How to Drag Data from a Grid to a List Box in VB 3.0

- Microsoft Visual Basic programming system for Windows, version 3.0

SUMMARY

This article shows by example how to select a cell from a grid control and drag the selection to a list box control. The sample code uses data from the BIBLIO.MDB database that came with Visual Basic. The data will be used to populate the Grid control.

By using the technique demonstrated in this article, you will have the ability to allow your users to click on any line of the grid control and drag the data to a sorted list box control. You could use this to build documents that contain certain fields of data from a database.

MORE INFORMATION

Example of Dragging and Dropping from a Grid Control to a List Box

1. Start a new project in Visual Basic. Form1 is created by default.

2. Add a List box (List1) and a Grid (Grid1) to the form.

3. Place the following code in the general declarations section of the form:

      ' Dragging is a flag used for each control to determine
      ' if something is being dragged.
      Dim dragging As Integer
      Dim text_to_drag$
   
   

4. Add the following code to the Form_Load event procedure:

      Sub Form_Load ()
         ' Initialize the grid control:
         Grid1.Cols = 3
         Grid1.Rows = 60
         Dim db As database
         Dim ds As dynaset
         Dim counter%
         grid1.ColWidth(1) = 3000      'For Author name
         grid1.ColWidth(2) = 1000      'For Author ID
         grid1.Col = 1
         grid1.Row = 0
         grid1.Text = "Author Name"    'Header for Author Name
         grid1.Col = 2
         grid1.Row = 0
         grid1.Text = "Author ID"      'Header for Author ID
         Set db = OpenDatabase("BIBLIO.MDB")
         Set ds = db.CreateDynaset("Authors")
         counter% = 1                  'Start counter at Row=1
         Do Until ds.EOF Or counter% = 60
            grid1.Col = 1
            grid1.Row = counter%
            grid1.Text = "" & ds(1)       'Load the Author Name
            grid1.Col = 2
            grid1.Row = counter%
            grid1.Text = "" & ds(0)       'Load the Author ID
            counter% = counter% + 1
            ds.MoveNext
         Loop
         ds.Close
         db.Close
      End Sub
   
   

5. Add the following code to the Grid1_Click event procedure:

      Sub Grid1_Click ()
         ' Highlight entire row:
         Dim highlight%
         highlight% = grid1.Row
         grid1.SelStartRow = highlight%
         grid1.SelEndRow = highlight%
         grid1.SelStartCol = 1
         grid1.SelEndCol = 2
      End Sub
   
   

6. Add the following code to the Grid1_DragDrop event procedure:

      Sub Grid1_DragDrop (Source As Control, X As Single, Y As Single)
         grid1.Drag 0
         dragging = False
      End Sub
   
   

7. Add the following code to the Grid1_MouseDown event procedure:

      ' Enter the following two lines as one, single line:
      Sub Grid1_MouseDown (Button As Integer, Shift As Integer,
         X As Single, Y As Single)
         ' If the mouse goes down, set the dragging flag in case this
         ' is for a drag:
         Dim selected%
         dragging = True
         selected% = grid1.Row
         grid1.Col = 1
         text_to_drag$ = Trim$(grid1.Text)
      End Sub
   
   

8. Add the following code to the Grid1_MouseMove event procedure:

      ' Enter the following two lines as one, single line:
      Sub Grid1_MouseMove (Button As Integer, Shift As Integer, X As
         Single, Y As Single)
         ' If the dragging flag was set, then we will enable the drag
         ' MouseDown has to set the flag first
         If dragging Then
            dragging = False  ' Cancel the flag.
            grid1.Drag 1      ' Start the drag mode.
         Else
            grid1.Drag 0      ' Cancel if flag was not set.
         End If
      End Sub
   
   

9. Add the following code to the Grid1_MouseUp event procedure:

      ' Enter the following two lines as one, single line:
      Sub Grid1_MouseUp (Button As Integer, Shift As Integer, X As
         Single, Y As Single)
         ' Mouse released on text box, so cancel the dragging mode:
         grid1.Drag 0
         dragging = False
      End Sub
   
   

10. Add the following code to the List1_DragDrop event procedure:

        Sub List1_DragDrop (Source As Control, X As Single, Y As Single)
           List1.AddItem text_to_drag$  ' This inserts the text.
        End Sub
    

11. Run the program.