Java tutorial
/* * Copyright (C) 2014 The Illinois-Indiana Sea Grant * * 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 org.iisgcp.waterwalk.fragment; import org.iisgcp.waterwalk.R; import org.iisgcp.waterwalk.utils.ImageFetcher; import org.iisgcp.waterwalk.utils.OnPageSelectedListener; import org.iisgcp.waterwalk.utils.Utils; import org.iisgcp.waterwalk.utils.ImageCache.ImageCacheParams; import android.app.Activity; import android.content.res.TypedArray; import android.os.Bundle; import android.os.Parcelable; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentStatePagerAdapter; import android.support.v4.view.ViewPager; import android.support.v4.view.ViewPager.OnPageChangeListener; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; public class PointOfInterestGridViewPagerFragment extends Fragment { private static final String INTENT_POSITION = "position"; private static final String IMAGE_CACHE_DIR = "poi_thumbs"; private ImageFetcher mImageFetcher; private OnPageSelectedListener mListener; private ViewPager mPager; private GridPagerAdapter mAdapter; public static PointOfInterestGridViewPagerFragment newInstance(int position) { PointOfInterestGridViewPagerFragment f = new PointOfInterestGridViewPagerFragment(); // Supply title and poi input as an argument. Bundle args = new Bundle(); args.putInt(INTENT_POSITION, position); f.setArguments(args); return f; } @Override public void onAttach(Activity activity) { super.onAttach(activity); try { mListener = (OnPageSelectedListener) activity; } catch (ClassCastException e) { throw new ClassCastException(activity.toString() + " must implement OnPageSelectedListener"); } } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setRetainInstance(true); ImageCacheParams cacheParams = new ImageCacheParams(getActivity(), 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(getActivity(), Utils.getLargestGridDimension(getActivity())); mImageFetcher.setLoadingImage(R.drawable.empty_photo); mImageFetcher.addImageCache(getActivity().getSupportFragmentManager(), cacheParams); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { super.onCreateView(inflater, container, savedInstanceState); // Inflate the layout for this fragment View view = inflater.inflate(R.layout.fragment_point_of_interest_grid_view_pager, container, false); mPager = (ViewPager) view.findViewById(R.id.pager); return view; } public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); // Instantiate a ViewPager and a PagerAdapter. mAdapter = new GridPagerAdapter(getChildFragmentManager()); mPager.setAdapter(mAdapter); mPager.setOnPageChangeListener(new OnPageChangeListener() { @Override public void onPageScrollStateChanged(int arg0) { } @Override public void onPageScrolled(int arg0, float arg1, int arg2) { } @Override public void onPageSelected(int position) { mListener.onPageSelected(position); String title = null; TypedArray routes = PointOfInterestGridViewPagerFragment.this.getResources() .obtainTypedArray(R.array.routes); for (int i = 0; i < routes.length(); i++) { if (i == position) { int resid = routes.getResourceId(i, -1); TypedArray route = PointOfInterestGridViewPagerFragment.this.getResources() .obtainTypedArray(resid); title = getString(route.getResourceId(0, -1)); route.recycle(); } } routes.recycle(); PointOfInterestGridViewPagerFragment.this.getActivity().setTitle(title); } }); mPager.setCurrentItem(getArguments().getInt(INTENT_POSITION)); } @Override public void onResume() { super.onResume(); mImageFetcher.setExitTasksEarly(false); mAdapter.notifyDataSetChanged(); } @Override public void onPause() { super.onPause(); mImageFetcher.setPauseWork(false); mImageFetcher.setExitTasksEarly(true); mImageFetcher.flushCache(); } @Override public void onDestroy() { super.onDestroy(); mImageFetcher.closeCache(); } /** * Called by the ViewPager child fragments to load images via the one ImageFetcher */ public ImageFetcher getImageFetcher() { return mImageFetcher; } private class GridPagerAdapter extends FragmentStatePagerAdapter { public GridPagerAdapter(FragmentManager fm) { super(fm); } @Override public Fragment getItem(int position) { Fragment fragment = null; String title = null; int resid = -1; TypedArray routes = PointOfInterestGridViewPagerFragment.this.getResources() .obtainTypedArray(R.array.routes); for (int i = 0; i < routes.length(); i++) { if (i == position) { resid = routes.getResourceId(i, -1); TypedArray route = PointOfInterestGridViewPagerFragment.this.getResources() .obtainTypedArray(resid); title = getString(route.getResourceId(0, -1)); route.recycle(); } } fragment = PointOfInterestGridFragment.newInstance(title, resid); routes.recycle(); return fragment; } @Override public int getCount() { TypedArray routes = PointOfInterestGridViewPagerFragment.this.getResources() .obtainTypedArray(R.array.routes); int count = routes.length(); routes.recycle(); return count; } @Override public Parcelable saveState() { return null; } } }