Sticky Header Flickering

4 posts, 0 answers
  1. Shawn
    Shawn avatar
    30 posts
    Member since:
    Mar 2011

    Posted 25 May 2012 Link to this post

    Occassionally while scrolling with a Sticky Header, the item underneath (assuming that's what it is) is flickering through. Any idea why this might be happening? I am using a Sticky header that is the width of the page. Here is the template for my Sticky header (same as I am using for my group header:

    <DataTemplate x:Name="customerJumpListHeader">
        <Grid HorizontalAlignment="Stretch"
                Background="Black">
            <Border Background="{StaticResource PhoneAccentBrush}"
                    Padding="{StaticResource PhoneTextBoxInnerMargin}"
                    HorizontalAlignment="Left"
                    Width="50"
                    Height="50"
                    Margin="{StaticResource PhoneBorderThickness}">
                <TextBlock Text="{Binding Key}"
                            HorizontalAlignment="Left"
                            VerticalAlignment="Bottom"
                            FontSize="28"
                            Foreground="{StaticResource PhoneForegroundBrush}"
                            Style="{StaticResource PhoneTextExtraLargeStyle}"
                            FontFamily="Segoe WP"
                            Margin="6,0,0,0" />
            </Border>
        </Grid>
    </DataTemplate>

    Any hints on making it stop flickering? (perhaps setting the grid's width?)

    UPDATE: Seems that this may be related to the fact that the item container for the jumplist starts at that same level as the sticky header. Which means that the change in in the sticky header isn't affected until it is scrolled up past the height of the sticky header. 
  2. Deyan
    Admin
    Deyan avatar
    2038 posts

    Posted 28 May 2012 Link to this post

    Hello Shawn,

    Thanks for writing.

    RadJumpList now uses the native ScrollViewer component since this allows us to utilize the offthread manipulation approach for scrolling introduced in Windows Phone Mango. This greatly optimizes user experience when using the scrollviewer since scrolling is performed on a separate thread which makes scrolling smooth and responsive while the UI virtualization mechanism works on the UI thread. These performance improvements, however, imply some limitations for third party developers. For instance, the scrolling properties exposed by the ScrollViewer component are updated on the UI thread in certain intervals like when the user scrolls 1/4 of the viewport's length. This does not allow us to always know the exact scrolling position and thus updating the sticky header is a bit tricky.

    We hope that in future releases Microsoft will improve their APIs thus making it possible for us to fine tune the behavior of some user experiences within our controls.

    Let me know in case you have further questions or need assistance.

    Greetings,
    Deyan
    the Telerik team

    Explore the entire Telerik portfolio by downloading the Ultimate Collection trial package. Get it now >>

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  4. Shawn
    Shawn avatar
    30 posts
    Member since:
    Mar 2011

    Posted 22 Jun 2012 Link to this post

    Not thrilled by this answer. If you can't make it work they you shouldn't have released the control...period.
  5. Deyan
    Admin
    Deyan avatar
    2038 posts

    Posted 25 Jun 2012 Link to this post

    Hello Shawn,

    Thanks for writing back.

    Is it possible that you isolate the case in a separate project and send it to us for further investigation? Pasting a sample code that is sufficient for us to reproduce the scenario on our side is also an option. The reasons mentioned in my previous post are probably the cause for the behavior but we want to make sure that there aren't any further issues that might be causing the glithes.

    Please note that you will have to open a new support ticket in order to be able to attach your project.

    All the best,
    Deyan
    the Telerik team

    Explore the entire Telerik portfolio by downloading the Ultimate Collection trial package. Get it now >>

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