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Windows Forms-1 Notes

Review Questions

1. If your .Net solution has more than one Main method, how does the CLR know which one to use?

2. What do these symbols mean in C#? Some have more than one meaning.
   +   &   /   %   ^   #   @   ( )   { }   [ ]

3. What are the values of these expressions?
   "1" + 2 + 3     18 / 4 * 2.0

4. What does 328.76M mean?

5. Which operators use short circuit evaluation?

6. How do you know if & denotes logical or bitwise and?

7. Give four ways to declare and initialize a one-dimensional array of five zeros.

8. For what are base 64 strings used?

9. Why are the enumerations important?

10. What does "{3,8:#.00}" mean as a format string?

11. Give three methods in which a format string can be used.

Examples

Part A:   The System.Windows.Forms.Control Class.

1. Controls as Classes   Intro.Controls Example
   • Each control in C# is defined by a class.

   • Control properties can be set
     1. Using the properties window (at design time) or

     2. In the source code (at run time).

   • Every class defining a control inherits the class Control. Here is the complete inheritance hierarchy:
     object   (Any C# object)
         MarshalByRefObject   (Objects that can be managed remotely)
            Component  (Primarily handles containment and cleanup)
               Control   (Any Windows control)
                  Derived classes of Control  (Specific Windows controls)

   • This online chapter from the Troelsen text explains how MarshalByRefObject objects can be used for remoting.

2. Form Instantiation
   • The primary form for a project is instantiated in the Main method of the startup class.

   • Secondary forms are instantiated using the new operator as needed.

3. Event Handlers
   • An event handler has the following form:
     private void button1_Click(object sender, EventArgs e)
     {
         ...
     }

   • sender and e that are passed in as parameters when an event occurs.
     sender is the control that caused the event.
     e supplies addition information about the event.

   • To register the event handler button1_Click with the Button.Click event:
     button1.Click += new EventHandler(button1_Click);

   • The code
     new EventHandler(button1_Click);
     creates a delegate that contains a reference to the button1_Click method.

4. The Control Class.
   • Hungarian Notation Prefixes for Control Names

     Class Name	Prefix		Class Name	Prefix
     Label	lbl		ListBox	lsb or lst
     TextBox	txt		ComboBox	cbo
     Button	btn		GroupBox	grb
     CheckBox	chk		Panel	pnl
     RadioButton	rad		ImageList	iml
     TrackBar	trk		ListView	lvw
     HScrollBar	hsb		VScrollBar	vsb
     TreeView	tvw		Form	frm

   • Control Properties
     Properties of Identity and Function: Name, Enabled, Visible

     Properties of Size and Location: Location, Size, ClientSize, ClientRectangle, Bounds, Anchor, Dock

     Properties of Color and Images: BackColor, ForeColor, BackgroundImage, BackgroundImageLayout, Image, ImageAlign, TextImageRelation

     Properties of Text: Text, Font, RightToLeft, Tag

     Properties of Creation and Disposing: Created, Disposing, IsDisposed.

     Properties of Focus and Tabbing:   FutureValue1 Example
     CausesValidation, CanFocus, CanSelect, ContainsFocus, Focused, TabIndex, TabStop

     Properties of Mouse and Cursor: Capture, Cursor.

     Here are two custom cursors:   arrow-usa.cur   hand-usa.cur.
     Download the one you want to use into the executable directory. To switch to a custom cursor, use this code:
     controlName.Cursor = new Cursor("arrow-usa.cur");

     Properties of Containment: Controls, HasChildren, Parent, TopLevelControl

     Properties of Accessibility: AccessibleDescription, AccessibleDefaultActionDescription, AccessibleName, AccessibleRole, AccessibilityObject, IsAccessible

     Property of Drag and Drop: AllowDrop

   • Control Methods
     Methods of Creation and Disposing: Constructor, Dispose, Destructor

     Method of Focus: Focus, Select

     Methods of Containment: Contains, GetChildAtPoint, GetContainerControl, GetNextControl

     Reset Methods: ResetBackColor, ResetText

     Methods of Display and Painting:BringToFront, Hide, Show, Invalidate, Refresh, SetStyle, Update

     Methods of Measurement and Scaling: PointToClient, PointToScreen, RectangleToClient, RectangleToScreen, Scale

