Picasso

1.简介

Picasso是Square公司出品的一个强大的图片下载和缓存图片库
1）在adapter中需要取消已经不在视野范围的ImageView图片资源的加载，否则会导致图片错位，Picasso已经解决了这个问题。
2）使用复杂的图片压缩转换来尽可能的减少内存消耗
3）自带内存和硬盘二级缓存功能

2.基本用法

①普通加载图片

Picasso.with(PicassoActivity.this)

　　　　.load("http://n.sinaimg.cn/translate/20160819/9BpA-fxvcsrn8627957.jpg")

　　　　.into(ivPicassoResult1);

②裁剪的方式加载图片

Picasso.with(PicassoActivity.this)

　　　　.load("http://n.sinaimg.cn/translate/20160819/9BpA-fxvcsrn8627957.jpg")

　　　　.resize(100,100)

　　　　.into(ivPicassoResult1);　　

③选择180度

Picasso.with(PicassoActivity.this)

　　　　.load("http://n.sinaimg.cn/translate/20160819/9BpA-fxvcsrn8627957.jpg")

　　　　.rotate(180)

　　　　.into(ivPicassoResult1);

　　

3.ListView资源加载的方法

- placeholder(xxx). 设置资源加载过程中的显示的Drawable。
- error(xxx).设置load失败时显示的Drawable。
- into(xxx) 设置资源加载到的目标 包括ImageView Target等

eg:Adapter中getView()方法中

// 加载图片

Picasso.with(mContext)

	.load(Constants.IMAGES[position])

	.placeholder(R.drawable.atguigu_logo)

	.error(R.drawable.atguigu_logo)

	.into(holder.iv);

　　

4.常用工具类

 public class PicassoUtil {

     //加载本地图片

     public static void setImg(Context context, int resId, ImageView imgView){

         Picasso.with(context)

                 .load(resId)

                 .config(Bitmap.Config.RGB_565)//8位RGB位图

                 .fit()

                 .into(imgView);

     }

     //按照一定的宽高加载本地图片，带有加载错误和默认图片

     public static void setImg(Context context,int resId,ImageView imgView,int weight,int height){

         Picasso.with(context)

                 .load(resId)//加载本地图片

                 .config(Bitmap.Config.RGB_565)//8位RGB位图

                 .resize(weight,height)//设置图片的宽高

                 .into(imgView);//把图片加载到控件上

     }

     //加载网络图片到imgview,带有加载错误和默认图片

     public static void setImg(Context context, String imgurl, int resId, ImageView imgView){

         Picasso.with(context)

                 .load(imgurl)//加载网络图片的url

                 .config(Bitmap.Config.RGB_565)//8位RGB位图

                 .placeholder(resId)//默认图片

                 .error(resId)//加载错误的图片

                 .fit()//图片的宽高等于控件的宽高

                 .into(imgView);//把图片加载到控件上

     }

     public static void setImg(Context context, String imgurl, ImageView imgView){

         Picasso.with(context)

                 .load(imgurl)//加载网络图片的url

                 .config(Bitmap.Config.RGB_565)//8位RGB位图

                 .fit()//图片的宽高等于控件的宽高

                 .into(imgView);//把图片加载到控件上

     }

     //加载网络图片到Viewpager

     public static void setImg(Context context, String imgurl, ViewPager imgView){

         Picasso.with(context)

                 .load(imgurl)//加载网络图片的url

                 .config(Bitmap.Config.RGB_565)//8位RGB位图

                 .fit()//图片的宽高等于控件的宽高

                 .into((Target) imgView);//把图片加载到控件上

     }

     //加载网络图片到Viewpager，带有加载错误和默认图片

     public static void setImg(Context context, String imgurl, int resId, ViewPager imgView){

         Picasso.with(context)

                 .load(imgurl)//加载网络图片的url

                 .config(Bitmap.Config.RGB_565)//8位RGB位图

                 .placeholder(resId)//默认图片

                 .error(resId)//加载错误的图片

                 .fit()//图片的宽高等于控件的宽高

                 .into((Target) imgView);//把图片加载到控件上

     }

     //按照设定的宽高加载网络图片到imgview

     public static void setImg(Context context, String imgurl,ImageView imgView,int weight,int height){

         Picasso.with(context)

                 .load(imgurl)//加载网络图片的url

                 .config(Bitmap.Config.RGB_565)//8位RGB位图

                 .resize(weight,height)//设置图片的宽高

                 .into(imgView);//把图片加载到控件上

     }

     //按照设定的宽高加载网络图片到imgview，带有加载错误和默认图片

     public static void setImg(Context context, String imgurl, int resId,int weight,int height, ImageView imgView){

         Picasso.with(context)

