[RFC PATCH 4/6] libcamera: converter_v4l2_m2m: Add vertex mapping class

[Laurent Pinchart]

On Wed, Jul 24, 2024 at 03:52:20PM +0200, Jacopo Mondi wrote:
> On Fri, Jul 12, 2024 at 10:59:18AM GMT, Umang Jain wrote:
> > Add a vertex mapping protected class to V4L2M2M converter class.

Given the rationale explained in the cover letter (no design of a
generic API with a single implementation), should this be part of the
DW100 converter class ?

> > Instances of this class will store a dewarp vertex mappings along
> > with their input/output configuration.
> >
> > Add a vector of Mapping class and applyMapping() helper as well,
> > to apply relevant mappings to V4L2Stream. ConverterDW100 will
> > use this helper to set vertex maps, in subsequent patch.
> >
> > Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
> > ---
> >  .../internal/converter/converter_v4l2_m2m.h   | 20 +++++++++++++++++++
> >  1 file changed, 20 insertions(+)
> >
> > diff --git a/include/libcamera/internal/converter/converter_v4l2_m2m.h b/include/libcamera/internal/converter/converter_v4l2_m2m.h
> > index 2697eed9..f61beef8 100644
> > --- a/include/libcamera/internal/converter/converter_v4l2_m2m.h
> > +++ b/include/libcamera/internal/converter/converter_v4l2_m2m.h
> > @@ -61,6 +61,26 @@ public:
> >  	int setCrop(const Stream *stream, Rectangle *rect);
> >  	std::pair<Rectangle, Rectangle> getCropBounds(const Stream *stream);
> >
> > +protected:
> > +	class Mapping
> > +	{
> > +	public:
> > +		Mapping(const Size &input, const Size &output, const std::vector<uint32_t> &map)
> > +			: input_(input), output_(output), map_(map) {}
> > +		Size inputSize() const { return input_; }
> > +		Size outputSize() const { return output_; }
> > +		std::size_t size() const { return map_.size(); }
> 
> Is the size of the array directly dependent on the input or output
> sizes or it doesn't have a correlation with them ?
> 
> > +		const uint32_t *mapping() const { return map_.data(); }
> > +
> > +	private:
> > +		Size input_;
> > +		Size output_;
> > +		std::vector<uint32_t> map_;
> 
> Maybe documentation will help, but how is mapping expressed with an
> array of uint32_t points ?
> 
> > +	};
> > +
> > +	int applyMapping(const Stream *stream, Mapping &mapping);
> 
> Does this work without providing an implementation ?

It would fail to link if the function was called.

> > +	std::vector<Mapping> mappings_;
> > +
> >  private:
> >  	class V4L2M2MStream : protected Loggable
> >  	{

-- 
Regards,

Laurent Pinchart