Будьте ленивым, но продуктивным Android-разработчиком, часть 6: ступенчатый GridView

repositories {
mavenCentral()
}
dependencies {
compile 'com.etsy.android.grid:library:x.x.x' // read below comment
}

<com.etsy.android.grid.StaggeredGridView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/grid_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:item_margin="8dp"
app:column_count="@integer/grid_column_count" />
<!-- define grid_column_count as '2' inside integers.xml file -->

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/panel_content"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:descendantFocusability="blocksDescendants"
android:orientation="horizontal" >
<com.etsy.android.grid.util.DynamicHeightImageView
android:id="@+id/imgView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="centerCrop" />
</FrameLayout>

package com.technotalkative.staggeredgriddemo;
import java.util.ArrayList;
import java.util.Random;
import android.content.Context;
import android.util.Log;
import android.util.SparseArray;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import com.etsy.android.grid.util.DynamicHeightImageView;
import com.nostra13.universalimageloader.core.ImageLoader;
public class SampleAdapter extends ArrayAdapter<String> {
private static final String TAG = "SampleAdapter";
private final LayoutInflater mLayoutInflater;
private final Random mRandom;
private static final SparseArray<Double> sPositionHeightRatios = new SparseArray<Double>();
public SampleAdapter(Context context, int textViewResourceId,
ArrayList<String> objects) {
super(context, textViewResourceId, objects);
this.mLayoutInflater = LayoutInflater.from(context);
this.mRandom = new Random();
}
@Override
public View getView(final int position, View convertView,
final ViewGroup parent) {
ViewHolder vh;
if (convertView == null) {
convertView = mLayoutInflater.inflate(R.layout.row_grid_item,
parent, false);
vh = new ViewHolder();
vh.imgView = (DynamicHeightImageView) convertView
.findViewById(R.id.imgView);
convertView.setTag(vh);
} else {
vh = (ViewHolder) convertView.getTag();
}
double positionHeight = getPositionRatio(position);
vh.imgView.setHeightRatio(positionHeight);
ImageLoader.getInstance().displayImage(getItem(position), vh.imgView);
return convertView;
}
static class ViewHolder {
DynamicHeightImageView imgView;
}
private double getPositionRatio(final int position) {
double ratio = sPositionHeightRatios.get(position, 0.0);
// if not yet done generate and stash the columns height
// in our real world scenario this will be determined by
// some match based on the known height and width of the image
// and maybe a helpful way to get the column height!
if (ratio == 0) {
ratio = getRandomHeightRatio();
sPositionHeightRatios.append(position, ratio);
Log.d(TAG, "getPositionRatio:" + position + " ratio:" + ratio);
}
return ratio;
}
private double getRandomHeightRatio() {
return (mRandom.nextDouble() / 2.0) + 1.0; // height will be 1.0 - 1.5
// the width
}
}

package com.technotalkative.staggeredgriddemo;
import java.util.ArrayList;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AbsListView;
import android.widget.AdapterView;
import android.widget.Toast;
import com.etsy.android.grid.StaggeredGridView;
public class StaggeredGridActivity extends Activity implements AbsListView.OnScrollListener, AbsListView.OnItemClickListener {
private static final String TAG = "StaggeredGridActivity";
public static final String SAVED_DATA_KEY = "SAVED_DATA";
private StaggeredGridView mGridView;
private boolean mHasRequestedMore;
private SampleAdapter mAdapter;
private ArrayList<String> mData;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_sgv);
setTitle("TechnoTalkative - SGV Demo");
mGridView = (StaggeredGridView) findViewById(R.id.grid_view);
mAdapter = new SampleAdapter(this,android.R.layout.simple_list_item_1, generateData());
// do we have saved data?
if (savedInstanceState != null) {
mData = savedInstanceState.getStringArrayList(SAVED_DATA_KEY);
}
if (mData == null) {
mData = generateData();
}
for (String data : mData) {
mAdapter.add(data);
}
mGridView.setAdapter(mAdapter);
mGridView.setOnScrollListener(this);
mGridView.setOnItemClickListener(this);
}
@Override
protected void onSaveInstanceState(final Bundle outState) {
super.onSaveInstanceState(outState);
outState.putStringArrayList(SAVED_DATA_KEY, mData);
}
@Override
public void onScrollStateChanged(final AbsListView view, final int scrollState) {
Log.d(TAG, "onScrollStateChanged:" + scrollState);
}
@Override
public void onScroll(final AbsListView view, final int firstVisibleItem, final int visibleItemCount, final int totalItemCount) {
Log.d(TAG, "onScroll firstVisibleItem:" + firstVisibleItem +
" visibleItemCount:" + visibleItemCount +
" totalItemCount:" + totalItemCount);
// our handling
if (!mHasRequestedMore) {
int lastInScreen = firstVisibleItem + visibleItemCount;
if (lastInScreen >= totalItemCount) {
Log.d(TAG, "onScroll lastInScreen - so load more");
mHasRequestedMore = true;
onLoadMoreItems();
}
}
}
private void onLoadMoreItems() {
final ArrayList<String> sampleData = generateData();
for (String data : sampleData) {
mAdapter.add(data);
}
// stash all the data in our backing store
mData.addAll(sampleData);
// notify the adapter that we can update now
mAdapter.notifyDataSetChanged();
mHasRequestedMore = false;
}
private ArrayList<String> generateData() {
ArrayList<String> listData = new ArrayList<String>();
listData.add("http://i62.tinypic.com/2iitkhx.jpg");
listData.add("http://i61.tinypic.com/w0omeb.jpg");
listData.add("http://i60.tinypic.com/w9iu1d.jpg");
listData.add("http://i60.tinypic.com/iw6kh2.jpg");
listData.add("http://i57.tinypic.com/ru08c8.jpg");
listData.add("http://i60.tinypic.com/k12r10.jpg");
listData.add("http://i58.tinypic.com/2e3daug.jpg");
listData.add("http://i59.tinypic.com/2igznfr.jpg");
return listData;
}
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {
Toast.makeText(this, "Item Clicked: " + position, Toast.LENGTH_SHORT).show();
}
}