android-developer-programming.md

EPIC (Earth Polychromatic Imaging Camera) Imagery

API Information

API interaction

• Find available dates via the all endpoint. This returns a JSON array of objects containing date strings indicating the dates that have image data available. The date string is used in the URL of the next call.
• Find images for a given date via the date endpoint. This returns a JSON array of objects. Each object has an identifier, a timestamp, and a filename fragment. You can use the timestamp and the filename fragment to derive the image URL.
• Fetch the images for a given date via an archive URL.

App Specification

• Day list (home screen):
  • A list that shows the dates with available data. Each row will show a date. On the left side of the row, there will be an indicator:
    • If no data is downloaded for that day, show an empty circle.
    • If data is being downloaded for that day, show a progress indicator.
    • If all data is downloaded for that day, show a checkmark.
  • Selecting a row takes you to the photo list.
• Photo list:
  • A grid view of images for this day.
  • If an image has been downloaded, show a thumbnail of the image.
  • If the image is being downloaded, show a progress indicator similar to the one used above. A placeholder thumbnail should be shown.
  • Tapping the area of a downloaded image takes you to the photo screen.
  • In the toolbar menu at the top of the screen is a play icon. This button is disabled while this day’s downloads are in progress. Tapping this takes you to the player screen.
• Photo screen
  • Show a downloaded photo scaled to fit the screen.
  • Allow the user to pinch to zoom, use one finger to pan the image.
  • Provide a menu icon on the toolbar to show metadata about the photo.
• Player screen
  • Show an animated sequence of the images for the day. The animation should proceed at 24 frames per second.
  • Sliding one finger over the image should scrub forward or backward through the animation.
  • Allow the user to pinch to zoom, use two fingers to pan the image.

Skills

• UI
  • Recycler view (ViewHolders and Adapters with both LinearLayoutManager and GridLayoutManager)
  • Animating a sequence of images
  • Controlling animation via touch gestures
• Networking
  • Sequentially chained network calls
  • JSON parsing
  • File downloading
• Data management
  • Image and metadata caching
• Concurrency
  • Multiple downloads in parallel
  • Background processing of downloaded image data
  • Non-blocking UI shows data as it arrives