feat: load current folder pics and nav using pageup and pagedown

mainwindow.h

@@ -26,6 +26,10 @@ public:
     void showUrls(const QList<QUrl> &urls);
     void adjustWindowSizeBySceneRect();
 
+    void loadGalleryBySingleLocalFile(const QString &path);
+    void galleryPrev();
+    void galleryNext();
+
 protected slots:
     void showEvent(QShowEvent *event) override;
     void enterEvent(QEvent *event) override;
@@ -59,6 +63,9 @@ private:
     BottomButtonGroup *m_bottomButtonGroup;
     bool m_protectedMode = false;
     bool m_clickedOnWindow = false;
+
+    QList<QUrl> m_files;
+    int m_currentFileIndex = -1;
 };
 
 #endif // MAINWINDOW_H