gstreamer: Generate controls from control_ids_*.yaml files

This commit implements gstreamer controls for the libcamera element by
generating the controls from the control_ids_*.yaml files using a new
gen-gst-controls.py script. The appropriate meson files are also changed
to automatically run the script when building.

The gen-gst-controls.py script works similar to the gen-controls.py
script by parsing the control_ids_*.yaml files and generating C++ code
for each exposed control.
For the controls to be used as gstreamer properties the type for each
control needs to be translated to the appropriate glib type and a
GEnumValue is generated for each enum control. Then a
g_object_install_property(), _get_property() and _set_property()
function is generated for each control.
The vendor controls get prefixed with "$vendor-" in the final gstreamer
property name.

The C++ code generated by the gen-gst-controls.py script is written into
the template gstlibcamerasrc-controls.cpp.in file. The matching
gstlibcamerasrc-controls.h header defines the GstCameraControls class
which handles the installation of the gstreamer properties as well as
keeping track of the control values and setting and getting the
controls. The content of these functions is generated in the Python
script.

Finally the libcamerasrc element itself is edited to make use of the new
GstCameraControls class. The way this works is by defining a PROP_LAST
enum variant which is passed to the installProperties() function so the
properties are defined with the appropriate offset. When getting or
setting a property PROP_LAST is subtracted from the requested property
to translate the control back into a libcamera::controls:: enum
variant.

Signed-off-by: Jaslo Ziska <jaslo@ziska.de>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