                 .load(imgurl)//加载网络图片的url

                 .config(Bitmap.Config.RGB_565)//8位RGB位图

                 .placeholder(resId)//默认图片

                 .error(resId)//加载错误的图片

                 .resize(weight,height)//设置图片的宽高

                 .into(imgView);//把图片加载到控件上

     }

 }

PicassoUtil

5.图片变换

在module的gradle中添加转换库:

dependencies {

 	compile 'jp.wasabeef:picasso-transformations:2.1.0'

    // If you want to use the GPU Filters

    compile 'jp.co.cyberagent.android.gpuimage:gpuimage-library:1.4.1'

}

repositories {

    jcenter()

}

　　

Activity中:

List<String> data = new ArrayList<>();

for (int i = 1; i<= 36; i++){

	data.add(i+"");

}

// 初始化listview

PicassoTransformationsAdapter picassoTransformationsAdapter = new PicassoTransformationsAdapter(PicassoTransfromationsActivity.this,data);

lvPicassoTransfromations.setAdapter(picassoTransformationsAdapter);

PicassoListviewAdapter：

public class PicassoTransformationsAdapter extends BaseAdapter {

    private Context mContext;

    private List<String> mData;

    public PicassoTransformationsAdapter(Context context, List<String> data) {

        mContext = context;

        mData = data;

    }

    @Override

    public int getCount() {

        return mData == null ? 0 : mData.size();

    }

    @Override

    public Object getItem(int position) {

        return null;

    }

    @Override

    public long getItemId(int position) {

        return 0;

    }

    @Override

    public View getView(int position, View convertView, ViewGroup parent) {

        ViewHolder holder;

        if(convertView == null) {

            convertView = View.inflate(mContext, R.layout.item_picasso_transformations,null);

            holder = new ViewHolder(convertView);

            convertView.setTag(holder);

        }else {

            holder = (ViewHolder) convertView.getTag();

        }

        // 显示名称

        holder.name.setText("item"+(position + 1));

        int integer = Integer.parseInt(mData.get(position));

        switch (integer) {

            case 1: {

                int width = Utils.dip2px(mContext, 133.33f);

                int height = Utils.dip2px(mContext, 126.33f);

                Picasso.with(mContext)

                        .load(R.drawable.check)

                        .resize(width, height)

                        .centerCrop()

                        .transform((new MaskTransformation(mContext, R.drawable.mask_starfish)))

                        .into(holder.image);

                break;

            }

            case 2: {

                int width = Utils.dip2px(mContext, 150.0f);

                int height = Utils.dip2px(mContext, 100.0f);

                Picasso.with(mContext)

                        .load(R.drawable.check)

                        .resize(width, height)

                        .centerCrop()

                        .transform(new MaskTransformation(mContext, R.drawable.chat_me_mask))

                        .into(holder.image);

                break;

            }

            case 3:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation(300, 100, CropTransformation.GravityHorizontal.LEFT,

                                CropTransformation.GravityVertical.TOP))

                        .into(holder.image);

                break;

            case 4:

                Picasso.with(mContext).load(R.drawable.demo)

                        // 300, 100, CropTransformation.GravityHorizontal.LEFT, CropTransformation.GravityVertical.CENTER))

                        .transform(new CropTransformation(300, 100)).into(holder.image);

                break;

            case 5:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation(300, 100, CropTransformation.GravityHorizontal.LEFT,

                                CropTransformation.GravityVertical.BOTTOM))

                        .into(holder.image);

                break;

            case 6:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation(300, 100, CropTransformation.GravityHorizontal.CENTER,

                                CropTransformation.GravityVertical.TOP))

                        .into(holder.image);

                break;

            case 7:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation(300, 100))

                        .into(holder.image);

                break;

            case 8:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation(300, 100, CropTransformation.GravityHorizontal.CENTER,

                                CropTransformation.GravityVertical.BOTTOM))

                        .into(holder.image);

                break;

            case 9:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation(300, 100, CropTransformation.GravityHorizontal.RIGHT,

                                CropTransformation.GravityVertical.TOP))

                        .into(holder.image);

                break;

            case 10:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation(300, 100, CropTransformation.GravityHorizontal.RIGHT,

                                CropTransformation.GravityVertical.CENTER))

                        .into(holder.image);

                break;

            case 11:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation(300, 100, CropTransformation.GravityHorizontal.RIGHT,

                                CropTransformation.GravityVertical.BOTTOM))

                        .into(holder.image);

                break;

            case 12:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation((float) 16 / (float) 9,

                                CropTransformation.GravityHorizontal.CENTER,

                                CropTransformation.GravityVertical.CENTER))

                        .into(holder.image);

                break;

            case 13:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation((float) 4 / (float) 3,

