bitmap dissapears on window resize

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I have a document/view aplication that opens a bitmap

I use the following OnDraw override to draw the bitmap on a window and OnOpenDocument to opening the image from file

The bitmap handle ( HBITMAP bmaphandle ) is taken from the Document object that does LoadImage in it's OnOpenDocument method
HBITMAP bmaphandle = pDoc->GetHandleToBitmap();

The problem I have is that on resizeing the window or when i move another window over it the image dissapears from the view. How do I make it persistent?

thx

C++ Syntax (Toggle Plain Text)
BOOL CImageFilterDoc::OnOpenDocument( LPCTSTR strFilename )
{
	if ( ( m_hBitmap = (HBITMAP)LoadImage(NULL, strFilename, IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE) )  == NULL ) 
		return FALSE;
 
	return TRUE;
 
}
 
void CImageFilterView::OnDraw(CDC* pDC)
{
	CImageFilterDoc* pDoc = GetDocument();
	ASSERT_VALID(pDoc);
	if (!pDoc)
		return;
 
	// TODO: add draw code for native data here
	HBITMAP bmaphandle = pDoc->GetHandleToBitmap();
	if ( bmaphandle )
	{
		CClientDC dc(this);
		CDC *mdc=new CDC;
		mdc->CreateCompatibleDC(&dc);
 
		CBitmap bitmap;
 
		bitmap.m_hObject = bmaphandle;
 
		mdc->SelectObject(bitmap);
		CRect rect;
		GetClientRect(&rect);
 
		dc.BitBlt(0,0,rect.right,rect.bottom,mdc,0,0,SRCCOPY);
 
		delete mdc;
 
	}
}
BOOL CImageFilterDoc::OnOpenDocument( LPCTSTR strFilename )
{
	if ( ( m_hBitmap = (HBITMAP)LoadImage(NULL, strFilename, IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE) )  == NULL ) 
		return FALSE;

	return TRUE;

}

void CImageFilterView::OnDraw(CDC* pDC)
{
	CImageFilterDoc* pDoc = GetDocument();
	ASSERT_VALID(pDoc);
	if (!pDoc)
		return;

	// TODO: add draw code for native data here
	HBITMAP bmaphandle = pDoc->GetHandleToBitmap();
	if ( bmaphandle )
	{
		CClientDC dc(this);
		CDC *mdc=new CDC;
		mdc->CreateCompatibleDC(&dc);

		CBitmap bitmap;
		
		bitmap.m_hObject = bmaphandle;
		
		mdc->SelectObject(bitmap);
		CRect rect;
		GetClientRect(&rect);

		dc.BitBlt(0,0,rect.right,rect.bottom,mdc,0,0,SRCCOPY);

		delete mdc;

	}
}

kux

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Junior Poster

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since Jan 2008

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Nov 18th, 2008

Re: bitmap dissapears on window resize

I'm not sure, and I haven't done this for a few years, but you could try a this->refresh() when you're done resizing

Last edited by Nick Evan; Nov 18th, 2008 at 9:11 am.

Nick Evan

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Industrious Poster

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since Oct 2006

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Nov 19th, 2008

Re: bitmap dissapears on window resize

Ok, i found the problem.
The CBitmap bitmap object from OnDraw(CDC*) took a handle to the bitmap and on destruction deleted the object pointed by the handle

kux

Reputation Points: 66

Solved Threads: 11

Junior Poster

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since Jan 2008

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