Android仿微信朋友圈图片查看器

        看博文之前,希望大家先打开自己的微信点到朋友圈中去,仔细观察是不是发现朋友圈里的有个“九宫格”的图片区域,点击图片又会跳到图片的详细查看页面,并且支持图片的滑动和缩放?这个功能是不是很常用呢?!那么我今天正好做了这个Demo,下面为大家讲解一下。首先按照惯例先看一下效果图吧,尤其不会录制gif动画(哎~没办法,模拟器不支持多点触控,刚好我的手机又没有Root,不能录屏,悲催啊,大家见谅,想要看真实效果的话,烦请移到博文最下方,点击下载源码,运行后再看效果哈~~),这里先就拿几张静态的图片顶替一下好了。见谅!

主页ListView的效果:
Android仿微信朋友圈图片查看器

点击九宫格图片跳转到大图
Android仿微信朋友圈图片查看器

多点触控,缩放图片
Android仿微信朋友圈图片查看器

       效果嘛,将就着看吧!实在看不明白就想想微信朋友圈,或者拖到下方,点击下载源码!这里,首先分析一下主界面吧,布局都是很简单的,主界面仅仅就是一个ListView的控件,ListView的Item上值得注意的是,Item上包含了一个GridView,这个GridView呗用作实现“九宫格”的效果,主界面布局就是一个ListView,这里不说了,我们先来看看ListView的Item的布局吧,以下是item_list.xml
<?xml version="1.0" encoding="utf-8"?>  
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    android:paddingBottom="5dp"  
    android:paddingTop="5dp" >  
  
    <ImageView  
        android:id="@+id/iv_avatar"  
        android:layout_width="50dp"  
        android:layout_height="50dp"  
        android:background="@drawable/ic_launcher"  
        android:scaleType="centerCrop" />  
  
    <TextView  
        android:id="@+id/tv_title"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:layout_marginLeft="5dp"  
        android:layout_toRightOf="@id/iv_avatar"  
        android:text="爷,今天心情好!"  
        android:textSize="16sp" />  
  
    <TextView  
        android:id="@+id/tv_content"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:layout_below="@+id/tv_title"  
        android:layout_marginLeft="5dp"  
        android:layout_marginTop="3dp"  
        android:layout_toRightOf="@id/iv_avatar"  
        android:text="今天又是雾霾!"  
        android:textSize="16sp" />  
  
    <com.example.imagedemo.NoScrollGridView  
        android:id="@+id/gridview"  
        android:layout_width="220dp"  
        android:layout_height="wrap_content"  
        android:layout_below="@id/tv_content"  
        android:layout_marginLeft="5dp"  
        android:layout_marginTop="3dp"  
        android:layout_toRightOf="@id/iv_avatar"  
        android:columnWidth="70dp"  
        android:gravity="center"  
        android:horizontalSpacing="2.5dp"  
        android:numColumns="3"  
        android:stretchMode="columnWidth"  
        android:verticalSpacing="2.5dp" />  
  
</RelativeLayout>

        好了,大家看到了,布局也是极其简单的,但是有个问题就是ListView嵌套进了GridView,那么就会出现一个问题,导致GridView显示的不全,那么该怎么解决这个问题呢?其实也简单,就是重写一个GridView,测量一下GridView的高度,再设置上去。具体解决方案请看上篇博文ListView嵌套GridView显示不全解决方法或者源码,如下NoScrollGridView.java
package com.example.imagedemo;  
  
import android.content.Context;  
import android.util.AttributeSet;  
import android.widget.GridView;  
  
