PRB: Incremental Search with Grid Causes Screen Flicker
ID: Q156630
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The information in this article applies to:
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Microsoft Visual FoxPro for Windows, versions 5.0, 6.0
SYMPTOMS
The Refresh method of the Grid control does not move the record pointer in
the grid to the selected record when the record pointer is moved from a
control external to the grid. The grid has to get the focus in order for
the record pointer in it to move to the selected record. Because of this
problem, an incremental search routine, involving the grid and another
control, causes the screen to flicker every time a character is entered.
This article describes a way to avoid the screen flicker when using an
incremental search routine with a grid.
WORKAROUND
You can use the LockScreen property of the Form to eliminate most of the
screen flicker. For example, you can make the following modifications to
the Form created in the STEPS TO REPRODUCE BEHAVIOR section below:
- Create a New Property for the Form and name it lRefreshingGrid. Set
the property to .F.
- Change the code in Text1.InterActiveChange event as follows:
ThisForm.lRefreshingGrid = .T.
ThisForm.LockScreen = .T.
SELECT customer
SEEK UPPER(ALLTRIM(ThisForm.Text1.Value))
ThisForm.grid1.SetFocus
ThisForm.text1.SetFocus
ThisForm.LockScreen = .F.
ThisForm.lRefreshingGrid = .F.
- To ensure that the Valid event of the text box does not fire when the
focus is moved to the grid and then back to the text box, add the
following code to the Valid event of the text box:
IF ThisForm.lRefreshingGrid
RETURN .T.
ENDIF
STATUS
Microsoft is researching this behavior and will post new information here
in the Microsoft Knowledge Base as it becomes available.
MORE INFORMATION
Steps to Reproduce Behavior
- Create a Form, and set the LockScreen property to False (.F.).
- Add the Customer table, in the home()+"SAMPLES\DATA" folder, to the Data
Environment. By default, the table is added to the Data Environment with
the Name "cursor1". Set the Order property of the cursor to "cust_id".
- Drag the table onto the form to create a grid. Set the Name property of
the Grid to "Grid1".
- Add a TextBox control to the form. Make sure that SelectOnEntry property
of the Textbox control is set to .F. (the default). Add the following
code to the TextBox control's InterActiveChange event:
SELECT customer
SEEK UPPER(ALLTRIM(This.Value))
ThisForm.Grid1.Refresh
- Run the Form and type a few characters in the text box.
- Although the REFRESH method of the grid is being called from
Text1.InterActiveChangeEvent, the record pointer in the grid does not
move to the correct record.
- Now change the code in Text1.InterActiveChange event as follows:
SELECT customer
SEEK UPPER(ALLTRIM(This.Value))
ThisForm.grid1.SetFocus
ThisForm.text1.SetFocus
- Repeat step 5.
- Now the Record Pointer in the grid is moving correctly but there is a
lot of screen flicker every time a character is entered into the text
box.
Additional query words:
kbdse VFoxWin Flash
Keywords : FxtoolFormdes
Version : 5.00
Platform : WINDOWS
Issue type :