|In our last tutorials we learned to use components and
textboxes as part of a database exercise. In this tutorial we return
to the use
of textboxes setting up a password and a splash screen for our application.
In this exercise we read an encrypted password from an setup.ini file.
Then when the user enters the correct password, we start up a splash
screen. Two advantages of using a splash screen is that it not only
to advertise your program and highlight its wares; but also you have
time to initialize a programs global variables, reference tables and
connections. This may not seem important now - but trust me a VB program
with several database connections and long listboxes to initialize can
take 10-25 seconds to load - a splash screen is much better than just
staring at the password dialog.
Here is the trick. Do 1/3 of the initializing on the Form_Load of the password procedure. Then if the password
is okay; do the next 1/3 of the initializing on the Form_Load of the splash screen. Then do the final initialization
on start-up of your final main form. But first, lets see how to code a password screen.
Figure 1 - Password Dialog
Add two textboxes to a new project form, call it "passby". The labels for the two textboxes are as
shown in Figure 1. The first textbox does not require any special setting but the password textbox does. Its PasswordChar
property is set to the character "*". This causes the textbox to be filled with asterisks for each character
typed. But the value of passwd.Text seen by the program is the password typed in by the user.
|The second trick we have used is to make sure whenever the password textbox gains focus, the text in the box is
automatically selected with the following code:
REM 'This code highlights/selects the text when you enter
Screen.ActiveControl.SelStart = 0
ii = Len(Screen.ActiveControl.Text)
Screen.ActiveControl.SelLength = ii
Now readers of VB Tutorial seven will find portions of this code very familiar. Screen.ActiveControl refers to
the control which currently has focus or is active. This of course is the textbox "passwd". By setting
the active control's SelStart property to 0 and its SelLength property equal to the length of the text in the box
- this selects or highlights the text in the password immediately on entry. This means the user does not have to
be sure to erase the contents before entering the password - just a convenience.
The next trick we have is to recognize if the user types the Enter key when he is done entering the password. VB
does not recognize entry of the Enter key - you have to check for it with the following code:
Private Sub passwd_KeyPress(KeyAscii As Integer)
' detect when user presses "Enter" key and if so validate password
If KeyAscii = 13 Then
' this is the call on the routine that does the password checking
This subroutine is called every time a letter is typed in the password textbox. It is look for one KeyAscii code,
13, which is the value of the Enter key. When that is pressed then control is immediately passed to the password
validation procedure. Of course we also call the password validation after the Okay button is clicked or when the
password textbox is exited.
The password validation procedure is fairly simple. On Form_Load we have already gotten the decrypted password
from the setups file. So now all we need to do is check if the entered password matches the decrypted password.
If it does not we issue a warning message asking the user to re-enter the password. We could keep a count of the
tries and then exit from the password procedure altogether.
However, if the password is valid then we call the splash screen routine as follows:
' We are in call the splash screen
where passplash is the name of the Splash screen form. Its here where the last 2 tricks are performed in our program.
First, we need to hide the password form from the user - because its is the calling window we cannot just destroy/kill
it but have to hide it with the code line PassForm.hide. The second trick is to do any leftover initialization
required. And with these tricks we have a solid set of program start up code.
In this tutorial we have shown some tricks associated with using text boxes and getting passwords and the use
of splash screens. We have again used VB's predefined objects to good use. Finally we take advantage of some of
the many procedures and events associated with textboxes like Keypress or Validate.
The book Beginning VB6/Wrox covers VB textboxes on pages 73-94; VB6 Black Book/Coriolis
touches on textboxes on pages 197-221.