Windows Forms

Windows Forms

Windows forms provide many enhancements over standard VB forms including:

Rich set of Controls: By using the classes in the System.Windows.Forms namespace, you can create windows applications that take full advantage of the rich user interface features available in Microsoft Windows Operating System. This namespace provides “Form” class and many other controls that can be added to the form to create user interface.

Advanced Printing Support: .net provides different controls and dialog boxes to handle printing options. Ex: PrintSetupDialog, PrintPreviewDialog, PrintPreviewControl etc.

Advanced Graphics Support: we can design 2D graphics with the use of namespaces like System.Drawing, System.Drawing.Drawing2D etc.

Visual Inheritance: windows forms are classes and can benefit from inheritance. Windows forms can be inherited from derived form that automatically inherits the controls and code defined by base forms.

Form:

          A form is the window that is used to present information to or accept information from the end use. The form can be a single window, and MDI window or a Dialog Box.

A form will have two windows. Designer and code

The Windows Forms Designer:

• Contains comments in XML Documentation
• A Container object is required if you need to group the objects together.

The advantage of this object is, even though there may be elements in the application that are not controls, the “Container” object allows us to group everything together.

Private System.ComponentModel.Container Components=NULL;

• The Dispose() method is used to perform any operation that are necessary when garbage collection is done.
• In the InitializeComponent() method, the controls are instantiated and are set to their initial behavior.
• Then Main() method specifies the starting point of the application.

Form Properties:

Property	Description
AcceptButton	Specifies which buttons click event has to be executed when the user presses enter key
CancelButton	Specifies which buttons click event has to be executed when the user presses ‘Esc’ key
BackColor	Sets the forms back color
ControlBox	True/false to display min,max,close controls
FormBorderStyle	Specifies how the form border look like
StartPosition	Specifies at which position of the desktop the form has to be displayed.

Form Events:

          Certain events are triggered as a form is opened, closed, moved and so on.

Event	Description
Load	Triggers just before the form is loaded into the memory. It happens with Load()/Show() methods
Activated	When a form is activated in code or becomes visible through user movement amongst forms.
Deactivated	It is caused when the form loses focus
Closing	To examine the  method in which the used closed the form
Closed	Just prior to dispose event this event occurs, you could verity the closing intensions
Dispose	There is no terminate event in .net. it is used to provide any finalization code.

Windows Controls:

          The System.Windows.Forms.Control class is the base class for all controls that are to be created. This class is derived from System.ComponentModel.Component class.

Hierarchy of Control classes:

• System.ComponentModel.Component
• Control
• ButtonBase
• Button
• ScrollableControl
• ContainerControl
• Form

Types of Controls:

Type	Controls
Command	Button, LinkLabel, NofityIcon, ToolBar
Menu	MainMenu, ContextMenu
Selection	CheckedListBox, ComboBox, ListBox, ListView, TreeView
Text	TextBox, RitchTextBox, Label, LinkLabel, StatusBar
Graphics	PictureBox, ImageList
Value	CheckBox, CheckedListBox, RadioButton
Date	DateTimePicker, MonthCalander
Grouping	Panel, GroupBox, TabControl
CommonDialog	Color, Font, OpenFile, SaveFile, Print, PrintPreview

Windows Controls:

Control	Description
Button	Control that can be clicked to perform some desired action.
CheckBox	Primarily used for displaying a binary state of an object. Clicking the check box causes it to toggle between a checked or unchecked state.
CheckListBox	List box with a column of check boxes.
ComboBox	A drop-down list of choices that operates similar to the list box. The primary difference is that the combo box is more compact and efficient with screen real estate.
DataGridView	An extremely powerful control that permits a program to bind to a data source.
DateTimePicker	Provides a capability to select a date and time without typing.
DomainUpDown	Permits a user to scroll through a list of data items that can only be shown one at a time.
Form	The main window of an application, a dialog, or a multiple-document interface (MDI) child. It provides all the capabilities for hosting child controls.
GroupBox	Houses a group of other controls often used to encapsulate a group of radio buttons. It can help organize a form and has a customizable title.
Label	Primarily used to display static text but can also contain Images.
LinkLabel	The same as a label, but it can contain an URL that can be clicked to invoke an Internet connection.
ListBox	Holds selectable lists of data items. When the viewable portion of the list box is filled, a scrollbar appears so that all of its contained items may be selected.
ListView	Provides capabilities for multiple columns, column headers, column resizing, and list sorting It can also be configured in four different display modes. More Sophisticated than a list box.
MessageBox	Provides notifications to users on certain program events. It has a configurable message, title bar, icon, and button.
MonthCalendar	A visual calendar control.
NumericUpDown	The same as a DomainUpDown, with the restriction that its contents are numeric.
Panel	Blank forms with little or no decoration that are used primarily for organization and form layout.
PictureBox	Displays an image.
ProgressBar	Used to display the status of an ongoing operation. It has a graph-ical indicator, set by a program to show the percentage of task completion.
RadioButton	Mutually exclusive buttons that permit users to make a choice. Also called option buttons.
RichTextBox	An enhanced text box control that provides more control over its text. It has the capability of creating Rich Text Format (RTF) files.
ScrollBar	Often used to help position the current location in a document That’s too large to fit onscreen or in whatever space is available.
Splitter	Permit a user to resize multiple portions of a workspace. When the splitter is moved, one portion of the workspace gets larger, and others become smaller.
StatusBar	Performs multiple functions. Primarily it’s a place to notify users of a program’s status or other forms of current information.
TabControl	User interfaces that appear like file folder tabs. When selected, they open a specific page where the tab and content match.
TextBox	Allows a user to type text. They can be single line or multiline and have many capabilities for text manipulation such as selection, cut, copy, and paste.
Timer	Non visual controls that raise events at specified intervals. They can be used for such things as reminders or auto-save operations.
ToolBar	Permits a user to invoke selected operations in a program; similar in functionality to menus.
ToolTip	Helpful messages that appear when a cursor hovers over a control for a specified amount of time.
TrayIcon	Icons displayed on the icon tray of the window’s taskbar. They usually have different pictures to indicate the current state of a program.
TreeView	Displays items in a hierarchical fashion. It has a root node at the top of the tree and can have multiple branches and nodes. Traditionally, it has collapsible branches and is coordinated with another control to display details of selected nodes.

