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BitMap Contour To Windows Region

, 16 Sep 2005
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An article on how to generate an outline of a bitmap. Used when designing user shaped dialogs.

Sample screenshot


The CBitmapHandling class was designed to calculate the contour points in a bitmap. It looks at the bitmap and finds pixel points different from white, it then places these start and stop pixel points in a Vertex of CPoint class. When it has found the outline of the bitmap, it then generates a Windows region. If you use this region in your OnInitDialog and then set the window region using SetWindowRgn(m_WinRgn, TRUE ), your window will then be shaped like the outline.

Using the code

The code consists of a header file and a CPP file.

#include "BitMapHandling.h"
using namespace HandlingBitmaps;

BOOL CMyShapedWindowDlg::OnInitDialog()
 VERIFY( SetWindowPos( NULL, 0, 0, m_nW, 
         m_nH, SWP_NOMOVE | SWP_NOOWNERZORDER ) ); // size and pos. of window
         // cut of areas of region, which you do not really need. 
         // fx. maybe you have bitmap buttons drawn under your bitmap window.
 CBitmapHandling bh;
 bh.BitMapContourToWinRgn(&m_WinRgn, IDB_BITMAP);
 VERIFY( SetWindowRgn(m_WinRgn , TRUE ) );

 return TRUE; // return TRUE unless you set the focus to a control


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Software Developer (Senior) Nokia
Denmark Denmark
I have been working with languages ranging from assembly 68000 to COBOL, OOC, MySQL, Perl, VC++ MFC and WinSockets.
I am currently working as a senior software architect at Nokia Mobile Phones Denmark
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Comments and Discussions

GeneralDemo Project Pinmembergancev18-Apr-07 3:14 
GeneralBitmap PinmemberSangeetha_J25-Jan-07 20:17 
Generalembedded systems Pinmemberjamal odibat18-Sep-05 21:05 
GeneralBetter solution Pinmemberserup31-Aug-05 2:15 
GeneralRe: Better solution Pinmemberserup31-Aug-05 2:35 
GeneralSome Bugs Pinmembernebbi27-Jan-04 21:47 
There are some bugs in this example.
Without trying to run this code i saw some mistakes in the code.
- When you search a startpoint you are testing for white pixels. This looks ok. But when you look for an endpoint you test that R and G and B are not full. This is wrong. Any Colour which has one component at 255 will be taken which is wrong.
- The other thing is that, as you said before, you will not get figures with holes. e.g.(pixels):
xxx xxx
Also you will not get figures correctly which have more than one up and downs.
xx xx xx
And you will not get figures which have two separatet parts.
xxxx xx
xx x
But to get this all is a really hard work.

GeneralRe: Some Bugs Pinmemberserup28-Jan-04 20:32 
GeneralA guess (or two) at your low mark... PinmemberIain Clarke26-Nov-03 5:10 
GeneralRe: A guess (or two) at your low mark... PinsitebuilderUwe Keim26-Nov-03 5:25 
GeneralRe: A guess (or two) at your low mark... PinmemberIain Clarke26-Nov-03 5:33 
GeneralRe: A guess (or two) at your low mark... Pinmemberserup27-Nov-03 3:38 
GeneralRe: A guess (or two) at your low mark... Pinmembergordon8824-Jul-08 12:50 

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