PiczillaMVVM

A simple MVVM app to fetch images from Flickr Api and use LiveData and LRU cache without using any external library.

App Screens

App features

• App shows random images from Flickr Api.
• App has single full screen imageView to show images.
• App has two buttons (next & previous) to navigate through images.
• App uses cache strategy which means if an image has been fetched from url then it will be stored and served from cache.
• App follows MVVM (Model View ViewModel) pattern.
• No external library used for networking or image caching.
• HttpUrlConnection with AsyncTask used for api calling and LRU cache used for effective loading and caching.
• App supports landscape and portrait modes.

Api used

Below Flickr api is used to fetch images urls: https://api.flickr.com/services/rest/?method=<photos_method>&api_key=<api_key>&format=json&nojsoncallback=1&safe_search=1&tags=kitten&per_page=10&page=1

where, photos_method = flickr.photos.search api_key = 3e7cc266ae2b0e0d78e279ce8e361736 Please register at https://www.flickr.com/services/api/ in case the given api key does not work.

Build image url from response object (farm, server, id, secret are present in response object)

https://farm${this.farm}.staticflickr.com/${this.server}/${this.id}_${this.secret}_q.jpg

App structure

App follows below structure:

• model
  • Package contains POJO class for photo from api response.
• viewmodel
  • ImagesViewModel: ViewModel containing logic to fetch image urls and check cache if any bitmap is available else download bitmap from url.
• repository
  • Package contains class for fetching data repository of images list(JSON) and image i.e asyncTasks for fetching image urls and bitmaps.
  • DownloadImageTask: AsyncTask for downloading bitmap from given url. Also saves downloaded bitmap into cache.
  • FetchImageUrlsTask: AsyncTask for fetching images urls from Flickr api in chunks of 10 images per hit. Also parses json response.
• utils
  • Package contains utility class and generic cache class.
  • ImagesCache: Common LRU cache defined class. Any changes related to cache can be done here.
  • Utility: Utility class where HttpUrlConnection is defined for fetch images and download bitmaps.
• view
  • Package contains UI classes which needs to be shown on app.
  • MainActivity: Single activity which contains a fragment.
  • MainFragment: Fragment class which contains ImageView and two buttons which will be shown to the user.