Smalltalk and Object Orientation: an Introduction - Free

29. Using a View Within a Window
29.1 Introduction
This chapter describes how a custom view can be incorporated into the type of window seen in the last
two chapters. This is important because although the user interface builder is extremely good at creating
buttons, input/output field style windows, it cannot be used to display graphical information. For
example, if you wish to construct a graph of nodes to illustrate a particular route in a path finding
application then this must be generated using the basic MVC (Model-View-Control) features.
In this chapter we consider a simple drawing application which we will call SmallDraw . This
application is illustrated in Figure 29.1.
Figure 29.1: The SmallDraw application
SmallDraw allows boxes, circles and points to be placed on a scrollable drawing. The three widget
buttons and the exit button have been defined using the user interface builder. The scrollable drawing
area is a scrollable view which has be created by the user interface builder but which is controller by a
separate model, view and controller.
In the remainder of this chapter we will consider how this application was constructed.
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