Vollbildmodus für HDMI

include/videowidget.h

@@ -12,6 +12,33 @@
 
 #include "v4l2worker.h"
 
+// A borderless top-level window that mirrors the live video frame at full
+// screen size. Opened from VideoWidget's "⛶" button; closes itself on
+// Escape or a double-click anywhere on it.
+class FullscreenVideoView : public QWidget
+{
+    Q_OBJECT
+
+public:
+    explicit FullscreenVideoView(QWidget *parent = nullptr);
+
+    void setFrame(const QImage &frame);
+
+signals:
+    // Emitted from closeEvent() so VideoWidget can drop its pointer before
+    // the WA_DeleteOnClose deletion actually happens.
+    void closed();
+
+protected:
+    void paintEvent(QPaintEvent *event) override;
+    void keyPressEvent(QKeyEvent *event) override;
+    void mouseDoubleClickEvent(QMouseEvent *event) override;
+    void closeEvent(QCloseEvent *event) override;
+
+private:
+    QImage m_frame;
+};
+
 // VideoWidget shows the live V4L2 preview and can additionally record it
 // to an MP4 file. Recording works by piping raw BGRA frames into an
 // external `ffmpeg` process (via QProcess/stdin), which encodes them to
@@ -54,6 +81,7 @@ private slots:
     void onFreeze(bool frozen);
     void onScreenshot();
     void onRecordToggled(bool checked);
+    void onFullscreenToggle();
     void refreshDeviceList();
 
 protected:
@@ -83,8 +111,14 @@ private:
     QPushButton *m_freezeBtn     = nullptr;
     QPushButton *m_screenshotBtn = nullptr;
     QPushButton *m_recordBtn     = nullptr;
+    QPushButton *m_fullscreenBtn = nullptr;
     QLabel      *m_infoLabel     = nullptr;
 
+    // Fullscreen overlay window (nullptr when not open). Owns itself via
+    // Qt::WA_DeleteOnClose; VideoWidget just tracks whether one currently
+    // exists and forwards frames to it while it's open.
+    FullscreenVideoView *m_fullscreenView = nullptr;
+
     // Recording state. m_recordProcess is the running ffmpeg instance (or
     // nullptr when not recording); m_recordSize is the frame size the
     // recording was started with, so a mid-stream resolution change (which