Construct a rounded rectangle from its left, top, right, and bottom edges, and the same radius in each corner.
Source
RRect.fromLTRBR(double left, double top, double right, double bottom,
Radius radius) {
_value
..[0] = left
..[1] = top
..[2] = right
..[3] = bottom
..[4] = radius.x
..[5] = radius.y
..[6] = radius.x
..[7] = radius.y
..[8] = radius.x
..[9] = radius.y
..[10] = radius.x
..[11] = radius.y;
}