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.ActivityOptions; import android.content.Context; import android.content.Intent; import android.content.res.Resources; import android.os.Build.VERSION_CODES; import android.os.Bundle; import android.support.v4.app.Fragment; import android.util.Log; 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 android.widget.AbsListView; import android.widget.AdapterView; import android.widget.BaseAdapter; import android.widget.LinearLayout; import android.widget.ListView; import android.widget.TextView; 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; import com.brkc.traffic.adapter.VehicleResult; import com.brkc.traffic.ui.VehicleQueryActivity; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; /** * The main fragment that powers the ImageGridActivity screen. Fairly straight forward GridView * implementation with the key addition being the ImageWorker class w/ImageCache to load children * asynchronously, keeping the UI nice and smooth and caching thumbnails for quick retrieval. The * cache is retained over configuration changes like orientation change so the images are populated * quickly if, for example, the user rotates the device. */ public class ImageListFragment extends Fragment implements AdapterView.OnItemClickListener { private static final String TAG = "ImageListFragment"; private static final String IMAGE_CACHE_DIR = "thumbs"; private ImageAdapter mAdapter; private ImageFetcher mImageFetcher; private static VehicleResult[] result; /** * Empty constructor as per the Fragment documentation */ public ImageListFragment() { } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setHasOptionsMenu(true); String extraStr = getActivity().getIntent().getStringExtra(VehicleQueryActivity.EXTRA_RESULT_NAME); initList(extraStr); mAdapter = new ImageAdapter(getActivity()); ImageCache.ImageCacheParams cacheParams = new ImageCache.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(), 0); mImageFetcher.setLoadingImage(R.drawable.empty_photo); mImageFetcher.addImageCache(getActivity().getSupportFragmentManager(), cacheParams); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { final View v = inflater.inflate(R.layout.image_list_fragment, container, false); final ListView mListView = (ListView) v.findViewById(R.id.listView); mListView.setAdapter(mAdapter); mListView.setOnItemClickListener(this); mListView.setOnScrollListener(new AbsListView.OnScrollListener() { @Override public void onScrollStateChanged(AbsListView absListView, int scrollState) { // Pause fetcher to ensure smoother scrolling when flinging if (scrollState == AbsListView.OnScrollListener.SCROLL_STATE_FLING) { // Before Honeycomb pause image loading on scroll to help with performance if (!Utils.hasHoneycomb()) { mImageFetcher.setPauseWork(true); } } else { mImageFetcher.setPauseWork(false); } } @Override public void onScroll(AbsListView absListView, int firstVisibleItem, int visibleItemCount, int totalItemCount) { } }); return v; } @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(); } @TargetApi(VERSION_CODES.JELLY_BEAN) @Override public void onItemClick(AdapterView<?> parent, View v, int position, long id) { Log.d(TAG, "v=" + v.getId() + ",id=" + id + ",position=" + position); final Intent i = new Intent(getActivity(), ImageDetailActivity.class); i.putExtra(ImageDetailActivity.EXTRA_IMAGE, (int) id); if (Utils.hasJellyBean()) { // makeThumbnailScaleUpAnimation() looks kind of ugly here as the loading spinner may // show plus the thumbnail image in GridView is cropped. so using // makeScaleUpAnimation() instead. ActivityOptions options = ActivityOptions.makeScaleUpAnimation(v, 0, 0, v.getWidth(), v.getHeight()); getActivity().startActivity(i, options.toBundle()); } else { startActivity(i); } } @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { inflater.inflate(R.menu.main_menu, menu); } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case R.id.clear_cache: mImageFetcher.clearCache(); Toast.makeText(getActivity(), R.string.clear_cache_complete_toast, Toast.LENGTH_SHORT).show(); return true; } return super.onOptionsItemSelected(item); } private void initList(String