There are six arguments for transform() and setTransform():
transform(a, b, c, d, e, f) setTransform(a, b, c, d, e, f)
Those six arguments are used in equations that encompass all the equations that we've seen for translating, scaling, and rotating.
x' = ax + cy + e y' = bx + dy + f
The letters a...f represent the six arguments to transform() and setTransform().
The arguments e and f, when combined with a = 1, b = 0, c = 0, and d = 1, represent a pure translation.
Those equations simplify as the follows:
x' = x + e y' = y + f
To scale, you use the arguments a and d, with all the other arguments set to 0.
Those equations simplify to the equations.
x' = ax y' = dy
To rotate about the origin through an angle in radians, use the following arguments:
x' = cos(angle) times x + sin(angle) times y + 0 y' = sin(angle) times x + cos(angle) times y + 0