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Tip of the Day
Language: Visual Basic
Expertise: Intermediate
Aug 20, 1997

Editing Grid Cells

Grids provide a nice way to present certain types of spreadsheet information. Unfortunately, the grid in VB does not allow editing. With just a little bit of code you can simulate editing on top of a grid.
To begin, you need to create a form with a grid and add a hidden text box. Name the grid control grdFields, and the text box txtEdit.
When the user double-clicks on a cell you need to move the hidden text box over that cell and make it visible. Use this code in the grid's DblClick event:
 Sub grdFields_DblClick () 
miLastRow = grdFields.Row 
miLastCol = grdFields.Col 
Call GridEdit(grdFields, txtEdit) 
End Sub 
You'll need two module-level variables to track which row and column the cursor is on. These variables will be used later to replace the information from the text box back into the grid.
To find the location on the screen for the text box, you need to calculate the cell's distance from the top and left of the form. You also need to add each row height and column width individually, because each cell can be a different size. Add this GridEdit() routine to calculate the position and move the text box on top of the grid:
 Sub GridEdit (grdCurrent As Control, _ 
ctlEdit As Control) 
Dim iWidth As Single ' Total Height 
Dim iHeight As Single ' Total Width 
Dim iLoop As Integer 

iWidth = _ 
grdCurrent.Left + Screen.TwipsPerPixelX 
iHeight = _ 
grdCurrent.Top + Screen.TwipsPerPixelY 

' Get Total Width 
For iLoop = 0 To grdCurrent.Col - 1 
iWidth = iWidth + grdCurrent.ColWidth(iLoop) 
If grdCurrent.GridLines Then 
iWidth = iWidth + (Screen.TwipsPerPixelX * _ 
End If 

' Get Total Height 
For iLoop = 0 To grdCurrent.Row - 1 
iHeight = iHeight + grdCurrent.RowHeight(iLoop) 
If grdCurrent.GridLines Then 
iHeight = iHeight + (Screen.TwipsPerPixelY * _ 
End If 

' Move the Text Box On Top Of The Grid 
ctlEdit.Move iWidth, iHeight 
ctlEdit.Height = _ 
ctlEdit.Text = grdCurrent.Text 
ctlEdit.Width = _ 
ctlEdit.Visible = True 
ctlEdit.ZOrder 0 
End Sub 
After you've calculated the width and height, use the Move method to place the text box at the proper location. Next, make the text box visible and set its ZOrder to 0, to put it on top of the grid. You also need to move the text from the grid into the Text Box.
After the user finishes editing the text in the text box, you need to put the text back into the grid and hide the text box. Use this in the grid's Click event:
 Sub grdFields_Click () 
If txtEdit.Visible Then 
Call GridReset(grdFields, txtEdit, _ 
miLastRow, miLastCol) 
End If 
End Sub 
Check to see if the text box is visible. If it is, you need to take the edited data and put it back into the grid with the GridReset() procedure:
 Sub GridReset (grdFields As Grid, _ 
ctlEdit As Control, iRow As Integer, _ 
iCol As Integer) 
Dim iOldRow As Integer 
Dim iOldCol As Integer 

iOldRow = grdFields.Row 
iOldCol = grdFields.Col 

grdFields.Row = iRow 
grdFields.Col = iCol 
grdFields.Text = ctlEdit.Text 
ctlEdit.Visible = False 
ctlEdit.Move 0, 0 

grdFields.Row = iOldRow 
grdFields.Col = iOldCol 
End Sub 
When the user clicks on another cell after editing the text box, the grid has been updated to the new row and column. Go back to the last row and column where the user was editing, take the contents of the text box, and put that value into the grid's cell. You can then make the text box invisible and move it to an area on the form that is out of the way.
This tip won't work if the grid has scrollbars, except when scrolled all the way to the left and top. To fix this would require additional loops to add up the height/width of fixed rows/columns. In that case, the other loops would need to be adjusted to calculate only from TopRow to Row, rather than from 0 to Row - 1 (but I'd want to test it to be sure!).
Also, it goes nuts if the scrollbar is clicked while text box is visible. At any rate, it will work if scrollbars aren't enabled.
Paul D. Sheriff
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