Conditional XAML

To reduce load time or to increase layout performance one may need to conditionally detach layout controls from visual tree. For example, when layout part loads images from the Net, but a user has disabled image loading in the application settings, XAML layout does not need to load the view part responsible for image showing.

In Angular, there is a NgIf directive that solves this issue. So please, take a look: https://angular.io/api/common/NgIf

So, maybe Avalonia framework should have such control in its standard library? Something named AvalonIf that we can use in our application like this:

<AvalonIf Value="{Binding ShouldLoad, Mode=OneWay}">
    <Image Source="{Binding Image, Mode=OneTime}"/>
</AvalonIf>

Thanks!

[maxkatz6]

UWP has build in x:DeferLoadStrategy attribute for lazy loading and x:Load attribute (Creators Update+) for loading and unloading with binding, which can replace UwpIf/AvaloniaIf

<Grid>
    <Image x:Name="MyImage" 
           x:DeferLoadStrategy="Lazy" 
           Source="{Binding Image, Mode=OneTime}"
           Visibility="Collapsed"/>
    <VisualStateManager.VisualStateGroups>
      <VisualStateGroup>
        <VisualState>
          <VisualState.StateTriggers>
            <StateTrigger IsActive="{Binding ShouldLoad, Mode=OneWay}"/>
          </VisualState.StateTriggers>
          <VisualState.Setters>
            <Setter Target="MyImage.Visibility"
                    Value="Visible"/>
          </VisualState.Setters>
        </VisualState>
    </VisualStateManager.VisualStateGroups>
</Grid>

Or

    <Image x:Load="{Binding ShouldLoad, Mode=OneWay}" 
           Source="{Binding Image, Mode=OneTime}"/>

[maxkatz6]

@robloo, yes, it does.

<Panel>
   <OnPlatform>
       <OnPlatform.Default>
            <DataGrid />
       </OnPlatform.Default>
       <OnPlatform.Android>
            <ListBox />
       </OnPlatform.Android>
   </OnPlatform>
</Panel>

It will be translated into IL code like: Panel.Children.Add(IsOnAndroid() ? new ListBox() : new DataGrid()) which means only one “branch” will be executed and intialized.

This, or users can use OnFormFactor which has Mobile or Default options, which is closer to what you asked.