node2d.cpp

可用于嵌入式编程学习

/*

Copyright (c) 1995-2000 Microsoft Corporation.  All rights reserved.

*/
#include "precomp.h"


Node2D::Node2D(
	int width,
	int height,
	int x,
	int y,
	int align,			// = 4
	Node2D *pParent )	// = NULL
{
	DEBUGMSG(GPE_ZONE_CREATE,(TEXT("Creating initial Node2d which is %d x %d\r\n"), width, height ));
	m_nX = x;
	m_nY = y;
	m_nWidth = width;
	m_nHeight = height;
	m_nAlign = align;
	m_pParent = pParent;
	m_pChild1 = (Node2D *)NULL;
	m_pChild2 = (Node2D *)NULL;
}
			   
void Node2D::GetClosest( int width, int height, int *pLeastWaste, Node2D **ppBestFit )
{
	if( m_nWidth < width || m_nHeight < height )
		return; // this one (and any children) are too small
	if( m_pChild2 ) // This is a parent node, just check child nodes for better fit
	{
		m_pChild1->GetClosest( width, height, pLeastWaste, ppBestFit );
		m_pChild2->GetClosest( width, height, pLeastWaste, ppBestFit );
	}
	else if( !m_pChild1 )
	{
		// This node is free & big enough - check for fit
		int waste = m_nWidth * m_nHeight - width * height;
		if( *ppBestFit == (Node2D *)NULL || waste < *pLeastWaste )
		{
			*pLeastWaste = waste;
			*ppBestFit = this;
		}
	}
	// else, this node is in use
}

Node2D * Node2D::Split( int width, int height )
{
	DEBUGMSG(GPE_ZONE_CREATE,(TEXT("Splitting Node2d (%dx%d) to give %dx%d space\r\n"),
		m_nWidth, m_nHeight, width, height ));
	if ( height < m_nHeight )
	{
		// Split into top & bottom pieces - the top part will be further cut down to the correct width
		m_pChild1 = new Node2D( m_nWidth, height, m_nX, m_nY, m_nAlign, this );
		m_pChild2 = new Node2D( m_nWidth, m_nHeight-height, m_nX, m_nY+height, m_nAlign, this );
		return m_pChild1->Split( width, height );
	}
	else if( width < m_nWidth )
	{
		// Split into left & right pieces
		m_pChild1 = new Node2D( width, m_nHeight, m_nX, m_nY, m_nAlign, this );
		m_pChild2 = new Node2D( m_nWidth-width, m_nHeight, m_nX+width, m_nY, m_nAlign, this );
		return m_pChild1;
	}
	return this;
}

Node2D * Node2D::Alloc( int width, int height )
{
	Node2D *pNode = (Node2D *)NULL;
	int waste;
	width = ( width + m_nAlign - 1 ) & ( - m_nAlign );	// Round up to alignment
	// Find the best node to contain the new area
	DEBUGMSG(GPE_ZONE_CREATE,(TEXT("Attempting to allocate %dx%d space\r\n"), width, height ));
	GetClosest( width, height, &waste, &pNode );
	if( pNode )
	{
		// Split the node into the required space & remainder piece(s)
		pNode = pNode->Split( width, height );
		DEBUGMSG(GPE_ZONE_CREATE, (TEXT("Succesfully allocated %dx%d at x=%d,y=%d\r\n"),
			pNode->m_nWidth, pNode->m_nHeight, pNode->m_nX, pNode->m_nY ));
		pNode->m_pChild1 = (Node2D *)(-1);
	}
	else
	{
		DEBUGMSG(GPE_ZONE_CREATE,(TEXT("Failed to allocate Node2d !!\r\n")));
	}
	return pNode;
}

void Node2D::Free()
{
	DEBUGMSG(GPE_ZONE_CREATE,(TEXT("Freeing %dx%d at x=%d,y=%d\r\n"),
		m_nWidth, m_nHeight, m_nX, m_nY ));

	if( m_pChild2 )
	{
		// We are being told to delete both child nodes as they are now free
		delete m_pChild1;
		delete m_pChild2;
		m_pChild1 = m_pChild2 = (Node2D *)NULL;
	}
	else
	{
		// m_pChild2 already is NULL, this Node was completely used by a surfobj
		m_pChild1 = (Node2D *)NULL;
	}
	if( m_pParent )
	{
		if( m_pParent->m_pChild1->m_pChild1 == m_pParent->m_pChild2->m_pChild1 )
		{
			// Now this & sibling are free so we can erase both & coalesce
			m_pParent->Free();
		}
	}
}

unsigned long Node2D::AvailSpace()
{
	if( m_pChild2 )
		return m_pChild1->AvailSpace()+m_pChild2->AvailSpace();
	else if( m_pChild1 != (Node2D *)NULL )
		return 0;
	else
		return m_nWidth * m_nHeight;
}