[libcamera-devel] [PATCH v4 5/5] libcamera: pipeline: raspberrypi: Implementation of digital zoom

[David Plowman]

During configure() we update the ScalerCropMaximum to the correct
value for this camera mode (which we also note internally) and work
out the minimum crop size allowed by the ISP.

Whenever a new ScalerCrop request is received we check it's valid and
apply it to the ISP V4L2 device. We also forward it to the IPA so that
the IPA can return the values used in the image metadata.

Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
---
 include/libcamera/ipa/raspberrypi.h           |  1 +
 src/ipa/raspberrypi/raspberrypi.cpp           |  7 ++
 .../pipeline/raspberrypi/raspberrypi.cpp      | 70 +++++++++++++++----
 3 files changed, 63 insertions(+), 15 deletions(-)

diff --git a/include/libcamera/ipa/raspberrypi.h b/include/libcamera/ipa/raspberrypi.h
index b3041591..bb4e1a8c 100644
--- a/include/libcamera/ipa/raspberrypi.h
+++ b/include/libcamera/ipa/raspberrypi.h
@@ -60,6 +60,7 @@ static const ControlInfoMap Controls = {
 	{ &controls::Saturation, ControlInfo(0.0f, 32.0f) },
 	{ &controls::Sharpness, ControlInfo(0.0f, 16.0f, 1.0f) },
 	{ &controls::ColourCorrectionMatrix, ControlInfo(-16.0f, 16.0f) },
+	{ &controls::ScalerCrop, ControlInfo(Rectangle{}, Rectangle(65535, 65535, 65535, 65535), Rectangle{}) },
 };
 
 } /* namespace RPi */
diff --git a/src/ipa/raspberrypi/raspberrypi.cpp b/src/ipa/raspberrypi/raspberrypi.cpp
index 48a72dd2..e777f0b4 100644
--- a/src/ipa/raspberrypi/raspberrypi.cpp
+++ b/src/ipa/raspberrypi/raspberrypi.cpp
@@ -699,6 +699,13 @@ void IPARPi::queueRequest(const ControlList &controls)
 			break;
 		}
 
+		case controls::SCALER_CROP: {
+			/* Just copy the information back. */
+			Rectangle crop = ctrl.second.get<Rectangle>();
+			libcameraMetadata_.set(controls::ScalerCrop, crop);
+			break;
+		}
+
 		default:
 			LOG(IPARPI, Warning)
 				<< "Ctrl " << controls::controls.at(ctrl.first)->name()
diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
index 26dbd257..43b860ae 100644
--- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
+++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
@@ -193,6 +193,11 @@ public:
 	bool flipsAlterBayerOrder_;
 	BayerFormat::Order nativeBayerOrder_;
 
+	/* For handling digital zoom. */
+	CameraSensorInfo sensorInfo_;
+	Rectangle lastIspCrop_;
+	Size ispMinSize_;
+
 	unsigned int dropFrameCount_;
 
 private:
@@ -677,26 +682,30 @@ int PipelineHandlerRPi::configure(Camera *camera, CameraConfiguration *config)
 		return ret;
 	}
 
-	/* Adjust aspect ratio by providing crops on the input image. */
-	Rectangle crop{ 0, 0, sensorFormat.size };
-
-	int ar = maxSize.height * sensorFormat.size.width - maxSize.width * sensorFormat.size.height;
-	if (ar > 0)
-		crop.width = maxSize.width * sensorFormat.size.height / maxSize.height;
-	else if (ar < 0)
-		crop.height = maxSize.height * sensorFormat.size.width / maxSize.width;
+	/* Figure out the smallest selection the ISP will allow. */
+	Rectangle testCrop(0, 0, 1, 1);
+	data->isp_[Isp::Input].dev()->setSelection(V4L2_SEL_TGT_CROP, &testCrop);
+	data->ispMinSize_ = testCrop.size();
 
-	crop.width &= ~1;
-	crop.height &= ~1;
+	/* Adjust aspect ratio by providing crops on the input image. */
+	Rectangle crop = sensorFormat.size.boundedToAspectRatio(maxSize).centeredTo(sensorFormat.size.center());
+	data->lastIspCrop_ = crop;
 
