[libcamera-devel] [PATCH 1/5] libcamera: v4l2_subdevice: Make crop/compose rectangle a reference

[Niklas Söderlund]

Hi Jacopo,

Thanks for your patch.

On 2019-02-20 14:17:53 +0100, Jacopo Mondi wrote:
> As the crop/compose rectangle provided to setCrop and setCompose methods
> is never modified, make it a const reference.

I think this is the wrong thing to do. Instead I think you should change 
this patch to update the rectangle after VIDIOC_SUBDEV_S_SELECTION.

The kernel can update the requested selection rectangle and the caller 
should be made aware of this. Look at V4L2Subdevice::setFormat() which 
have a similar pattern but for VIDIOC_SUBDEV_S_FMT.

> 
> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> ---
>  src/libcamera/include/v4l2_subdevice.h |  6 +++---
>  src/libcamera/v4l2_subdevice.cpp       | 18 +++++++++---------
>  2 files changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/src/libcamera/include/v4l2_subdevice.h b/src/libcamera/include/v4l2_subdevice.h
> index 40becd0ca99b..18000d6ed06b 100644
> --- a/src/libcamera/include/v4l2_subdevice.h
> +++ b/src/libcamera/include/v4l2_subdevice.h
> @@ -44,8 +44,8 @@ public:
>  	std::string deviceNode() const { return deviceNode_; }
>  	std::string deviceName() const { return deviceName_; }
>  
> -	int setCrop(unsigned int pad, Rectangle *rect);
> -	int setCompose(unsigned int pad, Rectangle *rect);
> +	int setCrop(unsigned int pad, const Rectangle &rect);
> +	int setCompose(unsigned int pad, const Rectangle &rect);
>  
>  	int enumFormat(unsigned int pad, V4L2SubdeviceFormatEnum *formatEnum);
>  	int getFormat(unsigned int pad, V4L2SubdeviceFormat *format);
> @@ -53,7 +53,7 @@ public:
>  
>  private:
>  	int setSelection(unsigned int pad, unsigned int target,
> -			 Rectangle *rect);
> +			 const Rectangle &rect);
>  
>  	std::string deviceNode_;
>  	std::string deviceName_;
> diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp
> index 4411ffa51460..2e73edee68c9 100644
> --- a/src/libcamera/v4l2_subdevice.cpp
> +++ b/src/libcamera/v4l2_subdevice.cpp
> @@ -203,11 +203,11 @@ void V4L2Subdevice::close()
>  /**
>   * \brief Set a crop rectangle on one of the V4L2 subdevice pads
>   * \param[in] pad The 0-indexed pad number the rectangle is to be applied to
> - * \param[inout] rect The rectangle describing crop target area
> + * \param[in] rect The rectangle describing crop target area
>   *
>   * \return 0 on success, or a negative error code otherwise
>   */
> -int V4L2Subdevice::setCrop(unsigned int pad, Rectangle *rect)
> +int V4L2Subdevice::setCrop(unsigned int pad, const Rectangle &rect)
>  {
>  	return setSelection(pad, V4L2_SEL_TGT_CROP, rect);
>  }
> @@ -215,11 +215,11 @@ int V4L2Subdevice::setCrop(unsigned int pad, Rectangle *rect)
>  /**
>   * \brief Set a compose rectangle on one of the V4L2 subdevice pads
>   * \param[in] pad The 0-indexed pad number the rectangle is to be applied to
> - * \param[inout] rect The rectangle describing the compose target area
> + * \param[in] rect The rectangle describing the compose target area
>   *
>   * \return 0 on success, or a negative error code otherwise
>   */
> -int V4L2Subdevice::setCompose(unsigned int pad, Rectangle *rect)
> +int V4L2Subdevice::setCompose(unsigned int pad, const Rectangle &rect)
>  {
>  	return setSelection(pad, V4L2_SEL_TGT_COMPOSE, rect);
>  }
> @@ -333,7 +333,7 @@ int V4L2Subdevice::setFormat(unsigned int pad, V4L2SubdeviceFormat *format)
>  }
>  
>  int V4L2Subdevice::setSelection(unsigned int pad, unsigned int target,
> -				Rectangle *rect)
> +				const Rectangle &rect)
>  {
>  	struct v4l2_subdev_selection sel = {};
>  
> @@ -342,10 +342,10 @@ int V4L2Subdevice::setSelection(unsigned int pad, unsigned int target,
>  	sel.target = target;
>  	sel.flags = 0;
>  
> -	sel.r.left = rect->y;
> -	sel.r.top = rect->x;
> -	sel.r.width = rect->w;
> -	sel.r.height = rect->h;
> +	sel.r.left = rect.y;
> +	sel.r.top = rect.x;
> +	sel.r.width = rect.w;
> +	sel.r.height = rect.h;
>  
>  	int ret = ioctl(fd_, VIDIOC_SUBDEV_S_SELECTION, &sel);
>  	if (ret < 0) {
> -- 
> 2.20.1
> 
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-- 
Regards,
Niklas Söderlund