Android™ How to Program, Second Edition

DoodleView static and Instance Variables

Class DoodleView’s static and instance variables (Fig. 7.21, lines 30–43) are used to manage the data for the set of lines that the user is currently drawing and to draw those lines. Line 38 creates the pathMap, which maps each finger ID (known as a pointer) to a corresponding Path object for the lines currently being drawn. Lines 39–40 create the previousPointMap, which maintains the last point for each finger—as each finger moves, we draw a line from its current point to its previous point. We discuss the other fields as we use them in class DoodleView.

Click here to view code image

26   // the main screen that is painted27   public class DoodleView extends View28   {29      // used to determine whether ...