Android 交错 GridView

原文地址

本文演示在你的 Android 应用程序中显示交错 GridView（Staggered GridView ）。

下载 Demo

交错 GridView

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交错 GridView 只是具有不等大小行、多个列的 GridView。你可能已经使用过 Pinterest，Expedia 或 Etsy Android app。

目前，已经有 2、3 个很不错的开源库。

交错 GridView 库

• Staggered GridView by Etsy
• Staggered GridView by Maurycy Wojtowicz

下面说明最流行使用最广泛的 Etsy 的交错 gridview。

Etsy 交错 GridView

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自定义的交错 GridView 是根据 AbsListView 类扩展的，它当然也就支持 AbsListView.OnScrollListener。

功能

• 可以配置横向和纵向的列数量。
• 跨方向变化的异步行位置。
• 可配置项的边距（margin）
• 支持页眉（header）和页脚（footer）。
• 内部填充（Internal padding ），不影响页眉和页脚。

Etsy 的交错 gridview 不支持项的长按事件和选择器 drawables，而 Maurycy 的交错 gridview 则支持长按事件。

环境

• Windows 2008 R2 64 位
• Eclipse ADT V22.6.2，Android 4.4.2（API 19）
• SAMSUNG GT-8618，Android OS 4.1.2

项目结构

图 1 项目结构

• StaggeredGrid 项目是 com.etsy.android.grid 库。
• StaggeredGridDemo 项目是示例。

示例：Etsy 交错 GridView

图 2 演示交错 GridView

• 下载/包含库 com.etsy.android.grid

com.etsy.android.grid 库目前配置为只能通过 Gradle 生成，因此，如果您使用 Android Studio，那么你可以直接的方式包括这个库，作为 gradle 依赖来生成。如果你使用 Eclipse/ Ant，那么你必须执行额外的步骤。

对 Android Studio 环境：

repositories {
    mavenCentral()
}

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

对 Eclipse/Ant build：

下载 com.etsy.android.grid，并导入到项目。

• 把 StaggeredGridView 放到你的布局——activity_sgv.xml

<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:column_count="@integer/grid_column_count"
    app:item_margin="8dp" />

• 为 StaggeredGridView 定义行布局——row_grid_item.xml

<?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>

自定义行应该包含 DynamicHeightImageView 或 DynamicHeightTextView。

• 自定义 adapter

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
    }
}

自定义 adapter 类用来在交错 GridView 中显示动态高度的图片。另外，还使用了 Universal image loader 库用来异步加载图片。

• 把自定义 adapter 设置给 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://images.cnblogs.com/cnblogs_com/liuning8023/610092/o_2iitkhx.jpg");
        listData.add("http://images.cnblogs.com/cnblogs_com/liuning8023/610092/o_w0omeb.jpg");
        listData.add("http://images.cnblogs.com/cnblogs_com/liuning8023/610092/o_w9iu1d.jpg");
        listData.add("http://images.cnblogs.com/cnblogs_com/liuning8023/610092/o_iw6kh2.jpg");
        listData.add("http://images.cnblogs.com/cnblogs_com/liuning8023/610092/o_ru08c8.jpg");
        listData.add("http://images.cnblogs.com/cnblogs_com/liuning8023/610092/o_k12r10.jpg");
        listData.add("http://images.cnblogs.com/cnblogs_com/liuning8023/610092/o_2e3daug.jpg");
        listData.add("http://images.cnblogs.com/cnblogs_com/liuning8023/610092/o_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();
    }
}

表 1 交错 GridView 可配置的属性

属性	说明
item_margin	The margin around each grid item (default 0dp).
column_count	The number of columns displayed. Will override column_count_portrait and column_count_landscape if present (default 0).
column_count_portrait	The number of columns displayed when the grid is in portrait (default 2).
column_count_landscape	The number of columns displayed when the grid is in landscape (default 3).
grid_paddingLeft	Padding to the left of the grid. Does not apply to headers and footers (default 0).
grid_paddingRight	Padding to the right of the grid. Does not apply to headers and footers (default 0).
grid_paddingTop	Padding to the top of the grid. Does not apply to headers and footers (default 0).
grid_paddingBottom	Padding to the bottom of the grid. Does not apply to headers and footers (default 0).

参考资料

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• StaggeredGridView 库

下载 Demo