[Pixman] [PATCH 1/2] pixman: Add support for argb/xrgb float formats, v4.

[Chris Wilson]

Quoting Maarten Lankhorst (2018-10-25 12:25:15)
> Op 03-10-18 om 11:11 schreef Chris Wilson:
> > Quoting Maarten Lankhorst (2018-08-01 13:41:33)
> >> diff --git a/pixman/pixman.h b/pixman/pixman.h
> >> index 509ba5e534a8..c9bf4faa80d4 100644
> >> --- a/pixman/pixman.h
> >> +++ b/pixman/pixman.h
> >> @@ -647,19 +647,24 @@ struct pixman_indexed
> >>   * sample implementation allows only packed RGB and GBR
> >>   * representations for data to simplify software rendering,
> >>   */
> >> -#define PIXMAN_FORMAT(bpp,type,a,r,g,b)        (((bpp) << 24) |  \
> >> +#define PIXMAN_FORMAT_PACKC(val) ((val) <= 10 ? (val) : \
> >> +                                (val) == 32 ? 11 : 0)
> >> +#define PIXMAN_FORMAT_UNPACKC(val) ((val) <= 10 ? (val) : \
> >> +                                   (val) == 11 ? 32 : 0)
> > We have 4bits, why not reserve 0xf for float32? Certainly you
> > want space for
> >
> > #define PIXMAN_FORMAT_PACKED_FLOAT16 0xb
> > #define PIXMAN_FORMAT_PACKED_FLOAT32 0xc
> > #define PIXMAN_FORMAT_PACKED_FLOAT64 0xd
> >
> > I just wonder if we may have 12bpc one day as well, so leaving 0xc clear
> > has some some appeal.
> > -Chris
> 
> I don't think we support double precision in pixman yet, but here's v4. :)
> 
> Apply with --scissors
> ------8<------------------------------------
> Pixman is already using the floating point formats internally, expose
> this capability in case someone wants to support higher bit per
> component formats.
> 
> This is useful for igt which depends on cairo to do the rendering.
> It can use it to convert floats internally to planar Y'CbCr formats,
> or to F16.
> 
> Changes since v1:
> - Use RGBA 128 bits and RGB 96 bits memory layouts, to better match the opengl format.
> Changes since v2:
> - Add asserts in accessor and for strides to force alignment.
> - Move test changes to their own commit.
> Changes since v3:
> - Define 32bpc as PIXMAN_FORMAT_PACKED_C32
> - Rename pixman accessors from rgb*_float_float to rgb*f_float
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>

I'm confident that we are not shooting ourselves in the foot here wrt to
potential future api directions, so
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris