Вам необходимо переопределить onInterceptTouchEvent - вы можете использовать это, чтобы получить MotionEvent с, прежде чем они будут доставлены на ScrollView, а затем перенаправить их на ваш ViewGroup (в данном случае Gallery), если Вы хотите.
Следующий класс перенаправляет MotionEvent s на Gallery, если пользователь перемещает палец слишком далеко влево или вправо. Кроме того, если пользователь немного перемещает палец вверх или вниз, то перемещение пальца влево или вправо больше не будет иметь эффекта, поэтому вам не придется беспокоиться об изменении галереи при выполнении большой прокрутки.
class ScrollViewGallery extends Gallery {
/**
* The distance the user has to move their finger, in density independent
* pixels, before we count the motion as A) intended for the ScrollView if
* the motion is in the vertical direction or B) intended for ourselfs, if
* the motion is in the horizontal direction - after the user has moved this
* amount they are "locked" into this direction until the next ACTION_DOWN
* event
*/
private static final int DRAG_BOUNDS_IN_DP = 20;
/**
* A value representing the "unlocked" state - we test all MotionEvents
* when in this state to see whether a lock should be make
*/
private static final int SCROLL_LOCK_NONE = 0;
/**
* A value representing a lock in the vertical direction - once in this state
* we will never redirect MotionEvents from the ScrollView to ourself
*/
private static final int SCROLL_LOCK_VERTICAL = 1;
/**
* A value representing a lock in the horizontal direction - once in this
* state we will not deliver any more MotionEvents to the ScrollView, and
* will deliver them to ourselves instead.
*/
private static final int SCROLL_LOCK_HORIZONTAL = 2;
/**
* The drag bounds in density independent pixels converted to actual pixels
*/
private int mDragBoundsInPx = 0;
/**
* The coordinates of the intercepted ACTION_DOWN event
*/
private float mTouchStartX;
private float mTouchStartY;
/**
* The current scroll lock state
*/
private int mScrollLock = SCROLL_LOCK_NONE;
public ScrollViewGallery(Context context) {
super(context);
initCustomGallery(context);
}
public ScrollViewGallery(Context context, AttributeSet attrs) {
super(context, attrs);
initCustomGallery(context);
}
public ScrollViewGallery(Context context, AttributeSet attrs,
int defStyle) {
super(context, attrs, defStyle);
initCustomGallery(context);
}
private void initCustomGallery(Context context) {
final float scale = context.getResources().getDisplayMetrics().density;
mDragBoundsInPx = (int) (scale*DRAG_BOUNDS_IN_DP + 0.5f);
}
/**
* This will be called before the intercepted views onTouchEvent is called
* Return false to keep intercepting and passing the event on to the target view
* Return true and the target view will recieve ACTION_CANCEL, and the rest of the
* events will be delivered to our onTouchEvent
*/
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
final int action = ev.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
mTouchStartX = ev.getX();
mTouchStartY = ev.getY();
mScrollLock = SCROLL_LOCK_NONE;
/**
* Deliver the down event to the Gallery to avoid jerky scrolling
* if we decide to redirect the ScrollView events to ourself
*/
super.onTouchEvent(ev);
break;
case MotionEvent.ACTION_MOVE:
if (mScrollLock == SCROLL_LOCK_VERTICAL) {
// keep returning false to pass the events
// onto the ScrollView
return false;
}
final float touchDistanceX = (ev.getX() - mTouchStartX);
final float touchDistanceY = (ev.getY() - mTouchStartY);
if (Math.abs(touchDistanceY) > mDragBoundsInPx) {
mScrollLock = SCROLL_LOCK_VERTICAL;
return false;
}
if (Math.abs(touchDistanceX) > mDragBoundsInPx) {
mScrollLock = SCROLL_LOCK_HORIZONTAL; // gallery action
return true; // redirect MotionEvents to ourself
}
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
// if we're still intercepting at this stage, make sure the gallery
// also recieves the up/cancel event as we gave it the down event earlier
super.onTouchEvent(ev);
break;
}
return false;
}
}