feat: enable back to original size after exit fullscreen.

QtScrcpy/ui/videoform.cpp

@@ -467,6 +467,8 @@ void VideoForm::switchFullScreen()
         }
 
         showNormal();
+        // back to normal size.
+        resize(m_normalSize);
         // fullscreen window will move (0,0). qt bug?
         move(m_fullScreenBeforePos);
 
@@ -487,6 +489,9 @@ void VideoForm::switchFullScreen()
             ui->keepRatioWidget->setWidthHeightRatio(-1.0f);
         }
 
+        // record current size before fullscreen, it will be used to rollback size after exit fullscreen.
+        m_normalSize = size();
+
         m_fullScreenBeforePos = pos();
         // 这种临时增加标题栏再全屏的方案会导致收不到mousemove事件，导致setmousetrack失效
         // mac fullscreen must show title bar

QtScrcpy/ui/videoform.h

@@ -79,6 +79,7 @@ class VideoForm : public QWidget, public qsc::DeviceObserver
 
     //inside member
     QSize m_frameSize;
+    QSize m_normalSize;
     QPoint m_dragPosition;
     float m_widthHeightRatio = 0.5f;
     bool m_skin = true;