Sometimes there is a requirement of coloring a line chart depending on some reference value.
Background color expression is not always suitable, because the line segments are colored according to the start point.
As a workaround I suggest to use another approach based on a background image.
Usually it doesn’t contradict with the requirements because the areas above and below are just as important as the reference value.
Shortly it’ can be described in three steps:
- Background image
- Dynamic Min/Max calculation
- Dynamic reference calculation
These steps are described in the doc.
The sample is also attached.