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on a form using the DateTimePicker class, as summarized in .NET Table 11.3. This class displays a date and/or time to the user, and allows the user to change the values from the keyboard or from a dropdown calendar control. The dropdown calendar is based on the MonthCalendar class, which we will examine in the next section.

.NET Table 11.3 DateTimePicker class

The DateTimePicker class represents a date and/or time value on a form. It allows the user to select a specific date and/or time, and presents this selection in a specified format. The DateTime value is presented in a text box control, with a down arrow providing access to a calendar from which an alternate date can be selected. The various parts of the DateTime value can alternately be modified using an up-down button or the arrow keys on the keyboard.

This class is part of the System.Windows.Forms namespace, and inherits from the Control class. See .NET Table 4.1 on page 104 for a list of members inherited from this class.

	CalendarFont	Gets or sets the Font to apply to the calendar
		portion of the control.
	CalendarForeColor	Gets or sets the foreground color for the
		calendar.
	Checked	When the ShowCheckBox property is true, gets
		or sets whether the check box is checked.
	CustomFormat	Gets or sets the custom date-time format.
	Format	Gets or sets how the date-time value is
		formatted in the control.
Public Properties	MaxDate	Gets or sets the maximum date-time value for
	MaxDate	Gets or sets the maximum date-time value for
		the control.
	MinDate	Gets or sets the minimum date-time value for
		the control.
	ShowCheckBox	Gets or sets whether a check box displays to the
		left of the selected date.
	ShowUpDown	Gets or sets whether an up-down control is used
		to adjust the date-time value.
	Value	Gets or sets the DateTime value assigned to the
		control. Default is the current date and time.

	CloseUp	Occurs when the dropdown calendar is
		dismissed and disappears.
Public Events	DropDown	Occurs when the dropdown calendar is shown.
Public Events
	FormatChanged	Occurs when the Format property changes.
	ValueChanged	Occurs when the Value property changes.

11.3.1DATES AND TIMES

Our Photo Properties dialog with a DateTimePicker control in place is shown in figure 11.5. As you can see, the dropdown calendar control is displayed for the object.

DATES AND TIMES

367

Figure 11.5

The DateTimePicker shown here displays the Long date format, which is the default.

We can add this control to our dialog using the following steps. We will begin with the default display settings for this control, and look at how to modify these settings later in the section.

Set the version number of the MyPhotoAlbum application to 11.3.

REPLACE THE DATE TEXT BOX WITH A DATETIMEPICKER CONTROL

			Action		Result

1	In the PhotoEditDlg.cs [Design]
	window, delete the TextBox control
	next to the Date Taken label.

2	Place a DateTimePicker control				Note: The location of this control is shown in
	where the text box used to be.				figure 11.5.
		Settings

		Property		Value
		(Name)		dtpDateTaken
		TabIndex		5

3	Locate the ResetSettings method				protected override void ResetSettings()
	in the MainForm.cs source file.				{
					// Initialize the ComboBox settings
					. . .

4	Set the Value property for the date				Photograph photo = _album.CurrentPhoto;
	and time control.				if (photo != null)
	How-to				if (photo != null)
	How-to				{
	Use the DateTaken property.				txtPhotoFile.Text = photo.FileName;
					txtCaption.Text = photo.Caption;
					dtpDateTaken.Value = photo.DateTaken;
					cmbxPhotographer.SelectedItem
					= photo.Photographer;
					txtNotes.Text = photo.Notes;
					}
					}

368	CHAPTER 11 MORE CONTROLS

REPLACE THE DATE TEXT BOX WITH A DATETIMEPICKER CONTROL (continued)

	Action	Result

5	Locate the SaveSettings method.	protected override void SaveSettings()
		{

6	Set the DateTaken property to the	Photograph photo = _album.CurrentPhoto;
	date-time value specified by the user.	if (photo != null)
		if (photo != null)
		{
		photo.Caption = txtCaption.Text;
		photo.DateTaken = dtpDateTaken.Value;
		photo.Photographer
		= cmbxPhotographer.Text;
		photo.Notes = txtNotes.Text;
		}
		}

And there you have it. One DateTimePicker control ready to work. Compile and run the application, and set the dates for your photographs as appropriate. Make sure your albums preserve the selected date after exiting and restarting the program.

