overscroll-decor


Source link: https://github.com/EverythingMe/overscroll-decor

Over-Scroll Support For Android's RecyclerView, ListView, GridView, ScrollView ...

The library provides an iOS-like over-scrolling effect applicable over almost all Android native scrollable views. It is also built to allow for very easy adaptation to support custom views.

The core effect classes are loose- decorators of Android views, and are thus decoupled from the actual view classes' implementations. That allows developers to apply the effect over views while keeping them as untampered 'black-boxes'. Namely, it allows for keeping important optimizations such as view-recycling intact.

Gradle Dependency

Add the following to your module's build.gradle file:

dependencies {

  // ...

 compile 'me.everything:overscroll-decor-android:1.0.4' 
}

Usage

RecyclerView

Supports both linear and staggered-grid layout managers (i.e. all native Android layouts). Can be easily adapted to support custom layout managers.

RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view);

// Horizontal OverScrollDecoratorHelper.setUpOverScroll(recyclerView, OverScrollDecoratorHelper.ORIENTATION_HORIZONTAL);
 // Vertical OverScrollDecoratorHelper.setUpOverScroll(recyclerView, OverScrollDecoratorHelper.ORIENTATION_VERTICAL);

RecyclerView with items swiping / dragging

See Advanced Usage.

ListView

ListView listView = (ListView) findViewById(R.id.list_view);
 OverScrollDecoratorHelper.setUpOverScroll(listView);

GridView

GridView gridView = (GridView) findViewById(R.id.grid_view);
 OverScrollDecoratorHelper.setUpOverScroll(gridView);

ViewPager

ViewPager viewPager = (ViewPager) findViewById(R.id.view_pager);
 OverScrollDecoratorHelper.setUpOverScroll(viewPager);

ScrollView, HorizontalScrollView

ScrollView scrollView = (ScrollView) findViewById(R.id.scroll_view);
 OverScrollDecoratorHelper.setUpOverScroll(scrollView);

HorizontalScrollView horizontalScrollView = (HorizontalScrollView) findViewById(R.id.horizontal_scroll_view);
 OverScrollDecoratorHelper.setUpOverScroll(horizontalScrollView);

Any View - Text, Image... (Always Over-Scroll Ready)

View view = findViewById(R.id.demo_view);

// Horizontal OverScrollDecoratorHelper.setUpStaticOverScroll(view, OverScrollDecoratorHelper.ORIENTATION_HORIZONTAL);
 // Vertical OverScrollDecoratorHelper.setUpStaticOverScroll(view, OverScrollDecoratorHelper.ORIENTATION_VERTICAL);

Advanced Usage

// Horizontal RecyclerView RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
 new HorizontalOverScrollBounceEffectDecorator(new RecyclerViewOverScrollDecorAdapter(recyclerView));
  // ListView (vertical) ListView listView = (ListView) findViewById(R.id.list_view);
 new VerticalOverScrollBounceEffectDecorator(new AbsListViewOverScrollDecorAdapter(listView));
  // GridView (vertical) GridView gridView = (GridView) findViewById(R.id.grid_view);
 new VerticalOverScrollBounceEffectDecorator(new AbsListViewOverScrollDecorAdapter(gridView));
  // ViewPager ViewPager viewPager = (ViewPager) findViewById(R.id.view_pager);
 new HorizontalOverScrollBounceEffectDecorator(new ViewPagerOverScrollDecorAdapter(viewPager));
  // A simple TextView - horizontal View textView = findViewById(R.id.title);
 new HorizontalOverScrollBounceEffectDecorator(new StaticOverScrollDecorAdapter(view));

RecyclerView with ItemTouchHelper based swiping / dragging

As of version 1.0.1, the effect can work smoothly with the RecyclerView's built-in mechanism for items swiping and dragging (based on ItemTouchHelper). BUT, it requires some (very little) explicit configuration work:

// Normally you would attach an ItemTouchHelper & a callback to a RecyclerView, this way: RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
 ItemTouchHelper.Callback myCallback = new ItemTouchHelper.Callback() {
  ... 
}
; ItemTouchHelper myHelper = new ItemTouchHelper(myCallback);
 myHelper.attachToRecyclerView(recyclerView);
  // INSTEAD of attaching the helper yourself, simply use the dedicated adapter c'tor, e.g.: new VerticalOverScrollBounceEffectDecorator(new RecyclerViewOverScrollDecorAdapter(recyclerView, myCallback));
 

For more info on the swiping / dragging mechanism, try this useful tutorial.

Over-Scroll Listeners

As of version 1.0.2, the effect provides a means for registering listeners of over-scroll related events. There are two types of listeners, as follows.

