如何在Android中禁用左右拖动ImageView？

在我的应用程序中，我希望通过触摸屏拖放Imageview。我可以在屏幕上从四个方向拖动它，但我只想从顶部拖动到底部，并禁用向右和向左拖动Imageview

srceen中拖放imageview的我的代码：

public class MainActivity extends Activity implements OnTouchListener,
        OnDragListener {
    private static final String LOGCAT = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findViewById(R.id.textView1).setOnTouchListener(this);
        findViewById(R.id.pinkLayout).setOnDragListener(this);
        findViewById(R.id.yellowLayout).setOnDragListener(this);
    }

    public boolean onTouch(View view, MotionEvent motionEvent) {
        if (motionEvent.getAction() == MotionEvent.ACTION_DOWN) {
            DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
            view.startDrag(null, shadowBuilder, view, 0);
            view.setVisibility(View.INVISIBLE);
            return true;
        } else {
            return false;
        }
    }

    public boolean onDrag(View layoutview, DragEvent dragevent) {
        int action = dragevent.getAction();
        switch (action) {
        case DragEvent.ACTION_DRAG_STARTED:
            Log.d(LOGCAT, "Drag event started");
            break;
        case DragEvent.ACTION_DRAG_ENTERED:
            Log.d(LOGCAT, "Drag event entered into " + layoutview.toString());
            break;
        case DragEvent.ACTION_DRAG_EXITED:
            Log.d(LOGCAT, "Drag event exited from " + layoutview.toString());
            break;
        case DragEvent.ACTION_DROP:
            Log.d(LOGCAT, "Dropped");
            View view = (View) dragevent.getLocalState();
            ViewGroup owner = (ViewGroup) view.getParent();
            owner.removeView(view);
            LinearLayout container = (LinearLayout) layoutview;
            container.addView(view);
            view.setVisibility(View.VISIBLE);
            break;
        case DragEvent.ACTION_DRAG_ENDED:
            Log.d(LOGCAT, "Drag ended");
            break;
        default:
            break;
        }
        return true;
    }
}

如何解决？

---

谢谢使用这可能会对你有所帮助

switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
savedMatrix.set(matrix);
start.set(event.getX(), event.getY());
Log.d(TAG, "mode=DRAG" );
mode = DRAG;
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
Log.d(TAG, "mode=NONE" );
break;
case MotionEvent.ACTION_MOVE:
if (mode == DRAG) {
matrix.set(savedMatrix);
matrix.postTranslate(event.getX() - start.x,
event.getY() - start.y);
}
break;
}

---

静态最终int NONE=0；静态最终整数阻力=1；int模式=无；这不起作用，因为左右移动都起作用了。我想在屏幕上禁用左右移动