android: camera_device: Calculate metadata size

As we move to have more and more dynamically generated static metadata
entries, the size of the metadata buffer has to be calculated
dynamically inspecting the information collected from the camera.

Provide a method to perform metadata buffers size calculation and
use it when generating camera static metadata.

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

2 files changed, 30 insertions, 6 deletions

diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
index 1dcf985c..887db8da 100644
--- a/src/android/camera_device.cpp
+++ b/src/android/camera_device.cpp
@@ -8,6 +8,7 @@
 #include "camera_device.h"
 #include "camera_ops.h"
 
+#include <tuple>
 #include <vector>
 
 #include <libcamera/controls.h>
@@ -367,6 +368,29 @@ void CameraDevice::setCallbacks(const camera3_callback_ops_t *callbacks)
 	callbacks_ = callbacks;
 }
 
+std::tuple<uint32_t, uint32_t> CameraDevice::calculateStaticMetadataSize()
+{
+	/*
+	 * \todo Keep this in sync with the actual number of entries.
+	 * Currently: 50 entries, 647 bytes of static metadata
+	 */
+	uint32_t numEntries = 50;
+	uint32_t byteSize = 647;
+
+	/*
+	 * Calculate space occupation in bytes for dynamically built metadata
+	 * entries.
+	 *
+	 * Each stream configuration entry requires 52 bytes:
+	 * 4 32bits integers for ANDROID_SCALER_AVAILABLE_STREAM_CONFIGURATIONS
+	 * 1 32bits integer for ANDROID_SCALER_AVAILABLE_FORMATS
+	 * 4 64bits integers for ANDROID_SCALER_AVAILABLE_MIN_FRAME_DURATIONS
+	 */
+	byteSize += streamConfigurations_.size() * 52;
+
+	return { numEntries, byteSize };
+}
+
 /*
  * Return static information for the camera.
  */
@@ -380,12 +404,10 @@ const camera_metadata_t *CameraDevice::getStaticMetadata()
 	 * example application, but a real camera implementation will require
 	 * more.
 	 */
-
-	/*
-	 * \todo Keep this in sync with the actual number of entries.
-	 * Currently: 50 entries, 666 bytes
-	 */
-	staticMetadata_ = new CameraMetadata(50, 700);
+	uint32_t numEntries;
+	uint32_t byteSize;
+	std::tie(numEntries, byteSize) = calculateStaticMetadataSize();
+	staticMetadata_ = new CameraMetadata(numEntries, byteSize);
 	if (!staticMetadata_->isValid()) {
 		LOG(HAL, Error) << "Failed to allocate static metadata";
 		delete staticMetadata_;
diff --git a/src/android/camera_device.h b/src/android/camera_device.h
index 4e8911da..ed11410a 100644
--- a/src/android/camera_device.h
+++ b/src/android/camera_device.h
@@ -9,6 +9,7 @@
 
 #include <map>
 #include <memory>
+#include <tuple>
 #include <vector>
 
 #include <hardware/camera3.h>
@@ -68,6 +69,7 @@ private:
 	};
 
 	int initializeStreamConfigurations();
+	std::tuple<uint32_t, uint32_t> calculateStaticMetadataSize();
 	void notifyShutter(uint32_t frameNumber, uint64_t timestamp);
 	void notifyError(uint32_t frameNumber, camera3_stream_t *stream);
 	std::unique_ptr<CameraMetadata> getResultMetadata(int frame_number,