Halo outline rendering

In addition to the Outline styling options that are available for all generic draw objects, you can enable a global "halo outline" which will be rendered around all included draw objects, including tactical graphics with advanced line textures.

This can be enabled through styling:

      <compositeitem name="Line">
        <valueitem name="DrawHaloOutline" value="true" />
      </compositeitem>

or through the DrawHaloOutline data field.

The color and thickness of this outline is controlled through code by the following properties in the IMariaDrawObjectLayer interface:

        /// <summary>
        /// Shared outline color used for draw objects whose Line.DrawHaloOutline styling is enabled.
        /// </summary>
        Color HaloOutlineColor { get; set; }

        /// <summary>
        /// Shared outline thickness in logical pixels. Note that high values here
        /// might cause performance issues. Default: 3.0
        /// </summary>
        double HaloOutlineThickness { get; set; }

The purpose of this feature is mainly to improve visibility and readability of tactical graphics. For styling of individual objects, see the Outline styling options of the Line Styling documentation.

Note: This currently does not include point symbols, only vector objects.