AndroidAPS/app/src/main/java/info/nightscout/androidaps/utils/SpinnerHelper.java

package info.nightscout.androidaps.utils;

import android.view.MotionEvent;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.Spinner;
import android.widget.SpinnerAdapter;

/**
 * Spinner Helper class that works around some common issues
 * with the stock Android Spinner
 *
 * A Spinner will normally call it's OnItemSelectedListener
 * when you use setSelection(...) in your initialization code.
 * This is usually unwanted behavior, and a common work-around
 * is to use spinner.post(...) with a Runnable to assign the
 * OnItemSelectedListener after layout.
 *
 * If you do not call setSelection(...) manually, the callback
 * may be called with the first item in the adapter you have
 * set. The common work-around for that is to count callbacks.
 *
 * While these workarounds usually *seem* to work, the callback
 * may still be called repeatedly for other reasons while the
 * selection hasn't actually changed. This will happen for
 * example, if the user has accessibility options enabled -
 * which is more common than you might think as several apps
 * use this for different purposes, like detecting which
 * notifications are active.
 *
 * Ideally, your OnItemSelectedListener callback should be
 * coded defensively so that no problem would occur even
 * if the callback was called repeatedly with the same values
 * without any user interaction, so no workarounds are needed.
 *
 * This class does that for you. It keeps track of the values
 * you have set with the setSelection(...) methods, and
 * proxies the OnItemSelectedListener callback so your callback
 * only gets called if the selected item's position differs
 * from the one you have set by code, or the first item if you
 * did not set it.
 *
 * This also means that if the user actually clicks the item
 * that was previously selected by code (or the first item
 * if you didn't set a selection by code), the callback will
 * not fire.
 *
 * To implement, replace current occurrences of:
 *
 *     Spinner spinner =
 *         (Spinner)findViewById(R.id.xxx);
 *
 * with:
 *
 *     SpinnerHelper spinner =
 *         new SpinnerHelper(findViewById(R.id.xxx))
 *
 * SpinnerHelper proxies the (my) most used calls to Spinner
 * but not all of them. Should a method not be available, use:
 *
 *      spinner.getSpinner().someMethod(...)
 *
 * Or just add the proxy method yourself :)
 *
 * (Quickly) Tested on devices from 2.3.6 through 4.2.2
 *
 * @author Jorrit "Chainfire" Jongma
 * @license WTFPL (do whatever you want with this, nobody cares)
 */
public class SpinnerHelper implements OnItemSelectedListener {
    private final Spinner spinner;
    private boolean userTouched;

    private int lastPosition = -1;
    private OnItemSelectedListener proxiedItemSelectedListener = null;

    public SpinnerHelper(Object spinner) {
        this.spinner = (spinner != null) ? (Spinner)spinner : null;
    }

    public Spinner getSpinner() {
        return spinner;
    }

    public void setSelection(int position) {
        lastPosition = Math.max(-1, position);
        spinner.setSelection(position);
    }

    public void setSelection(int position, boolean animate) {
        lastPosition = Math.max(-1, position);
        spinner.setSelection(position, animate);
    }

    public void setOnItemSelectedListener(OnItemSelectedListener listener) {
        proxiedItemSelectedListener = listener;
        setTouchListener();
        spinner.setOnItemSelectedListener(listener == null ? null : this);
    }

    public void setTouchListener() {
        spinner.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                userTouched = true;
                return false;
            }
        });
    }

    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        if (position != lastPosition && userTouched) {
            lastPosition = position;
            if (proxiedItemSelectedListener != null) {
                proxiedItemSelectedListener.onItemSelected(
                        parent, view, position, id
                );
            }
        }
    }

    public void onNothingSelected(AdapterView<?> parent) {
        if (-1 != lastPosition) {
            lastPosition = -1;
            if (proxiedItemSelectedListener != null) {
                proxiedItemSelectedListener.onNothingSelected(
                        parent
                );
            }
        }
    }

    public void setAdapter(SpinnerAdapter adapter) {
        if (adapter.getCount() > 0) {
            lastPosition = 0;
        }
        spinner.setAdapter(adapter);
    }

    public SpinnerAdapter getAdapter() { return spinner.getAdapter(); }
    public int getCount() { return spinner.getCount(); }
    public Object getItemAtPosition(int position) { return spinner.getItemAtPosition(position); }
    public long getItemIdAtPosition(int position) { return spinner.getItemIdAtPosition(position); }
    public Object getSelectedItem() { return spinner.getSelectedItem(); }
    public long getSelectedItemId() { return spinner.getSelectedItemId(); }
    public int getSelectedItemPosition() { return spinner.getSelectedItemPosition(); }
    public void setEnabled(boolean enabled) { spinner.setEnabled(enabled); }
    public boolean isEnabled() { return spinner.isEnabled(); }
}