Construct a rounded rectangle from its bounding box and a radius that is the same in each corner.
Source
RRect.fromRectAndRadius(Rect rect, Radius radius) {
_value
..[0] = rect.left
..[1] = rect.top
..[2] = rect.right
..[3] = rect.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;
}