Develop Reference

Gallery swipe adjustment

I need to lessen the amount of distance to be swiped in order to change my gallery's picture to the next. Right now this distance is at the standard rate and it's about half of the width of the gallery, but I need it to be about 1/3 or 1/4 of the total gallery width.
Thanks.
UPD: right now my custom gallery onFling returns false in order to list per page:
#Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
return false;
}

How to limit the bound of Scrolling While using onScroll method?

I am trying to achieve scrolling of layout by overriding onScroll method of Gesture Listener
#Override
public boolean onScroll(MotionEvent e1, MotionEvent e2,
float distanceX, float distanceY) {
Log.d("Scroll"," X " + this.get +" Y " + this.getScrollY() );
// this- Relative Layout
this.scrollBy((int)distanceX,(int)distanceY);
invalidate();
return false;
}
With the above code I am able to scroll the layout but my layout's background is moving out of bound i.e. screen ? How will I limit it ?
I tried various thing by getScrolly() , getLeft() but i am not getting any link by which I can go ahead ? please help me ...

How can I determine motion direction in an Android Gallery?

I have been creating a Gallery derivative that uses a limited number of Views and, as such, the Adapter needs to be able to populate these Views ahead of time during a scroll or a fling. To do this, I need to get the direction of motion from the onFling(...) and onScroll(...) events.
How can I use the distanceX parameter in onScroll(...) and the velocityX parameter in onFling(...) to determine which way the Gallery is travelling, and therefore which View to prepare next?

The signs of the velocity parameters in onFling(...) and the distance parameters on onScroll(...) are opposite. In order to correctly determine which direction a Gallery is moving, the code should be as follows:
#Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
//if distanceX is POSITIVE, the Views are travelling left
//therefore the selection position is INCREASING
return super.onScroll(e1, e2, distanceX*mVelocityFactor, distanceY*mVelocityFactor);
}
#Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
//if velocityX is NEGATIVE, the Views are travelling left
//therefore the selection position is DECREASING
return super.onFling(e1, e1, velocityX*mVelocityFactor, velocityY*mVelocityFactor);
}
By the way, mVelocityFactor is just a constant I introduced to make the scroll/fling a little less energetic. I found 0.6 to be quite a nice value—it still feels intuitive to scroll but the flings are less violent.

smooth horizontal scrolling in webview

I have a wevbiew with a number of 'pages' (columns of text) in it, and want to be able to scroll horizontally between columns in response to Fling gestures. I can do this fine using scrollTo(), but that is rather sudden and I'd really like to be able to do a smooth transition from one 'page' to the next.
The problem as I see it: you can't attach a Scroller to a WebView, and shouldn't nest a WebView in a ScrollView.
Does anyone have any good ideas for implementing smooth or animated horizontal scrolling in a WebView?
Edited to add: I'm trying to implement an idea of knotmanish's where I use an unattached Scroller to compute the distance..
// vx and vy are from the onfling event of the gesture detector
scroller.fling(page*x, 0, vx, vy, page*(x + 1), page*(x + 1), 0, 0);
while(scroller.computeScrollOffset()){
webview.scrollTo(scroller.getCurrX(), 0);
webview.invalidate();
}
... but the while loop seems too slow to capture the scroller's movement, or something, because the behavior looks just like the scrollTo() method (the view jump to the end of the scroll).

You cannot attach a scroller to a webview however you can make use of the gesture to do the same.
The gesture detects the fling using this method
onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY)
Give the velocityX, velocityY to the scoller method along with other parameters
fling(int startX, int startY, int velocityX, int velocityY, int minX, int maxX, int minY, int maxY)
scan the computeScrollOffset() value to find the getCurrX(),getCurrY() positions.
Extend the webview and override the methods onTouchEvent(MotionEvent ev), dispatchTouchEvent(MotionEvent ev) to return false so that by default the touch events are not consumed by the webview itself.
Now implement the gestureListener and override the onfling method mentioned above.
pass the velocity and other parameters to the scroller.
Start a loop to scan the computeScrollOffset() value to find the getCurrX() and getCurrY() and invalidate the view each time.
Pass this value to scroll the webview as needed.
Please let me know in case you need anything.

How to best handle fling gesture for Android ListActivity

I have an Android app with a ListActivity in the main view. The list contains a LinearLayout with a TextView and a hidden delete Button. The delete Button will be hidden by default. I want to use a fling gesture to show the button. I am able to detect the fling gesture thanks to question #937313 on stackoverflow. It's not clear to me how to determine which item in the list was flung, since the onTouch listener listens to the ListView. The item is not necessarily selected so getSelected* methods can't be used reliably. I am using the SimpleListAdaptor so I don't have direct access to the View Objects in the ListView.
Any ideas?

Try using AbsListView.pointToPosition() to determine the list item for the X,Y coordinate in your list view.
If you're using the recipe from #937313, you should be able to override onFling() more or less as follows:
#Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
try {
Toast.makeText(listAdapter.getItem( listView.pointToPosition( (int) e1.getX(), (int) e1.getY() ).toString() );
return super.onFling();
} catch( Exception e ) {
// do nothing
}
}