Android仿微信朋友圈图片查看器

标签：朋友圈   图片缩放   imageloader   photoview   matrix   

        转载请注明出处：http://blog.csdn.net/allen315410/article/details/40264551

        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：                                  点击九宫格图片跳转到大图                                     多点触控，缩放图片

        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 lichao
 * @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);
	}

}

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 Administrator
 * 
 */
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);
	}
}

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" />

      ......
@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;
	}
     ......

<?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>

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;
		}
	}

}

/**
 * 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>

/**
 * 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);
            }
        }
    }

源码请在这里下载

Android仿微信朋友圈图片查看器

标签：朋友圈   图片缩放   imageloader   photoview   matrix   

原文地址：http://blog.csdn.net/allen315410/article/details/40264551