changing background colour

Posted on 1998-12-30
Last Modified: 2010-04-01
I want to change details from a window class before it is created, such as background colour of the window. It seems I can only get a pointer to the class name (a string). I am currently using this code

CRect rect;
GetClientRect( rect );
pDC->FillSolidRect( rect, RGB( 0, 0xbb, 0 ) );

in the OnDraw function but this is highly inefficient. How can I do better?

Also, a trivial but annoying thing (not worth points but bugging me all the same) I have edited the document icon in my application but windows continues to use the old one on my system (I have not tried distributing the app yet). I have tried importing the .reg file but still no good. I guess this must be a windows thing because the application definitely recognises the new icon.
Question by:agrillage
  • 3
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Expert Comment

ID: 1181328
Before the class is registered, your app has a WNDCLASS structure, it contains members like hbrBackground which is an HBRUSH used to erase the background, if you fill it in then it will be used by every window of the class.

After the class is created, you can use SetClassLong to change the properties of a class.  The change will only affect new windows, not existing ones.

Since you use MFC, you might want to use AfxRegisterWndClass to get exactly the class you want.


Accepted Solution

stsanz earned 50 total points
ID: 1181329
Create a solid brush in your init code :
CBrush  BackgroundBrush ;
BackgroundBrush.CreateSolidBrush(RGB(0,0xbb,0)) ;

Then, when you want to change the background color for the window, use :
SetClassLong(m_hWnd,GCL_HBRBACKGROUND,(LONG)HBRUSH(BackgroundBrush)) ;

Don't forget to destroy the brush in your exit code :
BackgroundBrush.DeleteObject() ;

About your icon problem, is it an icon you associate with files having a particular extension or what is it associated with ?


Author Comment

ID: 1181330
The icon is associated with the document ( the only document ) class for the application. It is the default from the app wizard. All I did was edit it.

I am trying the SetClassLong Function in the meantime.

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Expert Comment

ID: 1181331
For the icon problem, I think you have edited the 32x32 version of the icon, but not the 16x16 version, which is used to display the document icon in MFC.
WHen you edit the icon in Visual C++, you have a combobox where you can choose between the 32x32 version and the 16x16 version to edit.


Author Comment

ID: 1181332
Points are for the background colour. I edited both icons and niether comes through correctly. I think it must be a bug but I would be interested to hear any more thoughts you might have.

Expert Comment

ID: 1181333
Which version of Visual C++ do you use ?
Is your MFC application SDI or MDI ?

Try to open your application .EXE with Visual C++
using "Open as : resource" and tell me if the icon
in the .EXE appears as you modified it or as the default.

Author Comment

ID: 1181334
Visual C++ 5.0 Enterprise
The icons appear as I want, correctly modified.

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