Permanently Enabled Scrollbars Possible?

Question

I am having a problem trying to come up with a way to keep ScrollBars/ScrollViewers permanently enabled. I am working on a Data Entry application where certain users might only have "read" rights. This needs to disabled all controls so they are not able to make any changes.

When a control is disabled the user cannot view all information in scrollable controls (Infragistics XamDataGrid, DevExpress GridControl, TextBoxes with Wrap, ListBox, etc). I was hoping I could "outsmart" Microsoft, and implement a Trigger to set IsEnabled to true when it was set to false, but of course, it didn't work (for a variety of reasons, I'm sure).

I've been focusing strictly on a textbox for now, to try to disabled the contents, but keep the ScrollViewer enabled and have had no luck.

I was hoping there might be a solution, I.E. Overriding the IsEnabled dependency property of the ScrollViewer to always return true, or provide some sort of Style that does not allow for the ScrollViewer to become disabled.

I know a TextBox has an IsReadOnly property, but this is of no use for many of the other controls I need to resolve this issue for.

Is there any way I can go about solving this, in a fairly simple manner (simple as in that I can make a style that's applied everywhere, without changing the 200+ code files).

Thanks

EDIT: Here is the code I'm using in a sample project to try to resolve this issue.

<Window x:Class="WPFScrollViewerStyles.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:Microsoft_Windows_Themes="clr-namespace:Microsoft.Windows.Themes;assembly=PresentationFramework.Aero"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="350" Width="525">
<Window.Resources>
    <Style BasedOn="{x:Null}" TargetType="{x:Type TextBox}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type TextBox}">
                    <Microsoft_Windows_Themes:ListBoxChrome x:Name="Bd" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" RenderMouseOver="{TemplateBinding IsMouseOver}" RenderFocused="{TemplateBinding IsKeyboardFocusWithin}" SnapsToDevicePixels="true">
                        <ScrollViewer x:Name="PART_ContentHost" HorizontalScrollBarVisibility="Visible" 
                                      SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" IsEnabled="True" />
                    </Microsoft_Windows_Themes:ListBoxChrome>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsEnabled" Value="false">
                            <Setter Property="IsEnabled" Value="True" TargetName="PART_ContentHost" />
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</Window.Resources>
<Grid IsEnabled="False">
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="100" />
        <ColumnDefinition Width="100" />
        <ColumnDefinition Width="100" />
    </Grid.ColumnDefinitions>
    <Grid.RowDefinitions>
        <RowDefinition Height="100" />
        <RowDefinition Height="100" />
        <RowDefinition Height="100" />
    </Grid.RowDefinitions>

    <TextBox x:Name="txtScroller" Width="100" Height="100" AcceptsReturn="True" VerticalScrollBarVisibility="Auto" TextWrapping="Wrap" ScrollViewer.CanContentScroll="True">
        Lorem ipsum dolor sit amet, consectetur adipiscing elit. Cras faucibus hendrerit lorem, auctor vehicula sem molestie nec. Quisque non massa quam. Nullam tempor blandit tempor. Integer in molestie ipsum. Donec augue mi, auctor vitae scelerisque a, vehicula ac ipsum. Etiam posuere vulputate augue quis convallis. Nullam aliquet purus nec lacus fermentum hendrerit egestas purus tincidunt. Suspendisse quis lacinia libero. Quisque facilisis turpis at augue dignissim aliquam ultrices sem porta. Etiam sagittis arcu id nibh ultrices dictum. Nulla non lectus luctus est malesuada luctus. Praesent sed lobortis nisi. Morbi et porttitor massa. Sed pellentesque, nisl eu imperdiet varius, ligula augue cursus nisl, eu egestas metus velit non elit. Phasellus elementum hendrerit risus, eu tincidunt ante gravida vel.
    </TextBox>

    <ListBox x:Name="lstScroller" Width="100" Height="100" Grid.Column="1">
        <ListBox.Items>
            <ListBoxItem Content="Item 1" />
            <ListBoxItem Content="Item 2" />
            <ListBoxItem Content="Item 3" />
            <ListBoxItem Content="Item 4" />
            <ListBoxItem Content="Item 5" />
            <ListBoxItem Content="Item 6" />
            <ListBoxItem Content="Item 7" />
            <ListBoxItem Content="Item 8" />
            <ListBoxItem Content="Item 9" />
            <ListBoxItem Content="Item 10" />
            <ListBoxItem Content="Item 11" />
            <ListBoxItem Content="Item 12" />
            <ListBoxItem Content="Item 13" />
            <ListBoxItem Content="Item 14" />
            <ListBoxItem Content="Item 15" />
        </ListBox.Items>
    </ListBox>
</Grid>

I got the brilliant idea to use the code posted here: http://stackoverflow.com/questions/974598/find-all-controls-in-wpf-window-by-type to find all instances of the "ScrollViewer" class in the window. I loop through each of these instances when the control is disabled and set the IsEnabled property to true. As brilliant as this idea seemed, it still proved to be a futile effort. — Travis, Mar 01 '11 at 20:48

score 5 · Accepted Answer · answered Mar 01 '11 at 23:54

Thanks to Cedric Dussud over at Microsoft, I have found a solution.

