Common understanding of edit controls

EhLib has a set of data-aware edit controls to edit data:

TDBEditEh

Editing text data and other data types that can be predtavlyat to see the text.

TDBDateTimeEditEh

Editing data of date or time type.

TDBComboBoxEh

Editing text data with an additional drop-down list to select the values.

TDBNumberEditEh

Editing the data of number type.

TDBLookupComboboxEh

Editing based on drop-down list with the record key values instead of the displayed value.

TDBMemoEh

Editing multiline text data.

TDBImageEh

Editing graphic data.

TDBRadioGroupEh

Editing data mapping in a set of flags.

TDBRichEditEh

Editing text data with RichText format.

EhLib doesn’t have not data-aware version of these controls because every control can work as in data-aware mode and not in data-aware mode.

The base class for every edit control is TCustomDBEditEh. TCustomDBEditEh encapsulates the behavior that is common for all edit controls for editing text and if it is required for editing a DataSet’s field by introducing methods and properties that provide:

• Basic text editing functions such as selecting text, modifying selected text, and case conversions.

• Properties for making it read-only or introducing a password character to hide the actual value.

• Validity checking using an edit mask.

• Writing edited text to database field.

• Showing one or several edit buttons (with variable glyphs: dropdown arrow, Ellipsis arrow, up-down arrows, plus sign, minus sign or custom bitmap) at right part of edit box,

• Showing image from image list at the left part of the edit box.

Application can use Text (String type) and Value (Variant type) properties to get and set string or variant values to controls. Text property is a text that you can see in control. Value property hold value of variant type and can hold values of types depending of control type. It can hold Null value or:

• String type value for TDBEditEh and TDBComboBoxEh,
• TDateTime, TDate, TTime, Double type value for TDBDateTimeEditEh,
• All numeric types value for TDBNumberEditEh,
• TDBLookupComboboxEh control hold value that depends on type of the field.

If control is connected to the field then the assignment data to the Text or Value properties automatically write data to the field.

Every control has Flat and AlwaysShowBorder properties to control the border appearance.

All controls have EmptyDataInfo property that allows customize edit control to draw special text and font when control have no data (Edit1.Text = ‘’).