Game Development Reference
In-Depth Information
The TouchHandler Interface
In order to use our two handler classes interchangeably, we need to define a common interface.
Listing 5-9 presents the
TouchHandler
interface.
Listing 5-9. TouchHandler.java, to Be Implemented for Android 1.5 and 1.6
package
com.badlogic.androidgames.framework.impl;
import
java.util.List;
import
android.view.View.OnTouchListener;
import
com.badlogic.androidgames.framework.Input.TouchEvent;
public interface
TouchHandler
extends
OnTouchListener {
public boolean
isTouchDown(int pointer);
public int
getTouchX(
int
pointer);
public int
getTouchY(
int
pointer);
public
List<TouchEvent>getTouchEvents();
}
All
TouchHandler
is must implement the
OnTouchListener
interface, which is used to register the
handler with a
View
. The methods of the interface correspond to the respective methods of the
Input
interface defined in Chapter 3. The first three are for polling the state of a specific pointer
ID, and the last is for getting
TouchEvent
is with which to perform event-based input handling.
Note that the polling methods take pointer IDs that can be any number and are given by the
touch event.
The SingleTouchHandler Class
In the case of our single-touch handler, we ignore any IDs other than zero. To recap, we'll recall
the
TouchEvent
class defined in Chapter 3 as part of the
Input
interface.
public static class
TouchEvent {
public static final int
TOUCH_DOWN
=0;
public static final int
TOUCH_UP
=1;
public static final int
TOUCH_DRAGGED
=2;
public int
type;
public int
x, y;
public int
pointer;
}
Like the
KeyEvent
class, the
TouchEvent
class defines a couple of constants that echo the touch
event's type, along with the x and y coordinates in the coordinate system of the
View
and the
pointer ID. Listing 5-10 shows the implementation of the
TouchHandler
interface for Android 1.5
and 1.6, broken up by commentary.