.NET Table 11.4 DateTimePickerFormat enumeration

The DateTimePickerFormat enumeration specifies how to display a date-time value in a

DateTimePicker control. This enumeration is part of the System.Windows.Forms namespace. For each value, the default setting for the U.S. English culture is provided. The format codes used here correspond to the codes supported by the DateTimeFormatInfo class.

Enumeration

Values

Custom	A custom format is used, as specified by the
	CustomFormat property.
Long	The long date format is used. In Windows, this is typically
	“dddd, MMMM dd, yyyy” for U.S. English environments.
	This is the default value.
Short	The short date format is used. In Windows, this is
	typically “MM/dd/yyyy” for U.S. English environments.
Time	The time format is used. In Windows, this is typically
	“HH:mm:ss tt” for U.S. English environments.

You may have noticed that our control does not display the time. By default, the date and time control displays what .NET calls the long date. This includes the day of the week and month written out in the local language as well as the two-digit day and four-digit year. The format used by the control is specified by the Format property, using the DateTimePickerFormat enumeration described in .NET Table 11.4. As you can see from the table, various values allow either the date or time to be displayed in a format specified by the operating system.

11.3.2CUSTOMIZING A DATETIMEPICKER CONTROL

As can be seen in .NET Table 11.4, a custom display setting for the DateTimePicker control is used when the Format property is set to DateTimePicker-

DATES AND TIMES

369

Format.Custom. The CustomFormat property contains the string value to use in this case. A number of format codes are available within this string. These codes are managed by the sealed DateTimeFormatInfo class. The following table shows a number of these codes, along with some corresponding properties in the DateTimeFormatInfo class, which can be especially useful when operating in a multi-language environment. Consult the .NET documentation for the complete list of codes and additional information on the specified properties.

Date-time codes for the DateTimeFormatInfo class

Pattern	Description	Default U.S. English	DateTimeFormatInfo
Pattern	Description	Values	Property
		Values	Property

d	Day of the month.	1 to 31
dd	Two-digit day of the month.	01 to 31
ddd	Abbreviated day of the week.	Sun to Sat	AbbreviatedDayNames
dddd	Full day of the week.	Sunday to Saturday	DayNames
M	Numeric month.	1 to 12
MM	Two-digit numeric month.	01 to 12
MMM	Abbreviated month name.	Jan to Dec	AbbreviatedMonthNames
MMMM	Full month name.	January to December	MonthNames
y	Year without century.	1 to 99
yy	Two-digit year without century.	01 to 99
yyyy	Four-digit century.	0001 to 9999
gg	Period or era, if any.	B.C. or A.D.
h	Hour on a 12-hour clock.	1 to 12
hh	Two-digit hour on a 12-hour clock.	01 to 12
H	Hour on a 24-hour clock.	1 to 24
HH	Two-digit hour on a 24-hour clock.	01 to 24
m	Minute.	0 to 59
mm	Two-digit minute.	00 to 59
s	Second.	0 to 59
ss	Two-digit second.	00 to 59
tt	AM/PM designator.	AM or PM	AMDesignator and
			PMDesignator
:	Default time separator.	: ( a colon)	TimeSeparator
/	Default date separator.	/ (a slash)	DateSeparator
‘c’	Displays the specified character. For
	example, ‘s’ will display the
	character s rather than the number
	of seconds.

Let’s modify our date and time control to display a customized value. We will include both the date and time in the display.

370	CHAPTER 11 MORE CONTROLS

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DATES AND TIMES

Action

Result