4 files changed, 404 insertions, 3 deletions

diff --git a/src/gstreamer/gstlibcamera-controls.cpp.in b/src/gstreamer/gstlibcamera-controls.cpp.in
new file mode 100644
index 00000000..ace36b71
--- /dev/null
+++ b/src/gstreamer/gstlibcamera-controls.cpp.in
@@ -0,0 +1,332 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024, Jaslo Ziska
+ *
+ * GStreamer Camera Controls
+ *
+ * This file is auto-generated. Do not edit.
+ */
+
+#include <vector>
+
+#include <libcamera/control_ids.h>
+#include <libcamera/controls.h>
+#include <libcamera/geometry.h>
+
+#include "gstlibcamera-controls.h"
+
+using namespace libcamera;
+
+static void value_set_rectangle(GValue *value, const Rectangle &rect)
+{
+	Point top_left = rect.topLeft();
+	Size size = rect.size();
+
+	GValue x = G_VALUE_INIT;
+	g_value_init(&x, G_TYPE_INT);
+	g_value_set_int(&x, top_left.x);
+	gst_value_array_append_and_take_value(value, &x);
+
+	GValue y = G_VALUE_INIT;
+	g_value_init(&y, G_TYPE_INT);
+	g_value_set_int(&y, top_left.y);
+	gst_value_array_append_and_take_value(value, &y);
+
+	GValue width = G_VALUE_INIT;
+	g_value_init(&width, G_TYPE_INT);
+	g_value_set_int(&width, size.width);
+	gst_value_array_append_and_take_value(value, &width);
+
+	GValue height = G_VALUE_INIT;
+	g_value_init(&height, G_TYPE_INT);
+	g_value_set_int(&x, size.height);
+	gst_value_array_append_and_take_value(value, &height);
+}
+
+static Rectangle value_get_rectangle(const GValue *value)
+{
+	const GValue *r;
+	r = gst_value_array_get_value(value, 0);
+	int x = g_value_get_int(r);
+	r = gst_value_array_get_value(value, 1);
+	int y = g_value_get_int(r);
+	r = gst_value_array_get_value(value, 2);
+	int w = g_value_get_int(r);
+	r = gst_value_array_get_value(value, 3);
+	int h = g_value_get_int(r);
+
+	return Rectangle(x, y, w, h);
+}
+
+{% for vendor, ctrls in controls %}
+{%- for ctrl in ctrls if ctrl.is_enum %}
+static const GEnumValue {{ ctrl.name|snake_case }}_types[] = {
+{%- for enum in ctrl.enum_values %}
+	{
+		controls::{{ ctrl.namespace }}{{ enum.name }},
+		{{ enum.description|format_description|indent_str('\t\t') }},
+		"{{ enum.gst_name }}"
+	},
+{%- endfor %}
+	{0, NULL, NULL}
+};
+
+#define TYPE_{{ ctrl.name|snake_case|upper }} \
+	({{ ctrl.name|snake_case }}_get_type())
+static GType {{ ctrl.name|snake_case }}_get_type()
+{
+	static GType {{ ctrl.name|snake_case }}_type = 0;
+
+	if (!{{ ctrl.name|snake_case }}_type)
+		{{ ctrl.name|snake_case }}_type =
+			g_enum_register_static("{{ ctrl.name }}",
+					       {{ ctrl.name|snake_case }}_types);
+
+	return {{ ctrl.name|snake_case }}_type;
+}
+{% endfor %}
+{%- endfor %}
+
+void GstCameraControls::installProperties(GObjectClass *klass, int lastPropId)
+{
+{%- for vendor, ctrls in controls %}
+{%- for ctrl in ctrls %}
+
+{%- set spec %}
+{%- if ctrl.is_rectangle -%}
+gst_param_spec_array(
+{%- else -%}
+g_param_spec_{{ ctrl.gtype }}(
+{%- endif -%}
+{%- if ctrl.is_array %}
+	"{{ ctrl.vendor_prefix }}{{ ctrl.name|kebab_case }}-value",
+	"{{ ctrl.name }} Value",
+	"One {{ ctrl.name }} element value",
+{%- else %}
+	"{{ ctrl.vendor_prefix }}{{ ctrl.name|kebab_case }}",
+	"{{ ctrl.name }}",
+	{{ ctrl.description|format_description|indent_str('\t') }},
+{%- endif %}
+{%- if ctrl.is_enum %}
+	TYPE_{{ ctrl.name|snake_case|upper }},
+	{{ ctrl.default }},
+{%- elif ctrl.is_rectangle %}
+	g_param_spec_int(
+		"rectangle-value",
+		"Rectangle Value",
+		"One rectangle value, either x, y, width or height.",
+		{{ ctrl.min }}, {{ ctrl.max }}, {{ ctrl.default }},
+		(GParamFlags) (GST_PARAM_CONTROLLABLE | G_PARAM_READWRITE |
+			       G_PARAM_STATIC_STRINGS)
+	),
+{%- elif ctrl.gtype == 'boolean' %}
+	{{ ctrl.default }},
+{%- elif ctrl.gtype in ['float', 'int', 'int64', 'uchar'] %}
+	{{ ctrl.min }}, {{ ctrl.max }}, {{ ctrl.default }},
+{%- endif %}
+	(GParamFlags) (GST_PARAM_CONTROLLABLE | G_PARAM_READWRITE |
+		       G_PARAM_STATIC_STRINGS)
+)
+{%- endset %}
+
+	g_object_class_install_property(
+		klass,
+		lastPropId + controls::{{ ctrl.namespace }}{{ ctrl.name|snake_case|upper }},
+{%- if ctrl.is_array %}
+		gst_param_spec_array(
+			"{{ ctrl.vendor_prefix }}{{ ctrl.name|kebab_case }}",
+			"{{ ctrl.name }}",
+			{{ ctrl.description|format_description|indent_str('\t\t\t') }},
+			{{ spec|indent_str('\t\t\t') }},
+			(GParamFlags) (GST_PARAM_CONTROLLABLE |
+				       G_PARAM_READWRITE |
+				       G_PARAM_STATIC_STRINGS)
+		)
+{%- else %}
+		{{ spec|indent_str('\t\t') }}
+{%- endif %}
+	);
+{%- endfor %}
+{%- endfor %}
+}
+
+bool GstCameraControls::getProperty(guint propId, GValue *value,
+				    [[maybe_unused]] GParamSpec *pspec)
+{
+	if (!controls_acc_.contains(propId)) {
+		GST_WARNING("Control '%s' is not available, default value will "
+			    "be returned",
+			    controls::controls.at(propId)->name().c_str());
+		return true;
+	}
+	const ControlValue &cv = controls_acc_.get(propId);
+
+	switch (propId) {
+{%- for vendor, ctrls in controls %}
+{%- for ctrl in ctrls %}
+
+	case controls::{{ ctrl.namespace }}{{ ctrl.name|snake_case|upper }}: {
+		auto control = cv.get<{{ ctrl.type }}>();
+
+{%- if ctrl.is_array %}
+		for (size_t i = 0; i < control.size(); ++i) {
+			GValue element = G_VALUE_INIT;
+{%- if ctrl.is_rectangle %}
+			g_value_init(&element, GST_TYPE_PARAM_ARRAY_LIST);
+			value_set_rectangle(&element, control[i]);
+{%- else %}
+			g_value_init(&element, G_TYPE_{{ ctrl.gtype|upper }});
+			g_value_set_{{ ctrl.gtype }}(&element, control[i]);
+{%- endif %}
+			gst_value_array_append_and_take_value(value, &element);
+		}
+{%- else %}
+{%- if ctrl.is_rectangle %}
