HasUnevenRows fires ItemAppearing for invisible screen items when the cell is an Image

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a/listviewe/5 :clock5:help wantedinactivep/Androidt/bug :bug:up-for-grabs

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Descrizione

Description

If a ListView has cells that are made up of only Image instances (or wrapper layouts whose only content is an Image) and HasUnevenRows is set to true, then ItemAppearing will be fired for virtually every list item even if it does not appear on the screen. This is bad for scenarios involving infinite scrolling. The issue seems to exist on both Android and iOS.

Ref: an old issue (27845) that's been resolved.

Steps to Reproduce

Run the attached repro
Observe that ItemAppearing is fired for dozens of items even though it should be fired only a few times upon page load

Reproduction Link

App2.zip

Guida contributor

Direzione di ricerca: Riprodurre il problema eseguendo l'app allegata. Analizzare la logica di misurazione e layout di ListView con HasUnevenRows, in particolare quando le celle contengono solo immagini. Cercare dove viene attivato ItemAppearing e perché viene attivato per elementi fuori schermo.
Tech stack: csharp
Dominio: frontend
Tipo issue: Bug
Difficoltà: 2
Tempo stimato: 1-3 ore
Stato attività: Datata
Chiarezza: Chiara
Prerequisiti: csharp
Adatta ai principianti: 70