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

[Paul Elder]

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. */
 	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);
 
-- 
2.27.0