Literal Style / add support for color interpolation

src/ol/style/LiteralStyle.js

@@ -17,11 +17,15 @@
  *   * `['time']` returns the time in seconds since the creation of the layer
  *
  * * Math operators:
- *   * `['*', value1, value1]` multiplies value1 by value2
- *   * `['+', value1, value1]` adds value1 and value2
- *   * `['clamp', value1, value2, value3]` clamps value1 between values2 and value3
- *   * `['stretch', value1, value2, value3, value4, value5]` maps value1 from [value2, value3] range to
- *     [value4, value5] range, clamping values along the way
+ *   * `['*', value1, value1]` multiplies `value1` by `value2`
+ *   * `['+', value1, value1]` adds `value1` and `value2`
+ *   * `['clamp', value, low, high]` clamps `value` between `low` and `high`
+ *   * `['stretch', value, low1, high1, low2, high2]` maps `value` from [`low1`, `high1`] range to
+ *     [`low2`, `high2`] range, clamping values along the way
+ *
+ * * Color operators:
+ *   * `['interpolate', ratio, color1, color2]` returns a color through interpolation between `color1` and
+ *     `color2` with the given `ratio`
  *
  * * Logical operators:
  *   * `['<', value1, value2]` returns `1` if `value1` is strictly lower than value 2, or `0` otherwise.
@@ -33,9 +37,13 @@
  *   * `['between', value1, value2, value3]` returns `1` if `value1` is contained between `value2` and `value3`
  *     (inclusively), or `0` otherwise.
  *
- * Values can either be literals (numbers) or another operator, as they will be evaluated recursively.
+ * Values can either be literals or another operator, as they will be evaluated recursively.
+ * Literal values can be of the following types:
+ * * `number`
+ * * `string`
+ * * {@link module:ol/color~Color}
  *
- * @typedef {Array<*>|number} ExpressionValue
+ * @typedef {Array<*>|import("../color.js").Color|string|number} ExpressionValue
  */
 
 /**