/*
* 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.example.android.bitmapfun.ui;
import sample.bitmapfun.R;
import android.app.Fragment;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
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 com.dianping.app.MyApplication;
import com.dianping.loader.MyResources;
import com.example.android.bitmapfun.provider.Images;
import com.example.android.bitmapfun.util.ImageCache.ImageCacheParams;
import com.example.android.bitmapfun.util.ImageFetcher;
/**
* 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 ImageGridFragment 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 ImageFetcher mImageFetcher;
/**
* Empty constructor as per the Fragment documentation
*/
public ImageGridFragment() {}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setHasOptionsMenu(true);
MyResources res = MyResources.getResource(ImageGridFragment.class);
mImageThumbSize = res.getResources().getDimensionPixelSize(R.dimen.image_thumbnail_size);
mImageThumbSpacing = res.getResources().getDimensionPixelSize(R.dimen.image_thumbnail_spacing);
// The empty_photo bitmap is in our package, so we use res.getResources() instead of context.getResources()
Bitmap emptyPhoto = BitmapFactory.decodeResource(res.getResources(), R.drawable.empty_photo);
mAdapter = new ImageAdapter(getActivity());
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(), mImageThumbSize);
mImageFetcher.setLoadingImage(emptyPhoto);
mImageFetcher.addImageCache(getActivity().getFragmentManager(), cacheParams);
}
@Override
public View onCreateView(
LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
MyResources res = MyResources.getResource(ImageGridFragment.class);
final View v = res.inflate(getActivity(), 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) {
mImageFetcher.setPauseWork(true);
} else {
mImageFetcher.setPauseWork(false);
}
}
@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() {
@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);
Log.d(TAG, "onCreateView - numColumns set to " + numColumns);
}
}
}
});
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();
}
@Override
public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
Intent i = new Intent(Intent.ACTION_VIEW,
Uri.parse(MyApplication.PRIMARY_SCHEME + "://image"));
i.putExtra("imageUrl", Images.imageUrls[(int) id]);
startActivity(i);
}
/**
* 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 GridView.LayoutParams mImageViewLayoutParams;
public ImageAdapter(Context context) {
super();
mContext = context;
mImageViewLayoutParams = new GridView.LayoutParams(
LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
}
@Override
public int getCount() {
// Size + number of columns for top empty row
return Images.imageThumbUrls.length;
}
@Override
public Object getItem(int position) {
return Images.imageThumbUrls[position];
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public int getViewTypeCount() {
return 1;
}
@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) {
// Now handle the main ImageView thumbnails
ImageView imageView;
if (convertView == null) { // if it's not recycled, instantiate and initialize
imageView = new RecyclingImageView(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
mImageFetcher.loadImage(Images.imageThumbUrls[position], 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);
mImageFetcher.setImageSize(height);
notifyDataSetChanged();
}
public void setNumColumns(int numColumns) {
mNumColumns = numColumns;
}
public int getNumColumns() {
return mNumColumns;
}
}
}