Bug 31081 - ListView.LastItemAppearing
Summary: ListView.LastItemAppearing
Status: RESOLVED ANSWERED
Alias: None
Product: Forms
Classification: Xamarin
Component: Forms ()
Version: 1.4.4
Hardware: All All
: --- normal
Target Milestone: ---
Assignee: Bugzilla
URL:
Depends on:
Blocks:
 
Reported: 2015-06-12 16:09 UTC by Kasper
Modified: 2015-06-16 13:47 UTC (History)
3 users (show)

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

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Status:
RESOLVED ANSWERED

Description Kasper 2015-06-12 16:09:39 UTC
This is perhaps not a bug per se, but more of a feature request. 

Could you add a: 

public event EventHandler<ItemVisibilityEventArgs> LastItemAppearing;

to ListView. The event should be raised when the last item in the item source appears. This will allow us to implement lazy loading with ease.

The semantic should be like this "pseudo" code:

    public class MyListView : ListView {
        public event EventHandler<ItemVisibilityEventArgs> LastItemAppearing;

        public MyListView ()
        {
            this.ItemAppearing += (s, e) => {
                if (e.Item == ItemsSource.LastOrDefault())
                    LastItemAppearing?.Invoke(s, e);
            };
        }
    }  

The problem with the above code is, that LastOrDefault() cannot be implemented in an efficient manner. Hence the feature request.
Comment 1 Eric Maupin 2015-06-16 13:47:22 UTC
Thank you for your feature request.