chore: adjusted the project directory structure

app/bottombuttongroup.h

@@ -0,0 +1,29 @@
+#ifndef BOTTOMBUTTONGROUP_H
+#define BOTTOMBUTTONGROUP_H
+
+#include <QAbstractButton>
+#include <QGroupBox>
+
+class OpacityHelper;
+class BottomButtonGroup : public QGroupBox
+{
+    Q_OBJECT
+public:
+    explicit BottomButtonGroup(QWidget *parent = nullptr);
+
+    void setOpacity(qreal opacity, bool animated = true);
+    void addButton(QAbstractButton *button);
+
+signals:
+    void resetToOriginalBtnClicked();
+    void toggleWindowMaximum();
+    void zoomInBtnClicked();
+    void zoomOutBtnClicked();
+    void toggleCheckerboardBtnClicked();
+    void rotateRightBtnClicked();
+
+private:
+    OpacityHelper * m_opacityHelper;
+};
+
+#endif // BOTTOMBUTTONGROUP_H