support for setting the diameter of pie charts from an attribute have been committed in r6962 .
the same functionality for bar charts has not been implemented as
- there are two variables to change (width /and/ height) => we'd need additional processing keywords
- the concept of dynamic size for a bar chart doesn't really make sense
this commit also supports setting
PROCESSING "CHART_SIZE_RANGE = itemname"
without the minsize,maxsize,minval,maxval values for when the diameter can be read directly from an attribute without need for rescaling