ID Number: Q84584
1.00
WINDOWS
Summary:
The Grid custom control (GRID.VBX) will refresh (update the control's
contents) on all change events occurring to cells in the grid. So, for
example, when entering text into a cell in the grid, a refresh of the
grid occurs after every letter of a word is entered. This behavior is
by design.
This information applies to Microsoft Professional Toolkit for
Microsoft Visual Basic programming system version 1.0 for Windows.
More Information:
It is normal behavior for the Grid control to refresh whenever a
change occurs to a cell contained in it. This is desirable behavior,
because it ensures that current information is always displayed in the
grid.
However, slowdowns due to the refreshing time can be a problem. If a
grid is large enough, it can take a significant amount of time to
refresh it. If there is a large number of data items to enter, the
wait is compounded. There is no way to toggle the refresh of the grid
when text is entered into a cell--it always occurs. There are,
however, methods for minimizing the number of change events that occur
to the grid, thus minimizing the wait. Two of these methods are shown
below.
Steps to Reproduce Behavior
---------------------------
1. Run Visual Basic, or from the File menu, choose New Project (ALT,
F, N) if Visual Basic is already running. Form1 is created by
default.
2. From the File menu, choose Add File. In the Files box, select the
GRID.VBX custom control file. The Grid tool appears in the
Toolbox.
3. Add a Grid control to default Form1 by double-clicking on its icon
in the Toolbox. Also add a text box control in the same manner.
4. Set the following properties for Grid1: Cols = 10, Rows = 20. Size
the grid so that you can see all the columns and rows. Also, set
the Text property of Text1 to "" (blank).
5. Add the following code:
Sub Form_Load ()
Form1.Show 'This code fills the grid with ASCII values
For columns = 0 To 9 'to show the effect of refreshing Grid1.
For rows = 0 To 9
Grid1.Row = rows
Grid1.Col = columns
Grid1.Text = Chr$(63 + rows + columns)
Next rows
Next columns
Text1.SetFocus
End Sub
Sub Text1_KeyPress (KeyAscii As Integer)
Grid1.Text = Text1.Text 'This sets the contents of Grid1.Text to
End Sub 'what is entered into Text1.
6. Press F5 to run the program.
Enter some text into Text1. Notice how every entry on the keyboard
causes the grid to update. You can tell this is occurring by the
flickering of the contents of Grid1 on every key press.
If direct entry of data into a cell is desired, a slight
modification to the code above significantly reduce the number of
times the grid refreshes. The code below allows entry of text into
a text box, and the contents are transferred to a cell in the grid
when the user presses ENTER. To demonstrate this, change the code
in the Text1_KeyPress event to:
Sub Text1_KeyPress (KeyAscii As Integer)
If KeyAscii = 13 Then 'Did the user press the ENTER key?
Grid1.Text = Text1.Text 'Yes - assign Text1.Text to Grid1.Text.
KeyAscii = 0 'Suppresses the default "beep" sound.
Text1.Text = "" 'Clear the text box for the next entry.
End If
End Sub
This change filters the input somewhat by only updating Grid1.Text
when the user presses ENTER. (If you want to change it to some
other value, use a different KeyAscii value.) The benefit of this
method is that an update only occurs whenever the user presses
ENTER, not on every key press event.
Yet another alternative is to first store the data entered in the
text box into an array. Then, when data entry is complete,
transfer the contents of the array to the grid. This forces all
changes to the grid to be done in one refresh, thus reducing the
total waiting time required for the grid to refresh. To
accomplish this, do the following:
7. Add a command button to Form1. Set the Caption property to "Place
array items into grid".
8. Add the following code to the general Declarations section of
Form1:
Dim Words$(100)
Dim GridNum As Integer
'(Add the following to the Command1 Click event procedure:)
Sub Command1_Click ()
For y = 0 To (GridNum - 1)
Grid1.Row = Int(19 * Rnd + 1)'Sets the row and column to a random
Grid1.Col = Int(9 * Rnd + 1)'place in the grid, and
Grid1.Text = Words$(y) 'prints the item there.
Next y
Erase Words$ 'Clears the array.
GridNum = 0 'Resets the array item counter.
Text1.SetFocus 'Sets the focus back to the Text box
End Sub
9. Replace the code in the Text1_KeyPress event of Form1 with the
following:
Sub Text1_KeyPress (KeyAscii As Integer)
If KeyAscii = 13 Then
Words$(GridNum) = Text1.Text 'Transfers contents of Text1.Text to a
'string array.
Text1.Text = ""
GridNum = GridNum + 1 'Increments the array item counter to
'prepare for the next word to be
'entered.
Debug.Print GridNum 'Prints the current record number in
'the immediate window. (optional)
KeyAscii = 0
End If
End Sub
10. Press F5 to run the program.
Enter in a few words, and press ENTER after each word. Notice the
grid does not refresh after the ENTER key is pressed. The items
are being placed into an array with each press of the ENTER key.
When you are finished, choose Command1 to place the new items in
the grid. The grid will refresh only once now, as the new items
are randomly placed in the grid.
Additional reference words: 1.00