/** 
 * 自定义的“九宫格”——用在显示帖子详情的图片集合 解决的问题:GridView显示不全,只显示了一行的图片,比较奇怪,尝试重写GridView来解决 
 *  
 * @author iaiai 
 * @since 2014-10-16 16:41 
 *  
 */  
public class NoScrollGridView extends GridView {  
  
    public NoScrollGridView(Context context) {  
        super(context);  
        // TODO Auto-generated constructor stub  
    }  
  
    public NoScrollGridView(Context context, AttributeSet attrs) {  
        super(context, attrs);  
        // TODO Auto-generated constructor stub  
    }  
  
    public NoScrollGridView(Context context, AttributeSet attrs, int defStyle) {  
        super(context, attrs, defStyle);  
        // TODO Auto-generated constructor stub  
    }  
  
    @Override  
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {  
        // TODO Auto-generated method stub  
        int expandSpec = MeasureSpec.makeMeasureSpec(Integer.MAX_VALUE >> 2,  
                MeasureSpec.AT_MOST);  
        super.onMeasure(widthMeasureSpec, expandSpec);  
    }  
  
}

       接下来看看ListView上面Item的实体是什么样的数据结构,这就显得非常简单了。
public class ItemEntity {  
    private String avatar; // 用户头像URL  
    private String title; // 标题  
    private String content; // 内容  
    private ArrayList<String> imageUrls; // 九宫格图片的URL集合  
  
    public ItemEntity(String avatar, String title, String content,  
            ArrayList<String> imageUrls) {  
        super();  
        this.avatar = avatar;  
        this.title = title;  
        this.content = content;  
        this.imageUrls = imageUrls;  
    }  
       ...  
}

        好了,有了ListView,那么不可避免的就是做Item上的数据适配了。继承一个BaseAdapter,代码如下,都比较简单:
/** 
 * 首页ListView的数据适配器 
 *  
 * @author iaiai 
 *  
 */  
public class ListItemAdapter extends BaseAdapter {  
  
    private Context mContext;  
    private ArrayList<ItemEntity> items;  
  
    public ListItemAdapter(Context ctx, ArrayList<ItemEntity> items) {  
        this.mContext = ctx;  
        this.items = items;  
    }  
  
    @Override  
    public int getCount() {  
        return items == null ? 0 : items.size();  
    }  
  
    @Override  
    public Object getItem(int position) {  
        return items.get(position);  
    }  
  
    @Override  
    public long getItemId(int position) {  
        return position;  
    }  
  
    @Override  
    public View getView(int position, View convertView, ViewGroup parent) {  
        ViewHolder holder;  
        if (convertView == null) {  
            holder = new ViewHolder();  
            convertView = View.inflate(mContext, R.layout.item_list, null);  
            holder.iv_avatar = (ImageView) convertView  
                    .findViewById(R.id.iv_avatar);  
            holder.tv_title = (TextView) convertView  
                    .findViewById(R.id.tv_title);  
            holder.tv_content = (TextView) convertView  
                    .findViewById(R.id.tv_content);  
            holder.gridview = (NoScrollGridView) convertView  
                    .findViewById(R.id.gridview);  
            convertView.setTag(holder);  
        } else {  
            holder = (ViewHolder) convertView.getTag();  
        }  
        ItemEntity itemEntity = items.get(position);  
        holder.tv_title.setText(itemEntity.getTitle());  
        holder.tv_content.setText(itemEntity.getContent());  
        // 使用ImageLoader加载网络图片  
        DisplayImageOptions options = new DisplayImageOptions.Builder()//  
                .showImageOnLoading(R.drawable.ic_launcher) // 加载中显示的默认图片  
                .showImageOnFail(R.drawable.ic_launcher) // 设置加载失败的默认图片  
                .cacheInMemory(true) // 内存缓存  
                .cacheOnDisk(true) // sdcard缓存  
                .bitmapConfig(Config.RGB_565)// 设置最低配置  
                .build();//  
        ImageLoader.getInstance().displayImage(itemEntity.getAvatar(),  
                holder.iv_avatar, options);  
        final ArrayList<String> imageUrls = itemEntity.getImageUrls();  
        if (imageUrls == null || imageUrls.size() == 0) { // 没有图片资源就隐藏GridView  
            holder.gridview.setVisibility(View.GONE);  
        } else {  
            holder.gridview.setAdapter(new NoScrollGridAdapter(mContext,  
                    imageUrls));  
        }  
        // 点击回帖九宫格,查看大图  
        holder.gridview.setOnItemClickListener(new OnItemClickListener() {  
  
