Serializing to / from a text file




To serialize the tree view control override the Serialize() function. The
Serialize() function is a virtual function defined in Cobject.

In the code below we save the outline to a text file and can read it
back from a text file. When saving the outline to the archive, tabs are
used to indent the item text. Again, when reading back, tabs are used to
determine the level that the newly read item should be placed at.

 

void CTreeCtrlX::Serialize(CArchive& ar)
{
if (ar.IsStoring())
{
// storing code
HTREEITEM hti = GetRootItem();
while( hti )
{
int indent = GetIndentLevel( hti );
while( indent– )
ar.WriteString( “t” );
ar.WriteString( GetItemText( hti ) + “rn”);
hti = GetNextItem( hti );
}

}
else
{
// loading code
CString sLine;
if( !ar.ReadString( sLine ) )
return;

HTREEITEM hti = NULL;
int indent, baseindent = 0;
while( sLine[baseindent] == ‘t’ )
baseindent++;
do
{
if( sLine.GetLength() == 0 )
continue;
for( indent = 0; sLine[indent] == ‘t’; indent++ )
; // We don’t need a body
sLine = sLine.Right( sLine.GetLength() – indent );
indent -= baseindent;

HTREEITEM parent;
int previndent = GetIndentLevel( hti );
if( indent == previndent)
parent = GetParentItem( hti );
else if( indent > previndent )
parent = hti;
else
{
int nLevelsUp = previndent – indent;
parent = GetParentItem( hti );
while( nLevelsUp– )
parent = GetParentItem( parent );
}
hti = InsertItem( sLine, parent ? parent : TVI_ROOT, TVI_LAST );
}while( ar.ReadString( sLine ) );

}
}

int CTreeCtrlX::GetIndentLevel( HTREEITEM hItem )
{
int iIndent = 0;

while( (hItem = GetParentItem( hItem )) != NULL )
iIndent++;
return iIndent;
}

// GetNextItem – Get next item as if outline was completely expanded
// Returns – The item immediately below the reference item
// hItem – The reference item
HTREEITEM CTreeCtrlX::GetNextItem( HTREEITEM hItem )
{
HTREEITEM hti;

if( ItemHasChildren( hItem ) )
return GetChildItem( hItem ); // return first child
else{
// return next sibling item
// Go up the tree to find a parent’s sibling if needed.
while( (hti = GetNextSiblingItem( hItem )) == NULL ){
if( (hItem = GetParentItem( hItem ) ) == NULL )
return NULL;
}
}
return hti;
}


 

More by Author

Must Read