SDL's pixel formats have the following naming convention:
- Names with a list of components and a single bit count, such as RGB24 and
ABGR32, define a platform-independent encoding into bytes in the order
specified. For example, in RGB24 data, each pixel is encoded in 3 bytes
(red, green, blue) in that order, and in ABGR32 data, each pixel is
encoded in 4 bytes (alpha, blue, green, red) in that order. Use these
names if the property of a format that is important to you is the order
of the bytes in memory or on disk.
- Names with a bit count per component, such as ARGB8888 and XRGB1555, are
"packed" into an appropriately-sized integer in the platform's native
endianness. For example, ARGB8888 is a sequence of 32-bit integers; in
each integer, the most significant bits are alpha, and the least
significant bits are blue. On a little-endian CPU such as x86, the least
significant bits of each integer are arranged first in memory, but on a
big-endian CPU such as s390x, the most significant bits are arranged
first. Use these names if the property of a format that is important to
you is the meaning of each bit position within a native-endianness
integer.
- In indexed formats such as INDEX4LSB, each pixel is represented by
encoding an index into the palette into the indicated number of bits,
with multiple pixels packed into each byte if appropriate. In LSB
formats, the first (leftmost) pixel is stored in the least-significant
bits of the byte; in MSB formats, it's stored in the most-significant
bits. INDEX8 does not need LSB/MSB variants, because each pixel exactly
fills one byte.
The 32-bit byte-array encodings such as RGBA32 are aliases for the
appropriate 8888 encoding for the current platform. For example, RGBA32 is
an alias for ABGR8888 on little-endian CPUs like x86, or an alias for
RGBA8888 on big-endian CPUs.
Pixel format.
SDL's pixel formats have the following naming convention:
- Names with a list of components and a single bit count, such as RGB24 and ABGR32, define a platform-independent encoding into bytes in the order specified. For example, in RGB24 data, each pixel is encoded in 3 bytes (red, green, blue) in that order, and in ABGR32 data, each pixel is encoded in 4 bytes (alpha, blue, green, red) in that order. Use these names if the property of a format that is important to you is the order of the bytes in memory or on disk. - Names with a bit count per component, such as ARGB8888 and XRGB1555, are "packed" into an appropriately-sized integer in the platform's native endianness. For example, ARGB8888 is a sequence of 32-bit integers; in each integer, the most significant bits are alpha, and the least significant bits are blue. On a little-endian CPU such as x86, the least significant bits of each integer are arranged first in memory, but on a big-endian CPU such as s390x, the most significant bits are arranged first. Use these names if the property of a format that is important to you is the meaning of each bit position within a native-endianness integer. - In indexed formats such as INDEX4LSB, each pixel is represented by encoding an index into the palette into the indicated number of bits, with multiple pixels packed into each byte if appropriate. In LSB formats, the first (leftmost) pixel is stored in the least-significant bits of the byte; in MSB formats, it's stored in the most-significant bits. INDEX8 does not need LSB/MSB variants, because each pixel exactly fills one byte.
The 32-bit byte-array encodings such as RGBA32 are aliases for the appropriate 8888 encoding for the current platform. For example, RGBA32 is an alias for ABGR8888 on little-endian CPUs like x86, or an alias for RGBA8888 on big-endian CPUs.