libcamera: controls: Improve the API towards applications

Rework the control-related classes to improve the API towards
applications. The goal is to enable writing code similar to

	Request *req = ...;
	ControlList &controls = req->controls();
	controls->set(controls::AwbEnable, false);
	controls->set(controls::ManualExposure, 1000);

	...

	int32_t exposure = controls->get(controls::ManualExposure);

with the get and set operations ensuring type safety for the control
values. This is achieved by creating the following classes:

- Control defines controls and is the main way to reference a control.
  It is a template class to allow methods using it to refer to the
  control type.

- ControlId is the base class of Control. It stores the control ID, name
  and type, and can be used in contexts where a control needs to be
  referenced regardless of its type (for instance in lists of controls).
  This class replaces ControlIdentifier.

- ControlValue is kept as-is.

The ControlList class now exposes two template get() and set() methods
that replace the operator[]. They ensure type safety by infering the
value type from the Control reference that they receive.

The main way to refer to a control is now through the Control class, and
optionally through its base ControlId class. The ControlId enumeration
is removed, replaced by a list of global Control instances. Numerical
control IDs are turned into macros, and are still exposed as they are
required to communicate with IPAs (especially to deserialise control
lists). They should however not be used by applications.

Auto-generation of header and source files is removed for now to keep
the change simple. It will be added back in the future in a more
elaborate form.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

2 files changed, 24 insertions, 44 deletions

diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
index 0d56758e..d5d30932 100644
--- a/src/libcamera/pipeline/uvcvideo.cpp
+++ b/src/libcamera/pipeline/uvcvideo.cpp
@@ -10,6 +10,7 @@
 #include <tuple>
 
 #include <libcamera/camera.h>
+#include <libcamera/control_ids.h>
 #include <libcamera/controls.h>
 #include <libcamera/request.h>
 #include <libcamera/stream.h>
@@ -230,33 +231,20 @@ int PipelineHandlerUVC::processControls(UVCCameraData *data, Request *request)
 	V4L2ControlList controls;
 
 	for (auto it : request->controls()) {
-		const ControlInfo *ci = it.first;
+		const ControlId &id = *it.first;
 		ControlValue &value = it.second;
 
-		switch (ci->id()) {
-		case Brightness:
+		if (id == controls::Brightness) {
 			controls.add(V4L2_CID_BRIGHTNESS, value.get<int32_t>());
-			break;
-
-		case Contrast:
+		} else if (id == controls::Contrast) {
 			controls.add(V4L2_CID_CONTRAST, value.get<int32_t>());
-			break;
-
-		case Saturation:
+		} else if (id == controls::Saturation) {
 			controls.add(V4L2_CID_SATURATION, value.get<int32_t>());
-			break;
-
-		case ManualExposure:
+		} else if (id == controls::ManualExposure) {
 			controls.add(V4L2_CID_EXPOSURE_AUTO, 1);
 			controls.add(V4L2_CID_EXPOSURE_ABSOLUTE, value.get<int32_t>());
-			break;
-
-		case ManualGain:
+		} else if (id == controls::ManualGain) {
 			controls.add(V4L2_CID_GAIN, value.get<int32_t>());
-			break;
-
-		default:
-			break;
 		}
 	}
 
@@ -352,23 +340,23 @@ int UVCCameraData::init(MediaEntity *entity)
 	for (const auto &ctrl : controls) {
 		unsigned int v4l2Id = ctrl.first;
 		const V4L2ControlInfo &info = ctrl.second;
-		ControlId id;
+		const ControlId *id;
 
 		switch (v4l2Id) {
 		case V4L2_CID_BRIGHTNESS:
-			id = Brightness;
+			id = &controls::Brightness;
 			break;
 		case V4L2_CID_CONTRAST:
-			id = Contrast;
+			id = &controls::Contrast;
 			break;
 		case V4L2_CID_SATURATION:
-			id = Saturation;
+			id = &controls::Saturation;
 			break;
 		case V4L2_CID_EXPOSURE_ABSOLUTE:
-			id = ManualExposure;
+			id = &controls::ManualExposure;
 			break;
 		case V4L2_CID_GAIN:
-			id = ManualGain;
+			id = &controls::ManualGain;
 			break;
 		default:
 			continue;
@@ -376,7 +364,7 @@ int UVCCameraData::init(MediaEntity *entity)
 
 		controlInfo_.emplace(std::piecewise_construct,
 				     std::forward_as_tuple(id),
-				     std::forward_as_tuple(id, info.min(), info.max()));
+				     std::forward_as_tuple(*id, info.min(), info.max()));
 	}
 
 	return 0;
diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
index e549dc64..608a47ae 100644
--- a/src/libcamera/pipeline/vimc.cpp
+++ b/src/libcamera/pipeline/vimc.cpp
@@ -15,6 +15,7 @@
 #include <ipa/ipa_interface.h>
 #include <ipa/ipa_module_info.h>
 #include <libcamera/camera.h>
+#include <libcamera/control_ids.h>
 #include <libcamera/controls.h>
 #include <libcamera/request.h>
 #include <libcamera/stream.h>
@@ -283,24 +284,15 @@ int PipelineHandlerVimc::processControls(VimcCameraData *data, Request *request)
 	V4L2ControlList controls;
 
 	for (auto it : request->controls()) {
-		const ControlInfo *ci = it.first;
+		const ControlId &id = *it.first;
 		ControlValue &value = it.second;
 
-		switch (ci->id()) {
-		case Brightness:
+		if (id == controls::Brightness) {
 			controls.add(V4L2_CID_BRIGHTNESS, value.get<int32_t>());
-			break;
-
-		case Contrast:
+		} else if (id == controls::Contrast) {
 			controls.add(V4L2_CID_CONTRAST, value.get<int32_t>());
-			break;
-
-		case Saturation:
+		} else if (id == controls::Saturation) {
 			controls.add(V4L2_CID_SATURATION, value.get<int32_t>());
-			break;
-
-		default:
-			break;
 		}
 	}
 
@@ -427,17 +419,17 @@ int VimcCameraData::init(MediaDevice *media)
 	for (const auto &ctrl : controls) {
 		unsigned int v4l2Id = ctrl.first;
 		const V4L2ControlInfo &info = ctrl.second;
-		ControlId id;
+		const ControlId *id;
 
 		switch (v4l2Id) {
 		case V4L2_CID_BRIGHTNESS:
-			id = Brightness;
+			id = &controls::Brightness;
 			break;
 		case V4L2_CID_CONTRAST:
-			id = Contrast;
+			id = &controls::Contrast;
 			break;
 		case V4L2_CID_SATURATION:
-			id = Saturation;
+			id = &controls::Saturation;
 			break;
 		default:
 			continue;
@@ -445,7 +437,7 @@ int VimcCameraData::init(MediaDevice *media)
 
 		controlInfo_.emplace(std::piecewise_construct,
 				     std::forward_as_tuple(id),
-				     std::forward_as_tuple(id, info.min(), info.max()));
+				     std::forward_as_tuple(*id, info.min(), info.max()));
 	}
 
 	return 0;