Add a new method to write the contents of a framebuffer to a file
descriptor. This can be used to capture frames from writeback
connectors.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Replace the hand-rolled draw_color_bar call in FlipState::draw_bar with
pixpat's "vbar" pattern via a new draw_vbar_pattern helper in kms++util.
The pattern fills the full buffer, so the old_xpos bookkeeping for
clearing the previous bar is no longer needed.

Switch draw_test_pattern() to call libpixpat (linked statically into
libkms++util.so) instead of the in-tree pattern generator. Pixpat
covers every pattern (kmstest, smpte, solid colors) and every pixel
format the previous generator handled, so behavior is unchanged for
all callers.

Drop the now-unused machinery: conv.h and conv-*.h template writers,
color16.h (RGB16/YUV16 plus conversions), the *_old / _single / _multi
declarations that had no definitions or callers, and the c_draw_test_pattern
C ABI which had no callers anywhere in the tree. RecStandard and
ColorRange move from color16.h directly into kms++util.h, since they
are still part of the public TestPatternOptions struct.

We can generate test patterns for pixel formats not in DRM, so we can't
take DRM fourcc as a parameter for c_draw_test_pattern(). Switch it to
format name instead.

This is a ABI change, but it is marked as super experimental.

Also, it feels a bit odd to add non-DRM format handling to kms++. But it
feels a bit pointless to split the testpat generation to a separate
library.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

The calculation was not right, producing bad values. Fix it, and this
time actually test the output...

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

Add a draw_test_pattern for C ABI (i.e. not C++). This function can be
easily called from Python with ctypes, without any kind of bindings.

Experimental, ABI can change.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

New templated conversion and test pattern code.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>