C++/CLI Form Resize Problem After Fill Panel

Question

I want resize my Panel Filled Form with BOTTOMLEFT, BOTTOM in addition to BOTTOMRIGHT

My Default Resizing Code Resize only Form without Panel :

          const int cGrip = 16;
          const int cCaption = 32;
      void WndProc(Message% m) override
       {
           switch (m.Msg)
           {
           case WM_NCHITTEST:
               Point pos = Point(m.LParam.ToInt32());
               pos = PointToClient(pos);
               if (pos.Y < cCaption)
               {
                   m.Result = IntPtr(HTCAPTION);
                   return;
               }
               if (pos.X >= ClientSize.Width - cGrip && pos.Y >= ClientSize.Height - cGrip)
               {
                   m.Result = IntPtr(HTBOTTOMRIGHT);
                   return;
               }
               break;
           }
           __super::WndProc(m);
       }

Answer 1

To resize the child control automatically after resizing the form, set its Anchor properties. This can be done in Form Designer manually, or programmatically:

panel1->Anchor = (AnchorStyles)(AnchorStyles::Left | AnchorStyles::Top | AnchorStyles::Right | AnchorStyles::Bottom);

Show more details if you need a special behaviour.

Answer 2

According to the Doc:

If the mouse is not captured, the message is sent to the window beneath the cursor. Otherwise, the message is sent to the window that has captured the mouse.

As far as I'm concerned, When the DOCK attribute of the panel is Fill, the message is sent to the panel window instead of the form window. So we couldn't resize the form after fill panel.

I suggest you could try to override OnSizeChanged of form and set the region of panel same size as form and then exclude its bottom right corner. This way, the excluded region doesn't belong to panel anymore and all messages including WM_NCHITTEST will be received by our WndProc; the panel even doesn't draw that region.

Here is my code:

protected:  
	void OnSizeChanged(EventArgs ^ e) override  
	{			  
		region = gcnew System::Drawing::Region(System::Drawing::RectangleF(0, 0, this->Width, this->Height));  
		sizeGripRectangle = gcnew System::Drawing::RectangleF (this->Width - tolerance, this->Height - tolerance, tolerance, tolerance);  
		region->Exclude(*sizeGripRectangle);  
		this->panel1->Region = region;  
		this->Invalidate();  

	}  

Best Regards,

Jeanine

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Answer 3

hi there!

I would suggest you catch WM_MOUSEMOVE messages. WM_NCHITTEST if for different purposes