State-Change Listener

The over-scroll manager dispatches events onto a state-change listener denoting transitions in the effect's state:

// Note: over-scroll is set-up using the helper method. IOverScrollDecor decor = OverScrollDecoratorHelper.setUpOverScroll(recyclerView, OverScrollDecoratorHelper.ORIENTATION_HORIZONTAL);
  decor.setOverScrollStateListener(new IOverScrollStateListener() {

  @Override  public void onOverScrollStateChange(IOverScrollDecor decor, int oldState, int newState) {

switch (newState) {

 case STATE_IDLE:

  // No over-scroll is in effect.

  break;

 case STATE_DRAG_START_SIDE:

  // Dragging started at the left-end.

  break;

 case STATE_DRAG_END_SIDE:

  // Dragging started at the right-end.

  break;

 case STATE_BOUNCE_BACK:

  if (oldState == STATE_DRAG_START_SIDE) {

// Dragging stopped -- view is starting to bounce back from the *left-end* onto natural position.

  
}
 else {
 // i.e. (oldState == STATE_DRAG_END_SIDE)

// View is starting to bounce back from the *right-end*.

  
}

  break;

}
  
}
 
}

Real-time Updates Listener

The over-scroll manager can also dispatch real-time, as-it-happens over-scroll events denoting the current offset resulting due to an over-scroll being in-effect (the offset thus denotes the current 'intensity').

// Note: over-scroll is set-up by explicity instantiating a decorator rather than using the helper; The two methods can be used interchangeably for registering listeners. VerticalOverScrollBounceEffectDecorator decor = new VerticalOverScrollBounceEffectDecorator(new RecyclerViewOverScrollDecorAdapter(recyclerView, itemTouchHelperCallback));
  decor.setOverScrollUpdateListener(new IOverScrollUpdateListener() {

  @Override
  public void onOverScrollUpdate(IOverScrollDecor decor, int state, float offset) {

final View view = decor.getView();

if (offset > 0) {

 // 'view' is currently being over-scrolled from the top.

}
 else if (offset < 0) {

 // 'view' is currently being over-scrolled from the bottom.

}
 else {

 // No over-scroll is in-effect.

 // This is synonymous with having (state == STATE_IDLE).

}

  
}
 
}
);
 

The two type of listeners can be used either separately or in conjunction, depending on your needs. Refer to the demo project's RecyclerView-demo section for actual concrete usage.

Custom Views

public class CustomView extends View {

  // ... 
}

final CustomView view = (CustomView) findViewById(R.id.custom_view);
 new VerticalOverScrollBounceEffectDecorator(new IOverScrollDecoratorAdapter() {

@Override
  public View getView() {

return view;
  
}

@Override
  public boolean isInAbsoluteStart() {

// canScrollUp() is an example of a method you must implement

return !view.canScrollUp();

  
}

@Override
  public boolean isInAbsoluteEnd() {

 // canScrollDown() is an example of a method you must implement

return !view.canScrollDown();

  
}
 
}
);

Effect Behavior Configuration

/// Make over-scroll applied over a list-view feel more 'stiff' new VerticalOverScrollBounceEffectDecorator(new AbsListViewOverScrollDecorAdapter(view),

5f, // Default is 3

VerticalOverScrollBounceEffectDecorator.DEFAULT_TOUCH_DRAG_MOVE_RATIO_BCK,

VerticalOverScrollBounceEffectDecorator.DEFAULT_DECELERATE_FACTOR);

// Make over-scroll applied over a list-view bounce-back more softly new VerticalOverScrollBounceEffectDecorator(new AbsListViewOverScrollDecorAdapter(view),

VerticalOverScrollBounceEffectDecorator.DEFAULT_TOUCH_DRAG_MOVE_RATIO_FWD,

VerticalOverScrollBounceEffectDecorator.DEFAULT_TOUCH_DRAG_MOVE_RATIO_BCK,

-1f // Default is -2

);

Dynamic Effect Disabling

As of version 1.0.4, the effect can be dynamically disabled (detached) and reenabled (attached) at runtime:

IOverScrollDecor decor = OverScrollDecoratorHelper.setUpOverScroll(view);
  // Detach. You are strongly encouraged to only call this when overscroll isn't // in-effect: Either add getCurrentState()==STATE_IDLE as a precondition, // or use a state-change listener. decor.detach();
 // Attach. decor.attach();

attach() and detach() can be used repeatedly - as necessary, as can be seen in the demo project (refer to action-bar menu in recycler-view demo).

Credits

App icons by P.J. Onori, Timothy Miller, Icons4Android, Icons8.com

Resources

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