// Method with the same name as the class is a "constructor".
//
// This method makes a new PaintbrushControlModel. Every time you make a new PaintbrushControlModel,
// you have to provide it with a Control (something on the screen that a user can click on) and
// an IPaintbrushEventHandler (something that defines the methods in the IPaintbrushEventHandler interface).
public PaintbrushControlModel(Control control, IPaintbrushEventHandler handler)
{
_control = control;
_handler = handler;
// MouseUp, MouseDown, and MouseMove are a special kind of variable called a "delegate".
// A "delegate" is a place to which you can attach an event handler.
//
// The method "HandleMouseUp" is an event handler (it's a method that handles an event).
// When I say "_control.MouseUp += HandleMouseUp", I'm saying, "Add my HandleMouseUp method
// to the list of event handlers to which you send a MouseUp event."
//
// This is so that lots of different event handlers can listen to a single event, without
// "getting in each other's way". I could add an event handler to the control's MouseUp
// delegate, and someone else could add an event handler to the control's MouseUp delegate,
// and both of those event handlers would get called when the mouse button was released.
_control.MouseUp += HandleMouseUp;
// HandleMouseUp is an event handler -- a method that knows how to handle MouseUp events.
//
// This is another way of making a "method that knows how to handle MouseUp events". It is
// called an "anonymous function" or "a lambda" (for historical reasons).
// It says, "Make an anonymous function that takes an object called 'sender' and some MouseEventArgs
// called 'e', and show a message with MessageBox.Show().
// _control.MouseUp += (sender, e) => MessageBox.Show("second event handler" + e.Location);
// This is another event handler (also a lambda). It's only different in that it calls
// the second parameter "args" instead of "e", and says "third event handler" instead of "second event handler"
// _control.MouseUp += (sender, args) => MessageBox.Show("third event handler" + args.Location);
// "I want to listen to the MouseDown event of this control with my HandleMouseDown event handler method."
_control.MouseDown += HandleMouseDown;
// "I want to listen to the MouseMove event of this control with my HandleMouseMove event handler method."
_control.MouseMove += HandleMouseMove;
}
// Method with the same name as the class is a "constructor".
//
// This method makes a new PaintbrushControlModel. Every time you make a new PaintbrushControlModel,
// you have to provide it with a Control (something on the screen that a user can click on) and
// an IPaintbrushEventHandler (something that defines the methods in the IPaintbrushEventHandler interface).
public PaintbrushControlModel(Control control, IPaintbrushEventHandler handler)
{
_control = control;
_handler = handler;
// MouseUp, MouseDown, and MouseMove are a special kind of variable called a "delegate".
// A "delegate" is a place to which you can attach an event handler.
//
// The method "HandleMouseUp" is an event handler (it's a method that handles an event).
// When I say "_control.MouseUp += HandleMouseUp", I'm saying, "Add my HandleMouseUp method
// to the list of event handlers to which you send a MouseUp event."
//
// This is so that lots of different event handlers can listen to a single event, without
// "getting in each other's way". I could add an event handler to the control's MouseUp
// delegate, and someone else could add an event handler to the control's MouseUp delegate,
// and both of those event handlers would get called when the mouse button was released.
_control.MouseUp += HandleMouseUp;
// HandleMouseUp is an event handler -- a method that knows how to handle MouseUp events.
//
// This is another way of making a "method that knows how to handle MouseUp events". It is
// called an "anonymous function" or "a lambda" (for historical reasons).
// It says, "Make an anonymous function that takes an object called 'sender' and some MouseEventArgs
// called 'e', and show a message with MessageBox.Show().
// _control.MouseUp += (sender, e) => MessageBox.Show("second event handler" + e.Location);
// This is another event handler (also a lambda). It's only different in that it calls
// the second parameter "args" instead of "e", and says "third event handler" instead of "second event handler"
// _control.MouseUp += (sender, args) => MessageBox.Show("third event handler" + args.Location);
// "I want to listen to the MouseDown event of this control with my HandleMouseDown event handler method."
_control.MouseDown += HandleMouseDown;
// "I want to listen to the MouseMove event of this control with my HandleMouseMove event handler method."
_control.MouseMove += HandleMouseMove;
}
