Saving remote jpg without the need to go from jpg->bitmap->jpg

[lokewate]

When a jpg is downloaded from a server using load(url).into(target), target only allows for accessing the image using a Bitmap through onBitmapLoaded(). However, if we want to save this image locally, then the bitmap needs to be converted to a jpg, which would cause quality loss. There should be a way to save the downloaded data directly.

[jacobtabak]

I would suggest you download the image first using okhttp and then load it from disk using Picasso. This type of feature doesn't really make sense to duplicate in Picasso.

[dnkoutso]

Custom Downloader will give you access to the InputStream. Disk cache is completely transparent to Picasso.

You cannot attach a custom downloader per request at the moment, if that is what you are trying to achieve, you are better off with a different implementation to achieve this.

[lokewate]

@jacobtabak: Just to clarify, I am downloading images on demand when the user swipes through a fullscreen view. What you are suggesting is that in the PagerAdapter's instantiateItem() method, I set a placeholder image and then trigger an AsyncTask that will take the ImageView object, and download the image using okhttp and use Picasso to then set the downloaded image to the ImageView. Is there any pitfalls in this approach related to lifecycle of ImageView?

[JakeWharton]

Dupe #506

[jacobtabak]

@lokewate I'd probably do it like this until official support is added:

1. Inject an OkHttpClient with a disk cache into your Picasso instance using Picasso.Builder
2. Load an image using Picasso normally (don't do what you said above)
3. Use the same OkHttpClient instance to download the image to file. It should be cached.

Here's some code to download a file with okhttp/okio -

    Request request = new Request.Builder().url("http://test.com/image.jpg").build();
    okHttpClient.newCall(request).enqueue(new Callback() {
      @Override public void onFailure(Request request, IOException e) {
        // handle failure
      }

      @Override public void onResponse(Response response) throws IOException {
        File outputFile = new File(getCacheDir(), "tmp.jpg");
        response.body().source().readAll(Okio.sink(outputFile));
      }
    });

[JakeWharton]

response.body().source().readAll(Okio.sink(outputFile));

should be

BufferedSource source = response.body().source()
Sink sink = Okio.sink(file);
source.readAll(sink);
source.close();
sink.close();

and those close calls should probably be in a finally block.

[lokewate]

Thanks all for the interim solution. Just to clarify, this is how I created the Picasso object.

OkHttpClient okHttpClient = new OkHttpClient();
OkHttpDownloader okHttpDownloader = new OkHttpDownloader(okHttpClient);
Picasso picasso = new Picasso.Builder(context).downloader(okHttpDownloader).build();