[libcamera-devel] [RFC PATCH] android: Plumb lens focus distance

[Laurent Pinchart]

Hi Paul,

Thank you for the patch.

On Mon, Sep 13, 2021 at 04:31:25PM +0900, Paul Elder wrote:
> Plumb the controls related to lens focus distance:
> - LENS_INFO_FOCUS_DISTANCE_CALIBRATION (static)
> - LENS_INFO_MINIMUM_FOCUS_DISTANCE (static)
> - LENS_FOCUS_DISTANCE (request, result)
> 
> Conceptually, the first two controls determine the range of possible
> values of the third. None of our lenses are calibrated, so hardcode the
> first to uncalibrated. The valid focus distances are then [0, min].
> Since we don't yet support variable-focus lenses, hardcode the second to
> 0.0f, making the range of valid focus distances [0, 0]. Hence, hardcode
> the focus distance in the result metadata to 0, and ignore the control
> in the request. Add todos for adding proper controls later, once we have
> focus support.
> 
> Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
> ---
> This is also on top of my ctsw branch, so it won't apply on master, but
> I would like comments to confirm the direction and design.
> ---
>  src/android/camera_capabilities.cpp | 13 +++++++++++++
>  src/android/camera_device.cpp       |  4 ++++
>  2 files changed, 17 insertions(+)
> 
> diff --git a/src/android/camera_capabilities.cpp b/src/android/camera_capabilities.cpp
> index 461c208b..a807712d 100644
> --- a/src/android/camera_capabilities.cpp
> +++ b/src/android/camera_capabilities.cpp
> @@ -717,6 +717,7 @@ int CameraCapabilities::initializeStaticMetadata()
>  		ANDROID_LENS_INFO_AVAILABLE_APERTURES,
>  		ANDROID_LENS_INFO_AVAILABLE_FOCAL_LENGTHS,
>  		ANDROID_LENS_INFO_AVAILABLE_OPTICAL_STABILIZATION,
> +		ANDROID_LENS_INFO_FOCUS_DISTANCE_CALIBRATION,
>  		ANDROID_LENS_INFO_HYPERFOCAL_DISTANCE,
>  		ANDROID_LENS_INFO_MINIMUM_FOCUS_DISTANCE,
>  		ANDROID_NOISE_REDUCTION_AVAILABLE_NOISE_REDUCTION_MODES,
> @@ -805,6 +806,7 @@ int CameraCapabilities::initializeStaticMetadata()
>  		ANDROID_JPEG_THUMBNAIL_SIZE,
>  		ANDROID_LENS_APERTURE,
>  		ANDROID_LENS_FOCAL_LENGTH,
> +		ANDROID_LENS_FOCUS_DISTANCE,
>  		ANDROID_LENS_OPTICAL_STABILIZATION_MODE,
>  		ANDROID_LENS_STATE,
>  		ANDROID_NOISE_REDUCTION_MODE,
> @@ -1247,10 +1249,21 @@ int CameraCapabilities::initializeStaticMetadata()
>  	staticMetadata_->addEntry(ANDROID_LENS_INFO_AVAILABLE_OPTICAL_STABILIZATION,
>  				  opticalStabilizations);
>  
> +	/*
> +	 * Must be populated for FULL, optional for LIMITED. The value doesn't
> +	 * matter, so just hardcode to uncalibrated. Uncalibrated means that
> +	 * the max focus distance is zero (= infinite focus) and the min focus
> +	 * distance is specified in LENS_INFO_MINIMUM_FOCUS_DISTANCE.
> +	 */
> +	int distanceCalibration = ANDROID_LENS_INFO_FOCUS_DISTANCE_CALIBRATION_UNCALIBRATED;
> +	staticMetadata_->addEntry(ANDROID_LENS_INFO_FOCUS_DISTANCE_CALIBRATION,
> +				  distanceCalibration);
> +
>  	float hypeFocalDistance = 0;
>  	staticMetadata_->addEntry(ANDROID_LENS_INFO_HYPERFOCAL_DISTANCE,
>  				  hypeFocalDistance);
>  
> +	/* \todo Get this from the HAL config. */

Once we'll have focus support in the libcamera core, I think this will
come from libcamera, not the HAL config. The minimum focus distance is
useful in general.

With this todo updated,

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

>  	float minFocusDistance = 0;
>  	staticMetadata_->addEntry(ANDROID_LENS_INFO_MINIMUM_FOCUS_DISTANCE,
>  				  minFocusDistance);
> diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
> index 373e0f98..cfbb84aa 100644
> --- a/src/android/camera_device.cpp
> +++ b/src/android/camera_device.cpp
> @@ -1396,6 +1396,10 @@ CameraDevice::getResultMetadata(const Camera3RequestDescriptor &descriptor) cons
>  	float focal_length = 1.0;
>  	resultMetadata->addEntry(ANDROID_LENS_FOCAL_LENGTH, focal_length);
>  
> +	/* \todo Add a libcamera control for this, and plumb it. */
> +	float focalDistance = 0.0;
> +	resultMetadata->addEntry(ANDROID_LENS_FOCUS_DISTANCE, focalDistance);
> +
>  	value = ANDROID_LENS_STATE_STATIONARY;
>  	resultMetadata->addEntry(ANDROID_LENS_STATE, value);
>  

-- 
Regards,

Laurent Pinchart