libcamera: pipeline: raspberrypi: Implementation of digital zoom

During configure() we update the ScalerCropMaximum to the correct
value for this camera mode 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. When the IPA returns its metadata to
us we add the ScalerCrop information, rescaled to sensor native
pixels.

Signed-off-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

2 files changed, 81 insertions, 17 deletions

diff --git a/src/ipa/raspberrypi/raspberrypi.cpp b/src/ipa/raspberrypi/raspberrypi.cpp
index 1c255aa2..f338ff8b 100644
--- a/src/ipa/raspberrypi/raspberrypi.cpp
+++ b/src/ipa/raspberrypi/raspberrypi.cpp
@@ -699,6 +699,11 @@ void IPARPi::queueRequest(const ControlList &controls)
 			break;
 		}
 
+		case controls::SCALER_CROP: {
+			/* We do nothing with this, but should avoid the warning below. */
+			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 763451a8..a48013d8 100644
--- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
+++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
@@ -135,7 +135,7 @@ public:
 	RPiCameraData(PipelineHandler *pipe)
 		: CameraData(pipe), sensor_(nullptr), state_(State::Stopped),
 		  supportsFlips_(false), flipsAlterBayerOrder_(false),
-		  dropFrameCount_(0), ispOutputCount_(0)
+		  updateScalerCrop_(true), dropFrameCount_(0), ispOutputCount_(0)
 	{
 	}
 
@@ -193,6 +193,13 @@ public:
 	bool flipsAlterBayerOrder_;
 	BayerFormat::Order nativeBayerOrder_;
 
+	/* For handling digital zoom. */
+	CameraSensorInfo sensorInfo_;
+	Rectangle ispCrop_; /* crop in ISP (camera mode) pixels */
+	Rectangle scalerCrop_; /* crop in sensor native pixels */
+	bool updateScalerCrop_;
+	Size ispMinCropSize_;
+
 	unsigned int dropFrameCount_;
 
 private:
@@ -677,26 +684,31 @@ 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->ispMinCropSize_ = testCrop.size();
 
-	crop.width &= ~1;
-	crop.height &= ~1;
+	/* Adjust aspect ratio by providing crops on the input image. */
+	Size size = sensorFormat.size.boundedToAspectRatio(maxSize);
+	Rectangle crop = size.centeredTo(Rectangle(sensorFormat.size).center());
+	data->ispCrop_ = 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;
 }
 
@@ -1154,8 +1166,8 @@ 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;
@@ -1164,7 +1176,7 @@ 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;
@@ -1243,8 +1255,26 @@ void RPiCameraData::queueFrameAction([[maybe_unused]] unsigned int frame,
 		FrameBuffer *buffer = isp_[Isp::Stats].getBuffers().at(bufferId);
 
 		handleStreamBuffer(buffer, &isp_[Isp::Stats]);
+
 		/* Fill the Request metadata buffer with what the IPA has provided */
-		requestQueue_.front()->metadata() = std::move(action.controls[0]);
+		Request *request = requestQueue_.front();
+		request->metadata() = std::move(action.controls[0]);
+
+		/*
+		 * Also update the ScalerCrop in the metadata with what we actually
+		 * used. But we must first rescale that from ISP (camera mode) pixels
+		 * back into sensor native pixels.
+		 *
+		 * Sending this information on every frame may be helpful.
+		 */
+		if (updateScalerCrop_) {
+			updateScalerCrop_ = false;
+			scalerCrop_ = ispCrop_.scaledBy(sensorInfo_.analogCrop.size(),
+							sensorInfo_.outputSize);
+			scalerCrop_.translateBy(sensorInfo_.analogCrop.topLeft());
+		}
+		request->metadata().set(controls::ScalerCrop, scalerCrop_);
+
 		state_ = State::IpaComplete;
 		break;
 	}
@@ -1595,6 +1625,35 @@ 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 nativeCrop = request->controls().get<Rectangle>(controls::ScalerCrop);
+
+		if (!nativeCrop.width || !nativeCrop.height)
+			nativeCrop = { 0, 0, 1, 1 };
+
+		/* Create a version of the crop scaled to ISP (camera mode) pixels. */
+		Rectangle ispCrop = nativeCrop.translatedBy(-sensorInfo_.analogCrop.topLeft());
+		ispCrop.scaleBy(sensorInfo_.outputSize, sensorInfo_.analogCrop.size());
+
+		/*
+		 * The crop that we set must be:
+		 * 1. At least as big as ispMinCropSize_, 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 = ispMinCropSize_.expandedToAspectRatio(nativeCrop.size());
+		Size size = ispCrop.size().expandedTo(minSize);
+		ispCrop = size.centeredTo(ispCrop.center()).enclosedIn(Rectangle(sensorInfo_.outputSize));
+
+		if (ispCrop != ispCrop_) {
+			isp_[Isp::Input].dev()->setSelection(V4L2_SEL_TGT_CROP, &ispCrop);
+			ispCrop_ = ispCrop;
+			/* queueFrameAction will have to update its scalerCrop_ */
+			updateScalerCrop_ = true;
+		}
+	}
+
 	/*
 	 * 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