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How to know when ListView finished rendering elements?

    Question

  • I have a ListView with many items inside.

    After I assign the ListView an ItemsSource, I need to know when all items finished rendering on my page.

    I can just nothing with my eyes it takes like 2 seconds to render all elements, and I need to subscribe to an event like "ListView.RenderingCompleted", because I can proceed with other operations after all elements are rendered and visible to the user ( meanwhile I can show a loading bar ).

    I cannot find something similar, how can I do that?

    Monday, March 9, 2015 4:39 PM

Answers

  • >>I need to know when all items finished rendering on my page.

    I am afraid there is "all containers generated" event.

    The ListView uses UI virtualization so visual containers are only created for the currently visible items, i.e. not all the containers will be created at once.

    You could handle the Loaded event of the root item in the ItemTemplate to know when each individual container is ready for interaction:

    <ListView x:Name="listview" Height="200">
                <ListView.ItemTemplate>
                    <DataTemplate>
                        <Grid Loaded="grid_Loaded">
                            <TextBlock Text="{Binding}"></TextBlock>
                        </Grid>
                    </DataTemplate>
                </ListView.ItemTemplate>
            </ListView>

    If you know the approximate number of items you can then for example write some code in the code-behind that hides the loading bar when a certain number of Loaded events has been raised.

    Or you could possibly handle the Loaded event of the ListView. The Loaded event occurs when the element has been constructed, added to the visual tree and is ready for interaction.

    Please remember to close your threads by marking helpful posts as answer and please start a new thread if you have a new question.

    Monday, March 9, 2015 10:08 PM
  • Why are you trying to do this? Wouldn't it make more sense to let Windows just do its thing? Are there so many items in the list that it takes a long time to render them even after the data is generated?

    I would just show a 'loading bar' while downloading/processing/generating the data, then remove that once the data is loaded into the ListView. There should be no need to wait for anything. If you're populating the data asynchronously there is no need to wait for it to finish before proceeding with another task.

    What is the scenario here? Without more information it seems like you're doing it wrong.


    I'm a self-taught noob amateur. Please take this into account when responding to my posts or when taking advice from me.

    Friday, March 13, 2015 6:47 AM

All replies

  • >>I need to know when all items finished rendering on my page.

    I am afraid there is "all containers generated" event.

    The ListView uses UI virtualization so visual containers are only created for the currently visible items, i.e. not all the containers will be created at once.

    You could handle the Loaded event of the root item in the ItemTemplate to know when each individual container is ready for interaction:

    <ListView x:Name="listview" Height="200">
                <ListView.ItemTemplate>
                    <DataTemplate>
                        <Grid Loaded="grid_Loaded">
                            <TextBlock Text="{Binding}"></TextBlock>
                        </Grid>
                    </DataTemplate>
                </ListView.ItemTemplate>
            </ListView>

    If you know the approximate number of items you can then for example write some code in the code-behind that hides the loading bar when a certain number of Loaded events has been raised.

    Or you could possibly handle the Loaded event of the ListView. The Loaded event occurs when the element has been constructed, added to the visual tree and is ready for interaction.

    Please remember to close your threads by marking helpful posts as answer and please start a new thread if you have a new question.

    Monday, March 9, 2015 10:08 PM
  • I disabled virtualization using a StackPanel instead of an ItemsStackPanel as ItemsPanel.

    Unfortunately the Loaded event of the ListView fires before rendering is complete. It fires when control is loaded but not when all its content is rendered. I will try in this way:

    You could handle the Loaded event of the root item in the ItemTemplate to know when each individual container is ready for interaction:

    <ListView x:Name="listview" Height="200">
                <ListView.ItemTemplate>
                    <DataTemplate>
                        <Grid Loaded="grid_Loaded">
                            <TextBlock Text="{Binding}"></TextBlock>
                        </Grid>
                    </DataTemplate>
                </ListView.ItemTemplate>
            </ListView>

    If you know the approximate number of items you can then for example write some code in the code-behind that hides the loading bar when a certain number of Loaded events has been raised.

    I will write here it it works or if not during next days.</itemsstackpanel></stackpanel>

    Thanks


    • Edited by Dr Doctor Wednesday, March 11, 2015 8:33 AM
    Wednesday, March 11, 2015 8:33 AM
  • Why are you trying to do this? Wouldn't it make more sense to let Windows just do its thing? Are there so many items in the list that it takes a long time to render them even after the data is generated?

    I would just show a 'loading bar' while downloading/processing/generating the data, then remove that once the data is loaded into the ListView. There should be no need to wait for anything. If you're populating the data asynchronously there is no need to wait for it to finish before proceeding with another task.

    What is the scenario here? Without more information it seems like you're doing it wrong.


    I'm a self-taught noob amateur. Please take this into account when responding to my posts or when taking advice from me.

    Friday, March 13, 2015 6:47 AM