Detect when the Android soft keyboard is shown or hidden

DetectAndroidKeyboardHiddenOrShownRxJava.java

/*
 * Copyright (c) Terl Tech Ltd • 29/06/18 14:03 • goterl.com
 *
 * 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.
 */


/**
 * This file shows how to use RxJava/RxAndroid to
 * detect when the keyboard is opened or closed.
 * The source code here can also be used in an Activity. This
 * is certainly by no means the only way you can do this, there's
 * also a method involving attaching a global view tree observer. 
 * The following code is inspired by a few answers in the thread 
 * https://stackoverflow.com/q/4745988/3526705.
 */
public class SomeFragment extends Fragment {

    // Subscribe to this from anywhere.
    private PublishSubject<Boolean> publishKeyBoardOpen = PublishSubject.create();
	
    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        
        // First get the bottom of the window
        final int defBottom = getBottomOfWindow();

        // Setup a loop that detects when the
        // bottom changes
        Disposable keyBoardIntervalDisposable = 
            Observable.interval(1000, 100, TimeUnit.MILLISECONDS)
            .observeOn(Schedulers.io())
            .subscribe(aLong -> {
                // On every 100 milliseconds, get the bottom
                // of the window again. If it's changed
                // then the keyboard has most likely pushed
                // the bottom of the view up.
                int newBottom = getBottomOfWindow();
                publishKeyBoardOpen.onNext(defBottom != newBottom);
            });
        
        // Now, we can subscribe to the PublishSubject
        // and receive changes
        Disposable keyboardDetector = publishKeyBoardOpen
            .distinctUntilChanged()
            .observeOn(AndroidSchedulers.mainThread())
            .subscribeOn(Schedulers.io())
            .subscribe(isOpen -> {
                if (isOpen) {
                    onKeyBoardOpen();
                } else {
                    onKeyBoardClosed();
                }
            });
    }
    
    public int getBottomOfWindow() {
        Rect rect = new Rect();
        Window window = getActivity().getWindow();
        window.getDecorView().getWindowVisibleDisplayFrame(rect);
        return rect.bottom;
    }
    
    @Override
    public void onDestroy() {
        super.onDestroy();
		// Remember to dispose of all the Disposables here!
		// You may need to use CompositeDisposable for this.
		// Or put all the Disposables into fields and call
		// .dispose() on each of them.
    }
    
}