Develop Reference

Android Picasso prefetching all images to disk

I want to prefetch images using Picasso and save them all to disk upon opening the app (no lazy loading on the fly). To make sure the cache is big enough I am using the following code in my Application onCreate
ContextWrapper cw = new ContextWrapper(getApplicationContext());
// path to /data/data/yourapp/app_data/imageDir
File directory = cw.getDir("imageDir", Context.MODE_PRIVATE);
OkHttpClient client = new OkHttpClient.Builder()
.cache(new Cache(directory, Integer.MAX_VALUE))
.build();
OkHttp3Downloader okHttp3Downloader = new OkHttp3Downloader(client);
Picasso.Builder builder = new Picasso.Builder(this);
builder.downloader(okHttp3Downloader);
Picasso built = builder.build();
built.setIndicatorsEnabled(false);
built.setLoggingEnabled(false);
Picasso.setSingletonInstance(built);
So here I set my cache size to Integer.MAX_VALUE which should be big enough ;)
I use code similar to this line to prefetch the image: Picasso.with(context).load(url).fetch();.
Now when I kill my internet and mobile data, no images are loaded even though the my code is fetching items. Any ideas why?

Maybe the problem is loosing state. Did you try to extend Application class (like this) and keep Picasso instance here?
In similar situation when I needed to fetch lots of images, I save them to internal memory (not just in some cache) - to prevent from reloading, and save uri's to files into SQLite and then use Picasso to work with such URI's. (don't forget to check that user don't delete anything).

In the end I created my own image manager that downloads and store images (still using picasso to download them).

Here is my approach:
In Application's onCreate method do:
Picasso picasso = new Picasso.Builder(this)
.downloader(new OkHttp3Downloader(this,Integer.MAX_VALUE))
.build();
picasso.setIndicatorsEnabled(BuildConfig.DEBUG);
picasso.setLoggingEnabled(BuildConfig.DEBUG);
Picasso.setSingletonInstance(picasso);
And then wherever you want to load your images call this for each image's url:
Picasso.with(context).load(url).fetch();
From doc:
fetch()
Asynchronously fulfills the request without a ImageView or Target. This is useful when you want to warm up the cache with an image.
You can even pass in callback to check for possible errors

Caching Images and strings using Retrofit, okhttp, picasso

I am working on an app with a lot of dynamic and changing content.
I pull all my data from my server when the app is loading.
As a result, nearly every activity/fragment is loading separately which will cause the user to wait a lot of time for each "page" to load individually.
My goal is to create one loading page when the app starts while being responssible for all the downloading and will disk cache all the images and info(strings) and ti pull them at the right time. (or at least to most of it)
I had the chance to use retrofit, okhttp and Picasso as a single additional library, I know though that they can work together and to be synced and that disk cacheing is available through at least two of this libraries (picasso and okhttp) I'm not sure though which one should do which part and how I can sync them together.
I will appreciate every Tip/Guidance, thanks ahead.

okhttp provides support for cache control headers. I've implemented them in an app before to provide a cache when network is flaky using this guide like so:
int cacheSize = 10 * 1024 * 1024; // 10 MiB
Cache cache = new Cache(cacheDirectory, cacheSize);
client = new OkHttpClient.Builder()
.cache(cache)
.build();
As Retrofit uses okhttp internally (if you're using the latest at least), you don't configure any caching for it. Just use the okhttp client you just configured:
RestAdapter restAdapter = new RestAdapter.Builder()
.setClient(new OkClient(client))
.setServer("http://example.com")
...
.build();
Picasso automatically caches images using some default cache size limit. You can change Picasso's default, and I've found some answers here and here. You could set the cache size in the onCreate of your application:
Picasso.Builder builder = new Picasso.Builder(this);
builder.downloader(new OkHttpDownloader(this,Integer.MAX_VALUE));
Picasso picasso = builder.build();
picasso.setIndicatorsEnabled(true);
picasso.setLoggingEnabled(true);
Picasso.setSingletonInstance(picasso);
Picasso also lets you prefetch images earlier on in an app's lifecycle if you have the time to begin with (say, on a loading screen) and want to make later parts of the app load quicker. To do that, I would use the fetch method from the Picasso builder to get the images, but not insert them into any ImageViews. You can Google it too, but there's a quick answer here which explains the background behind this:
Picasso.with(getApplicationContext())
.load(url)
.fetch();
IIRC you need to make sure you fetch the same sized and transformed image as you try and retrieve later, because Picasso caches the transformed image result rather than the raw downloaded image.

