Java tutorial
/* * This file is part of nori. * Copyright (c) 2014-2016 Tomasz Jan Gralczyk <tomg@fastmail.uk> * License: GNU GPLv2 */ package io.github.tjg1.nori.fragment; import android.app.WallpaperManager; import android.content.Context; import android.content.Intent; import android.content.SharedPreferences; import android.net.Uri; import android.os.AsyncTask; import android.os.Bundle; import android.preference.PreferenceManager; import android.support.annotation.NonNull; import android.support.design.widget.Snackbar; import android.support.v4.app.DialogFragment; import android.support.v4.app.Fragment; import android.support.v4.view.MenuItemCompat; import android.support.v7.widget.ShareActionProvider; import android.text.TextUtils; import android.view.LayoutInflater; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.view.ViewGroup; import java.io.IOException; import java.io.InputStream; import java.net.URL; import io.github.tjg1.library.norilib.Image; import io.github.tjg1.library.norilib.clients.SearchClient; import io.github.tjg1.nori.R; import io.github.tjg1.nori.util.NetworkUtils; /** Fragment used to display images in {@link io.github.tjg1.nori.ImageViewerActivity}. */ public abstract class ImageFragment extends Fragment { //region Constants (Bundle IDs and hardcoded URLs) /** Bundle identifier used to save the displayed image object in {@link #onSaveInstanceState(android.os.Bundle)}. */ protected static final String BUNDLE_ID_IMAGE = "io.github.tjg1.nori.Image"; /** String to prepend to Pixiv IDs to open them in the system web browser. */ private static final String PIXIV_URL_PREFIX = "http://www.pixiv.net/member_illust.php?mode=medium&illust_id="; //endregion //region Instance fields /** Image object displayed in this fragment. */ protected Image image; /** Class used for communication with the class that contains this fragment. */ protected ImageFragmentListener listener; /** True if this fragment is the currently active fragment (viewed by the user). */ protected boolean isActive = false; //endregion //region Fragment methods (Lifecycle) @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Get the image object from the fragment's arguments bundle. image = getArguments().getParcelable(BUNDLE_ID_IMAGE); // Enable options menu items for fragment. setHasOptionsMenu(true); } @Override public void onAttach(Context context) { super.onAttach(context); try { listener = (ImageFragmentListener) getContext(); } catch (ClassCastException e) { throw new ClassCastException(context.toString() + " must implement OnFragmentInteractionListener"); } } @Override public void onDetach() { super.onDetach(); listener = null; } @Override public abstract View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState); @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { inflater.inflate(R.menu.image, menu); // Set up ShareActionProvider MenuItem shareItem = menu.findItem(R.id.action_share); ShareActionProvider shareActionProvider = (ShareActionProvider) MenuItemCompat.getActionProvider(shareItem); shareActionProvider.setShareIntent(getShareIntent()); // Hide the view on Pixiv menu item, if the Image does not have a Pixiv source URL. MenuItem shareOnPixivItem = menu.findItem(R.id.action_viewOnPixiv); if (image.pixivId == null || TextUtils.isEmpty(image.pixivId)) { shareOnPixivItem.setVisible(false); } } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case R.id.action_tags: showTagListDialog(); return true; case R.id.action_download: downloadImage(); return true; case R.id.action_viewOnWeb: viewOnWeb(); return true; case R.id.action_viewOnPixiv: viewOnPixiv(); return true; case R.id.action_setAsWallpaper: setAsWallpaper(); return true; default: return super.onOptionsItemSelected(item); } } //endregion //region ViewPager onShown/onHidden /** * Called by the FragmentStatePagerAdapter when this fragment is currently the primary item * (shown to the user). */ public void onShown() { this.isActive = true; } /** * Called by the FragmentStatePagerAdapter when this fragment is scrolled away (hidden). */ public void onHidden() { this.isActive = false; } //endregion //region Options menu item helper methods /** * Get {@link android.content.Intent} to be sent by the {@link android.support.v7.widget.ShareActionProvider}. * * @return Share intent. */ protected Intent getShareIntent() { // Send web URL to image. Intent intent = new Intent(Intent.ACTION_SEND); intent.putExtra(Intent.EXTRA_TEXT, image.webUrl); intent.setType("text/plain"); return intent; } /** * Show the {@link io.github.tjg1.nori.fragment.TagListDialogFragment} for the current image. */ protected void showTagListDialog() { DialogFragment tagListFragment = TagListDialogFragment.newInstance(image, listener.getSearchClientSettings()); tagListFragment.show(getFragmentManager(), "TagListDialogFragment"); } /** * Use the system {@link android.app.DownloadManager} service to download the image. */ protected void downloadImage() { if (listener != null) { listener.downloadImage(image.fileUrl); } } /** * Opens the image Danbooru page in the system web browser. */ protected void viewOnWeb() { // Create and send intent to display the image in the web browser. Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(image.webUrl)); startActivity(intent); } /** * Opens the image Pixiv page in the system web browser. */ protected void viewOnPixiv() { // Create and send to intent to display the image's pixiv page in the web browser. Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(PIXIV_URL_PREFIX + image.pixivId)); startActivity(intent); } /** * Downloads the full-resolution image in the background and sets it as the wallpaper. */ protected void setAsWallpaper() { // Fetch and set full-screen image as wallpaper on background thread. final Context context = getContext(); final String imageUrl = image.fileUrl; final WallpaperManager wallpaperManager = WallpaperManager.getInstance(getContext()); new AsyncTask<Void, Void, Exception>() { @Override protected Exception doInBackground(Void... ignored) { try { InputStream inputStream = new URL(imageUrl).openStream(); wallpaperManager.setStream(inputStream); } catch (IOException e) { return e; } return null; } @Override protected void onPostExecute(Exception error) { if (error != null) { // Show error message to the user. View view = getView(); if (view != null) { Snackbar.make(view, String.format(context.getString(R.string.toast_couldNotSetWallpaper), error.getLocalizedMessage()), Snackbar.LENGTH_LONG).show(); } } } }.execute(); } //endregion //region Should load full-res images? /** * Evaluate the current network conditions using the {@link io.github.tjg1.nori.util.NetworkUtils} class to decide * if lower resolution images should be loaded to conserve bandwidth. * * @return True if lower resolution images should be used. */ protected boolean shouldLoadImageSamples() { SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(getContext()); return preferences.getBoolean(getString(R.string.preference_image_viewer_conserveBandwidth_key), true) || NetworkUtils.shouldFetchImageSamples(getContext()); } //endregion //region Activity listener interface public static interface ImageFragmentListener { /** * Should return the {@link SearchClient.Settings} object with the same settings used to fetch the image displayed by this fragment. */ public SearchClient.Settings getSearchClientSettings(); /** Downloads an image using {@link android.app.DownloadManager}, asking the user to grant storage write permission, if necessary. */ public void downloadImage(@NonNull String fireUrl); /** Called when the ImageView within the fragment is single-tapped. */ public void onViewTap(View view, float x, float y); } //endregion }