Complete Source refactor #2528
Description
This is a tracking issue for the refactor of iTowns' Source-derived classes and adjacent logic.
Context
The current source architecture and specific implementations leave much to be desired in terms of code quality, readability and extensibility due to the bastardized OO structure and API. As discussed and presented during the Spring 2025 Hackathon and following weekly meetings, we aim to completely redo sources, retaining only the business logic from their current state.
A complete rewrite directly in TypeScript provides significantly stronger soundness guarantees.
Tasks
- General structure and interfaces
- Working examples of each source variant
- Full implementation of all preexisting sources
Proposed structure
---
title: Proposed Source architecture
---
classDiagram
class Source~Key, Data~ {
<<Interface>>
+isSource: true
+load(key: Key) Data
}
note for Source "Blackbox interface that all sources must implement."
class Loader~Data~ {
<<Interface>>
+isLoader: true
+getData(uri: string) Data
}
note for Loader "Performs the fetching and parsing of data."
class RemoteSourceOptions~Key, Data~ {
<<Interface>>
+isRemoteSourceOptions: true
+loader: Loader~Data~
+crs: ProjectionLike
+url: string
+format: string
+networkOptions: RequestInit
}
Loader *-- RemoteSourceOptions
class RemoteSource~Key, Data~ {
<<Abstract>>
+isRemoteSource: true
+constructor(options: RemoteSourceOptions~Key, Data~)
+load(key: Key)* Promise~Data~
}
Source <|.. RemoteSource
RemoteSourceOptions <.. RemoteSource
class TmsSource~Data~ {
+isTmsSource: true
+zoom: Zoom
+isInverted: boolean
+tileMatrixSetLimits: Record~number, TmsLimit~
+extentSetLimits: Record~string, ExtentSetLimit~
+tileMatrixCallback: (level: number) string
-fetcher: Fetcher
+get url() string
+load(tile: Tile) Promise~Data~
}
RemoteSource <|-- TmsSource
class ProceduralSource~Key, Data~ {
<<Abstract>>
+isProceduralSource: true
+load(key: Key)* Data
}
Source <|.. ProceduralSource
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