[Bug report] Cannot keep position scroll offset when the streamed message content is too long.

[Kakapoo101]

5040878800106541190.mp4

chatObserver = ChatScrollObserver(observerController) ..fixedPositionOffset = -double.maxFinite ..toRebuildScrollViewCallback = () { setState(() {}); };

Look at the video. Everything is fine until 0:16 - then the scroll offset is no longer maintained and keeps getting pushed up continuously. How can I handle this case? Thanks, everyone!

[LinXunFeng]

In this example, ChatScrollObserverHandleMode.generative is used, which needs to rely on the previous message item as a reference, that is, the referenced item needs to be rendered, and the solution is as described in #111 (comment). You need to control the size of the message item or adjust the value of cacheExtent.

Excerpted from the last paragraph of [3.1、Basic usage]

---

There is also a way that does not rely on the previous message item. It specifies the reference to the latest message itself, but it is necessary to know the size difference of the latest message item before and after the update, and return it in customAdjustPositionDelta. Of course, you can also return the new offset of the ScrollView used to keep the position in customAdjustPosition.

standby(
  mode: ChatScrollObserverHandleMode.specified,
  refIndexType: ChatScrollObserverRefIndexType.itemIndex,
  refItemIndex: 0,
  refItemIndexAfterUpdate: 0,
  // Returns the size difference of item before and after update
  // customAdjustPositionDelta: (model) {},
  // Returns the new offset
  customAdjustPosition: (model) {},
)