Java tutorial
/* * Copyright (C) 2012 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 ginger.connexus.activity; import ginger.connexus.BuildConfig; import ginger.connexus.R; import ginger.connexus.fragment.ImageDetailFragment; import ginger.connexus.util.ImageCache; import ginger.connexus.util.ImageFetcher; import ginger.connexus.util.Utils; import java.util.Arrays; import java.util.List; import android.app.ActionBar; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentStatePagerAdapter; import android.support.v4.app.NavUtils; import android.support.v4.view.ViewPager; import android.util.DisplayMetrics; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.view.View.OnClickListener; import android.view.WindowManager.LayoutParams; public class ImageDetailActivity extends BaseActivity implements OnClickListener { @SuppressWarnings("unused") private static final String TAG = ImageDetailActivity.class.toString(); private static final String IMAGE_CACHE_DIR = "images"; public static final String EXTRA_IMAGE = "extra_image"; public static final String EXTRA_IMAGE_URLS = "extra_image_urls"; private ImagePagerAdapter mAdapter; private ImageFetcher mImageFetcher; private ViewPager mPager; @Override public void onCreate(Bundle savedInstanceState) { if (BuildConfig.DEBUG) { Utils.enableStrictMode(); } super.onCreate(savedInstanceState); setContentView(R.layout.pager_image_detail); // Fetch screen height and width, to use as our max size when loading // images as this // activity runs full screen final DisplayMetrics displayMetrics = new DisplayMetrics(); getWindowManager().getDefaultDisplay().getMetrics(displayMetrics); final int height = displayMetrics.heightPixels; final int width = displayMetrics.widthPixels; // For this sample we'll use half of the longest width to resize our // images. As the image scaling ensures the image is larger than this, // we should be left with a resolution that is appropriate for both // portrait and landscape. For best image quality we shouldn't divide by // 2, but this will use more memory and require a larger memory cache. final int longest = (height > width ? height : width) / 2; ImageCache.ImageCacheParams cacheParams = new ImageCache.ImageCacheParams(this, IMAGE_CACHE_DIR); // Set memory cache to 25% of app memory cacheParams.setMemCacheSizePercent(0.25f); // The ImageFetcher takes care of loading images into our ImageView // children asynchronously mImageFetcher = new ImageFetcher(this, longest); mImageFetcher.addImageCache(getSupportFragmentManager(), cacheParams); mImageFetcher.setImageFadeIn(false); // Set up ViewPager and backing adapter final List<String> imageUrls = Arrays.asList(getIntent().getStringArrayExtra(EXTRA_IMAGE_URLS)); mAdapter = new ImagePagerAdapter(getSupportFragmentManager(), imageUrls); mPager = (ViewPager) findViewById(R.id.pager); mPager.setAdapter(mAdapter); mPager.setPageMargin((int) getResources().getDimension(R.dimen.image_detail_pager_margin)); mPager.setOffscreenPageLimit(2); // Set up activity to go full screen getWindow().addFlags(LayoutParams.FLAG_FULLSCREEN); // Enable some additional newer visibility and ActionBar features to // create a more immersive photo viewing experience if (Utils.hasHoneycomb()) { final ActionBar actionBar = getActionBar(); // Hide title text and set home as up actionBar.setDisplayShowTitleEnabled(false); actionBar.setDisplayHomeAsUpEnabled(true); // Hide and show the ActionBar as the visibility changes mPager.setOnSystemUiVisibilityChangeListener(new View.OnSystemUiVisibilityChangeListener() { @Override public void onSystemUiVisibilityChange(int vis) { if ((vis & View.SYSTEM_UI_FLAG_LOW_PROFILE) != 0) { actionBar.hide(); } else { actionBar.show(); } } }); // Start low profile mode and hide ActionBar mPager.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LOW_PROFILE); actionBar.hide(); } // Set the current item based on the extra passed in to this activity final int extraCurrentItem = getIntent().getIntExtra(EXTRA_IMAGE, -1); if (extraCurrentItem != -1) { mPager.setCurrentItem(extraCurrentItem); } } @Override public void onResume() { super.onResume(); mImageFetcher.setExitTasksEarly(false); } @Override protected void onPause() { super.onPause(); mImageFetcher.setExitTasksEarly(true); mImageFetcher.flushCache(); } @Override protected void onDestroy() { super.onDestroy(); mImageFetcher.closeCache(); } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case android.R.id.home: NavUtils.navigateUpFromSameTask(this); return true; } return super.onOptionsItemSelected(item); } @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.main_menu, menu); return true; } /** * Called by the ViewPager child fragments to load images via the one * ImageFetcher */ public ImageFetcher getImageFetcher() { return mImageFetcher; } /** * The main adapter that backs the ViewPager. A subclass of * FragmentStatePagerAdapter as there could be a large number of items in * the ViewPager and we don't want to retain them all in memory at once but * create/destroy them on the fly. */ private class ImagePagerAdapter extends FragmentStatePagerAdapter { private final List<String> mImageUrls; public ImagePagerAdapter(FragmentManager fm, List<String> imageUrls) { super(fm); mImageUrls = imageUrls; } @Override public int getCount() { return mImageUrls.size(); } @Override public Fragment getItem(int position) { return ImageDetailFragment.newInstance(mImageUrls.get(position)); } } /** * Set on the ImageView in the ViewPager children fragments, to * enable/disable low profile mode when the ImageView is touched. */ @Override public void onClick(View v) { final int vis = mPager.getSystemUiVisibility(); if ((vis & View.SYSTEM_UI_FLAG_LOW_PROFILE) != 0) { mPager.setSystemUiVisibility(View.SYSTEM_UI_FLAG_VISIBLE); } else { mPager.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LOW_PROFILE); } } }