[PATCH] libcamera: controls: Handle enum values without a cast

[Laurent Pinchart]

When constructing a ControlValue from an enum value, an explicit cast to
int32_t is needed as we use int32_t as the underlying type for all
enumerated controls. This makes users of ControlValue more complex. To
simplify them, specialize the control_type template for enum types, to
support construction of ControlValue directly without a cast.

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 include/libcamera/controls.h         | 6 +++++-
 src/libcamera/pipeline/ipu3/ipu3.cpp | 2 +-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
index 25f67ed948a3..c5131870d402 100644
--- a/include/libcamera/controls.h
+++ b/include/libcamera/controls.h
@@ -39,7 +39,7 @@ enum ControlType {
 
 namespace details {
 
-template<typename T>
+template<typename T, typename = std::void_t<>>
 struct control_type {
 };
 
@@ -102,6 +102,10 @@ struct control_type<Span<T, N>> : public control_type<std::remove_cv_t<T>> {
 	static constexpr std::size_t size = N;
 };
 
+template<typename T>
+struct control_type<T, std::enable_if_t<std::is_enum_v<T>>> : public control_type<int32_t> {
+};
+
 } /* namespace details */
 
 class ControlValue
diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
index 430aa902eec8..29d3c6c194c1 100644
--- a/src/libcamera/pipeline/ipu3/ipu3.cpp
+++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
@@ -958,7 +958,7 @@ int PipelineHandlerIPU3::updateControls(IPU3CameraData *data)
 		values.reserve(testPatternModes.size());
 
 		for (auto pattern : testPatternModes)
-			values.emplace_back(static_cast<int32_t>(pattern));
+			values.emplace_back(pattern);
 
 		controls[&controls::draft::TestPatternMode] = ControlInfo(values);
 	}

base-commit: f2088eb91fd6477b152233b9031cb115ca1ae824
-- 
Regards,

Laurent Pinchart