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Belinda Bailey
Currently, data labels in Displayr support automatic contrast-aware font coloring via
data.label.font.autocolor
, which ensures readability by dynamically adjusting text color based on the background.
However, annotations (via
annotation.list
and
overlay.annotation.list
in
CChart()
) only support a fixed
color
parameter. This creates behavioral inconsistencies and can lead to readability issues when annotations are placed over varying chart colors.
Requested enhancement:
Introduce support for automatically coloring annotations, with functionality equivalent to that of data labels. This could include:
  • A parameter such as:
-
annotation.font.autocolor = TRUE
  • Or default behavior where annotation text automatically adjusts for contrast when no explicit color is set
Benefits:
  • Improved readability and accessibility
  • Consistency between annotations and data labels
  • Reduced need for manual formatting when chart palettes change
  • Better support for dynamic / template-driven reporting
Example use case:
In charts where data labels automatically switch between light/dark text depending on fill color, annotations currently remain fixed (e.g., always black), making them hard to read on darker backgrounds. Matching this behavior would resolve the issue.
Technical context:
Annotations are currently defined via:
```r
annotation.list = list(
list(type = ..., data = ..., color = ...)
)