            @Override  
            public void onItemClick(AdapterView<?> parent, View view,  
                    int position, long id) {  
                // TODO Auto-generated method stub  
                imageBrower(position, imageUrls);  
            }  
        });  
        return convertView;  
    }  
  
    /** 
     * 打开图片查看器 
     *  
     * @param position 
     * @param urls2 
     */  
    protected void imageBrower(int position, ArrayList<String> urls2) {  
        Intent intent = new Intent(mContext, ImagePagerActivity.class);  
        // 图片url,为了演示这里使用常量,一般从数据库中或网络中获取  
        intent.putExtra(ImagePagerActivity.EXTRA_IMAGE_URLS, urls2);  
        intent.putExtra(ImagePagerActivity.EXTRA_IMAGE_INDEX, position);  
        mContext.startActivity(intent);  
    }  
  
    /** 
     * listview组件复用,防止“卡顿” 
     *  
     * @author Administrator 
     *  
     */  
    class ViewHolder {  
        private ImageView iv_avatar;  
        private TextView tv_title;  
        private TextView tv_content;  
        private NoScrollGridView gridview;  
    }  
}


        这里有需要解释的地方了,看看listview上的图片处理,由于图片都是从网络获取的,为了避免图片过多造成OOM,那么这里加载图片的时候必不可少的需要做内存优化,图片的优化方式有很多,我这里采取了最简单最直接得方式,使用了开源的ImageLoader这个图片加载框架,这个框架简直是太优秀了,减少了开发者一系列不必要而且时常会出现的麻烦,关于ImageLoader并不是本篇博文需要讲解的知识,关于ImageLoader,欢迎在GitHub主页上下载,地址是 https://github.com/nostra13/Android-Universal-Image-Loader,既然使用了ImageLoader这个框架,就不得不在程序上做一些初始化的操作,首先需要自定义一个全局的上下文Application类,将ImageLoader的相关属性初始化上去,直接看代码好了,见名知意:MyApplication.java
public class MyApplication extends Application {  
    @Override  
    public void onCreate() {  
        super.onCreate();  
        DisplayImageOptions defaultOptions = new DisplayImageOptions.Builder() //  
                .showImageForEmptyUri(R.drawable.ic_launcher) //  
                .showImageOnFail(R.drawable.ic_launcher) //  
                .cacheInMemory(true) //  
                .cacheOnDisk(true) //  
                .build();//  
        ImageLoaderConfiguration config = new ImageLoaderConfiguration//  
        .Builder(getApplicationContext())//  
                .defaultDisplayImageOptions(defaultOptions)//  
                .discCacheSize(50 * 1024 * 1024)//  
                .discCacheFileCount(100)// 缓存一百张图片  
                .writeDebugLogs()//  
                .build();//  
        ImageLoader.getInstance().init(config);  
    }  
}

       定义这个Application之后,需要在清单文件中配置一下,在Manifest.xml中的Application节点上添加:
android:name="com.example.imagedemo.MyApplication"

此外由于ImageLoader是网络获取图片,又需要本地sdcard缓存图片,所以需要加上一下的权限,这是Imageloader标准权限:
<uses-permission android:name="android.permission.INTERNET" />  
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />  
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

       再看看上面的Item上数据,里面有个GridView,显然这个GridView也是需要做数据适配的,这个数据反应的是从网络加载图片,比较简单,看代码NoScrollGridAdapter.java
     ......  
Override  
public View getView(int position, View convertView, ViewGroup parent) {  
    View view = View.inflate(ctx, R.layout.item_gridview, null);  
    ImageView imageView = (ImageView) view.findViewById(R.id.iv_image);  
    DisplayImageOptions options = new DisplayImageOptions.Builder()//  
            .cacheInMemory(true)//  
            .cacheOnDisk(true)//  
            .bitmapConfig(Config.RGB_565)//  
            .build();  
    ImageLoader.getInstance().displayImage(imageUrls.get(position),  
            imageView, options);  
    return view;  
}  
    ......  

