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 com.bluetech.gallery5.ui; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentActivity; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentStatePagerAdapter; import android.support.v4.view.ViewPager; import android.util.DisplayMetrics; import android.view.Menu; import android.view.View; import android.view.View.OnClickListener; import android.view.WindowManager.LayoutParams; import com.bluetech.gallery5.BuildConfig; import com.bluetech.gallery5.R; import com.bluetech.gallery5.util.ImageCache; import com.bluetech.gallery5.util.ImageFetcher; import java.io.File; import java.util.ArrayList; import java.util.Arrays; import java.util.List; public class ImageDetailActivity extends FragmentActivity implements OnClickListener { private static final String IMAGE_CACHE_DIR = "images"; public static final String EXTRA_IMAGE = "extra_image"; private ImagePagerAdapter mAdapter; private ImageFetcher mImageFetcher; private ViewPager mPager; private String[] imageUrls; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.image_detail_pager); // 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); cacheParams.setMemCacheSizePercent(0.25f); // Set memory cache to 25% of app memory // The ImageFetcher takes care of loading images into our ImageView children asynchronously mImageFetcher = new ImageFetcher(this, longest); mImageFetcher.addImageCache(getSupportFragmentManager(), cacheParams); mImageFetcher.setImageFadeIn(false); String path = getIntent().getStringExtra("PATH"); File mainFile = new File(path); if (mainFile.exists() && mainFile.isDirectory()) { File[] files = mainFile.listFiles(); Arrays.sort(files); List<String> lists = new ArrayList<String>(); for (int i = 0; i < files.length; i++) { if (files[i].isFile()) { lists.add(files[i].getAbsolutePath()); } } imageUrls = lists.toArray(new String[0]); } // Set up ViewPager and backing adapter mAdapter = new ImagePagerAdapter(getSupportFragmentManager(), imageUrls.length); mPager = (ViewPager) findViewById(R.id.pager); mPager.setAdapter(mAdapter); mPager.setPageMargin((int) getResources().getDimension(R.dimen.horizontal_page_margin)); mPager.setOffscreenPageLimit(2); // Set up activity to go full screen getWindow().addFlags(LayoutParams.FLAG_FULLSCREEN); // 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(); } /** * 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 int mSize; public ImagePagerAdapter(FragmentManager fm, int size) { super(fm); mSize = size; } @Override public int getCount() { return mSize; } @Override public Fragment getItem(int position) { return ImageDetailFragment.newInstance(imageUrls[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); } } }