Creating a gambas2 program, step by step, a telephone index

 From : http://listingambas.blogspot.com/2011/06/modulo-ordenar-ordenar-un-gridviews-con.html


Module Sort: sorting a gridviews with _ColumnClick

And now, why not, we are going to sort our gridview like Excel or Calc style. When we click the title header of a column, we'd sort its contents (alphabetically).
How to do that?
We will use the _ColumnClick event, which occurs when we click on the column title. We will also create a variable SortList , to indicate which order mode (increasing from A to Z, or decreasing Z to A). This variable is global, and created in the module var .
In Module Sort, we create two procedures : the increasing sort ( ord_AZ ) or decreasing ( ord_ZA ), and pass to them the grid we want to sort (in our case Fmain.Gridviewdata) and which column , whose value is given when _ColumnClick event occurs.

In the module Var :
PUBLIC sortlist AS Integer


In the module Fmain :
PUBLIC SUB GridViewData_ColumnClick (Column AS Integer )
IF var. sortlist = 0 THEN
Sort. sorting_AZ (GridViewData, Column)
var. sortedlist = 1
ELSE
var. sortedlist = 0
Sort. sorting_ZA (GridViewDatos, Column)
ENDIF
END


In Module Sort : 'Gambas module file
PUBLIC SUB ord_AZ (grid AS GridView, a AS Integer )
'a: indicates the column to sort
'grid: the grid to be sorted
DIM limit AS Integer
DIM change1 AS String
DIM i AS Integer
DIM j AS Integer
DIM col AS Integer

grid. visible = FALSE
limit = grid. Rows . COUNT

IF (grid. Columns . COUNT <a + 1 ) OR a < 0 THEN
Message. Error ( "Error: bad column number" )
GOTO outsort
ENDIF
FOR i = 0 TO limit - 1
FOR j = 0 TO limit - 2
IF UCase $ (Grid[j, a]. Text ) > UCase $ (Grid[j + 1 , a].Text ) THEN
FOR col = 0 TO grid. Columns . COUNT - 1
change1 = Grid [j, col]. Text
Grid [j, col]. Text = Grid [j + 1 , col]. Text
Grid [j + 1, col]. Text = change1
NEXT
ENDIF
NEXT
NEXT
outsort:
grid. visible = TRUE
END

'------------------------------------------------------------------------
PUBLIC SUB ord_ZA (grid AS GridView, a AS Integer )
'a: indicates the column to sort
'grid: the grid to be sorted
DIM limit AS Integer
DIM change1 AS String
DIM i AS Integer
DIM j AS Integer
DIM col AS Integer

grid. visible = FALSE
limit = grid. Rows . COUNT
IF (grid. Columns . COUNT <a + 1 ) OR a < 0 THEN
Message. Error ( "Error: bad column number" )
GOTO outsort
ENDIF
FOR i = 0 TO limit - 2
FOR j = i TO limit - 1
IF UCase $ (Grid[j, a]. Text ) > UCase $ (Grid[j , a].Text ) THEN
FOR col = 0 TO grid. Columns . COUNT - 1
change1 = Grid [j, col]. ].Text )
Grid [j, col]. text = Grid [i, col]. ].Text )
Grid [i, col]. text = change1
NEXT
ENDIF
NEXT
NEXT
outsort:
grid. visible = TRUE
END



Several things to discuss:
1. The sort method chosen is called "Bubble".
On the Internet you can find the explanation of this sorting algorithm (I take it out from there )



2. To be case-unsensitive, we use UCase $ , it convert strings to uppercase. Then we perform the comparison.
If we click on the column of the images they are sorted by the pathname indicating where they are located.