BitmapImage DecodePixelHeight Property effects how RotatorTile functions

[michael-hawker]

Noticed this in the sample app. It looks like the first transition is correct, but every subsequent transition is shifting with a different image than the intended one. When the transition completes it swaps out the image as the final result:

You can see at the start the turtles appear and transition to the walkway, but then the transition to the skunk is messed up as it re-uses the sidewalk image for the slide instead of the skunk.

[michael-hawker]

I notice this issue in the previous and current sample apps, but I didn't notice it when trying to use the control on its own in another project.

[michael-hawker]

If I use this template instead:

  <Page.Resources>
        <DataTemplate x:Key="PhotoTemplate">
            <Grid>
                <Image HorizontalAlignment="Center"
                       Stretch="UniformToFill"
                       Source="{Binding Thumbnail}">
                </Image>
            </Grid>
        </DataTemplate>
    </Page.Resources>

It rotates correctly, but then blinks after each transition.

[michael-hawker]

The original issue is caused by setting DecodePixelHeight on the Bitmap Image for some reason. I've got a PR coming to remove that piece from the sample app.

Later, we should probably investigate later why this property has such a large effect on the control.

[michael-hawker]

Interesting, even with the fix, it'll still behave odd an app resume.