# OverlayUnit

Enumerates the unit types that an overlay viewport value may be.

Enumeration Members

- MinimumProportionOfCanvas

- Pixels

- ProportionOfCanvas

- ProportionOfOtherDimension

## Enumeration Members

### MinimumProportionOfCanvas

The value is specified as a portion of the viewing canvas’ minimum dimension. If the canvas is resized, the viewport’s dimensions will be recalculated based on the minimum of the X and Y proportions. This prevents the overlay from becoming oversized on very wide or very tall canvass.

### Pixels

The value is specified in CSS pixels.

### ProportionOfCanvas

The value is specified as a proportion of the viewing canvas. If the canvas is resized, the viewport’s dimensions will be recalculated accordingly. In this case the value should be specified in a range of 0.0 to 1.0.

### ProportionOfOtherDimension

The value is specified as a proportion its corresponding parameters calculated value. For example, given a viewport specified with width of 0.25 and unit type of ProportionOfCanvas, specifying height with value of 1.0 and type of ProportionOfOtherDimension will ensure that the calculated height value will be equal to the calculated width value should the canvas resize. In this case the value should be specified in a range of 0.0 to 1.0.