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FIRSTCOL()
Sets the first visible column of a virtual screen
------------------------------------------------------------------------------
Syntax
FIRSTCOL(<nFirstNewColumn>) --> nFirstOldColumn
Argument
<nFirstNewColumn> Designates which column is the first visible
column on the left side of a virtual screen.
Returns
If the parameter is passed, the function returns the previous setting.
If no parameter is passed, it returns the current setting.
Description
This function is important for use in setting virtual screen size in
conjunction with SETMAXROW() and SETMAXCOL(). You can select the first
column that you would like to be visible on the left side of the screen.
In this way the screen can be moved in any direction.
Note
. To simplify programming, values outside of the permissible
range are automatically corrected to the maximum or minimum values
(see example).
Example
The following example sets up a screen with 100 lines and 120 columns.
To help you with screen orientation, the current column number is
displayed at three locations on this virtual screen. The virtual screen
can be moved in any direction using cursor keys and PgUp and PgDn:
SETMAXROW( 99) // screen with 100 lines
SETMAXCOL(119) // and 120 columns
CLEAR
FOR nCount = 0 TO MAXROW() // Build screen
@ nCount, 0 SAY "Line" + NTOC(nCount, 10, 4)
@ nCount, MAXCOL()/2 -5 SAY "Line" + NTOC(nCount, 10, 4)
@ nCount, MAXCOL() -10 SAY "Line" + NTOC(nCount, 10, 4)
NEXT nCount
@ 99, 00 SAY CENTER("This is the last line")
nKeyVal := 0
DO WHILE nKeyVal <> 27
nKeyVal := INKEY(0)
DO CASE
CASE nKeyVal = 5
FIRSTROW(FIRSTROW() -1)
CASE nKeyVal = 24
FIRSTROW(FIRSTROW() +1)
CASE nKeyVal = 4
FIRSTCOL(FIRSTCOL() +1)
CASE nKeyVal = 19
FIRSTCOL(FIRSTCOL() -1)
CASE nKeyVal = 18
FIRSTROW(FIRSTROW() -10)
CASE nKeyVal = 3
FIRSTROW(FIRSTROW() +10)
ENDCASE
ENDDO
FIRSTROW(0) // reset
FIRSTCOL(0)
SETMAXCOL(79)
SETMAXROW(24)
CLEAR
See Also:
SETMAXCOL()
MAXCOL()
FIRSTROW()
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Written by Dave Pearson