-	crop.x = (sensorFormat.size.width - crop.width) >> 1;
-	crop.y = (sensorFormat.size.height - crop.height) >> 1;
 	data->isp_[Isp::Input].dev()->setSelection(V4L2_SEL_TGT_CROP, &crop);
 
 	ret = data->configureIPA(config);
 	if (ret)
 		LOG(RPI, Error) << "Failed to configure the IPA: " << ret;
 
+	/*
+	 * Update the ScalerCropMaximum to the correct value for this camera mode.
+	 * For us, it's the same as the "analogue crop".
+	 *
+	 * \todo Make this property the ScalerCrop maximum value when dynamic
+	 * controls are available and set it at validate() time
+	 */
+	data->properties_.set(properties::ScalerCropMaximum, data->sensorInfo_.analogCrop);
+
 	return ret;
 }
 
@@ -1147,8 +1156,8 @@ int RPiCameraData::configureIPA(const CameraConfiguration *config)
 		ipaConfig.data.push_back(static_cast<unsigned int>(lsTable_.fd()));
 	}
 
-	CameraSensorInfo sensorInfo = {};
-	int ret = sensor_->sensorInfo(&sensorInfo);
+	/* We store the CameraSensorInfo for digital zoom calculations. */
+	int ret = sensor_->sensorInfo(&sensorInfo_);
 	if (ret) {
 		LOG(RPI, Error) << "Failed to retrieve camera sensor info";
 		return ret;
@@ -1157,7 +1166,7 @@ int RPiCameraData::configureIPA(const CameraConfiguration *config)
 	/* Ready the IPA - it must know about the sensor resolution. */
 	IPAOperationData result;
 
-	ipa_->configure(sensorInfo, streamConfig, entityControls, ipaConfig,
+	ipa_->configure(sensorInfo_, streamConfig, entityControls, ipaConfig,
 			&result);
 
 	unsigned int resultIdx = 0;
@@ -1588,6 +1597,37 @@ void RPiCameraData::tryRunPipeline()
 	/* Take the first request from the queue and action the IPA. */
 	Request *request = requestQueue_.front();
 
+	if (request->controls().contains(controls::ScalerCrop)) {
+		Rectangle crop = request->controls().get<Rectangle>(controls::ScalerCrop);
+
+		if (crop.width && crop.height) {
+			/* First scale the crop from sensor native to camera mode pixels. */
+			crop.translateBy(-sensorInfo_.analogCrop.x, -sensorInfo_.analogCrop.y);
+			crop.rescaleTo(sensorInfo_.analogCrop.size(), sensorInfo_.outputSize);
+
+			/*
+			 * The crop that we set must be:
+			 * 1. At least as big as ispMinSize_, once that's been
+			 *    enlarged to the same aspect ratio.
+			 * 2. With the same mid-point, if possible.
+			 * 3. But it can't go outside the sensor area.
+			 */
+			Size minSize = ispMinSize_.expandedToAspectRatio(crop.size());
+			Size size = crop.size().expandedTo(minSize);
+			crop = size.centeredTo(crop.center()).clampedTo(Rectangle(sensorInfo_.outputSize));
+
+			if (crop != lastIspCrop_)
+				isp_[Isp::Input].dev()->setSelection(V4L2_SEL_TGT_CROP, &crop);
+			lastIspCrop_ = crop;
+		}
+
+		/* We must scale the actual crop used back into native pixels. */
+		crop = lastIspCrop_.rescaledTo(sensorInfo_.outputSize, sensorInfo_.analogCrop.size());
+		crop.translateBy(sensorInfo_.analogCrop.x, sensorInfo_.analogCrop.y);
+
+		request->controls().set(controls::ScalerCrop, crop);
+	}
+
 	/*
 	 * Process all the user controls by the IPA. Once this is complete, we
 	 * queue the ISP output buffer listed in the request to start the HW
-- 
2.20.1