DateTime, Code Regions, and Multiple Form Applications

1. DateTime, Code Regions, and Multiple Form Applications Part13dbg

2. DateTime • DateTime is used for storing and converting time and date values. • The Now property of the DateTime object delivers the present time and date from the system clock. DateTime currentDateTime = DateTime.Now; • The Today property of DateTime object is the date portion only. DateTime currentDate = DateTime.Today;

3. Working With DateTime • Declare a DateTime object:DateTime myDT = new DateTime(); • Get present time and date: myDT = DateTime.Now; • Extract time or date value: lblDay.Text = myDT.DayOfWeek.ToString(); • DayOfWeek, DayofYear, Day, Hour, Second, Month, Year properties allow access to various parts of DateTime.  DateTimeStruct

4. Formatting DateTime output • Use Format Specifiers with ToString() • or use ToLongDateString(), ToLongTimeString(), ToShortDateString(), or ToShortTimeString() methods.

5. Generate DateTime Values with DateTimePicker Control • The DateTimePicker control furnishes a visible interface for selecting DateTime values. • Dates are selected with a perpetual calendar display. • Times and dates may be displayed in several formats. • Use the TimeSpan class to manipulate and compare times and dates.  DatePicker

6. Code Regions Showing/Hiding and Creating Code Regions

7. Regions in Code • We have seen before that the region, Windows Form Designer Generated Code,is a collapsible region. • When we want to view the contents, we click the in front of region. • Tocollapsethe region, we click thein front of region.

8. Making Your Own Collapsible Regions in Code • You can make your own collapsible region in code, for example, a region for the class-level variables. • Type #region regionDescription above the class-level variable declarations. • Type #endregion after the last line of class-level variable declarations. • You will now have a user-defined region.

9. Multiple Form Applications Single Document Interface

10. Launching a Second Form • Use the Add Windows Form… selection from the Project menu. • A new form class is added to the project.

11. Launching a Second Form • An instance of the second form must be created within the original application form. • Once the form object is created, it may be displayed by running its Show() method. • Multiple instances of the second form can be created and displayed.  SecondSDI

12. Startup Form as “Parent” • Launching a second form in this way causes the second form to depend upon the first for survival. • Closing the first form causes the second form to close as well.

13. Hiding a Form • Run the Hide() method of the original form to remove it from view prior to showing the second form. • Now the second form commands the application and can not lose focus unless it is closed. • Closing the second form leaves the original form running, but not visible.  HideParent

14. Showing a Hidden Form • We could run the Show() method of the original form from the second form—but only if the second form is aware of the first form • If we created a new instance of the first form within the second form it would be different from the original. • One way to solve the problem is to pass the identity of the original form to the second form as a constructor argument.

15. Identifying the Parent Form • If the second form has a class scope variable of type Form, the constructor can use its argument to assign the identity of the “parent” form. • This then allows the second form to run the Show() method of the “parent”.  FormConstructor

16. Multiple Form Applications Owned Forms

17. Owned Forms • Subsequent SDI forms can be launched from a startup form as Owned Forms. • Although these forms can transfer focus back to the startup form they remain on top of the startup form at all times. • Add a new form to the Owned Forms collection of the startup form by setting its Owner property to the startup form.  OwnedForms

18. Owned Forms • Potential uses for owned forms are as specialized help forms, customized “toolboxes” or overview maps. • Use an owned form when you don’t want to lose sight of a form in a multiple SDI application, even if it loses focus.

19. Multiple Form Applications Multiple Document Interface

20. MDI Forms • Standard Windows forms may exist as either MDI parents or MDI children. • MDI children may only be displayed within the client area of their parent and may not be dragged outside that client area. • Like owned forms, MDI children always remain on top of their parent form.

21. MDI Parent Forms • Any standard Windows form can be converted to an MDI parent by setting its IsMdiContainer property to True. • By convention, MDI parent forms have a dark gray client area. • Because MDI parents are intended solely as containers for other forms, they should not include controls.

22. MDI Parent Forms • Use menu items in the MenuStrip control of the MDI parent to control activities associated with displaying MDI child forms.  MDIParent

23. MDI Child Forms • Forms destined to become children of an MDI parent should be instantiated within the MDI parent class. • Any standard Windows form can become an MDI child. • Set the MdiParent property of the child instance to the parent. • Show the child form.  MDIChildren

24. MDI Child Form Menus • When an MDI Child has focus within an MDI parent form, the menustrips of the Parent and Child are merged and menuitems from both are displayed. • The merging of the menus to present a sensible display is coordinated by adjusting the MergeAction and MergeIndex properties of each menuitem. • The Visible property of the child menustrip must be set to false if you do not wish to see both parent and child menustrips.

25. The Windows Menu • By design convention the Menustrip of an MDI parent form has a Window menu item that lists the displayed child forms and indicates which has focus. • The contents of this menuitem (mnuWindow) are automatically generated by simply setting the MdiWindowListItem property of the parentmenustrip to the appropriate menuitem (mnuWindow).

26. The Window Menu • Three different modes of display are available for child forms: cascade, horizontal tile, and vertical tile. • These modes can be set with the LayoutMdi() method of the parent form. • Use the foreach loop to close all forms in the child collection of the parent at once.  MDIWindows