LNextCell
Boolean hNext ; look horizontally (toward the right)? Boolean vNext ; look vertically (toward the bottom)? Cell *theCell ; starting position; receives next cell ListHandle theList ; handle leading to a ListRec returns Was a cell located?
LNextCell advances from one cell position to the next. You can advance horizontally only (across a row), vertically only (down a column), or both
(horizontally until at the end of a row and wrapping from row to row).
hNext and . . .
vNext Are Booleans that identify how to look for the next cell. There are three meaningful combinations:
hNext=TRUE (vNext=FALSE) Advance horizontally to the right. If beyond the end of the row, return FALSE. vNext=TRUE (hNext=FALSE) Advance vertically toward the bottom. If beyond the bottom of the list, return FALSE. Both TRUE Advance horizontally to the right. If beyond the last column, advance to first cell in the the next lower row. If beyond the
bottom of the list, return FALSE. theCell is the address of a 32-bit Cell (a.k.a. Point). On entry, it specifies where to start looking. Upon return, it contains the cell coordinates
of the next cell, according to the criteria set forth in hNext and
vNext. If the return value is FALSE, the value of theCell is un defined upon exit.
theList is a handle leading to a variable-length ListRec structure. It is a value previously obtained via LNew. Returns: a Boolean identifying whether a valid 'next' cell was obtained. It is one of:
FALSE No more cells - either at the end of a row, column, or list. The value of theCell is now un defined.
TRUE A valid 'next' cell was found, its coordinates are in theCell.
Notes: You can use LNextCell in place of a set of nested loops. For instance, you could use it to loop through and deselect all cells (a function NOT provided
by the List Manager). Another example: given a mouse location in local
coordinates, you could determine which cell was currently pointed to via:
found = FALSE; theCell.h=theCell.v=0; /* start at top left */ do {
LRect( &cellRect, theCell, theList ); /* get rect for this cell */ if ( PtInRect( mousePt, &cellRect ) ) /* if mouse is there ... */ found = TRUE; /* ... we're done looking */ } while ( LNextCell( TRUE,TRUE, &theCell, theList ) && !found );
if ( found) { /*. . . theCell is the cell of interest . . . */ }
LNextCell is also handy in locating a series of selected cells (see LGetSelect for an example of usage). To locate a cell containing some the contents of a list manually).