IPieChartOptions.DoughnutRadius Property
Radius of the center of the doughnut in Percent. 0 Means a Pie without hole. Note that in xls charts, 0 means a Pie chart. In xlsx, 0 still means a doughnut chart, but without hole in the middle. It is not possible to have a doughnut chart without hole in xls.
Syntax
Unit: FlexCel.Core
property IPieChartOptions.DoughnutRadius: Integer