How to Size the Rows and Columns of a Grid to Fit Exactly

ID: Q140519

4.00 WINDOWS

The information in this article applies to:

Professional and Enterprise Editions of Microsoft Visual Basic,
16-bit only, for Windows, version 4.0

SUMMARY

This article explains how to size the rows and columns of a Visual Basic grid control to allow for the display of all cells in the grid within the current bounds of the grid. This technique is useful when the number of rows and columns in the grid changes dynamically and you need to see all the cells at once.

MORE INFORMATION

To allow all cells to be proportional and sized so that all can be seen within the current grid, you need to set the ScaleMode property of the grid's parent window to pixels. If the grid is on a form, the grid's parent window is the form. However, if the grid is nested within a picture box, then the picture box is the grid's parent window. Changing the parent's ScaleMode property to pixels changes the grid control's Height and Width properties to pixels. Once the grid's height and width are in pixels, it is possible to calculate the row height and column width in pixels. The example routine given below changes the form's ScaleMode to pixels temporarily, and then changes it back after it is done.

The example code uses the following formula to calculate the height of a row in pixels:

   PixelRowHeight = (Grd.Height - 2) \ nRows

The formula subtracts two pixels from the grid height to take into account the top and bottom border. Then it divides the result by the number of rows to get the height in pixels.

To make the rows fit exactly into the grid, the example code calculates the remaining pixels. The number of remaining pixels is the remainder of the division used to calculate the row height. The remaining pixels are calculated by using the following formula:

   PixelsRemaining = (Grd.Height - 2) Mod nRows

The example distributes one pixel of the remaining pixels to the height of each row until it runs out of pixels.

Once you determine the height of a row in pixels, you can set the row height. The RowHeight property expects the height in twips. So it is necessary to multiply the pixel height by Screen.TwipsPerPixelY to convert to twips. The row height does not include the border, so one pixel must be subtracted from the row height prior to converting the height to twips and assigning it.

Similar methods are used to calculate the width of each row in pixels and assign it to the grid.

Step-by-Step Example

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

2. Add the following controls and set their properties using the following

   table as a guide:

      Name       Properties   Value
      -------------------------------

      Text1      Text         2
      Text2      Text         2
      Command1   Caption      Resize
      Grid1      ScrollBars   0-None

3. Put the following code in the General Declarations section of the form:

   ' Enter the following two lines as one, single line:
   Public Sub SizeGrid (Frm As Form, Grd As Grid, nRows As Integer,
      nCols As Integer)

      Dim FormScaleMode As Integer  'Used to save ScaleMode

      'Save ScaleMode of form and change to pixels:
      FormScaleMode = Frm.ScaleMode
      Frm.ScaleMode = 3 'Pixels

      'Determine the height of a row in pixels and the remaining pixels:
      PixelRowHeight = (Grd.Height - 2) \ nRows
      PixelsRemaining = (Grd.Height - 2) Mod nRows

      'Set the height of each column:
      Grd.Rows = nRows
      For i = 0 To nRows - 1
         If i < PixelsRemaining Then
            'Set the height of a row:
            'One pixel is added to eat up remainder and get a perfect fit.
            Grd.RowHeight(i) = PixelRowHeight * Screen.TwipsPerPixelY
         Else
            'Set the height of a row:
            Grd.RowHeight(i) = (PixelRowHeight - 1) * Screen.TwipsPerPixelY
         End If
      Next

      'Determine the width of a column and the remaining pixels:
      PixelColWidth = (Grd.Width - 2) \ nCols
      PixelsRemaining = (Grd.Width - 2) Mod nCols

      'Set the width of each column:
      Grd.Cols = nCols
      For i = 0 To nCols - 1
         If i < PixelsRemaining Then
            'Set the width of a column:
            'One pixel is added to eat up remainder and get a perfect fit
            Grd.ColWidth(i) = PixelColWidth * Screen.TwipsPerPixelX
         Else
            'Set the width of a column:
            Grd.ColWidth(i) = (PixelColWidth - 1) * Screen.TwipsPerPixelX
         End If
      Next

      'Return form to original ScaleMode:
      Frm.ScaleMode = FormScaleMode

   End Sub

4. Add the following code to the command button's click event:

   Private Sub Command1_Click ()
      Call SizeGrid(Form1, Grid1, CInt(Text1), CInt(Text2))
   End Sub

5. Save the project.

6. Run the example.

Enter values for the number of rows and columns in the two text boxes and click the command button. The grid should have the exact number of rows and columns that you specified. Also, the rows and columns should fit exactly into the grid.

Additional reference words: 4.00 vb416 vb4all KBCategory: KBSubcategory: PrgCtrlsCus

Keywords          : kbcode PrgCtrlsCus 
Version           : 4.00
Platform          : WINDOWS

Last Reviewed: May 22, 1998