     Method of Drag and Drop: DoDragDrop

   • Control Events
     Events of Mouse: Click, DoubleClick, MouseEnter, MouseDown, MouseMove, MouseUp, MouseLeave, MouseWheel

     Events of Focus:   FutureValue1 Example
     Enter, Validating, Validated, Leave

     Events of Display and Painting: Invalidated, Paint

     Events of Keyboard: KeyPress, KeyDown, KeyUp

     Events of Changed Properties: BackColorChanged, TextChanged, Resize, SizeChanged

     Events of Drag and Drop:   DragDrop Example
     DragEnter, DragDrop, DragLeave, DragOver, GiveFeedback, QueryContinueDrag

     Events of Adding or Removing Controls: ControlAdded, ControlRemoved

5. Additional Comment about Controls
   • Many individual controls derive directly from the Control class. Some other controls derive from other controls like ButtonBase, ListControl and TextBoxBase

Part B: Some Important Controls

1. Label
   • Properties:   Text, Font, BorderStyle, TextAlign

   • Methods:   Show, Hide

2. Button
   • Properties:   Text, Font, TextAlign, Image, ImageAlign

   • Methods:   PerformClick, DialogResult

   • Events:   Click

3. TextBox   KeyPress, Cascade and TextChanged1 Examples
   Properties:   Text, Font, Multiline, ScrollBars, AcceptsReturn, AcceptsTab, ReadOnly, PasswordChar, SelectedText, SelectionStart, SelectionLength

   Methods:   AppendText, Clear

   Events:   Click, DoubleClick, TextChanged, KeyPress

   AcceptButton and CancelButton Form properties

4. TrackBar   TrackBar Example
   Properties:   Value, Orientation, Minimum, Maximum, LargeChange, SmallChange, TickFrequency, TickStyle

   Events:   Scroll

5. PictureBox   PictureBox Example
   • Properties:   Image, BorderStyle, SizeMode

6. ErrorProvider   FutureValue2 and TextChanged2 Examples
   • Properties:   BlinkRate, BlinkStyle, Icon.

   • Methods:   GetError, SetError.

7. CheckBox   ThreeState Example
   • Properties:   Checked, CheckState, AutoCheck, CheckAlign, Appearance, ThreeState

   • Methods:   PerformClick

   • Events:   Click

8. RadioButton
   • Properties:   Checked, AutoCheck, CheckAlign, Appearance

   • Methods:   PerformClick

   • Events:   Click

9. GroupBox   Beverage Example
   • Properties:   Text, FlatStyle, Visible

   • Only one radiobutton in a groupbox can have Checked == true at a given time.

10. Panel   Panel Example
    • A panel is like a groupbox, but is usually invisible.

    • Only one radiobutton in a panel can have Checked = true at a given time.

Part C:   Message Boxes and Input Boxes

1. Syntax:   MessageBox.Show("Message")
   • Works only with Windows applications unless the System.Windows.Forms reference is added.

   • Overloaded versions are available for controlling the caption in title bar, icon used, buttons, position, etc.

Part D: More Controls

1. ListBox   ListBox Example
   • Properties: Items, Text, SelectedIndex, SelectedItem, SelectionMode, SelectedIndices, SelectedItems, Sorted

   • Methods:   Items.Add, Items.Remove, ClearSelected, SetSelected, GetSelected

   • Events:   Click, DoubleClick, SelectedIndexChanged

2. CheckedListBox   CheckedListBox Example
   • Properties:   CheckedIndices, CheckedItems, CheckOnClick, ThreeDBoxes

   • Methods:   GetItemChecked, SetItemChecked

   • Event:   ItemCheck

3. ComboBox   ComboBox Example
   • Properties: Items, Text, SelectedIndex, SelectedItem, SelectedText, SelectionStart, SelectionLength, DropDownStyle

   • Methods:   Same as ListBox.

   • Events:   Same as ListBox.

4. ImageList   ImageList Example
   • An ImageList control is for storing images in memory to be used in other controls.

   • Obtaining images from an ImageList is more efficient than loading images from disk every time they are needed.

   • The largest image that can be stored in an ImageList control is 256 x 256 pixels.

   • All of the images in an ImageList control must be the same size.

   • Properties:   ImageSize, ColorDepth, Images

   • Method:   Images.Add