FIX: Error Changing Grid s DynamicBackColor & DynamicForeColor

The information in this article applies to:

• Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b

SYMPTOMS

You get the following error when changing the DynamicBackColor and DynamicForeColor in a grid that has a class object added to a column and that class object is the active control with the Sparse Property set to false (.F.):

   Expression evaluated to an illegal value

RESOLUTION

Change either the DynamicBackColor or the DynamicForeColor but not both. Or use the default controls that the Form Builder offers.

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. This problem has been fixed in Visual FoxPro 5.0 for Windows.

MORE INFORMATION

Steps to Reproduce Problem

1. Create a new class named CenterChk based on Container, and store it in Mylib.vcx.

2. In the Class Designer, set the following properties for the container:

   Height = 19 Width = 68 BackStyle = 0-Transparent BorderWidth = 0

3. From the Form Controls toolbar, select the check box Control, and place a check box in the container.

4. Set the following Properties for the check box:

   BackStyle 0-Transparent Height = 16 Caption = "" Width = 14

5. With the check box selected, click Center Horizontally and Center Vertically on the Format menu. Then save and close the class.

6. Open the Tastrade.dbc in the VFP\Samples\Mainsamp\Data directory.

7. Create a new form called TestGrid, and add a new property to the form called nCurRec.

8. Using the right mouse button, click the form to bring up the Data Environment. Then using the right mouse button, click the Data Environment. Click Add, and add the Products table.

9. From the Form Controls toolbar, select the Grid control, and add a grid to the form.

10. Using the right mouse button, click the grid, and choose Builder. From

        the Grid Builder, select the Products table. From the Available Fields,
        select Product_id, Product_name, and Discontinued.
    

11. Close the Builder by clicking OK.

12. Set the following Property for the grid:

        RowHeight = 19
    

13. Using the right mouse button, click the grid, then click Edit.

14. From the Form Controls toolbar, click the View Classes button and

        choose Add. Select Mylib.vcx from the Open dialog box. From the Form
        Controls Toolbar, select the CenterChk control, and add it to the
        Discontinued Column on the grid.
    

15. Set the following Properties for Column 3 in the grid:

        CurrentControl CenterChk1
        Width = 68
        Sparse = .F.
    

16. Set the following Property for Column 3 CenterChk1 Check1 in the grid:

        ControlSource = products.discontinued
    

17. Add the following code to the Init event of the grid:

        THISFORM.nCurRec = RECNO()
        THISFORM.Grid1.SETALL('DynamicBackColor',;
           'IIF(THISFORM.nCurRec == RECNO(), rgb(0,0,128), rgb(255,255,0))',;
           'Column')
           THISFORM.Grid1.SETALL('DynamicForeColor', ;
              'IIF(THISFORM.nCurRec == RECNO(), rgb(0,0,255), rgb(0,0,0))', ;
              'Column')
           THIS.REFRESH
    
    

18. Add the following code to the AfterRowColChange event of the grid:

        THISFORM.nCurRec = RECNO()
        THIS.REFRESH
    

19. Save and run the form.