Specifies how YUV (and optionally A) are divided among planes. Planes are separated by
underscores in the enum value names. Within each plane the pixmap/texture channels are
mapped to the YUVA channels in the order specified, e.g. for kY_UV Y is in channel 0 of plane
0, U is in channel 0 of plane 1, and V is in channel 1 of plane 1. Channel ordering
within a pixmap/texture given the channels it contains:
A: 0:A
Luminance/Gray: 0:Gray
Luminance/Gray + Alpha: 0:Gray, 1:A
RG 0:R, 1:G
RGB 0:R, 1:G, 2:B
RGBA 0:R, 1:G, 2:B, 3:A
UV subsampling is also specified in the enum value names using J:a:b notation (e.g. 4:2:0 is
1/2 horizontal and 1/2 vertical resolution for U and V). If alpha is present it is not sub-
sampled. Note that Subsampling values other than k444 are only valid with PlaneConfig values
that have U and V in different planes than Y (and A, if present).
If the ColorType is supported for YUVA pixmaps this will return the number of YUVA channels
that can be stored in a plane of this color type and what the DataType is of those channels.
If the ColorType is not supported as a YUVA plane the number of channels is reported as 0
and the DataType returned should be ignored.