I am going to place text in gallery in android app. The text is in a scroll开发者_运维技巧View. Everything works fine but on draging the text towards right or left, no next page/ element shows (The screen remains still).If i have some thing outside the scrollView, it changes to the next element on dragging.
Can anyone help?
You need to override onInterceptTouchEvent
- you can use this to get the MotionEvent
s before they are delivered to the ScrollView
, and then redirect them to your ViewGroup
(Gallery
in this case) if you wish.
The following class redirects MotionEvent
s to your Gallery
if the user moves their finger too far left or right. Also if the user moves their finger up or down quite a bit then moving their finger left or right will have no longer have an effect, so you don't have to worry about the Gallery changing while doing a lot of scrolling.
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;
}
}
I understand your question. This situation is already handle by me after overriding method. I am not sure this will be the best solution, may be some one have more efficient solution then this, But it works for me.
I used customised object of gallery with the over ridden method.
public boolean isScrollingLeft(MotionEvent e1, MotionEvent e2) {
return e2.getX() > e1.getX();
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
return super.onFling(e1, e2, 0, velocityY);
}
I found that if you place a textview in a vertical scrollbar mode it only moves up or down. If we want to swipe horizontally, you have to touch outside of the textview.
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