iAngle
The angle of rotation, expressed in hundredths of degrees. A value of 0 produces a horizontal halftone pattern. This parameter specifies the number of degrees to change the pattern. Positive values rotate the pattern clockwise; negative values rotate the pattern counterclockwise.
This value is ignored if the selected halftone pattern is HALFTONE_RECT, HALFTONE_CIRC, HALFTONE_RAND or HALFTONE_USERDEF.