         这样,所有的数据适配就做好了,接下来就需要做图片查看器了,当我们点击ListView上Item里的“九宫格”——NoScrollGridView的某张图片的时候,需要把这个图片的url传给一个图片查看器,图片查看器里会根据传递进来的url去网络加载这张图片,那么其实图片查看器就是一个新的单独的Activity,这个Activity会包含一个ViewPager,用来管理多张图片的查看。image_detail_pager.xml
<?xml version="1.0" encoding="utf-8"?>  
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent" >  
  
    <com.example.imagedemo.HackyViewPager  
        android:id="@+id/pager"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        android:background="@android:color/black" />  
  
    <TextView  
        android:id="@+id/indicator"  
        android:layout_width="match_parent"  
        android:layout_height="wrap_content"  
        android:layout_gravity="bottom"  
        android:background="@android:color/transparent"  
        android:gravity="center"  
        android:text="@string/viewpager_indicator"  
        android:textColor="@android:color/white"  
        android:textSize="18sp" />  
  
</FrameLayout>

HackyViewPager.java
public class HackyViewPager extends ViewPager {  
  
    private static final String TAG = "HackyViewPager";  
  
    public HackyViewPager(Context context) {  
        super(context);  
    }  
  
    public HackyViewPager(Context context, AttributeSet attrs) {  
        super(context, attrs);  
    }  
  
    @Override  
    public boolean onInterceptTouchEvent(MotionEvent ev) {  
        try {  
            return super.onInterceptTouchEvent(ev);  
        } catch (IllegalArgumentException e) {  
            // 不理会  
            Log.e(TAG, "hacky viewpager error1");  
            return false;  
        } catch (ArrayIndexOutOfBoundsException e) {  
            // 不理会  
            Log.e(TAG, "hacky viewpager error2");  
            return false;  
        }  
    }  
  
}

ImagePagerActivity.java
/** 
 * 图片查看器 
 */  
public class ImagePagerActivity extends FragmentActivity {  
    private static final String STATE_POSITION = "STATE_POSITION";  
    public static final String EXTRA_IMAGE_INDEX = "image_index";  
    public static final String EXTRA_IMAGE_URLS = "image_urls";  
  
    private HackyViewPager mPager;  
    private int pagerPosition;  
    private TextView indicator;  
  
    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.image_detail_pager);  
  
        pagerPosition = getIntent().getIntExtra(EXTRA_IMAGE_INDEX, 0);  
        ArrayList<String> urls = getIntent().getStringArrayListExtra(  
                EXTRA_IMAGE_URLS);  
  
        mPager = (HackyViewPager) findViewById(R.id.pager);  
        ImagePagerAdapter mAdapter = new ImagePagerAdapter(  
                getSupportFragmentManager(), urls);  
        mPager.setAdapter(mAdapter);  
        indicator = (TextView) findViewById(R.id.indicator);  
  
        CharSequence text = getString(R.string.viewpager_indicator, 1, mPager  
                .getAdapter().getCount());  
        indicator.setText(text);  
        // 更新下标  
        mPager.setOnPageChangeListener(new OnPageChangeListener() {  
  
            @Override  
            public void onPageScrollStateChanged(int arg0) {  
            }  
  
            @Override  
            public void onPageScrolled(int arg0, float arg1, int arg2) {  
            }  
  
            @Override  
            public void onPageSelected(int arg0) {  
                CharSequence text = getString(R.string.viewpager_indicator,  
                        arg0 + 1, mPager.getAdapter().getCount());  
                indicator.setText(text);  
            }  
  