resultStr) { result = new VehicleResult[0]; try { JSONObject jsonObject = new JSONObject(resultStr); Resources res = getResources(); String totalKey = res.getString(R.string.vehicle_query_result_total); String rowsKey = res.getString(R.string.vehicle_query_result_rows); String noKey = res.getString(R.string.vehicle_query_result_plate_no); String colorKey = res.getString(R.string.vehicle_query_result_plate_color); String timeKey = res.getString(R.string.vehicle_query_result_pass_time); String crossKey = res.getString(R.string.vehicle_query_result_cross); String thumbKey = res.getString(R.string.vehicle_query_result_thumb); String imageKey = res.getString(R.string.vehicle_query_result_image); int total = jsonObject.getInt(totalKey); JSONArray rows = jsonObject.getJSONArray(rowsKey); if (rows.length() > total) { total = rows.length(); } result = new VehicleResult[total]; for (int i = 0; i < total; i++) { JSONObject row = rows.getJSONObject(i); String plateNo = row.getString(noKey); String plateColor = row.getString(colorKey); String cross = row.getString(crossKey); String time = row.getString(timeKey); String thumb = row.getString(thumbKey); String image = row.getString(imageKey); VehicleResult item = new VehicleResult(i, plateNo, plateColor, cross, time, thumb, image); result[i] = item; } } catch (JSONException e) { e.printStackTrace(); } Log.d(TAG, "?" + result.length); } public static String getImageUrl(int position) { return result[position].getImage(); } public static int getImageCount() { return result.length; } /** * The main adapter that backs the GridView. This is fairly standard except the number of * columns in the GridView is used to create a fake top row of empty views as we use a * transparent ActionBar and don't want the real top row of images to start off covered by it. */ private class ImageAdapter extends BaseAdapter { private final Context mContext; public ImageAdapter(Context context) { super(); mContext = context; } @Override public int getCount() { return result.length; } @Override public Object getItem(int position) { return result[position];// getThumbUrl(position); } @Override public long getItemId(int position) { return ((VehicleResult) getItem(position)).getXh(); } @Override public View getView(int position, View convertView, ViewGroup container) { // Now handle the main ImageView thumbnails VehicleResult item = (VehicleResult) getItem(position); View view; ViewHolder viewHolder; if (convertView == null) { // if it's not recycled, instantiate and initialize view = LayoutInflater.from(getContext()).inflate(R.layout.image_list_item, null); viewHolder = new ViewHolder(); viewHolder.thumbImage = (RecyclingImageView) view.findViewById(R.id.image_thumb); viewHolder.textPlateNo = (TextView) view.findViewById(R.id.plate_no); viewHolder.textPassTime = (TextView) view.findViewById(R.id.pass_time); viewHolder.textCrossName = (TextView) view.findViewById(R.id.cross_name); viewHolder.plate = (LinearLayout) view.findViewById(R.id.plate); view.setTag(viewHolder); } else { // Otherwise re-use the converted view view = convertView; viewHolder = (ViewHolder) view.getTag(); } int color = 0; if (item.getPlateColor().equals("1") || item.getPlateColor().contains("?")) { color = mContext.getResources().getColor(R.color.blue); } else { color = mContext.getResources().getColor(R.color.dark_orange); } String plate = item.getPlateNo() + "," + item.getPlateColor(); if (item.getThumb().length() > 0) { Log.d(TAG, "url=" + item.getThumb()); // Finally load the image asynchronously into the ImageView, this also takes care of // setting a placeholder image while the background thread runs mImageFetcher.loadImage(item.getThumb(), viewHolder.thumbImage); } else { viewHolder.thumbImage.setImageResource(R.drawable.no_image); } viewHolder.textPlateNo.setText(item.getPlateNo()); viewHolder.textPlateNo.setTextColor(color); viewHolder.textPassTime.setText(item.getPassTime()); viewHolder.textCrossName.setText(item.getCrossName()); viewHolder.plate.setTag(plate); return view; } } class ViewHolder { RecyclingImageView thumbImage; TextView textPlateNo; TextView textPassTime; TextView textCrossName; LinearLayout plate; } }