New flet build settings (Android SDK version, boot/startup screens) (#405)

* Android SDK version settings

* Android SDK version settings and app element in manifest

* Boot and Startup screens

Author: FeodorFitsner

docs/publish/android.md

@@ -98,6 +98,59 @@ Configuring splash in `pyproject.toml`:
 android = false
 ```
 
+## Android SDK version settings
+
+### `min_sdk_version`
+
+* Defines the minimum Android version (API level) your app can run on.
+* If a device has a lower version than `min_sdk_version`, your app won’t install or run on that device.
+* Increasing this value means dropping support for older devices.
+
+Configuring in `pyproject.toml`:
+
+```toml
+[tool.flet.android]
+min_sdk_version = 21
+```
+
+If `min_sdk_version` = `21`, your app will not install on Android 4.4 (API 19) or lower.
+
+Default is `21`.
+
+### `target_sdk_version`
+
+* Defines the Android version your app is optimized for.
+* Your app can run on higher Android versions but will behave as if it’s running on `targetSdkVersion` unless explicitly adapted.
+* Google Play requires you to update this regularly to meet new Android requirements.
+
+Configuring in `pyproject.toml`:
+
+```toml
+[tool.flet.android]
+target_sdk_version = 34
+```
+
+If `targetSdkVersion` = `34`, your app will run on Android 14 and above with the latest system behaviors. On newer Android versions, some strict security and API changes may apply automatically.
+
+Default `target_sdk_version` is `35`.
+
+#### Key differences
+
+| Feature           | `min_sdk_version` | `target_sdk_version` |
+|------------------|-----------------|------------------|
+| Defines...      | **Minimum Android version** required to install & run the app | **Optimized Android version** for best compatibility |
+| Impact          | Lowering it allows **more devices** to install the app | Raising it allows access to **newer Android features** |
+| If set too low | App may not support modern APIs & security | App might not follow latest Android restrictions |
+| If set too high | App won't install on older devices | No major downside (except adapting to new behaviors) |
+
+Configuring both settings in `pyproject.toml`:
+
+```toml
+[tool.flet.android]
+min_sdk_version = 21
+target_sdk_version = 34
+```
+
 ## Permissions
 
 Configuring Android permissions and features to be written into `AndroidManifest.xml`:
@@ -177,6 +230,16 @@ host = "mydomain.com"
 
 See [Deep linking](https://docs.flutter.dev/ui/navigation/deep-linking) section in Flutter docs for more information and complete setup guide.
 
+## Manifest application element properties
+
+Adding custom properties to `<application>` element in `AndroidManifest.xml`:
+
+```toml
+[tool.flet.android.manifest_application]
+usesCleartextTraffic = "true"
+requestLegacyExternalStorage = "true"
+```
+
 ## Troubleshooting Android
 
 To run interactive commands inside simulator or device:

docs/publish/index.md

@@ -210,6 +210,46 @@ ios = false # --no-ios-splash
 android = false # --no-android-splash
 ```
 
+## Boot screen
+
+Boot screen is shown while the archive with Python app is being unpacked to a device file system.
+It's shown after splash screen and before startup screen. App archive does not include 3rd-party site packages.
+If the archive is small and its unpacking is fast you can keep that screen disabled (default).
+
+To enable boot screen in `pyproject.toml` for all target platforms:
+
+```toml
+[tool.flet.app.boot_screen]
+show = true
+message = "Preparing the app for its first launch…"
+```
+
+Boot screen can be enabled for specific platforms only or its message customized. For example, enabling it for Android only:
+
+```toml
+[tool.flet.android.app.boot_screen]
+show = true
+```
+
+## Startup screen
+
+Startup screen is shown while the archive with 3rd-party site packages (Android only) is being unpacked and Python app is starting. Startup screen is shown after boot screen.
+
+To enable startup screen in `pyproject.toml` for all target platforms:
+
+```toml
+[tool.flet.app.startup_screen]
+show = true
+message = "Starting up the app…"
+```
+
+Startup screen can be enabled for specific platforms only or its message customized. For example, enabling it for Android only:
+
+```toml
+[tool.flet.android.app.startup_screen]
+show = true
+```
+
 ## Entry point
 
 By default, `flet build` command assumes `main.py` as the entry point of your Flet application, i.e. the file with `ft.app(main)` at the end. A different entry point could be specified with `--module-name` argument or in `pyproject.toml`: