Bug in Transparent Group

[Antonio Linares]

Hakan,

You can do it this way:

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#include 'fivewin.ch'

function Main()

   local oDlg, oGrp

   DEFINE DIALOG oDlg COLOR CLR_WHITE, CLR_BLUE SIZE 600, 400
   
   @ 20, 20 TO 100, 200 PIXEL OF oDlg TRANSPARENT
     
   @ 60, 20 GROUP oGrp TO 100, 200 PIXEL OF oDlg TRANSPARENT
     
   oGrp:bEraseBkGnd = { || nil }  
     
   ACTIVATE DIALOG oDlg CENTER

return nil
 

[nageswaragunupudi]

May I propose the following change to the EraseBkgnd method of TGroup?

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METHOD EraseBkGnd( hDC ) CLASS TGroup

   if ::oWnd:IsKindOf( 'TDIALOG' )
      return Super:EraseBkGnd( hDC )
   else

      if ! Empty( ::bEraseBkGnd )
         return Eval( ::bEraseBkGnd, hDC )
      endif

      if ::lTransparent

         if ! Empty( ::oWnd:oBrush:hBitmap )
            SetBrushOrgEx( hDC, nBmpWidth( ::oWnd:oBrush:hBitmap ) - ::nLeft, nBmpHeight( ::oWnd:oBrush:hBitmap ) - ::nTop )
         endif

         FillRect( hDC, GetClientRect( ::hWnd ), ::oWnd:oBrush:hBrush )
      else
         FillRect( hDC, GetClientRect( ::hWnd ), ::oBrush:hBrush )
      endif

   endif

return 0

//----------------------------------------------------------------------------//
 

With this change, the earlier behavior for dialogs is retained and transparency on windows is improved. This does not break earlier code for transparent groups on dialogs.

I have also found by experimentation that this code

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        SetBrushOrgEx( hDC, -::nLeft, -::nTop )
 

works exactly the same way as the following code.

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        if ! Empty( ::oWnd:oBrush:hBitmap )
            SetBrushOrgEx( hDC, nBmpWidth( ::oWnd:oBrush:hBitmap ) - ::nLeft, nBmpHeight( ::oWnd:oBrush:hBitmap ) - ::nTop )
         endif
 

This can be tested and seen to produce the same results on bitmapped and non-bitmapped brushes.
Why can't we adopt the former simpler code?

Still there were some other issues with transparent painting earlier and now, which I shall express in another post.

[Antonio Linares]

Rao,

If we do:

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  if ::oWnd:IsKindOf( 'TDIALOG' )
      return Super:EraseBkGnd( hDC )
  ...
 

then we are calling Class TControl Method EraseBkGnd() which does nothing for DATA lTransparent. No transparency is managed from there, unless I miss something...

Very nice finding for:

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SetBrushOrgEx( hDC, -::nLeft, -::nTop )
 

thanks!

[Horizon]

Thanks Antonio,

But I have lots of groups in my app. It will takes lots of time for me.

Hakan,

You can do it this way:

Code: Select all  Expand view

#include 'fivewin.ch'

function Main()

   local oDlg, oGrp

   DEFINE DIALOG oDlg COLOR CLR_WHITE, CLR_BLUE SIZE 600, 400
   
   @ 20, 20 TO 100, 200 PIXEL OF oDlg TRANSPARENT
     
   @ 60, 20 GROUP oGrp TO 100, 200 PIXEL OF oDlg TRANSPARENT
     
   oGrp:bEraseBkGnd = { || nil }  
     
   ACTIVATE DIALOG oDlg CENTER

return nil
 

[nageswaragunupudi]

>>
But I have lots of groups in my app. It will takes lots of time for me.
>>
Better to modify the TGroup class. Not your program code.

[Horizon]

Hi Rao,

I have done it since it was changed. But I regularly update fwh every month. I don't want to check it that it was changed or not in every download. I prefer to use unchanged class files from original lib files.

thank anyway.