DWMEventFilter::nativeEventFilter(const QByteArray& eventType, void* message, long*)
+{
+    if (eventType != "windows_generic_MSG") {
+        return false;
+    }
+
+    auto* msg = static_cast<MSG*>(message);
+    if (!msg->hwnd) {
+        return false;
+    }
+    switch (msg->message) {
+    case WM_CREATE:
+    case WM_INITDIALOG: {
+        if (winUtils()->isDarkMode()) {
+            // TODO: indicate dark mode support for black title bar
+        }
+        break;
+    }
+    }
+
+    return false;
+}
+
+bool WinUtils::isDarkMode()
+{
+    QSettings settings(R"(HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Themes\Personalize)",
+                       QSettings::NativeFormat);
+    return settings.value("AppsUseLightTheme", 1).toInt() == 0;
+}
diff --git a/src/gui/osutils/winutils/WinUtils.h b/src/gui/osutils/winutils/WinUtils.h
new file mode 100644
index 000000000..1a95716e1
--- /dev/null
+++ b/src/gui/osutils/winutils/WinUtils.h
@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2020 KeePassXC Team <team@keepassxc.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 or (at your option)
+ * version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef KEEPASSXC_WINUTILS_H
+#define KEEPASSXC_WINUTILS_H
+
+#include "gui/osutils/OSUtilsBase.h"
+
+#include <QAbstractNativeEventFilter>
+#include <QPointer>
+#include <QScopedPointer>
+
+class WinUtils : public OSUtilsBase
+{
+    Q_OBJECT
+
+public:
+    static WinUtils* instance();
+    static void registerEventFilters();
+
+    bool isDarkMode() override;
+
+protected:
+    explicit WinUtils(QObject* parent = nullptr);
+    ~WinUtils() override;
+
+private:
+    class DWMEventFilter : public QAbstractNativeEventFilter
+    {
+    public:
+        bool nativeEventFilter(const QByteArray& eventType, void* message, long*) override;
+    };
+
+    static QPointer<WinUtils> m_instance;
+    static QScopedPointer<DWMEventFilter> m_eventFilter;
+
+    Q_DISABLE_COPY(WinUtils)
+};
+
+inline WinUtils* winUtils()
+{
+    return WinUtils::instance();
+}
+
+#endif // KEEPASSXC_WINUTILS_H