Add transparent overlay window (#4746)

src/widgets/OverlayWindow.hpp

@@ -0,0 +1,87 @@
+#pragma once
+
+#include "common/Channel.hpp"
+#include "widgets/helper/ChannelView.hpp"
+#include "widgets/helper/OverlayInteraction.hpp"
+
+#include <pajlada/signals/scoped-connection.hpp>
+#include <pajlada/signals/signalholder.hpp>
+#include <QTimer>
+#include <QWidget>
+
+#ifdef Q_OS_WIN
+#    include <QtGui/qwindowdefs_win.h>
+#endif
+
+class QGraphicsDropShadowEffect;
+
+namespace chatterino {
+
+class OverlayWindow : public QWidget
+{
+    Q_OBJECT
+public:
+    OverlayWindow(IndirectChannel channel);
+    ~OverlayWindow() override;
+    OverlayWindow(const OverlayWindow &) = delete;
+    OverlayWindow(OverlayWindow &&) = delete;
+    OverlayWindow &operator=(const OverlayWindow &) = delete;
+    OverlayWindow &operator=(OverlayWindow &&) = delete;
+
+    void setOverrideCursor(const QCursor &cursor);
+
+    bool isInert() const;
+    void setInert(bool inert);
+    void toggleInertia();
+
+protected:
+#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
+    using NativeResult = qintptr;
+    using EnterEvent = QEnterEvent;
+#else
+    using NativeResult = long;
+    using EnterEvent = QEvent;
+#endif
+
+    bool eventFilter(QObject *object, QEvent *event) override;
+    void enterEvent(EnterEvent *event) override;
+    void leaveEvent(QEvent *event) override;
+
+#ifdef Q_OS_WIN
+    bool nativeEvent(const QByteArray &eventType, void *message,
+                     NativeResult *result) override;
+#endif
+
+private:
+    void triggerFirstActivation();
+
+    void addShortcuts();
+
+    void startInteraction();
+    void startShortInteraction();
+    void endInteraction();
+
+    void applyTheme();
+
+#ifdef Q_OS_WIN
+    void handleNCHITTEST(MSG *msg, NativeResult *result);
+
+    HCURSOR sizeAllCursor_;
+#endif
+
+    IndirectChannel channel_;
+    pajlada::Signals::SignalHolder holder_;
+
+    ChannelView channelView_;
+    QGraphicsDropShadowEffect *dropShadow_;
+
+    bool inert_ = false;
+
+    bool moving_ = false;
+    QPoint moveOrigin_;
+
+    OverlayInteraction interaction_;
+    QTimer shortInteraction_;
+};
+
+}  // namespace chatterino