Create a new project named DragAndDraw. Select API 19 as the minimum SDK and create an empty activity. Name the activity DragAndDrawActivity.

DragAndDrawActivity will be a subclass of SingleFragmentActivity that inflates the usual single-fragment-containing layout. Copy SingleFragmentActivity.java and its activity_fragment.xml layout file into the DragAndDraw project.

In DragAndDrawActivity.java, make DragAndDrawActivity a SingleFragmentActivity that creates a DragAndDrawFragment (a class that you will create next).

public class DragAndDrawActivity extends AppCompatActivity SingleFragmentActivity {

    @Override
    protected Fragment createFragment() {
        return DragAndDrawFragment.newInstance();
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        ...
    }
}

To prepare a layout for DragAndDrawFragment, rename the activity_drag_and_draw.xml layout file to fragment_drag_and_draw.xml.

DragAndDrawFragment’s layout will eventually consist of a BoxDrawingView, the custom view that you are going to write. All of the drawing and touch-event handling will be implemented in BoxDrawingView.

Create a new class named DragAndDrawFragment and make its superclass android.support.v4.app.Fragment. Override onCreateView(…) to inflate fragment_drag_and_draw.xml.

public class DragAndDrawFragment extends Fragment {

    public static DragAndDrawFragment newInstance() {
        return new DragAndDrawFragment();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment_drag_and_draw, container, false);
        return v;
    }
}

Run DragAndDraw to confirm that your app is set up properly. It should look like Figure 31.2.

Figure 31.2  DragAndDraw with default layout