document app icon generation

README.md

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 # WeForza App
 
+### Application icons
+
+To generate both application launcher icons and splash screen icons,
+you need a square vector asset (SVG) which contains a foreground layer (the icon itself)
+and a background layer (the background that fills the square).
+
+This asset should have its foreground layer fit within the inner 2/3 of the asset itself.
+For example, an asset that has a view box of 600x600 will only show its inner 400x400 pixels.
+
+#### Split the foreground and background layer
+
+Given the SG asset, create two copies of it.
+In a text editor of your choice, remove the background layer from the first copy. This file is now your foreground asset.
+In a text editor of your choice, remove the foreground layer from the second copy. This file is now your background asset.
+
+Now you should have the original asset, a foreground variant and a background variant.
+
+#### Generating iOS app icons and launch screen images
+
+For iOS, generating the app icons and launch screen images is straightforward, as the formats are predefined in XCode.
+
+1) Generate the app icons using the image generation script and use the original asset as input,
+since the app icon contains both a foreground and background layer.
+Update the `AppIcon.appiconset` folder with the newly generated images.
+
+2) Generate the launch screen images using the image generation script and use the foreground asset as input.
+Update the `LaunchImage.imageset` folder with the newly generated images.
+Finally, if not already set up, update the background color of the Launch Screen in XCode.
+
+#### Generating Android app icons
+
+1) Generate the app icon mipmaps using [Android Asset Studio](https://developer.android.com/studio/write/create-app-icons#access).
+This generates various `ic_launcher` assets, which refer to the Application Launcher. These assets are the app icons.
+
+#### Generating Android Splash Screen assets
+
+On Android S and higher, the splash screen is composed of the `windowSplashScreenBackground` and `windowSplashScreenAnimatedIcon`.
+The animated icon can be set to a vector asset and is typically set to the foreground layer of the app icon.
+
+On Android R and lower, the splash screen is defined by the `windowBackground`. This is usually set to a drawable resource.
+
+This drawable resource is composed of a background color and a bitmap.
+The bitmaps can be generated using the image generation script, using the app icon foreground layer as input.
+The generated `logo.png` files in the various `drawable/<dpi>` folders are the output bitmaps.
+
 ### Translations
 
 The application uses `flutter gen-l10n` to generate the translations.