sample/src/main/java/com/davemorrissey/labs/subscaleview/sample/AbstractPagesActivity.java

/*
Copyright 2017 David Morrissey

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.
*/

package com.davemorrissey.labs.subscaleview.sample;

import android.app.ActionBar;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.FragmentActivity;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;

import java.util.List;

public abstract class AbstractPagesActivity extends FragmentActivity {

    private static final String BUNDLE_PAGE = "page";

    private int page;

    private final int title;
    private final int layout;
    private final List<Page> notes;

    protected AbstractPagesActivity(int title, int layout, List<Page> notes) {
        this.title = title;
        this.layout = layout;
        this.notes = notes;
    }

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(layout);
        ActionBar actionBar = getActionBar();
        if (actionBar != null) {
            actionBar.setTitle(getString(title));
            actionBar.setDisplayHomeAsUpEnabled(true);
        }
        findViewById(R.id.next).setOnClickListener(new View.OnClickListener() {
            @Override public void onClick(View v) { next(); }
        });
        findViewById(R.id.previous).setOnClickListener(new View.OnClickListener() {
            @Override public void onClick(View v) { previous(); }
        });
        if (savedInstanceState != null && savedInstanceState.containsKey(BUNDLE_PAGE)) {
            page = savedInstanceState.getInt(BUNDLE_PAGE);
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        updateNotes();
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt(BUNDLE_PAGE, page);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        finish();
        return true;
    }

    private void next() {
        page++;
        updateNotes();
    }

    private void previous() {
        page--;
        updateNotes();
    }

    private void updateNotes() {
        if (page > notes.size() - 1) {
            return;
        }
        ActionBar actionBar = getActionBar();
        if (actionBar != null) {
            actionBar.setSubtitle(notes.get(page).getSubtitle());
        }
        ((TextView)findViewById(R.id.note)).setText(notes.get(page).getText());
        findViewById(R.id.next).setVisibility(page >= notes.size() - 1 ? View.INVISIBLE : View.VISIBLE);
        findViewById(R.id.previous).setVisibility(page <= 0 ? View.INVISIBLE : View.VISIBLE);
        onPageChanged(page);
    }

    protected final int getPage() {
        return page;
    }

    protected void onPageChanged(int page) {

    }

}