Function useMessageTargetParameters

native/chat/utils.js:91–171

(
  sourceMessage: ChatMessageInfoItemWithHeight,
  initialCoordinates: LayoutCoordinates,
  messageListVerticalBounds: VerticalBounds,
  currentInputBarHeight: number,
  targetInputBarHeight: number,
  sidebarThreadInfo: ?ThreadInfo,
)

}

function useMessageTargetParameters(
  sourceMessage: ChatMessageInfoItemWithHeight,
  initialCoordinates: LayoutCoordinates,
  messageListVerticalBounds: VerticalBounds,
  currentInputBarHeight: number,
  targetInputBarHeight: number,
  sidebarThreadInfo: ?ThreadInfo,
): {
  +position: number,
  +color: string,
} {
  const messageListData = useNativeMessageListData({
    searching: false,
    userInfoInputArray: [],
    threadInfo: sidebarThreadInfo,
  });

  const [messagesWithHeight, setMessagesWithHeight] =
    React.useState<?$ReadOnlyArray<ChatMessageItemWithHeight>>(null);
  const measureMessages = useHeightMeasurer();

  React.useEffect(() => {
    if (messageListData) {
      measureMessages(
        messageListData,
        sidebarThreadInfo,
        setMessagesWithHeight,
      );
    }
  }, [measureMessages, messageListData, sidebarThreadInfo]);

  const sourceMessageID = sourceMessage.messageInfo?.id;
  const targetDistanceFromBottom = React.useMemo(() => {
    if (!messagesWithHeight) {
      return 0;
    }

    let offset = 0;
    for (const message of messagesWithHeight) {
      offset += chatMessageItemHeight(message);
      if (message.messageInfo && message.messageInfo.id === sourceMessageID) {
        return offset;
      }
    }

    return (
      messageListVerticalBounds.height + chatMessageItemHeight(sourceMessage)
    );
  }, [
    messageListVerticalBounds.height,
    messagesWithHeight,
    sourceMessage,
    sourceMessageID,
  ]);

  if (!sidebarThreadInfo) {
    return {
      position: 0,