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.brkc.traffic.ui.image; import android.annotation.TargetApi; import android.app.ActionBar; import android.os.Build.VERSION_CODES; 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.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; import android.widget.Toast; import com.brkc.common.image.ImageCache; import com.brkc.common.image.ImageFetcher; import com.brkc.common.image.Utils; import com.brkc.traffic.R; 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; @TargetApi(VERSION_CODES.HONEYCOMB) @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); // Set up ViewPager and backing adapter mAdapter = new ImagePagerAdapter(getSupportFragmentManager(), ImageListFragment.getImageCount()); 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); // Enable some additional newer visibility and ActionBar features to create a more // immersive photo viewing experience if (Utils.hasHoneycomb()) { final ActionBar actionBar = getActionBar(); if (actionBar != null) { // 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; case R.id.clear_cache: mImageFetcher.clearCache(); Toast.makeText(this, R.string.clear_cache_complete_toast, Toast.LENGTH_SHORT).show(); 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 int mSize; public ImagePagerAdapter(FragmentManager fm, int size) { super(fm); mSize = size; } @Override public int getCount() { return mSize; } @Override public Fragment getItem(int position) { String thumb = ImageListFragment.getImageUrl(position); return ImageDetailFragment.newInstance(thumb); } } /** * Set on the ImageView in the ViewPager children fragments, to enable/disable low profile mode * when the ImageView is touched. */ @TargetApi(VERSION_CODES.HONEYCOMB) @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); } } }