Sorry but the standard canvas draw text is only horizontal.
Its possible to get rotated text onto a canvas by copying to an image bank but its not so straightforward and the rotations are multiples of 90 degrees.
(1) Assumes original image in offscreen buffer (canvas 0)
(2) Write text to canvas 0
(3) Copy text section to image bank
(4) Rotate image bank
(5) Copy image bank to section of target canvas