        });  
        if (savedInstanceState != null) {  
            pagerPosition = savedInstanceState.getInt(STATE_POSITION);  
        }  
  
        mPager.setCurrentItem(pagerPosition);  
    }  
  
    @Override  
    public void onSaveInstanceState(Bundle outState) {  
        outState.putInt(STATE_POSITION, mPager.getCurrentItem());  
    }  
  
    private class ImagePagerAdapter extends FragmentStatePagerAdapter {  
  
        public ArrayList<String> fileList;  
  
        public ImagePagerAdapter(FragmentManager fm, ArrayList<String> fileList) {  
            super(fm);  
            this.fileList = fileList;  
        }  
  
        @Override  
        public int getCount() {  
            return fileList == null ? 0 : fileList.size();  
        }  
  
        @Override  
        public Fragment getItem(int position) {  
            String url = fileList.get(position);  
            return ImageDetailFragment.newInstance(url);  
        }  
  
    }  
}

          已知图片查看的界面是继承自FragmentActivity的,所以支持显示的界面必须需要Fragment来实现,那么就自定义个Frangment吧,用这个Fragment来从url中获取图片资源,显示图片。image_detail_fragment.xml
<?xml version="1.0" encoding="utf-8"?>  
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    android:background="@android:color/black" >  
  
    <ImageView  
        android:id="@+id/image"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        android:adjustViewBounds="true"  
        android:contentDescription="@string/app_name"  
        android:scaleType="centerCrop" />  
  
    <ProgressBar  
        android:id="@+id/loading"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:layout_gravity="center"  
        android:visibility="gone" />  
  
</FrameLayout>

ImageDetailFragment.java
/** 
 * 单张图片显示Fragment 
 */  
public class ImageDetailFragment extends Fragment {  
    private String mImageUrl;  
    private ImageView mImageView;  
    private ProgressBar progressBar;  
    private PhotoViewAttacher mAttacher;  
  
    public static ImageDetailFragment newInstance(String imageUrl) {  
        final ImageDetailFragment f = new ImageDetailFragment();  
  
        final Bundle args = new Bundle();  
        args.putString("url", imageUrl);  
        f.setArguments(args);  
  
        return f;  
    }  
  
    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        mImageUrl = getArguments() != null ? getArguments().getString("url")  
                : null;  
    }  
  
    @Override  
    public View onCreateView(LayoutInflater inflater, ViewGroup container,  
            Bundle savedInstanceState) {  
        final View v = inflater.inflate(R.layout.image_detail_fragment,  
                container, false);  
        mImageView = (ImageView) v.findViewById(R.id.image);  
        mAttacher = new PhotoViewAttacher(mImageView);  
  
        mAttacher.setOnPhotoTapListener(new OnPhotoTapListener() {  
  
            @Override  
            public void onPhotoTap(View arg0, float arg1, float arg2) {  
                getActivity().finish();  
            }  
        });  
  
        progressBar = (ProgressBar) v.findViewById(R.id.loading);  
        return v;  
    }  
  
    @Override  
    public void onActivityCreated(Bundle savedInstanceState) {  
        super.onActivityCreated(savedInstanceState);  
  
        ImageLoader.getInstance().displayImage(mImageUrl, mImageView,  
                new SimpleImageLoadingListener() {  
                    @Override  
                    public void onLoadingStarted(String imageUri, View view) {  
                        progressBar.setVisibility(View.VISIBLE);  
                    }  
  
                    @Override  
                    public void onLoadingFailed(String imageUri, View view,  
                            FailReason failReason) {  
                        String message = null;  
                        switch (failReason.getType()) {  
                        case IO_ERROR:  
                            message = "下载错误";  
                            break;  
                        case DECODING_ERROR:  
                            message = "图片无法显示";  
                            break;  
                        case NETWORK_DENIED:  
                            message = "网络有问题,无法下载";  
                            break;  
                        case OUT_OF_MEMORY:  
                            message = "图片太大无法显示";  
                            break;  
                        case UNKNOWN:  
                            message = "未知的错误";  
                            break;  
                        }  
                        Toast.makeText(getActivity(), message,  
                                Toast.LENGTH_SHORT).show();  
                        progressBar.setVisibility(View.GONE);  
                    }  
  
