Returns the rectangle where the legend will be located on the Canvas. It also returns LongestWidth, which contains the longest text width of any label in the Lines property. What rectangle the BoundsRect method returns is dependent on the ARect parameter first of all, the labels being displayed in Lines, then the Align property, the MaxWidthPct, MaxRows, and Overlay properties.
Use the BoundsRect method to determine where the legend will draw itself.
The Legend, unlike other TRSChartGraphic classes, does not completely fill the canvas rectangle you give it for the Draw method. Instead, based on the properties above, it calculates where it will be within the rectangle and then draws itself there.