xref: /frameworks/support/frameworks/support/samples/Support4Demos/src/main/java/com/example/android/supportv4/widget/SlidingPaneLayoutActivity.java

/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * 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.example.android.supportv4.widget;

import android.app.ActionBar;
import android.app.Activity;
import android.os.Build;
import android.os.Bundle;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewTreeObserver;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;

import androidx.slidingpanelayout.widget.SlidingPaneLayout;

import com.example.android.supportv4.R;
import com.example.android.supportv4.Shakespeare;

/**
 * This example illustrates a common usage of SlidingPaneLayout in the Android support library.
 *
 * <p>A SlidingPaneLayout should be positioned at the top of your view hierarchy, placing it
 * below the action bar but above your content views. It is ideal as a two-pane layout
 * for larger screens, used in place of a horizontal LinearLayout.</p>
 *
 * <p>What separates SlidingPaneLayout from LinearLayout in this usage is that SlidingPaneLayout
 * allows these wide, two-pane layouts to overlap when horizontal space is at a premium. The user
 * can then access both panes by physically sliding the content pane into view or out of the way
 * or implicitly by moving focus between the two panes. This can greatly simplify development
 * of Android apps that support multiple form factors and screen sizes.</p>
 *
 * <p>When it comes to your navigation hierarchy, the left pane of a SlidingPaneLayout is always
 * considered to be one level up from the right content pane. As such, your Action Bar's
 * Up navigation should be enabled if the right pane is obscuring the left pane, and invoking it
 * should open the panes, revealing the left pane for normal interaction. From this open state
 * where the left pane is in primary focus, the Action Bar's Up affordance should act as if
 * both panes were fully visible in the activity window and navigate to the activity one level up
 * in the app's logical hierarchy. If the activity is the root of the application's task, the up
 * affordance should be disabled when the sliding pane is open and showing the left pane.
 * This code example illustrates this root activity case.</p>
 *
 * <p>Note that SlidingPaneLayout differs in usage from DrawerLayout. While DrawerLayout offers
 * sliding utility drawers for extended navigation options and actions, the panes of a
 * SlidingPaneLayout are firmly part of the content itself. If it would not make sense for
 * both panes to be visible all the time on a sufficiently wide screen, DrawerLayout and its
 * associated patterns are likely to be a better choice for your usage.</p>
 */
public class SlidingPaneLayoutActivity extends Activity {
    private SlidingPaneLayout mSlidingLayout;
    private ListView mList;
    private TextView mContent;

    private ActionBarHelper mActionBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.sliding_pane_layout);

        mSlidingLayout = findViewById(R.id.sliding_pane_layout);
        mList = findViewById(R.id.left_pane);
        mContent = findViewById(R.id.content_text);

        mSlidingLayout.setPanelSlideListener(new SliderListener());
        mSlidingLayout.openPane();

        mList.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,
                Shakespeare.TITLES));
        mList.setOnItemClickListener(new ListItemClickListener());

        mActionBar = createActionBarHelper();
        mActionBar.init();

        mSlidingLayout.getViewTreeObserver().addOnGlobalLayoutListener(new FirstLayoutListener());
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        /*
         * The action bar up action should open the slider if it is currently closed,
         * as the left pane contains content one level up in the navigation hierarchy.
         */
        if (item.getItemId() == android.R.id.home && !mSlidingLayout.isOpen()) {
            mSlidingLayout.openPane();
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * This list item click listener implements very simple view switching by changing
     * the primary content text. The slider is closed when a selection is made to fully
     * reveal the content.
     */
    private class ListItemClickListener implements ListView.OnItemClickListener {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            mContent.setText(Shakespeare.DIALOGUE[position]);
            mActionBar.setTitle(Shakespeare.TITLES[position]);
            mSlidingLayout.closePane();
        }
    }

    /**
     * This panel slide listener updates the action bar accordingly for each panel state.
     */
    private class SliderListener extends SlidingPaneLayout.SimplePanelSlideListener {
        @Override
        public void onPanelOpened(View panel) {
            mActionBar.onPanelOpened();
        }

        @Override
        public void onPanelClosed(View panel) {
            mActionBar.onPanelClosed();
        }
    }

    /**
     * This global layout listener is used to fire an event after first layout occurs
     * and then it is removed. This gives us a chance to configure parts of the UI
     * that adapt based on available space after they have had the opportunity to measure
     * and layout.
     */
    private class FirstLayoutListener implements ViewTreeObserver.OnGlobalLayoutListener {
        @Override
        public void onGlobalLayout() {
            mActionBar.onFirstLayout();
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                mSlidingLayout.getViewTreeObserver().removeOnGlobalLayoutListener(this);
            } else {
                //noinspection deprecation
                mSlidingLayout.getViewTreeObserver().removeGlobalOnLayoutListener(this);
            }
        }
    }

    /**
     * Create a compatible helper that will manipulate the action bar if available.
     */
    private ActionBarHelper createActionBarHelper() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
            return new ActionBarHelperICS();
        } else {
            return new ActionBarHelper();
        }
    }

    /**
     * Stub action bar helper; this does nothing.
     */
    private class ActionBarHelper {
        public void init() {}
        public void onPanelClosed() {}
        public void onPanelOpened() {}
        public void onFirstLayout() {}
        public void setTitle(CharSequence title) {}
    }

    /**
     * Action bar helper for use on ICS and newer devices.
     */
    private class ActionBarHelperICS extends ActionBarHelper {
        private final ActionBar mActionBar;
        private CharSequence mDrawerTitle;
        private CharSequence mTitle;

        ActionBarHelperICS() {
            mActionBar = getActionBar();
        }

        @Override
        public void init() {
            mActionBar.setDisplayHomeAsUpEnabled(true);
            mActionBar.setHomeButtonEnabled(true);
            mTitle = mDrawerTitle = getTitle();
        }

        @Override
        public void onPanelClosed() {
            super.onPanelClosed();
            mActionBar.setDisplayHomeAsUpEnabled(true);
            mActionBar.setHomeButtonEnabled(true);
            mActionBar.setTitle(mTitle);
        }

        @Override
        public void onPanelOpened() {
            super.onPanelOpened();
            mActionBar.setHomeButtonEnabled(false);
            mActionBar.setDisplayHomeAsUpEnabled(false);
            mActionBar.setTitle(mDrawerTitle);
        }

        @Override
        public void onFirstLayout() {
            if (mSlidingLayout.isSlideable() && !mSlidingLayout.isOpen()) {
                onPanelClosed();
            } else {
                onPanelOpened();
            }
        }

        @Override
        public void setTitle(CharSequence title) {
            mTitle = title;
        }
    }

}