Create ImageLoading.md

docs/Architecture/ImageLoading.md

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+# Image Loading 
+
+For images FotoPresenter uses [Coil](https://coil-kt.github.io/coil/), an image loading library. 
+Coil is mainly used for loading images from URL, however it has the feature to load images using a [`Fetcher`](https://coil-kt.github.io/coil/image_pipeline/#fetchers). 
+This is done in common code in two Fetchers:
+* SMBJFetcher - takes in a directory
+* SharedImageFetcher - takes in a shared image
+
+These fetchers are defined in the `MainActivity` or `Main.kt` in the `setSingletonImageLoaderFactory`, then when `AsyncImage` takes in either a `SharedImage` or `NetworkDirectoryDetails` they are automatically handled.
+
+## SMBJFetcher
+
+When the directory screen is shown the `DirectoryViewModel` will call to update the directories contents. This gets the Paths and IDs of the images in the directory.
+
+Those directories are passed to the `AsyncImage` via the `UIState`, and handled by the `SMBJFetcher`.
+
+The `SMBJFetcher` starts out by calling the `ImageRepository`, which gets the Image from the network via the `SMBJHandler`.
+
+The `SMBJHandler`:
+* Opens the SMBJ File at the Path
+* reads the bytes from the File
+* closes the File
+
+Then `getFetchResult` is called, which will return a `FetchResult`, which is required for Coil.
+* For Android this will be a `ImageFetchResult` which contains a `Bitmap`
+* For Desktop this will be a `SourceFetchResult` which contains an `ImageSource`
+TODO: This can be updated
+
+Then that `FetchResult` is sent back to the `SMBJFetcher` where it is handled by Coil.
+
+### Potential updates
+
+I think this can be cleaned up.
+1. It doesn't make sense in my mind why you can't use `SourceFetchResult` for both Android and Desktop.
+2. The `ImageDirectory` doesn't necessarily need the `val image: SharedImage?`
+3. The Image only needs the `path` to work, there's no need to add the entire `NetworkDirectoryDetails`.
+4. There doesn't really seem to be a need to have two fetchers? In theory As long as you have the path to the image then that should be all you need.
+5. There are a lot of `UseCases` and other classes that could probably be taken out.