Bug 40922 - ListView ItemAppearing Fires on Every Row On Each Add
Summary: ListView ItemAppearing Fires on Every Row On Each Add
Alias: None
Product: Forms
Classification: Xamarin
Component: Windows ()
Version: 2.2.0
Hardware: PC Windows
: --- normal
Target Milestone: ---
Assignee: Paul DiPietro [MSFT]
Depends on:
Reported: 2016-05-05 22:30 UTC by Ray Kelly
Modified: 2017-06-19 17:50 UTC (History)
3 users (show)

Is this bug a regression?: ---
Last known good build:

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Description Ray Kelly 2016-05-05 22:30:36 UTC
When a ListView is bound to an ObservableCollection, adding an object causes ItemAppearing to fire once for every item regardless if its already shown or not.

For instance.  

List View Items 1
IteamAppearig fires once

Add 1 item to collection
IteamAppearing fires twice

Add 1 item to collection
IteamAppearing 3 times

Add 1 item to collection
IteamAppearing 4 times

This may only happen if unevenrows set to true.
Comment 1 Paul DiPietro [MSFT] 2016-06-14 20:48:35 UTC
We'd be happy to help you resolve this issue. Please help us by attaching a reduced reproduction to the bug by starting with a clean Xamarin.Forms project and adding just the code necessary to demonstrate the issue. If you'd do this for us we would very much appreciate it. If you are able to reproduce the issue without modifying the platform specific projects that would eliminate a number of possibilities and likely expedite a resolution. 

Warm regards,
Xamarin Forms Team
Comment 2 Ray Kelly 2016-09-12 17:51:19 UTC
I believe this is related to this bug


As you "scrollto" to the bottom, it fires the ItemAppearing for every row (like 1000) and the screen flickers as it scrolls top to bottom.
Comment 3 Paul DiPietro [MSFT] 2017-06-19 17:50:41 UTC
This issue will be closed as the referred to issue appears to have been resolved. Please reopen this and attach a minimized reproduction project if the issue still exists as of the latest prerelease or nightly build.