05_响应多点触控

import android.app.Activity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.TextView;

public class MultiTouchTest extends Activity implements OnTouchListener {
    StringBuilder builder = new StringBuilder();
    TextView textView;
    float[] x = new float[10];
    float[] y = new float[10];
    boolean[] touched = new boolean[10];

    private void updateTextView() {
        builder.setLength(0);
        for(int i = 0; i < 10; i++) {
            builder.append(touched[i]);
            builder.append(", ");
            builder.append(x[i]);
            builder.append(", ");
            builder.append(y[i]);
            builder.append("\n");
        }
        textView.setText(builder.toString());
    }
   
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        textView = new TextView(this);
        textView.setText("Touch and drag (multiple fingers supported)!");
        textView.setOnTouchListener(this);
        setContentView(textView);
    }

    @Override
    public boolean onTouch(View v, MotionEvent event) {
     int curAction = event.getAction();
        int action = curAction & MotionEvent.ACTION_MASK;
        int pointerIndex = (curAction & MotionEvent.ACTION_POINTER_ID_MASK) >> MotionEvent.ACTION_POINTER_ID_SHIFT;
        int pointerId = event.getPointerId(pointerIndex);

        switch (action) {
        case MotionEvent.ACTION_DOWN:
        case MotionEvent.ACTION_POINTER_DOWN:
            touched[pointerId] = true;
            x[pointerId] = (int)event.getX(pointerIndex);
            y[pointerId] = (int)event.getY(pointerIndex);
            break;

        case MotionEvent.ACTION_UP:         
        case MotionEvent.ACTION_POINTER_UP:
        case MotionEvent.ACTION_CANCEL:
            touched[pointerId] = false;
            x[pointerId] = (int)event.getX(pointerIndex);
            y[pointerId] = (int)event.getY(pointerIndex);
            break;

        case MotionEvent.ACTION_MOVE:
            int pointerCount = event.getPointerCount();
            for (int i = 0; i < pointerCount; i++) {
                pointerIndex = i;
                pointerId = event.getPointerId(pointerIndex);
                x[pointerId] = (int)event.getX(pointerIndex);
                y[pointerId] = (int)event.getY(pointerIndex);
            }
            break;
        }
       
        updateTextView();      
        return true;
    }
}