+		value_set_rectangle(value, control);
+{%- else %}
+		g_value_set_{{ ctrl.gtype }}(value, control);
+{%- endif %}
+{%- endif %}
+
+		return true;
+	}
+{%- endfor %}
+{%- endfor %}
+
+	default:
+		return false;
+	}
+}
+
+bool GstCameraControls::setProperty(guint propId, const GValue *value,
+				    [[maybe_unused]] GParamSpec *pspec)
+{
+	/*
+	 * Check whether the camera capabilities are already available.
+	 * They might not be available if the pipeline has not started yet.
+	 */
+	if (!capabilities_.empty()) {
+ 		/* If so, check that the control is supported by the camera. */
+		const ControlId *cid = capabilities_.idmap().at(propId);
+		auto info = capabilities_.find(cid);
+
+		if (info == capabilities_.end()) {
+			GST_WARNING("Control '%s' is not supported by the "
+				    "camera and will be ignored",
+				    cid->name().c_str());
+			return true;
+		}
+	}
+
+	switch (propId) {
+{%- for vendor, ctrls in controls %}
+{%- for ctrl in ctrls %}
+
+	case controls::{{ ctrl.namespace }}{{ ctrl.name|snake_case|upper }}: {
+		ControlValue control;
+{%- if ctrl.is_array %}
+		size_t size = gst_value_array_get_size(value);
+{%- if ctrl.size != 0 %}
+		if (size != {{ ctrl.size }}) {
+			GST_ERROR("Incorrect array size for control "
+				  "'{{ ctrl.name|kebab_case }}', must be of "
+				  "size {{ ctrl.size }}");
+			return true;
+		}
+{%- endif %}
+
+		std::vector<{{ ctrl.element_type }}> values(size);
+		for (size_t i = 0; i < size; ++i) {
+			const GValue *element =
+				gst_value_array_get_value(value, i);
+{%- if ctrl.is_rectangle %}
+			if (gst_value_array_get_size(element) != 4) {
+				GST_ERROR("Rectangle in control "
+					  "'{{ ctrl.name|kebab_case }}' at"
+					  "index %zu must be an array of size 4",
+					  i);
+				return true;
+			}
+			values[i] = value_get_rectangle(element);
+{%- else %}
+			values[i] = g_value_get_{{ ctrl.gtype }}(element);
+{%- endif %}
+		}
+
+{%- if ctrl.size == 0 %}
+		control.set(Span<const {{ ctrl.element_type }}>(values.data(),
+								size));
+{%- else %}
+		control.set(Span<const {{ ctrl.element_type }},
+			         {{ ctrl.size }}>(values.data(),
+						  {{ ctrl.size }}));
+{%- endif %}
+{%- else %}
+{%- if ctrl.is_rectangle %}
+		if (gst_value_array_get_size(value) != 4) {
+			GST_ERROR("Rectangle in control "
+				  "'{{ ctrl.name|kebab_case }}' must be an "
+				  "array of size 4");
+			return true;
+		}
+		Rectangle val = value_get_rectangle(value);
+{%- else %}
+		auto val = g_value_get_{{ ctrl.gtype }}(value);
+{%- endif %}
+		control.set(val);
+{%- endif %}
+		controls_.set(propId, control);
+		controls_acc_.set(propId, control);
+		return true;
+	}
+{%- endfor %}
+{%- endfor %}
+
+	default:
+		return false;
+	}
+}
+
+void GstCameraControls::setCamera(const std::shared_ptr<libcamera::Camera> &cam)
+{
+	capabilities_ = cam->controls();
+
+	/*
+	 * Check the controls which were set before the camera capabilities were
+	 * known. This is required because GStreamer may set properties before
+	 * the pipeline has started and thus before the camera was known.
+	 */
+	ControlList new_controls;
+	for (auto control = controls_acc_.begin();
+	     control != controls_acc_.end();
+	     ++control) {
+		unsigned int id = control->first;
+		ControlValue value = control->second;
+
+		const ControlId *cid = capabilities_.idmap().at(id);
+		auto info = capabilities_.find(cid);
+
+		/* Only add controls which are supported. */
+		if (info != capabilities_.end())
+			new_controls.set(id, value);
+		else
+			GST_WARNING("Control '%s' is not supported by the "
+				    "camera and will be ignored",
+				    cid->name().c_str());
+	}
+
+	controls_acc_ = new_controls;
+	controls_ = new_controls;
+}
+
+void GstCameraControls::applyControls(std::unique_ptr<libcamera::Request> &request)
+{
+	request->controls().merge(controls_);
+	controls_.clear();
+}
+
+void GstCameraControls::readMetadata(libcamera::Request *request)
+{
+	controls_acc_.merge(request->metadata(),
+			    ControlList::MergePolicy::OverwriteExisting);
+}
diff --git a/src/gstreamer/gstlibcamera-controls.h b/src/gstreamer/gstlibcamera-controls.h
new file mode 100644
index 00000000..749220b5
--- /dev/null
+++ b/src/gstreamer/gstlibcamera-controls.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2023, Collabora Ltd.
+ *     Author: Nicolas Dufresne <nicolas.dufresne@collabora.com>
+ *
+ * GStreamer Camera Controls
+ */
+
+#pragma once
+
+#include <memory>
+
+#include <libcamera/camera.h>
+#include <libcamera/controls.h>
+#include <libcamera/request.h>
+
+#include "gstlibcamerasrc.h"
+
+namespace libcamera {
+
+class GstCameraControls
+{
+public:
+	static void installProperties(GObjectClass *klass, int lastProp);
+
+	bool getProperty(guint propId, GValue *value, GParamSpec *pspec);
+	bool setProperty(guint propId, const GValue *value, GParamSpec *pspec);
+
+	void setCamera(const std::shared_ptr<libcamera::Camera> &cam);
+
+	void applyControls(std::unique_ptr<libcamera::Request> &request);
+	void readMetadata(libcamera::Request *request);
+
+private:
+	/* Supported controls and limits of camera. */
+	ControlInfoMap capabilities_;
+	/* Set of user modified controls. */
+	ControlList controls_;
+	/* Accumulator of all controls ever set and metadata returned by camera */
+	ControlList controls_acc_;
+};
+
+} /* namespace libcamera */
diff --git a/src/gstreamer/gstlibcamerasrc.cpp b/src/gstreamer/gstlibcamerasrc.cpp
index 40b787c8..8efa25f4 100644
--- a/src/gstreamer/gstlibcamerasrc.cpp
+++ b/src/gstreamer/gstlibcamerasrc.cpp
@@ -37,10 +37,11 @@
 
