[libcamera-devel] [RFC PATCH v3 03/16] android: Add helpers for setting android metadata from libcamera controls

[Paul Elder]

Add helpers for setting android metadata from libcamera controls.

There are two versions, for scalars and collections, both of which take
a default value to fill in the android control if the libcamera control
is not found. A version for scalars exists for no default, to not set
the android control at all if it is not found in libcamera. The
functions take two template parameters, the first for the android type,
and the second for the libcamera type of the control. They can be
different, for example, if the former is an enum and the latter is a
boolean, or if the former is an enum (uint8_t) and the latter is an enum
(int32_t).

The versions that take a default value return the value that was set in
the android metadata.

Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>

---
Changes in v3:
- setMetadata for collection only works with vectors
- change enum to enum class
- add two template parameters for android type and libcamera type
- add docs

New in v2

TODO: make ControlList versions so that we can use them in result
metadata
---
 src/android/camera_capabilities.cpp | 137 ++++++++++++++++++++++++++++
 1 file changed, 137 insertions(+)

diff --git a/src/android/camera_capabilities.cpp b/src/android/camera_capabilities.cpp
index 54bd71da..1d4c44ce 100644
--- a/src/android/camera_capabilities.cpp
+++ b/src/android/camera_capabilities.cpp
@@ -124,6 +124,143 @@ hwLevelStrings = {
 	{ ANDROID_INFO_SUPPORTED_HARDWARE_LEVEL_EXTERNAL, "EXTERNAL" },
 };
 
+enum class ControlRange {
+	Min,
+	Def,
+	Max,
+};
+
+/**
+ * \brief Set android metadata from libcamera ControlInfo
+ * \tparam T Type of the control in android
+ * \tparam V Type of the control in libcamera
+ * \param[in] metadata Android metadata to add the control value to
+ * \param[in] tag Android metadata tag to add
+ * \param[in] controlsInfo libcamera ControlInfoMap from which to find the control info
+ * \param[in] control libcamera ControlId to find from \a controlsInfo
+ * \param[in] controlRange Whether to use the min, def, or max value from the control info
+ *
+ * Set the android metadata entry in \a metadata with tag \a tag based on the
+ * control info found for the libcamera control \a control in the libcamera
+ * ControlInfoMap \a controlsInfo. If no libcamera ControlInfo is found, then
+ * the function returns without modifying anything.
+ *
+ * This function is for scalar values.
+ */
+template<typename T,
+	 std::enable_if_t<std::is_arithmetic_v<T>> * = nullptr,
+	 typename V>
+void setMetadata(CameraMetadata *metadata, uint32_t tag,
+		 const ControlInfoMap &controlsInfo, const ControlId *control,
+		 enum ControlRange controlRange)
+{
+	const auto &info = controlsInfo.find(control);
+	if (info == controlsInfo.end())
+		return;
+
+	T ret;
+	switch (controlRange) {
+	case ControlRange::Min:
+		ret = info->second.min().get<V>();
+		break;
+	case ControlRange::Def:
+		ret = info->second.def().get<V>();
+		break;
+	case ControlRange::Max:
+		ret = info->second.max().get<V>();
+		break;
+	}
+
+	metadata->addEntry(tag, ret);
+	return;
+}
+
+/**
+ * \brief Set android metadata from libcamera ControlInfo or a default value
+ * \tparam T Type of the control in android
+ * \tparam U Type of the control in libcamera
+ * \param[in] metadata Android metadata to add the control value to
+ * \param[in] tag Android metadata tag to add
+ * \param[in] controlsInfo libcamera ControlInfoMap from which to find the control info
+ * \param[in] control libcamera ControlId to find from \a controlsInfo
+ * \param[in] controlRange Whether to use the min, def, or max value from the control info
+ * \param[in] defaultValue The value to set in \a metadata if \a control is not found
+ *
+ * Set the android metadata entry in \a metadata with tag \a tag based on the
+ * control info found for the libcamera control \a control in the libcamera
+ * ControlInfoMap \a controlsInfo. If no libcamera ControlInfo is found, then
+ * the android metadata entry is set to \a defaultValue.
+ *
+ * This function is for scalar values.
+ */
+template<typename T,
+	 typename U,
+	 typename V,
+	 std::enable_if_t<std::is_arithmetic_v<V>> * = nullptr>
+T setMetadata(CameraMetadata *metadata, uint32_t tag,
+	      const ControlInfoMap &controlsInfo, const ControlId *control,
+	      enum ControlRange controlRange, const V defaultValue)
+{
+	T ret = defaultValue;
+
+	const auto &info = controlsInfo.find(control);
+	if (info != controlsInfo.end()) {
+		switch (controlRange) {
+		case ControlRange::Min:
+			ret = info->second.min().get<U>();
+			break;
+		case ControlRange::Def:
+			ret = info->second.def().get<U>();
+			break;
+		case ControlRange::Max:
+			ret = info->second.max().get<U>();
+			break;
+		}
+	}
+
+	metadata->addEntry(tag, ret);
+	return ret;
+}
+
+/**
+ * \brief Set android metadata from libcamera ControlInfo or a default value
+ * \tparam T Type of the control in android
+ * \tparam V Type of the control in libcamera
+ * \param[in] metadata Android metadata to add the control value to
+ * \param[in] tag Android metadata tag to add
+ * \param[in] controlsInfo libcamera ControlInfoMap from which to find the control info
+ * \param[in] control libcamera ControlId to find from \a controlsInfo
+ * \param[in] defaultVector The value to set in \a metadata if \a control is not found
+ *
+ * Set the android metadata entry in \a metadata with tag \a tag based on the
+ * control info found for the libcamera control \a control in the libcamera
+ * ControlInfoMap \a controlsInfo. If no libcamera ControlInfo is found, then
+ * the android metadata entry is set to \a defaultVector.
+ *
+ * This function is for vector values.
+ */
+template<typename T,
+	 typename V>
+std::vector<T> setMetadata(CameraMetadata *metadata, uint32_t tag,
+			   const ControlInfoMap &controlsInfo,
+			   const ControlId *control,
+			   const std::vector<T> &defaultVector)
+{
+	std::vector<T> ret = {};
+
+	const auto &info = controlsInfo.find(control);
+	if (info != controlsInfo.end()) {
+		ret.reserve(info->second.values().size());
+		for (const auto &value : info->second.values())
+			ret.push_back(value.get<V>());
+	} else {
+		ret = defaultVector;
+	}
+
+	metadata->addEntry(tag, ret);
+	return ret;
+}
+
 } /* namespace */
 
 int CameraCapabilities::initialize(std::shared_ptr<libcamera::Camera> camera,
-- 
2.27.0