For reference: http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/3bf5e186-845c-4b63-acd9-17d294a30f77

Rather than subclassing the ScrollViewer control, I override the Metadata in the Application_Startup event of the application, like so:

ScrollViewer.IsEnabledProperty.OverrideMetadata(typeof(ScrollViewer), new UIPropertyMetadata(true, new PropertyChangedCallback(ScrollViewer_IsEnabledPropertyChanged), new CoerceValueCallback(ScrollViewerForceEnabled)));

I then handle the CoerceValueCallback to always return true, like so:

        private static void ScrollViewer_IsEnabledPropertyChanged(DependencyObject source, DependencyPropertyChangedEventArgs args) { }
    private static object ScrollViewerForceEnabled(DependencyObject source, object value)
    {
        return true;
    }

According to Cedric, this might have unforeseen consequences, but as of now (and my all mighty test application with a disabled grid and two scrollable controls) I have not found one. Hopefully this solution can help someone else out, without problems.

I have found an issue with this solution, pretty minor in the grand scheme of things. This will cause any controls nested inside of a ScrollViewer to also be enabled, when it's containing control is disabled. The solution is to edit the ControlTemplate of the inner item (ContentPresenter/ItemsPresenter/etc) with IsEnabled="{TemplateBinding IsEnabled}" Pretty simple fix overall, and accomplishes exactly what I need. I found this on a ListBox, but I'm sure more instances will arise over time... — Travis, Mar 03 '11 at 15:47
Thanks, this works. But there is one issue: If you start the parent control off in a disabled state, you have to enable the control and disable it again to make it work. The Coerce needs to be run once at the beginning. — brenth, Feb 16 '18 at 19:35

score 2 · Answer 2 · edited Sep 23 '12 at 21:31

I know this is an old question, but I think I found a similar but simpler solution which may help others: instead of overriding the propert metadata for the ScrollViewer's IsEnabledProperty, I applied excatly the same approach, but to the the ScrollBar's IsEnabledProperty. This seems to work okay and doesn't require me to create and apply a new template to the scroll-viewers. The only draw-back seems to be that the mouse-wheel and page-up/down keyboard commands do not work (since the scroll viewer itself is still disabled). The override metadata code is:

ScrollBar.IsEnabledProperty.OverrideMetadata(
  typeof(ScrollBar),
  new FrameworkPropertyMetadata(
  (PropertyChangedCallback) null,
  (CoerceValueCallback) AlwaysCoerceToTrue));

and the 'AlwaysCoerceToTrue' method is:

private static object AlwaysCoerceToTrue(DependencyObject o, object value)
{
    return true;
}

This is a better solution for me since the children of the scrollviewer arent affected. — buckley, Oct 30 '12 at 14:39
this one is causing the whole control enabled, which is similar to no effect on the control — BrainCoder, Mar 14 '16 at 06:28

Vlad · Answer 3 · 2011-03-01T00:44:09.570

0

I think you can restyle the UI elements, making them use a control template that includes

<ScrollViewer HorizontalScrollBarVisibility="Visible"
              VerticalScrollBarVisibility="Visible" ... />

For example, for the TextBox you can use a modified default control template:

<ControlTemplate TargetType="{x:Type TextBoxBase}">
    <Border Name="Border" CornerRadius="2" Padding="2" BorderThickness="1">
        ...
        <ScrollViewer Margin="0" x:Name="PART_ContentHost" 
                      HorizontalScrollBarVisibility="Visible"
                      VerticalScrollBarVisibility="Visible"/> <!-- HERE -->
    </Border>
</ControlTemplate>

edited Mar 01 '11 at 00:44

answered Mar 01 '11 at 00:38

Vlad

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Hi Vlad, The problem isn't that scrollbars aren't visible, it's that they are disabled and don't work. I will edit the original post and post some XAML of a textbox and listbox. When disabled, the scrollbars are still visible (when necessary) they just won't scroll. Thanks for the response and idea though. – Travis Mar 01 '11 at 15:35

Permanently Enabled Scrollbars Possible?

3 Answers3