在毕加索加载实际图像之前模糊缩略图

Question

我正在使用毕加索从URL显示图像，我在加载实际图像之前首先显示缩略图，我想模糊缩略图，我怎样才能在毕加索中实现？

这是我的源代码

pb.setVisibility(View.GONE);
        Picasso.with(getApplicationContext())
                .load(thumbUrl) // thumbnail url goes here
                //.placeholder(R.drawable.progress_animation)
                .resize(width, width)
                .transform(new BlurTransformation(getApplicationContext(), 25, 1))
                .into(imageview, new Callback()
                {
                    @Override
                    public void onSuccess()
                    {
                        pb.setVisibility(View.GONE);
                        Log.e(TAG,"OnSuccess");
                        Picasso.with(getApplicationContext())
                                .load(url) // image url goes here
                                .resize(width, width)
                                .placeholder(imageview.getDrawable())
                                .into(imageview);
                        iv_reDownload.setVisibility(View.GONE);
                    }

                    @Override
                    public void onError()
                    {
                        pb.setVisibility(View.GONE);
                        Log.e(TAG,"OnError");
                        Picasso.with(getApplicationContext())
                                .load(url) // image url goes here
                                .resize(width, width)
                                .placeholder(imageview.getDrawable())
                                .into(imageview);
                        iv_reDownload.setVisibility(View.VISIBLE);
                    }
                });

Answer 1

据我所知，毕加索目前并不支持这个＆＃34;功能＆＃34;。 Glide库具有非常相似的用途，它具有一个功能，可以轻松使用＆＃34;快速预览＆＃34;，即低分辨率缩略图，加载速度比全尺寸图像快。

函数为thumbnail(float)并接受比例因子作为参数，例如0.1f是原始图像大小的十分之一。

Glide的案例使用可能是这样的。

Glide.with(mFragment)
            .load(wFile.getUriForThumb())                
            .override(length, length)
            .thumbnail(.05f)
            .placeholder(R.drawable.placeholder_image_128px)
            .into(holder.mImageThumb);

方法override与毕加索的resize(int,int)相近。

有关两个库之间的完整比较，您可以查看这个很好的指南：Glide vs. Picasso

Answer 2

最后，我在这个名为picasso-transformations的Library的帮助下解决了我的问题，我在项目中添加了以下依赖项

from collections import defaultdict

# Your input data.
tuples = [(i, i+1) for i in range(1000)]
lists = [[1,2,3,4],[2,3,4,5],[2,3],[4,5,6]] * 1000

def original(tuples, lists):
    subsets = {t : set(t) for t in tuples}
    mainsets = [set(xs) for xs in lists]

    return { tup : sum(s.issubset(m) for m in mainsets) for tup, s in subsets.items() }

def jp(tuples, lists):
    subsets = list(map(frozenset, tuples))
    mainsets = list(map(set, lists))
    d = defaultdict(int)
    for item in mainsets:
        for sub in subsets:
            if sub.issubset(item):
                d[sub] += 1
    return d

%timeit original(tuples, lists)  # 707 ms per loop
%timeit jp(tuples, lists)        # 431 ms per loop

不仅支持 Picasso ，还支持 Glide 或 Fresco 我在毕加索里面打了compile 'jp.wasabeef:picasso-transformations:2.2.1' 课。

这里是完整的例子

BlurTransformation

Answer 3

毕加索的模糊变换，参考：https://futurestud.io/tutorials/picasso-image-rotation-and-transformation

 @Override
        public Bitmap transform(Bitmap bitmap) {
            // Create another bitmap that will hold the results of the filter.
            Bitmap blurredBitmap = bitmap.copy(Bitmap.Config.ARGB_8888, true);

        // Allocate memory for Renderscript to work with
        Allocation input = Allocation.createFromBitmap(rs, blurredBitmap, Allocation.MipmapControl.MIPMAP_FULL, Allocation.USAGE_SHARED);
        Allocation output = Allocation.createTyped(rs, input.getType());

        // Load up an instance of the specific script that we want to use.
        ScriptIntrinsicBlur script = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
        script.setInput(input);

        // Set the blur radius
        script.setRadius(10);

        // Start the ScriptIntrinisicBlur
        script.forEach(output);

        // Copy the output to the blurred bitmap
        output.copyTo(blurredBitmap);

        bitmap.recycle();

        return blurredBitmap;
    }

Answer 4

如果您在Picasso中调整图像大小，我已经测试了Glide和Picasso的快速加载，这将提高您的加载速度，这是代码

 Glide.with(context)
           .load(sArr.get(position).getThumbnail())
           .thumbnail(0.01f)
           .override(100,100)
           .centerCrop()
           .placeholder(R.drawable.default_picture)
           .into(holder.imgItem);

Piccaso的代码

Picasso.with(context)
            .load(sArr.get(position).getThumbnail())
            .resize(100,100)
            .placeholder(R.drawable.default_picture)
            .into(holder.imgItem);

  

，毕加索获胜！

Answer 5

不确定这是否有效但我之前已经看过你可以使用：

.add(new ImageTransform(IMAGE_URL, new BlurTransformation(this)));