[PATCH] libcamera: v4l2_videodevice: Add getSelection() function

[Jacopo Mondi]

Hi Laurent

On Wed, Sep 25, 2024 at 09:07:13PM GMT, Laurent Pinchart wrote:
> The V4L2VideoDevice class implements setSelection() but not
> getSelection(). The latter is useful for instance to query crop bounds.
> Implement the function.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>  include/libcamera/internal/v4l2_videodevice.h |  1 +
>  src/libcamera/v4l2_videodevice.cpp            | 32 +++++++++++++++++++
>  2 files changed, 33 insertions(+)
>
> diff --git a/include/libcamera/internal/v4l2_videodevice.h b/include/libcamera/internal/v4l2_videodevice.h
> index 9057be08f18a..f021c2a0177b 100644
> --- a/include/libcamera/internal/v4l2_videodevice.h
> +++ b/include/libcamera/internal/v4l2_videodevice.h
> @@ -208,6 +208,7 @@ public:
>  	int setFormat(V4L2DeviceFormat *format);
>  	Formats formats(uint32_t code = 0);
>
> +	int getSelection(unsigned int target, Rectangle *rect);
>  	int setSelection(unsigned int target, Rectangle *rect);
>
>  	int allocateBuffers(unsigned int count,
> diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
> index 93cb1697935e..14eba0561d6a 100644
> --- a/src/libcamera/v4l2_videodevice.cpp
> +++ b/src/libcamera/v4l2_videodevice.cpp
> @@ -1214,6 +1214,38 @@ std::vector<SizeRange> V4L2VideoDevice::enumSizes(V4L2PixelFormat pixelFormat)
>  	return sizes;
>  }
>
> +/**
> + * \brief Get the selection rectangle for \a target
> + * \param[in] target The selection target defined by the V4L2_SEL_TGT_* flags
> + * \param[out] rect The selection rectangle to retrieve
> + *
> + * \todo Define a V4L2SelectionTarget enum for the selection target
> + *
> + * \return 0 on success or a negative error code otherwise
> + */
> +int V4L2VideoDevice::getSelection(unsigned int target, Rectangle *rect)
> +{
> +	struct v4l2_selection sel = {};
> +
> +	sel.type = bufferType_;
> +	sel.target = target;
> +	sel.flags = 0;
> +
> +	int ret = ioctl(VIDIOC_G_SELECTION, &sel);
> +	if (ret < 0) {
> +		LOG(V4L2, Error) << "Unable to get rectangle " << target
> +				 << ": " << strerror(-ret);
> +		return ret;

Just noticed in this class we don't

		ret = -errno;
		LOG(V4L2, Error) <<
				 << strerror(-ret);
		return ret;

Not related to this patch though
Reviewed-by: Jacopo Mondi <jacopo.mondi at ideasonboard.com>

> +	}
> +
> +	rect->x = sel.r.left;
> +	rect->y = sel.r.top;
> +	rect->width = sel.r.width;
> +	rect->height = sel.r.height;
> +
> +	return 0;
> +}
> +
>  /**
>   * \brief Set a selection rectangle \a rect for \a target
>   * \param[in] target The selection target defined by the V4L2_SEL_TGT_* flags
>
> base-commit: 8bcec687344e5cc2ccef1361c03b87f0fd2cc59b
> --
> Regards,
>
> Laurent Pinchart
>