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InvalidateRect

Posted on 2002-03-18
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Last Modified: 2013-11-20
If I understand things correctly, if you want a certain area of a window to be redrawn you call the CWnd::InvalidateRect function.

Question: Given an edit box in a form: How do get the coordinates of said edit box (in the CRect structure) to plug into the CWnd::InvalidateRect function?

Thanx
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Question by:Smave
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4 Comments
 
LVL 49

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by:DanRollins
ID: 6878747
Not neccessary.  

You can use Invalidate() or InvalidateRect(0) for the Edit control itself (rather than get a rect for some subset of the screen or some other window).

Also, it is not needed, sinc rhe Edit control updates itself each time its contents change.

But to answer your question, use the GetWindowRect() member function of the control.

-- Dan
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Author Comment

by:Smave
ID: 6878825
GetWindowRect(IDC_EDIT_RecordCNT);

gave me a compiler error.

error C2664: 'GetWindowRect' : cannot convert parameter 1 from 'const int' to 'struct tagRECT *'
Conversion from integral type to pointer type requires reinterpret_cast, C-style cast or function-style cast

Do I need to create a member variable that is a control?

Thanx
Ace
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Accepted Solution

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DanRollins earned 50 total points
ID: 6878868
>> GetWindowRect(IDC_EDIT_RecordCNT);

You should check the online help because that command is wrong in at least two obvious ways.  IDC_EDIT_RecordCNT is just an integer that identifies a control.  

>>Do I need to create a member variable that is a control?

no, but if you do, the command would like like:

CRect rc;
m_ctlEdit1.GetWindowRect( & rc );

if you don't create a member-variable control, you could use:

GetDlgItem(IDC_EDIT_RecordCNT)->GetWindowRect( & rc );

But as I said in the other question, the edit control will display the value automatically and does not need to be updated

(Exception: The screeen won't update right away if you do a lot of work in OnInitDialog.  Just set things up and return, otherwise all message processing stops).

-- Dan
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LVL 1

Expert Comment

by:kirthir
ID: 6878992
One addition to what Dan Rollins suggested
1)The GetWindowRect returns the postion of the control in terms of screen coordinates, to get the position in terms of client coordinates - call ScreenToClient(rc);

Hope this helps

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