Aspect Ratio
An aspect ratio can be defined by providing the controlling axis relationship and then the actual ratio.
WidthControlsHeightThe width drives the heightHeightControlsWidthThe height drives the widthImageAspectThe aspect ratio is derived from the element'sBackgroundImage
style aspect {
AspectRatio = WidthControlsHeight 2 : 1;
AspectRatio = HeightControlsWidth 4 : 5;
AspectRatio = ImageAspect;
}