/*
* 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.volley.demo;
import android.annotation.TargetApi;
import android.app.ActivityOptions;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.Build.VERSION_CODES;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.util.TypedValue;
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.view.ViewGroup.LayoutParams;
import android.view.ViewTreeObserver;
import android.widget.AbsListView;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.Toast;
import com.android.volley.cache.DiskLruBasedCache.ImageCacheParams;
import com.android.volley.cache.SimpleImageLoader;
import com.android.volley.ui.NetworkImageView;
import com.volley.demo.util.Images;
import com.volley.demo.util.Utils;
/**
* 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 SimpleCacheFragment extends Fragment implements AdapterView.OnItemClickListener {
private static final String TAG = "ImageGridFragment";
private static final String IMAGE_CACHE_DIR = "thumbs";
private int mImageThumbSize;
private int mImageThumbSpacing;
private ImageAdapter mAdapter;
private SimpleImageLoader mImageLoader;
/**
* Empty constructor as per the Fragment documentation
*/
public SimpleCacheFragment() {
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setHasOptionsMenu(true);
mImageThumbSize = getResources().getDimensionPixelSize(R.dimen.image_thumbnail_size);
mImageThumbSpacing = getResources().getDimensionPixelSize(R.dimen.image_thumbnail_spacing);
mAdapter = new ImageAdapter(getActivity());
// The ImageFetcher takes care of loading images into our ImageView
// children asynchronously
mImageLoader = new SimpleImageLoader(getActivity(), null);
mImageLoader.setDefaultDrawable(R.drawable.empty_photo);
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
mImageLoader = new SimpleImageLoader(getActivity(), cacheParams);
mImageLoader.setDefaultDrawable(R.drawable.empty_photo);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
final View v = inflater.inflate(R.layout.image_grid_fragment, container, false);
final GridView mGridView = (GridView) v.findViewById(R.id.gridView);
mGridView.setAdapter(mAdapter);
mGridView.setOnItemClickListener(this);
mGridView.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()) {
mImageLoader.stopProcessingQueue();
}
} else {
mImageLoader.startProcessingQueue();
}
}
@Override
public void onScroll(AbsListView absListView, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
}
});
// This listener is used to get the final width of the GridView and then
// calculate the
// number of columns and the width of each column. The width of each
// column is variable
// as the GridView has stretchMode=columnWidth. The column width is used
// to set the height
// of each view so we get nice square thumbnails.
mGridView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@TargetApi(Build.VERSION_CODES.JELLY_BEAN)
@Override
public void onGlobalLayout() {
if (mAdapter.getNumColumns() == 0) {
final int numColumns = (int) Math.floor(mGridView.getWidth() / (mImageThumbSize + mImageThumbSpacing));
if (numColumns > 0) {
final int columnWidth = (mGridView.getWidth() / numColumns) - mImageThumbSpacing;
mAdapter.setNumColumns(numColumns);
mAdapter.setItemHeight(columnWidth);
if (BuildConfig.DEBUG) {
Log.d(TAG, "onCreateView - numColumns set to " + numColumns);
}
if (Utils.hasJellyBean()) {
mGridView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
} else {
mGridView.getViewTreeObserver().removeGlobalOnLayoutListener(this);
}
}
}
}
});
return v;
}
@Override
public void onResume() {
super.onResume();
mAdapter.notifyDataSetChanged();
}
@Override
public void onPause() {
super.onPause();
}
@Override
public void onDestroy() {
super.onDestroy();
}
@TargetApi(VERSION_CODES.JELLY_BEAN)
@Override
public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
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:
mImageLoader.clearCache();
Toast.makeText(getActivity(), R.string.clear_cache_complete_toast, Toast.LENGTH_SHORT).show();
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* 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;
private int mItemHeight = 0;
private int mNumColumns = 0;
private int mActionBarHeight = 0;
private GridView.LayoutParams mImageViewLayoutParams;
public ImageAdapter(Context context) {
super();
mContext = context;
mImageViewLayoutParams = new GridView.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
// Calculate ActionBar height
TypedValue tv = new TypedValue();
if (context.getTheme().resolveAttribute(android.R.attr.actionBarSize, tv, true)) {
mActionBarHeight = TypedValue.complexToDimensionPixelSize(tv.data, context.getResources().getDisplayMetrics());
}
}
@Override
public int getCount() {
// If columns have yet to be determined, return no items
if (getNumColumns() == 0) {
return 0;
}
// Size + number of columns for top empty row
return Images.imageThumbUrls.length + mNumColumns;
}
@Override
public Object getItem(int position) {
return position < mNumColumns ? null : Images.imageThumbUrls[position - mNumColumns];
}
@Override
public long getItemId(int position) {
return position < mNumColumns ? 0 : position - mNumColumns;
}
@Override
public int getViewTypeCount() {
// Two types of views, the normal ImageView and the top row of empty
// views
return 2;
}
@Override
public int getItemViewType(int position) {
return (position < mNumColumns) ? 1 : 0;
}
@Override
public boolean hasStableIds() {
return true;
}
@Override
public View getView(int position, View convertView, ViewGroup container) {
// First check if this is the top row
if (position < mNumColumns) {
if (convertView == null) {
convertView = new View(mContext);
}
// Set empty view with height of ActionBar
convertView.setLayoutParams(new AbsListView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, mActionBarHeight));
return convertView;
}
// Now handle the main ImageView thumbnails
ImageView imageView;
if (convertView == null) { // if it's not recycled, instantiate and
// initialize
imageView = new NetworkImageView(mContext);
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setLayoutParams(mImageViewLayoutParams);
} else { // Otherwise re-use the converted view
imageView = (ImageView) convertView;
}
// Check the height matches our calculated column width
if (imageView.getLayoutParams().height != mItemHeight) {
imageView.setLayoutParams(mImageViewLayoutParams);
}
// Finally load the image asynchronously into the ImageView, this
// also takes care of
// setting a placeholder image while the background thread runs
mImageLoader.get(Images.imageThumbUrls[position - mNumColumns], imageView);
return imageView;
}
/**
* Sets the item height. Useful for when we know the column width so the
* height can be set to match.
*
* @param height
*/
public void setItemHeight(int height) {
if (height == mItemHeight) {
return;
}
mItemHeight = height;
mImageViewLayoutParams = new GridView.LayoutParams(LayoutParams.MATCH_PARENT, mItemHeight);
mImageLoader.setMaxImageSize(height);
notifyDataSetChanged();
}
public void setNumColumns(int numColumns) {
mNumColumns = numColumns;
}
public int getNumColumns() {
return mNumColumns;
}
}
}