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288 Day 8
NOTE
The Edit component encapsulates the basic single-line edit control. This component has no
Align or Alignment property. It has no Alignment property because the text in a single-line
edit control can only be left-justified. The Edit component has no Align property because
it cannot (or more accurately, should not) be expanded to fill the client area of a window.
TIP
If you need text in an edit component to be right-justified or centered,
use a Memo component but make its height the height of a standard Edit
component. Then set the Alignment property as needed.
Keep your forms standard whenever possible. Although you can make
an Edit component as tall as you like, it will confuse users if you make
its height greater than a standard Windows edit control (it might
appear to the user to be a multiline edit).
The MaskEdit component is an Edit component with an input filter, or mask, attached. The
MaskEdit does not represent a Windows control per se, but rather is just a VCL extension of
a standard edit control. A mask is used to force input to a specific range of numbers or
characters. In addition, the mask can contain special characters that are placed in the edit
control by default. For example, a date is commonly formatted as follows:
10/25/97
An edit mask for a date can already have the slashes in place so that the user only has to enter
the numbers. The edit mask would specify that only numbers can be entered to avoid the
possibility of the user entering a nonnumeric character.
The EditMask property controls the mask used. When you press the ellipsis (…) button in
the Value column for the EditMask property, the Input Mask Editor is displayed. This dialog
box allows you to choose one of the predefined masks or to create your own. You can choose
prebuilt masks from several countries. Figure 8.3 shows the Input Mask Editor displaying the
United Kingdom set of predefined input masks.
For more information on building your own masks, see the C++Builder online help.
The Memo component encapsulates a multiline edit control. The Lines property is the most
significant property in a Memo component. As mentioned earlier in the discussion on
TStrings, the Lines property allows you to save the contents of the Memo component to disk