Dev:BlendMethods

alphabetically                  numerically

add              4              composite        0
alpha brighten  14              straight         1
alpha darken    15              brighten         2
alpha over      19              darken           3
behind          12              add              4
brighten         2              subtract         5
color            8              multiply         6
composite        0              divide           7
darken           3              color            8
difference      18              hue              9
divide           7              saturation      10
hard light      17              luminance       11
hue              9              behind          12
luminance       11              onto            13
multiply         6              alpha brighten  14
onto            13              alpha darken    15
overlay         20              screen          16
saturation      10              hard light      17
screen          16              difference      18
straight         1              alpha over      19
straight onto   21              overlay         20
subtract         5              straight onto   21