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.greendev.image; import android.annotation.TargetApi; import android.app.ActivityOptions; import android.content.Context; import android.content.Intent; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentActivity; import android.util.Log; import android.view.LayoutInflater; 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.TextView; import android.widget.Toast; import com.greendev.image.ImageCache.ImageCacheParams; import com.greendev.ldlmarketing.BuildConfig; import com.greendev.ldlmarketing.R; /** * 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; protected ImageAdapter mAdapter; protected ImageWorker mImageFetcher; private Context context; Class<?> detailClass; private String[] typeUrls; protected String[] typeUrlsThumbs; private String[] captions; /** * Constructor as per the Fragment documentation */ public ImageGridFragment(Context cxt, Class<?> c, String[] typeUrls, String[] thumbs, String[] captions) { this.context = cxt; this.detailClass = c; this.typeUrls = typeUrls; typeUrlsThumbs = thumbs; this.captions = captions; } public ImageGridFragment(Context cxt, Class<?> c, String[] thumbs) { this.context = cxt; this.detailClass = c; typeUrlsThumbs = thumbs; } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); try { setHasOptionsMenu(true); // true mImageThumbSize = getResources().getDimensionPixelSize(R.dimen.image_thumbnail_size); mImageThumbSpacing = getResources().getDimensionPixelSize(R.dimen.image_thumbnail_spacing); mAdapter = new ImageAdapter(context); ImageCacheParams cacheParams = new ImageCacheParams(context, IMAGE_CACHE_DIR); // Set memory cache to 25% of mem class cacheParams.setMemCacheSizePercent(context, 0.75f); // The ImageFetcher takes care of loading images into our ImageView // children asynchronously mImageFetcher = new ImageFetcher(context, mImageThumbSize); //mImageFetcher.setLoadingImage(R.drawable.empty_photo); mImageFetcher.addImageCache(((FragmentActivity) context).getSupportFragmentManager(), cacheParams); } catch (Exception e) { Log.e(TAG, "error in onCreate()"); } } @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) { 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); if (BuildConfig.DEBUG) { 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.setExitTasksEarly(true); mImageFetcher.flushCache(); } @Override public void onDestroy() { super.onDestroy(); mImageFetcher.closeCache(); } @TargetApi(16) @Override public void onItemClick(AdapterView<?> parent, View v, int position, long id) { /* transferring information to ImageDetailActivity */ Bundle b = new Bundle(); b.putStringArray("URLS_TYPE", typeUrls); b.putStringArray("CAPTIONS", captions); final Intent i = new Intent(context, ImageDetailActivity.class); i.putExtras(b); 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()); context.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(context, 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. */ protected 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); /** * weird bug when below. creates a white gap above the grid. size of action bar probs. */ // 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() { Log.i("getCOunt() is: ", typeUrlsThumbs.length + " "); // Size + number of columns for top empty row return typeUrlsThumbs.length + mNumColumns; } @Override public Object getItem(int position) { return position < mNumColumns ? null : typeUrlsThumbs[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; } /* * Displays the thumbnails */ @Override public View getView(int position, View convertView, ViewGroup container) { LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); View gridView; // 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; } ImageView imageView; /* The infamous album label */ //TextView textView; if (convertView == null) { // if it's not recycled, instantiate and // initialize gridView = new View(mContext); // get layout from mobile.xml gridView = (View) inflater.inflate(R.layout.image_grid_item, null); View blackShadow = gridView.findViewById(R.id.blackShadow); blackShadow.setVisibility(ImageView.GONE); imageView = (ImageView) gridView.findViewById(R.id.fragItem); mImageFetcher.loadImage(typeUrlsThumbs[position - mNumColumns], imageView); imageView.setScaleType(ImageView.ScaleType.CENTER_CROP); gridView.setLayoutParams(mImageViewLayoutParams); // textView = (TextView) gridView.findViewById(R.id.fragText); // textView.setText(setsNames[position - mNumColumns]); } else { // Otherwise re-use the converted view // imageView = (ImageView) convertView; gridView = (View) convertView; imageView = (ImageView) gridView.findViewById(R.id.fragItem); mImageFetcher.loadImage(typeUrlsThumbs[position - mNumColumns], imageView); // textView = (TextView) gridView.findViewById(R.id.fragText); // textView.setText(setsNames[position - mNumColumns]); } // Check the height matches our calculated column width if (gridView.getLayoutParams().height != mItemHeight) { gridView.setLayoutParams(mImageViewLayoutParams); // imageView.setLayoutParams(mImageViewLayoutParams); } return (View) gridView; } /** * 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); ((ImageResizer) mImageFetcher).setImageSize(height); notifyDataSetChanged(); } public void setNumColumns(int numColumns) { mNumColumns = numColumns; } public int getNumColumns() { return mNumColumns; } } }