libcamera: controls: Construct from valid values

Add a new constructor to the ControlInfo class that allows creating
a class instance from the list of the control valid values with
an optional default one.

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

include/libcamera/controls.h

@@ -12,6 +12,7 @@
 #include <stdint.h>
 #include <string>
 #include <unordered_map>
+#include <vector>
 
 #include <libcamera/geometry.h>
 #include <libcamera/span.h>
@@ -269,10 +270,13 @@ public:
 	explicit ControlInfo(const ControlValue &min = 0,
 			     const ControlValue &max = 0,
 			     const ControlValue &def = 0);
+	explicit ControlInfo(Span<const ControlValue> values,
+			     const ControlValue &def = {});
 
 	const ControlValue &min() const { return min_; }
 	const ControlValue &max() const { return max_; }
 	const ControlValue &def() const { return def_; }
+	const std::vector<ControlValue> &values() const { return values_; }
 
 	std::string toString() const;
 
@@ -290,6 +294,7 @@ private:
 	ControlValue min_;
 	ControlValue max_;
 	ControlValue def_;
+	std::vector<ControlValue> values_;
 };
 
 using ControlIdMap = std::unordered_map<unsigned int, const ControlId *>;

src/libcamera/controls.cpp

@@ -491,6 +491,28 @@ ControlInfo::ControlInfo(const ControlValue &min,
 {
 }
 
+/**
+ * \brief Construct a ControlInfo from the list of valid values
+ * \param[in] values The control valid values
+ * \param[in] def The control default value
+ *
+ * Construct a ControlInfo from a list of valid values. The ControlInfo
+ * minimum and maximum values are set to the first and last members of the
+ * values list respectively. The default value is set to \a def if provided, or
+ * to the minimum value otherwise.
+ */
+ControlInfo::ControlInfo(Span<const ControlValue> values,
+			 const ControlValue &def)
+{
+	min_ = values.front();
+	max_ = values.back();
+	def_ = !def.isNone() ? def : values.front();
+
+	values_.reserve(values.size());
+	for (const ControlValue &value : values)
+		values_.push_back(value);
+}
+
 /**
  * \fn ControlInfo::min()
  * \brief Retrieve the minimum value of the control
@@ -519,6 +541,17 @@ ControlInfo::ControlInfo(const ControlValue &min,
  * \return A ControlValue with the default value for the control
  */
 
+/**
+ * \fn ControlInfo::values()
+ * \brief Retrieve the list of valid values
+ *
+ * For controls that support a pre-defined number of values, the enumeration of
+ * those is reported through a vector of ControlValue instances accessible with
+ * this method.
+ *
+ * \return A vector of ControlValue representing the control valid values
+ */
+
 /**
  * \brief Provide a string representation of the ControlInfo
  */