Android library to observe scroll events on scrollable views.
It's easy to interact with the Toolbar introduced in Android 5.0 Lollipop and may be helpful to implement look and feel of Material Design apps.

If you are a wercker user, you can download the latest build artifact. See here for details.

Clone this repository and build the app using Gradle wrapper.

$ git clone https://github.com/ksoichiro/Android-ObservableScrollView.git 
$ cd Android-ObservableScrollView
$ ./gradlew installDevDebug

AAR is distributed on the Maven Central repository.

repositories {
    mavenCentral()
}

dependencies {
    compile 'com.github.ksoichiro:android-observablescrollview:1.5.0'
}

Eclipse is not supported but if you really want to build on Eclipse, see here.

Use one of the ObservableListView, ObservableScrollView, ObservableWebView, ObservableRecyclerView, ObservableGridView in your XML layout file.

Widgets above provides callbacks with ObservableScrollViewCallbacks interface.
You can listen scroll events of the widgets by using setScrollViewCallbacks().

    ObservableListView listView = (ObservableListView) findViewById(R.id.list);
    listView.setScrollViewCallbacks(this);

Then implement your interaction codes to the callbacks.
Example:

    @Override
    public void onUpOrCancelMotionEvent(ScrollState scrollState) {
        ActionBar ab = getSupportActionBar();
        if (scrollState == ScrollState.UP) {
            if (ab.isShowing()) {
                ab.hide();
            }
        } else if (scrollState == ScrollState.DOWN) {
            if (!ab.isShowing()) {
                ab.show();
            }
        }
    }

See sample app's Activity codes for more details.

Widgets are named with Observable prefix.
(e.g. ListView → ObservableListView)
You can handle these widgets with Scrollable interface.

This project is built and tested under the following environment.

• v1.5.0
  • Add a helper class CacheFragmentStatePagerAdapter to implement ViewPager pattern.
  • Fix that swipe down (over-scroll) causes item click.
• v1.4.0
  • Add a custom view named TouchInterceptionFrameLayout and a new API setTouchInterceptionViewGroup() for Scrollable.
    With these class and API, you can move Scrollable itself using its scrolling events.
  • Add a helper class ScrollUtils for implementing scrolling effects.
• v1.3.2
  • Fix that ObservableRecyclerView causes BadParcelableException on onRestoreInstanceState.
• v1.3.1
  • Fix that onDownMotionEvent not called and parameters of onScrollChanged are incorrect when children views handle touch events.
• v1.3.0
  • Add new interface Scrollable to provide common API for scrollable widgets.
• v1.2.1
  • Fix that the scroll states and other internal information are lost after onSaveInstanceState().
  • Fix that the scrollY is incorrect if the ListView/RecyclerView don't scroll from the top. (It's just approximating the scroll offset and not the complete solution but better than before.)
• v1.2.0
  • Add GridView support.
  • Fix ObservableListView cannot detect onScrollChanged on Android 2.3.
  • Fix ObservableScrollView cannot detect UP and DOWN state in onUpOrCancelMotionEvent before Android 4.4.
• v1.1.0
  • Add RecyclerView support.
• v1.0.0
  • Initial release.

• Jair Player by Akshay Chordiya
• My Gradle by Erick Chavez Alcarraz

If you're using this library in your app and you'd like to list it here,
please let me know via email or pull requests or issues.

Any contributions are welcome!
Please check the contributing guideline before submitting a new issue.

• Soichiro Kashima - [email protected]

• Inspired by ObservableScrollView in romannurik-code.

Copyright 2014 Soichiro Kashima

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.