Source
T get width => _width;
Sets the width of the rectangle.
The width must be non-negative. If a negative width is supplied, it is clamped to zero.
Setting the value will change the right edge of the rectangle, but will not change left.
Source
void set width(T width) {
if (width < 0) width = _clampToZero/*<T>*/(width);
_width = width;
}