[PATCH] Add m1bpp (monochrome, 1 bit/pixel) pixel format

Pekka Paalanen ppaalanen at gmail.com
Fri Sep 15 15:28:09 UTC 2017


On Fri, 15 Sep 2017 11:17:29 -0400
Drew DeVault <sir at cmpwn.com> wrote:

> On 2017-09-15  6:06 PM, Pekka Paalanen wrote:
> > I ask about endianess, because Pixman has some fun pixel formats where
> > endianess is defined to affect also the order of bits, not just bytes.  
> 
> This is such a format, and in theory the opposite endianness could
> exist, though I've never observed it in practice. The language in the
> description is sufficient to understand how to use this pixel format on
> any particular architecture.

To be exact, I was referring to this bit of code:

https://cgit.freedesktop.org/pixman/tree/pixman/pixman-access.c?h=0.34&id=pixman-0.34.0#n51

Depending on endianess, it starts counting from either MSB or LSB.

If we can be sure we never want to start counting from LSB, we're good.
Or just add another format.

> > Indeed, 2 and 4 bit formats are also missing, but 8 and 16 bit ones are
> > already defined unless you meant some new variation.  
> 
> The 8 and 16 bit ones, so far as I can tell, are 8/16 bits per component
> of an RGB(A) triple (quadruple), rather than 8/16 bits per pixel.

There are 8 and 16 bits per pixel: c8, rgb332, rgb565, argb4444,
argb1555, etc.


Thaks,
pq
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