inflate method
Increases the size of the GRect object by the specified amounts, in
pixels. The center point of the Rectangle object stays the same, and its
size increases to the left and right by the dx
value, and to the top and
the bottom by the dy
value.
Implementation
GRect inflate(double dx, double dy) {
x -= dx;
y -= dy;
width += dx * 2;
height += dy * 2;
return this;
}