[libcamera-devel] [PATCH] libcamera: camera_sensor: Match V4L2 specification

[Jacopo Mondi]

Adjust the top-left corner coordinates of the analogCrop rectangle
to match the libcamera and V4L2 specification.

As per the V4L2 selection API specification, all rectangles accessed
using V4L2_SEL_TGT_* are defined relatively to the full pixel array,
which is retrieved using the V4L2_SEL_TGT_NATIVE target. Libcamera
defines the analogCrop rectangle to be defined relatively
to the active pixel matrix rectangle.

To compensate the difference in the reference rectangle between the two
specification, subtract from the TGT_CROP rectangle top-left corner the
offset of the active pixel array previously obtained with
TGT_CROP_DEFAULT.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---

This patch depends on the inclusion of the following patch in the
Linux kernel:
[PATCH 4/4] media: i2c: imx219: Selection compliance fixes
---
 src/libcamera/camera_sensor.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
index 350f49accad9..8f09206ff635 100644
--- a/src/libcamera/camera_sensor.cpp
+++ b/src/libcamera/camera_sensor.cpp
@@ -508,6 +508,18 @@ int CameraSensor::sensorInfo(CameraSensorInfo *info) const
 		return ret;
 	}

+	/*
+	 * The top-left corner position of the selection rectangle returned by
+	 * the V4L2_SEL_TGT_CROP target is defined relatively to the full pixel
+	 * array, while libcamera's analogCrop is defined relatively to the
+	 * active portion of the pixel matrix.
+	 *
+	 * Subtract from the top-left coordinates the offsets of the
+	 * CROP_DEFAULT target rectangle to align the two.
+	 */
+	info->analogCrop.x -= rect.x;
+	info->analogCrop.y -= rect.y;
+
 	/* The bit depth and image size depend on the currently applied format. */
 	V4L2SubdeviceFormat format{};
 	ret = subdev_->getFormat(pad_, &format);
--
2.27.0