Modal onDismiss support for Android

proposals/0000-modal-ondismiss-android.md

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+---
+title: Modal onDismiss support for Android
+author:
+- Bernhard Owen Josephus
+date: 2024-03-04
+---
+
+# RFC0000: Modal onDismiss support for Android
+
+## Summary
+
+Modal `onDismiss` event is currently not supported on Android. This proposal aims to add the `onDismiss` support for Android by sending the dismiss event from the native component.
+
+## Basic example
+
+```js
+<Modal onDismiss={() => textInputRef.current.focus()}>
+```
+
+## Motivation
+
+The `onDismiss` event is only supported on iOS. This means that there is currently no way to know when a modal is dismissed on Android. Adding the `onDismiss` support allows us to do an action after a modal is dismissed, for example, refocusing a text input.
+
+## Detailed design
+
+1. Make Modal's `onDismiss` in `Modal.js` works for all platforms
+
+This would require us to remove the iOS platform check (`Platform.OS === 'ios'`), except for `ModalEventEmitter`.
+
+2. Send dismiss event from Android native component
+
+First, we need to create a new event class called `DismissEvent.java`. The content will be the same as `ShowEvent.java`, except the event name will be `"topDismiss"`.
+
+Next, we need to register a modal/dialog dismiss listener that will dispatch `DismissEvent` in `ReactModalHostManager.addEventEmitters` and `ReactModalHostView.showOrUpdate`.
+
+Last, we need to store the `visible` props value and use it to control whether to show or dismiss the modal when the `onAfterUpdateTransaction` is called
+
+```java
+// ReactModalHostManager.java
+protected void onAfterUpdateTransaction(ReactModalHostView view) {
+  super.onAfterUpdateTransaction(view);
+  view.showOrDismiss();
+}
+
+// ReactModalHostView.java
+protected void showOrDismiss() {
+  if (mVisible) {
+    showOrUpdate();
+  } else {
+    dismiss();
+  }
+}
+```
+
+## Drawbacks
+
+- Increased code size
+- It could be a breaking change if an app expects the Android Modal never fires `onDismiss` event, for example:
+The code uses `onDismiss` to listen for modal dismiss event on iOS and uses another (workaround) approach on Android. If the `onDismiss` is starting to fire on Android too, they would receive two dismiss events.
+
+## Alternatives
+
+N/A
+
+## Adoption strategy
+
+Check if there is an existing code that expects the Android Modal to never fire `onDismiss` event. If there is any, they need to update the code to adapt to the new changes. 
+
+From the drawback breaking change example, they need to remove the dismiss event workaround for Android and start to fully rely on the Modal onDismiss prop.
+
+## How we teach this
+
+Update the docs to reflect that onDismiss is available on both platforms
+
+## Unresolved questions
+
+N/A