transdroid/app/src/main/java/org/transdroid/core/gui/navigation/SelectionModificationSpinner.java

/*
 * Copyright 2010-2018 Eric Kok et al.
 *
 * Transdroid is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Transdroid is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Transdroid.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.transdroid.core.gui.navigation;

import org.transdroid.R;

import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.TextView;

/**
 * Spinner that holds actions that can be performed on list selections. The spinner itself has some title, which can for
 * example be used to show the number of selected items.
 *
 * @author Eric Kok
 */
public class SelectionModificationSpinner extends Spinner {

    private SelectionDropDownAdapter selectionAdapter;
    private OnModificationActionSelectedListener onModificationActionSelected = null;

    /**
     * Instantiates a spinner that contains some fixed actions for a user to modify selections.
     *
     * @param context The interface context where the spinner will be shown in
     */
    public SelectionModificationSpinner(Context context) {
        super(context);
        selectionAdapter = new SelectionDropDownAdapter(context);
        setAdapter(selectionAdapter);
    }

    /**
     * Updates the fixed title text shown in the spinner, regardless of spinner item action selection.
     *
     * @param title The new static string to show, such as the number of selected items
     */
    public void updateTitle(String title) {
        selectionAdapter.titleView.setText(title);
        invalidate();
    }

    /**
     * Sets the listener for action selection events.
     *
     * @param onModificationActionSelected The listener that handles performing of the actions as selected in this
     *                                     spinner by the user
     */
    public void setOnModificationActionSelectedListener(OnModificationActionSelectedListener onModificationActionSelected) {
        this.onModificationActionSelected = onModificationActionSelected;
    }

    @Override
    public void setSelection(int position) {
        if (position == 0) {
            onModificationActionSelected.selectAll();
        } else if (position == 1) {
            onModificationActionSelected.selectFinished();
        } else if (position == 2) {
            onModificationActionSelected.invertSelection();
        }
        super.setSelection(position);
    }

    /**
     * Local adapter that holds the actions which can be performed and a title text view that always shows instead of a
     * list item as in a normal spinner.
     */
    private class SelectionDropDownAdapter extends ArrayAdapter<String> {

        protected TextView titleView = null;

        public SelectionDropDownAdapter(Context context) {
            super(context, android.R.layout.simple_list_item_1, new String[]{
                    context.getString(R.string.navigation_selectall),
                    context.getString(R.string.navigation_selectfinished),
                    context.getString(R.string.navigation_invertselection)});
            titleView = new TextView(getContext());
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            // This returns the singleton text view showing the title with the number of selected items
            return titleView;
        }

        @Override
        public View getDropDownView(int position, View convertView, ViewGroup parent) {
            // This returns the actions to show in the spinner list
            return super.getView(position, convertView, parent);
        }

    }

    /**
     * Interface to implement if an interface want to respond to selection modification actions.
     */
    public interface OnModificationActionSelectedListener {
        public void selectAll();

        public void selectFinished();

        public void invertSelection();
    }

}