The Control Class

The Control class is in the System.Windows.Forms namespace. It serves as a base class for the Windows controls we'll see—such as rich text boxes—which have this class hierarchy (that is, the MarshalByRefObject class is derived from the Object class, and the Component class is derived from the MarshalByRef Object class, and so on):

Object
   MarshalByRefObject
      Component
         Control
            TextBoxBase
               RichTextBox

Because Windows controls are based on the Control class, they inherit many properties, methods, and events from that class, so I'll list the more interesting ones here. (Keep in mind that the Form class is also derived from Control, so it also shares these properties, methods, and events). You can find noteworthy public properties of the Control class in Table 5.1, noteworthy methods in Table 5.2, and events in Table 5.3.

Table 5.1: Noteworthy public properties of *Control* objects.
Property	Means
AllowDrop	Sets/gets a value specifying if the control can accept data dropped into it.
Anchor	Sets/gets which edges of the control are anchored.
BackColor	Sets/gets the background color of this control.
BackgroundImage	Sets/gets the background image in the control.
Bottom	Gets the distance between the bottom of the control and the top of its container's client area.
Bounds	Sets/gets the control's bounding rectangle.
CanFocus	Returns a value specifying if the control can receive the focus.
CanSelect	Returns a value specifying if the control can be selected.
Capture	Sets/gets a value specifying if the control has captured the mouse.
CausesValidation	Sets/gets a value specifying if the control causes validation for all controls that require validation.
ContainsFocus	Returns a value specifying if the control has the input focus.
ContextMenu	Sets/gets the shortcut menu associated with this control.
Controls	Sets/gets the collection of controls contained within the control.
Cursor	Sets/gets the cursor displayed when the user moves the mouse pointer over this control.
DataBindings	Gets the data bindings for the control.
Dock	Sets/gets which edge of the parent a control is docked to.
Enabled	Sets/gets a value specifying if the control is enabled.
Focused	Returns a value specifying if the control has input focus.
Font	Sets/gets the current font for the control.
ForeColor	Sets/gets the foreground color of the control.
HasChildren	Returns a value specifying if the control contains child controls.
Height	Sets/gets the height of the control.
Left	Sets/gets the x-coordinate of a control's left edge in pixels.
Location	Sets/gets the coordinates of the upper-left corner of the control with respect to the upper-left corner of its container.
Name	Sets/gets the control's name.
Parent	Sets/gets the control's parent container.
Right	Returns the distance between the right edge of the control and the left edge of its container.
RightToLeft	Sets/gets a value indicating if the alignment of the control's elements is reversed to support right-to-left fonts.
Size	Sets/gets the height and width of the control.
TabIndex	Sets/gets the tab order of this control in its container.
TabStop	Sets/gets a value specifying if the user can tab to this control with the Tab key.
Tag	Sets/gets an object that contains data about the control.
Text	Sets/gets the text connected to this control.
Top	Sets/gets the top coordinate of the control.
Visible	Sets/gets a value specifying if the control is visible.
Width	Sets/gets the width of the control.

Table 5.2: Noteworthy public methods of *Control* objects.
Method	Means
BringToFront	Brings the control to the front of the stacking order.
Contains	Retrieves a value specifying if the control is a child of this control.
CreateGraphics	Creates a Graphics object for the control.
Dispose	Releases the resources used by the control.
DoDragDrop	Starts a drag-and-drop operation.
Equals	Indicates if two controls are equal.
FindForm	Retrieves the form that this control is on.
Focus	Gives the focus to the control.
GetChildAtPoint	Gets the child control at the specified coordinates.
GetNextControl	Retrieves the next control in the tab order of child controls.
GetType	Gets the type of the control.
Hide	Hides the control.
Invalidate	Invalidates a part of the control and sends a paint message to the control.
PointToClient	Translates the location of the specified screen point to client coordinates.
PointToScreen	Translates the location of the specified client point to screen coordinates.
RectangleToClient	Translates the location of the specified screen rectangle to client coordinates.
RectangleToScreen	Translates the location of the specified client rectangle to screen coordinates.
Refresh	Forces the control to invalidate its client area and repaint itself (and any child controls).
Scale	Scales the control and any child controls.
Select	Activates this control.
SendToBack	Sends the control to the back of the stacking order.
SetBounds	Sets the bounds of the control.
Show	Displays the control (sets its visible property to True).
ToString	Returns a string that represents the current control.
Update	Forces the control to paint any currently invalid areas.

Table 5.3: Noteworthy public events of *Control* objects.
Event	Means
BackColorChanged	Occurs when the value of the BackColor property is changed.
BackgroundImageChanged	Occurs when the BackgroundImage property is changed.
Click	Occurs when the control is clicked.
ContextMenuChanged	Occurs when the ContextMenu property value is changed.
ControlAdded	Occurs when a new control is added.
ControlRemoved	Occurs when a control is removed.
CursorChanged	Occurs when the Cursor property value is changed.
Disposed	Represents the method which will handle the Disposed event of a Component.
DoubleClick	Occurs when the control is double-clicked.
DragDrop	Occurs when a drag-and-drop operation is completed.
DragEnter	Occurs when an object is dragged into the control's bounds.
DragLeave	Occurs when an object has been dragged into and out of the control's bounds.
DragOver	Occurs when an object has been dragged over the control's bounds.
EnabledChanged	Occurs when the Enabled property value is changed.
Enter	Occurs when the control is entered.
FontChanged	Occurs when the Font property value is changed.
ForeColorChanged	Occurs when the ForeColor property value is changed.
GotFocus	Occurs when the control receives focus.
Invalidated	Occurs when a control's display is updated.
KeyDown	Occurs when a key is pressed down while the control has focus.
KeyPress	Occurs when a key is pressed while the control has focus.
KeyUp	Occurs when a key is released while the control has focus.
Layout	Occurs when a control has to lay out its child controls.
Leave	Occurs when the control is left.
LocationChanged	Occurs when the Location property value is changed.
LostFocus	Occurs when the control loses focus.
MouseDown	Occurs when the mouse pointer is over the control and a mouse button is pressed.
MouseEnter	Occurs when the mouse pointer enters the control.
MouseHover	Occurs when the mouse pointer hovers over the control.
MouseLeave	Occurs when the mouse pointer leaves the control.
MouseMove	Occurs when the mouse pointer is moved over the control.
MouseUp	Occurs when the mouse pointer is over the control and a mouse button is released.
MouseWheel	Occurs when the mouse wheel moves while the control has focus.
Move	Occurs when the control is moved.
Paint	Occurs when the control is redrawn.
ParentChanged	Occurs when the Parent property value is changed.
Resize	Occurs when the control is resized.
RightToLeftChanged	Occurs when the Right-ToLeft property value is changed.
Validated	Occurs when the control is done validating.
Validating	Occurs when the control is validating.
VisibleChanged	Occurs when the Visible property value is changed.

I've included Tables 5.1, 5.2, and 5.3 for reference sake, and it's really worth looking through these tables, finding out, for example, what properties to use to change the background color of a control (BackColor), what method makes a control invisible (Hide), what event handles mouse button press events (MouseDown), and so on. Note that when listing the noteworthy properties, methods, and events of Windows controls in similar tables in this and the next chapters, I'm going to omit those inherited from the Control class, because there simply isn't room to list them all. You'll find all those common Control properties, methods, and events in Tables 5.1, 5.2, and 5.3.