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Dialog window size

V245
V245 asked
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Last Modified: 2013-12-03
I create a dialog window by using CreateIndirect(). And I have a problem.
I want to create the window with a certain size, for example with a client
rectangle size of a parent window. I can get wanted size by using GetClientRect().
But the values I get are measured in pixels. At the same time I have to set
x, y, cx and cy parameters of DLGTEMPLATE in dialog box units, not in pixels.
I make the following:

...
CRect MainWndClientRect;
pParentWnd->GetClientRect(&MainWndClientRect);
...
LONG  DlgBaseUnit = GetDialogBaseUnits();
UINT  DlgBaseUnitX = (UINT)( ( DlgBaseUnit << 16 ) >> 16 );
UINT  DlgBaseUnitY = (UINT)( DlgBaseUnit >> 16 );

DLGTEMPLATE  dlgTempl;
...
dlgTempl.x  = (short)( ( MainWndClientRect.left     * 4 ) / DlgBaseUnitX );
dlgTempl.y  = (short)( ( MainWndClientRect.top      * 8 ) / DlgBaseUnitY );
dlgTempl.cx = (short)( ( MainWndClientRect.Width()  * 4 ) / DlgBaseUnitX );
dlgTempl.cy = (short)( ( MainWndClientRect.Height() * 8 ) / DlgBaseUnitY );
...
CreateIndirect( &dlgTempl, &pParentWnd );
...

As a result I have the dialog window with a wrong size. Why?
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Commented:
I'm not sure why that doesn't work.  But I can suggest an improvement.  (Yes that's right a change that will make it not work even faster.)

instead of

UINT  DlgBaseUnitX = (UINT)( ( DlgBaseUnit << 16 ) >> 16 );
UINT  DlgBaseUnitY = (UINT)( DlgBaseUnit >> 16 );

use

UINT  DlgBaseUnitX = (UINT)( DlgBaseUnit && 0x0000FFFF );
UINT  DlgBaseUnitY = (UINT)( DlgBaseUnit >> 16 );

How far are you off by?  like could this be a rounding thing?  
Commented:
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Commented:
The calculation you make is only valid if you're using the system font.
There is a workaround.  See KB articles Q145994 and Q74280 for details.

Author

Commented:
I'm using system font. So I accept the Duneram answer also at common I don't like such solutions. To my mind it isn't a problem solution but it is a trick for go around the problem. In any case it works.
Thanks for Nietod and Alexo for your advices.

Commented:
I'm still curious, how far off was the positioning using your formulas?  was it close?

Author

Commented:
Sorry for my delay, I was in leave. Well, at the time I know that   GetDialogBaseUnits() is cause of my problem. This function returns wrong value (¬†DlgBaseUnitX=10 and ¬†DlgBaseUnitY=20 instead of 8 and 16 ). I tried 'Method Two' from article Q145994 - it works correct.
Thanks for all.
Vladimir

Commented:
Well, seems I was able to help after all :-)

Author

Commented:
'Method Two' can be used for calculating dialog units instead GetDialogBaseUnits(). But in my case I can't use it because I need the dialog units values before the window is created. So I can't call MapDialogRect(). In my program I implemented Duneram's solution: I create the window with wrong size and then call SetWindowPos() in OnInitDialog(). I guess His Majesty Bill Gates didn't let me any choice ;-)
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