Picasso Caching Doesn't Appear to be working

I am using Picasso to handle image loading and caching in my Android Udacity project and I am noticing the caching is not working as I'd expect:
As you can see on the left fragment, the image has already loaded in an earlier thread. Now, with the same URL link, I am asking Picasso to place that image in the fragment on the right.
Here is the code which generates the grid view on the left fragment (and occurs first):
https://github.com/esend7881/udacity-android-popmovie/blob/a9a1b9a19a37594bb5edd736b7ec59229fb5905a/app/src/main/java/com/ericsender/android_nanodegree/popmovie/adapters/GridViewAdapter.java#L71
String load = String.format(sImgUrl, sImgSize, movie.poster_path);
Picasso.with(mContext.getApplicationContext())
.load(load)
.placeholder(R.drawable.abc_btn_rating_star_on_mtrl_alpha)
.error(R.drawable.abc_btn_rating_star_off_mtrl_alpha)
.resize(550, 775)
.into(viewHolder.imageView);
And then here is the code which runs in the right fragment:
https://github.com/esend7881/udacity-android-popmovie/blob/a9a1b9a19a37594bb5edd736b7ec59229fb5905a/app/src/main/java/com/ericsender/android_nanodegree/popmovie/fragments/MovieDetailsFragment.java#L308
Picasso.with(getActivity().getApplicationContext())
.load(String.format(sImgUrl, sImgSize, mMovieObj.poster_path))
.error(R.drawable.blank)
.fit()// .resize(366, 516)
.into(mMovieThumb, new com.squareup.picasso.Callback() {
#Override
public void onSuccess() {
Utils.log(sw.toString());
Utils.hideViewSafe(mMovieThumbProgress);
}
#Override
public void onError() {
Utils.log(sw.toString());
Utils.hideViewSafe(mMovieThumbProgress);
}
});
I am using the same application context in each as well as the load text:
String.format(sImgUrl, sImgSize, mMovieObj.poster_path))
and
getActivity().getApplicationContext()
So, I would think Picasso ought to detect when the exact same URL load link appears in the same context within a short period of time from each other and Picasso would then load the exact same image back into the app.
If this is not how Picasso caching works, then how does it?

As a comment mentioned, I'd guess this is affected by the size of the image being different in both fragments.
I'd recommend using https://github.com/facebook/fresco instead of picasso. It's more efficient, especially with different sizes. You can also directly access cached files if required https://github.com/facebook/fresco/issues/80

It's probably related to the HTTP headers received when getting the image that do not allow caching, as Picasso relies on an HTTP component to do the caching.
Try uploading your image on imgur, try hardcoding that path and see if it works. If that's the case, you'll have to find a workaround on how to get the image from the movie database.

Android Image invalidate in fresco

I am migrating android image caching library from picasso to fresco. I want to know if there is any way to invalidate image already catched as I am adding feature to replace existing image there is way to do so in picasso like
Picasso.with(context).invalidate(URI);
This line remove the cached image and use new one using the url provided which is same like,
http://example.com/image_path
In fresco I have tried using
Fresco.getImagePipeline().evictFromMemoryCache(uri);
This is removing image from view but adding same old cached image again and not getting new one from network as it is working in picasso.
Please refer question Invalidate cache in Picasso The accepted answer doing great in case of picasso.

Fresco.getImagePipeline().evictFromMemoryCache(uri);
Above code line remove the image from the catche but image remains there in the disk and render same if called. We need to remove same image from disk as well. Bellow two lines remove the the image from disc cache also we need to remove the small that is thumbnail image if saved from disk cache.
Fresco.getImagePipelineFactory().getMainDiskStorageCache().remove(new SimpleCacheKey(uri.toString()));
Fresco.getImagePipelineFactory().getSmallImageDiskStorageCache().remove(new SimpleCacheKey(uri.toString()));
Note: if you are using custom cache key you need to change it that way.

Try this
public static void clearCache(){
//
ImagePipeline imagePipeline = com.facebook.drawee.backends.pipeline.Fresco.getImagePipeline();
imagePipeline.clearMemoryCaches();
imagePipeline.clearDiskCaches();
// combines above two lines
imagePipeline.clearCaches();
}

Picasso: Loading cached image from disk too much slow

So, I was starting my project and wants to use Picasso in my project because its popular and used by many projects out there.
I included picasso using gradle and tried loading facebook profile url with this. http://graph.facebook.com/rohitiskul/picture.
It worked very well. It loaded image from network without any issues. I restarted the app.(Without actually killing the process). It showed me the same image instantly cached in Memory.
But then, I killed the app (force stop) and restarted. It took almost 10+ seconds to load the image. And that image was loading from the disk when I checked in the debug logs.
My code looks like this -
In MainActivity-
Picasso.with(context)
.load("http://graph.facebook.com/rohitiskul/picture")
.into(imageView);
In application class-
Picasso picasso = new Picasso.Builder(this)
.indicatorsEnabled(true).loggingEnabled(true).build()
Picasso.setSingletonInstance(picasso);
Anyone with the similar problem? Any solution would be helpful.
I tried loading same Url with UniversalImageLoader and it was fast when fetching cached image from disk.
Edit
Earlier while playing with my app, I found out that Picasso wasn't loading the disk cached image when device was offline.

I encounter the same problem,
but find only slow for the first image, later images will be fast.
Probably it needs a warm-up (loading index cache) ?

Okay i got your problem. I have fixed it by doing this
Picasso.with(context)
.load("http://graph.facebook.com/rohitiskul/picture")
.networkPolicy(NetworkPolicy.OFFLINE)
.into(imageView, new Callback() {
#Override
public void onSuccess() { }
#Override
public void onError() {
// Try again online if cache failed
Picasso.with(context)
.load("http://graph.facebook.com/rohitiskul/picture")
.into(imageView);
}
});
Explanation:
Picasso will look for images in cache.
If it failed only then image will be downloaded over network. In your case from facebook.

This issue I had also faced earlier, with this what I understood that Picasso refer the cached image based on image name mentioned in the URL.
In your case you don't have image name in URL like 'image1.jpg'. Due to which Picasso is finding it difficult to read from cache and it downloads the image everytime
You can give a try to image containing the image name in URL and that will work

Picasso doesn't offer disk cache out of the box. Instead, it relies on an Http Cache.
Make sure you add OkHttp to your dependency list.

Add a string identifier with the stableKey method when making the request so Picasso can identify your requests and quickly load it from the cache.
Example:
Picasso.Builder(context).loggingEnabled(true).build()
.load(imageUrl)
.stableKey("myImage")
.into(imageView)