For drawing a filled rectangle, onto this Image.

.fillRect( x, y, width, height, isCentred=false )

Draws a filled rectangle. The x/y location refers to either the top-left corner, or the middle, depending on if 'isCentred' is false or true. The 'width' and 'height' are the total size of the rectangle.

.fillRect( x, y, width, height, xAlign, yAlign )

Draws a filled rectangle, but also provides x and y alignment options. See the article on How Alignment Works for more information.