                    @Override  
                    public void onLoadingComplete(String imageUri, View view,  
                            Bitmap loadedImage) {  
                        progressBar.setVisibility(View.GONE);  
                        mAttacher.update();  
                    }  
                });  
    }  
}

         写到这里,此篇博文也宣告结束了。需要提出的是,我这里的图片查看器实现的图片的缩放效果使用的是开源组件PhotoView,关于PhotoView的github项目地址在这里, https://github.com/chrisbanes/PhotoView 需要点进去这个项目的网址,去下载源码,将源码全部拷贝到项目中来,使用也是相当方便的,demo如下:
ImageView mImageView;  
PhotoViewAttacher mAttacher;  
  
@Override  
public void onCreate(Bundle savedInstanceState) {  
    super.onCreate(savedInstanceState);  
    setContentView(R.layout.activity_main);  
  
    // Any implementation of ImageView can be used!  
    mImageView = (ImageView) findViewById(R.id.iv_photo);  
  
    // Set the Drawable displayed  
    Drawable bitmap = getResources().getDrawable(R.drawable.wallpaper);  
    mImageView.setImageDrawable(bitmap);  
  
    // Attach a PhotoViewAttacher, which takes care of all of the zooming functionality.  
    mAttacher = new PhotoViewAttacher(mImageView);  
}  
  
  
// If you later call mImageView.setImageDrawable/setImageBitmap/setImageResource/etc then you just need to call  
attacher.update();

         刚开始这个图片查看器是我自己自定义View来实现的,其实需要实现图片的手势识别+多点触控+缩放,是可以使用矩阵Matrix来实现的,只不过这样显得特别的麻烦不说,而且极易出现BUG,这对于某些“急功近利”的项目来说,是个不好的兆头。所以,我这里摒弃了我用Matrix自定义的效果,改用github大牛为我们写好的开源组件,这样效率就上去了,大家也可以用Matrix自己去实现一下图片的多点触摸缩放的效果,关于Matrix的学习,请参加我以前的博文,Android自定义控件——3D画廊和图像矩阵。其实关于android上的图片缩放真没什么其它的方式,唯一能使用的还是Matrix这个类,不信先来瞧瞧Github大牛写的开源组件PhotoView是怎么实现的,查看以下部分源码:
// These are set so we don't keep allocating them on the heap  
    private final Matrix mBaseMatrix = new Matrix();  
    private final Matrix mDrawMatrix = new Matrix();  
    private final Matrix mSuppMatrix = new Matrix();  
    private final RectF mDisplayRect = new RectF();  
    private final float[] mMatrixValues = new float[9];  

/** 
    * Set's the ImageView's ScaleType to Matrix. 
    */  
   private static void setImageViewScaleTypeMatrix(ImageView imageView) {  
       /** 
        * PhotoView sets it's own ScaleType to Matrix, then diverts all calls 
        * setScaleType to this.setScaleType automatically. 
        */  
       if (null != imageView && !(imageView instanceof IPhotoView)) {  
           if (!ScaleType.MATRIX.equals(imageView.getScaleType())) {  
               imageView.setScaleType(ScaleType.MATRIX);  
           }  
       }  
   }

        以上只是PhotoView的部分源码,一目了然的发现它的实现也是基于Matrix的,时间与篇幅的局限性,大家需要更好的了解PhotoView的实现的话,就下载它的源码查看吧,要理解大神的想法是需要一些扎实的基础,关于PhotoView的具体实现细节,我也弄不太明白,可能是我对Matrix了解的不深刻吧,希望以后加强学习,也希望以后跟你们交流学习,共同进步!

源码请在这里下载: http://download.csdn.net/detail/waterseason/8717125

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