Introduction to PowerBuilder
 EditMask
The EditMask
control allows you to take formatted input from the user. For
example, you might want to accept zip code from the user in the
format #####-####. If the user tries to input information into
this control that doesn't conform to the mask, PowerBuilder
refuses to accept the keystrokes.
If you can go to
properties, you can see, there are different data types available
under the "Options/Type" DropDownListBox. For each of
these data types, there are some pre-defined masks available. For
example, if you select the String data type, you can format the
data in upper case (!), lower case (^), number (#) and
alphanumeric (a) characters. Most of the times, these masks are
enough for your needs. If you need a special mask, you can as
well create them by typing into the "Mask" option.
Note that the formatting of
data is for display purpose only. PowerBuilder doesn't store the
data in the way it is displayed, in particular "date"
type. Dates are usually stored as a number representing the
number of days from a fixed date. This allows PowerBuilder to
easily swap between formats by simply applying the rules for the
given format to this base number, rather than performing two
conversions and remembering what format the date is currently
stored in. For example, if the fixed date is 1st January 1994,
then 3rd January 1994 would be stored as 2 and the 25th December
1993 would be stored as -7. The point is that it doesn't matter
to us how PowerBuilder stores the date as long as we see it in a
format that we understand and require.
In versions prior
to v5.0, there was an option in the dialog box to test the mask
you defined. However, it is no longer available in v5.0. You need
to either preview or run the window to test the defined mask.
One note from our
experience is that, make sure you paint enough space (may be a
little extra than required) for the content to display in the
EditMask. For example, if you paint the height a little shorter
for the SingleLineEdit control, user can still type in data even
though he can't read the data comfortably. If you do the same to
the EditMask control, it displays no data at run-time.
AutoSkip is one of the interesting properties.
If you turn on this property for an EditMask control, focus will
automatically jump to the next control in the Tab List (We will
explain in a moment) when the user has completely filled the mask
with the input. User doesn't need to either press tab or click
with the mouse-button to jump to the next control.
The Spin Control property is most often used
with numeric data to allow the user to increase or decrease the
value in the EditMask control by clicking on the arrows that
appear at the corner of the control. You can see this property in
the print dialog box while specifying the number of copies to
print, in any application under MS-Windows.
You can enter the
relevant information in the appropriate fields to specify the
minimum and maximum values for the control and the size of the
increment ( which must be a whole number).
You can also use
the spin control option for the "date"
data type fields. In this case, only one part of the date will
increment or decrement depending on the cursor position. For
example, if the cursor is on the month part of the date, clicking
on the upper arrow will increment the month by one.
While previewing
the window, you won't be able to click on the spin control arrows
because you are previewing the window.
If you type in a
value which is outside the allowable range, as soon as you try to
increment or decrement it using the spin control, the value will
change to the minimum or maximum value and won't allow you to
move outside this range.
Code Tables
If you want to use
spin controls with string-type data, you can make use of Code
Tables. Code Tables work like look-up tables. That means, it
allows you to display the detail value, for the corresponding
abbreviation. For example, you may want to display "New
York" on the screen, and store "NY" in the
database whenever user selects "New York". All you need
to do is provide "New York" for the "Display
Value" property and "NY" for the "Data
Value" property. You can provide as many entries as you want
in this "Code Tables".
If you use
"Spin Control" and "Code Tables" for the
String data type values, PowerBuilder displays values from the
code tables that is specified in the "display value",
as the user keep clicking on the arrows in the "Spin
Control".
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