Menus

Most applications have a main menu, which is a quick way to access all the functionality of an application. Another popular feature of programs is to offer context-sensitive menus via right-click on parts of the program where they might make sense.

You can have more than one menu system per form which reduces the complexity of creating dynamic menus, and you can create context menus directly without designing them as top level menus first.

Menu Classes:

          Three menu classes are there that will use when creating menus.

MainMenu:    you use this class to create a standard windows associated menu bar at the top of a form.

ContextMenu: You use this class to define pop-up menus associated with particular controls

MenuItem: You use this class to define menu items within a MainMenu or a ContextMenu.

Creating a MainMenu at Design Time:

          When we add the MainMenu control it will be placed in the component tray. Once an instance of the control becomes part of your application, you will be presented with the first menu item a prompt to “Type Here”. The menu control leaves open space for us to add to the menu system at any time.

• To create a menu separator, type a “hyphen(-)” in the “type here” prompt.
• If you want to create sub menus, simply type in “type here” area that is displayed to the right of the current area. The control will add the appropriate arrows to indicate a sub menu.
• The main menu is made up of MenuItem children objects. The hierarchy is then created between parent and child objects.
• To create an access key for a menu item, select the menu item to which you would like to assign an access key. Type an “ampersand(&)” in-front of the letter that is to be underlined and is to function as the access key.
• To assign a shortcut key in main menu system, select the menu item, access the properties window and select the “Shortcut” property. Select the appropriate shortcut key combination from the drop-down menu that appears.

Note: To suppress the display of the shortcut key in the menu, set the “showShortcut” property of the menu item to false. Other properties for the menu item are:

Ø  Checked – displays the menu item with a check mark.

Ø  DefaultItem – specifies the menu item as the default.

Ø  Enabled – Grays out the menu item and makes it inaccessible.

Creating Menus Programmatically:

          This example programmatically creates a Windows Forms ContextMenu and associates it with a control.

private void Form1_Load(object sender, System.EventArgs e)

{

    System.Windows.Forms.ContextMenu contextMenu1;

    contextMenu1 = new System.Windows.Forms.ContextMenu();

    System.Windows.Forms.MenuItem menuItem1;

    menuItem1 = new System.Windows.Forms.MenuItem();

    System.Windows.Forms.MenuItem menuItem2;

    menuItem2 = new System.Windows.Forms.MenuItem();

    System.Windows.Forms.MenuItem menuItem3;

    menuItem3 = new System.Windows.Forms.MenuItem();

    contextMenu1.MenuItems.AddRange(new System.Windows.Forms.MenuItem[] {menuItem1, menuItem2, menuItem3});

    menuItem1.Index = 0;

    menuItem1.Text = "MenuItem1";

    menuItem2.Index = 1;

    menuItem2.Text = "MenuItem2";

    menuItem3.Index = 2;

    menuItem3.Text = "MenuItem3";

    textBox1.ContextMenu = contextMenu1;

}

MDI Forms

          Multiple-Document Interface(MDI) applications allow you to display multiple documents at the same time with each document displayed in its own window under a container.

Creating a Parent Form:

          You can use the “IsMdiContainer” property of a form to make it an MDI Parent form. This holds a Boolean value.

Creating Child Forms:

          You can create child forms by setting the “MdiParent” property of a form to the name of the already created MDI parent.

          Sub AddDoc()

                   Form2  frm=new Form2();

                   Frm.MdiParemt=this;

                   Frm.Show();