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Re: DrawImage with XOR undefined [message #9108 is a reply to message #9086]

Tue, 17 April 2007 21:20

nixnixnix
Messages: 415
Registered: February 2007
Location: Kelowna, British Columbia

Senior Member

I am using RectTracker to grab a node from a TreeCtrl and drag it onto another node in order to change the tree hierarchy.

I've subclassed from RectTracker and overwritten its DrawRect routine. My only problem is that I erase the background so I need to sample it and replace it. I've tried the following approaches:

1) I can get the TreeCtrl to repaint itself but TreeCtrl::GetLineCount() falls over when I'm in the local loop so I can't ask the nodes to repaint themselves.

2) I tried refresh but it gets carried out after I draw the dragged image so even though I only refresh the rect containing the old position of the dragged node (i.e. rc1), it still erases most of the dragged node. If there was a way to refresh a rect minus another rect that would work (clipping?).

3) If I could do this by sampling the screen, I would be able to apply this method to other views in which a refresh takes a long time. However my attempts to sample the screen are so far not successful. See below:

void LayerTracker::DrawRect(Rect rc1,Rect rc2)
{	
	ViewDraw w(&GetMaster()); 
	
	w.DrawImage(rc1,m_screen);
	
	// sample screen at rc2
	ImageBuffer ib(rc2.Size());
	
	ImageBuffer buf = w;
	
	for(int i=0;i<rc2.Height();i++)
	{
		RGBA* pS = buf[rc2.top+i];
		RGBA* pB = ib[rc2.top+i];
		memcpy(pB,pS,rc2.Width());		
	}
	
	m_screen = ib;

	w.DrawImage(rc2,m_image); 

}

m_image and m_screen are or type Image. My problem is there is no conversion from ViewDraw to Image. Ideally I would use a function of this form

Image ViewDraw::GetImage(Rect rcSample)

Is there a way to sample screen pixels at present?

Nick

[Updated on: Tue, 17 April 2007 22:17]

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