overlist.h

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// $Id: overlist.h 1282 2006-06-09 09:46:49Z alex $
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               Xara LX, a vector drawing and manipulation program.
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 */
// Merge list item

#ifndef OVERRIDELIST
#define OVERRIDELIST

//#include "list.h" - in camtypes.h [AUTOMATICALLY REMOVED]
#include "overitem.h"   //OverrideListItem

/***********************************************************************************************

>   class OverrideList

  Author:   Graham_Walmsley (Xara Group Ltd) <camelotdev@xara.com>
  Created:  21/4/97
  Purpose:  An override list contains items that can override each other.

            For example, imagine we are building a list of clickable areas in
            an imagemap. Our list of clickable areas already contains
            a rectangle with bottom left corner (0,0) and top right corner (200, 200),
            that links to the URL "http://www.xara.com".

            Now we add another clickable rectangle to the imagemap. This rectangle
            has bottom left corner (50,50) and top right corner (100,100) and also
            links to "http://www.xara.com".

            But our first rectangle is contained within our second rectangle! There
            is no need for the second rectangle at all.
            
            It is clear that the first rectangle overrides the second, so the 
            second rectangle should not be added to the list.

            Now imagine the small rectangle is already in the list and the large
            rectangle is added.

            Again, the large rectangle overrides the small one. So the large 
            rectangle should be added to the list and the smaller rectangle
            should be deleted.

            So, this class works as follows.

            When an OverrideListItem is added to this list, this function compares
            the item with every other item in the list. 
            
            It does this by calling either the function
            OverrideListItem::OverrideFromAbove (if the item in the list is before
            the item being added) or OverrideListItem::OverrideFromBelow(if the
            item in the list is below the item being added).

            Then:

            a. If an item in the list overrides the item being added, then the
                new item is not added to the list.

            b. If the item being added overrides an item in the list, then the
                new item is added and the item in the list is deleted.

***********************************************************************************************/

class OverrideList : public List
{   
    CC_DECLARE_DYNAMIC( OverrideList )

    //Constructor
public:
    OverrideList();

    //Overridden functions
public:
    virtual void AddHead( OverrideListItem* );  
    virtual void AddTail( OverrideListItem* );

    virtual LISTPOS InsertBefore(LISTPOS here, OverrideListItem* item);
    virtual ListItem *InsertBefore(OverrideListItem* here, OverrideListItem* item);

    virtual LISTPOS InsertAfter(LISTPOS here, OverrideListItem* item);
    virtual ListItem *InsertAfter(OverrideListItem* here, OverrideListItem* item);

    //Toolkit functions
protected:
    virtual BOOL CompareWithItemsAbove(OverrideListItem* pliStartPos, OverrideListItem* pliToInsert);
    virtual BOOL CompareWithItemsBelow(OverrideListItem* pliStartPos, OverrideListItem* pliToInsert);



};



#endif // OVERRIDELIST

---