Use Case: Remember Viewing State

Summary

• Scope: Map
• Level: User Goal
• Actors: App User
• Brief: The map's visibility settings are restored from the user's last session.
• Status: Andrei

Scenarios

• Precondition: The user is logged in and has opened a map.
• Main success scenario:
  • The user selects layer A.
    She zooms into the map.
    She scrolls/drags the map's viewport.
    She sets layer B invisible.
    She sets layer C with transparency.
    She turns off the grid display.
    She hides the plant labels.
    She resizes the toolbar.
    She changes the to the date D in the timeline.
    She closes the browser, opens it again and logs in. She opens the same map again which she edited in her previous session.
    She finds all the changes and settings from the last session being restored:
    • layer A selected
    • zoomed-in on the map
    • all plants visible on the map's viewport
    • layer B invisible
    • layer C has the same transparency
    • grid display turned off
    • plant labels hidden
    • toolbar resized
    • date D of timeline
• Alternative scenario:
  • The user does visibility changes on a map.
    She navigates to the seeds page.
    She uses browser-back to get back to the map.
    All the visibility changes the user applied before, are restored.
  • The user does visibility changes on map A.
    She opens another map B and changes some visibility settings there too.
    She goes back to map A and finds all the visibility changes she did on map A, still being applied.
    She goes back to map B and sees that all the visibility settings she changed on map B, are still being set.
• Error scenario: The app is experiencing technical difficulties and unable to restore one or more of the map's visibility settings, displaying an info message that the map's viewing state could not be fully restored.
• Postcondition:
  • The map is shown with the same visibility settings it had when the user left it the last time, which includes:
    • zoom
    • map's (x,y)-offset and zoom-level of the viewport
    • selected layer
    • all layers' visibility
    • grid display
    • plant labels display
    • toolbar sizes
• Non-functional Constraints:
  • Changes to maps while being in offline-mode, are not considered for restoring (for now).
  • Zustand's persist middleware should be used to store a map's state in a storage of any kind - not only do we already use Zustand as our global state management library, but it also supports de-/serialization of Maps and Sets.
    Persist's partialize option should then be used to only store the 'restore-worthy' data of a map.
  • Copy & Paste related data should not be restored, to not only reduce complexity of the storing/restoring- as well as the undo/redo-process, but also to prevent out-of-sync scenarios where copied elements are already deprecated/removed/outdated in the system/database. Besides that, applications offering the recovery of Copy & Paste state in a new session are extremely rare and therefore something the user does not necessarily expect to get.

Limitations

Not yet implemented:

• The user does visibility changes on a map in browser A. She logs in in another browser B. She opens the same map in browser B. All the visibility changes the user applied to the map in browser A, are restored in browser B.