                                CropTransformation.GravityHorizontal.CENTER,

                                CropTransformation.GravityVertical.CENTER))

                        .into(holder.image);

                break;

            case 14:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation(3, CropTransformation.GravityHorizontal.CENTER,

                                CropTransformation.GravityVertical.CENTER))

                        .into(holder.image);

                break;

            case 15:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation(3, CropTransformation.GravityHorizontal.CENTER,

                                CropTransformation.GravityVertical.TOP))

                        .into(holder.image);

                break;

            case 16:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation(1, CropTransformation.GravityHorizontal.CENTER,

                                CropTransformation.GravityVertical.CENTER))

                        .into(holder.image);

                break;

            case 17:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation((float) 0.5, (float) 0.5,

                                CropTransformation.GravityHorizontal.CENTER,

                                CropTransformation.GravityVertical.CENTER))

                        .into(holder.image);

                break;

            case 18:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation((float) 0.5, (float) 0.5,

                                CropTransformation.GravityHorizontal.CENTER,

                                CropTransformation.GravityVertical.TOP))

                        .into(holder.image);

                break;

            case 19:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation((float) 0.5, (float) 0.5,

                                CropTransformation.GravityHorizontal.RIGHT,

                                CropTransformation.GravityVertical.BOTTOM))

                        .into(holder.image);

                break;

            case 20:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropTransformation((float) 0.5, 0, (float) 4 / (float) 3,

                                CropTransformation.GravityHorizontal.CENTER,

                                CropTransformation.GravityVertical.CENTER))

                        .into(holder.image);

                break;

            case 21:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropSquareTransformation())

                        .into(holder.image);

                break;

            case 22:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new CropCircleTransformation())

                        .into(holder.image);

                break;

            case 23:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new ColorFilterTransformation(Color.argb(80, 255, 0, 0)))

                        .into(holder.image);

                break;

            case 24:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new GrayscaleTransformation())

                        .into(holder.image);

                break;

            case 25:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new RoundedCornersTransformation(30, 0,

                                RoundedCornersTransformation.CornerType.BOTTOM_LEFT))

                        .into(holder.image);

                break;

            case 26:

                Picasso.with(mContext)

                        .load(R.drawable.check)

                        .transform(new BlurTransformation(mContext, 25, 1))

                        .into(holder.image);

                break;

            case 27:

                Picasso.with(mContext)

                        .load(R.drawable.demo)

                        .transform(new ToonFilterTransformation(mContext))

                        .into(holder.image);

                break;

            case 28:

                Picasso.with(mContext)

                        .load(R.drawable.check)

                        .transform(new SepiaFilterTransformation(mContext))

                        .into(holder.image);

                break;

            case 29:

                Picasso.with(mContext)

                        .load(R.drawable.check)

                        .transform(new ContrastFilterTransformation(mContext, 2.0f))

                        .into(holder.image);

                break;

            case 30:

                Picasso.with(mContext)

                        .load(R.drawable.check)

                        .transform(new InvertFilterTransformation(mContext))

                        .into(holder.image);

                break;

            case 31:

                Picasso.with(mContext)

                        .load(R.drawable.check)

                        .transform(new PixelationFilterTransformation(mContext, 20))

                        .into(holder.image);

                break;

            case 32:

                Picasso.with(mContext)

                        .load(R.drawable.check)

                        .transform(new SketchFilterTransformation(mContext))

                        .into(holder.image);

                break;

            case 33:

                Picasso.with(mContext)

                        .load(R.drawable.check)

                        .transform(new SwirlFilterTransformation(mContext, 0.5f, 1.0f, new PointF(0.5f, 0.5f)))

                        .into(holder.image);

                break;

            case 34:

                Picasso.with(mContext)

                        .load(R.drawable.check)

                        .transform(new BrightnessFilterTransformation(mContext, 0.5f))

                        .into(holder.image);

                break;

            case 35:

                Picasso.with(mContext)

                        .load(R.drawable.check)

                        .transform(new KuwaharaFilterTransformation(mContext, 25))

                        .into(holder.image);

                break;

            case 36:

                Picasso.with(mContext)

                        .load(R.drawable.check)

                        .transform(new VignetteFilterTransformation(mContext, new PointF(0.5f, 0.5f),

                                new float[]{0.0f, 0.0f, 0.0f}, 0f, 0.75f))

                        .into(holder.image);

                break;

        }

        return convertView;

    }

    class ViewHolder{

        @Bind(R.id.iv_picasso)

        ImageView image;

        @Bind(R.id.tv_picasso)

        TextView name;

        public ViewHolder(View view) {

            ButterKnife.bind(this, view);

        }

    }

}