 #include <gst/base/base.h>
 
+#include "gstlibcamera-controls.h"
+#include "gstlibcamera-utils.h"
 #include "gstlibcameraallocator.h"
 #include "gstlibcamerapad.h"
 #include "gstlibcamerapool.h"
-#include "gstlibcamera-utils.h"
 
 using namespace libcamera;
 
@@ -128,6 +129,7 @@ struct GstLibcameraSrcState {
 
 	ControlList initControls_;
 	guint group_id_;
+	GstCameraControls controls_;
 
 	int queueRequest();
 	void requestCompleted(Request *request);
@@ -153,6 +155,7 @@ struct _GstLibcameraSrc {
 enum {
 	PROP_0,
 	PROP_CAMERA_NAME,
+	PROP_LAST
 };
 
 static void gst_libcamera_src_child_proxy_init(gpointer g_iface,
@@ -183,6 +186,9 @@ int GstLibcameraSrcState::queueRequest()
 	if (!request)
 		return -ENOMEM;
 
+	/* Apply controls */
+	controls_.applyControls(request);
+
 	std::unique_ptr<RequestWrap> wrap =
 		std::make_unique<RequestWrap>(std::move(request));
 
@@ -226,6 +232,9 @@ GstLibcameraSrcState::requestCompleted(Request *request)
 
 	{
 		GLibLocker locker(&lock_);
+
+		controls_.readMetadata(request);
+
 		wrap = std::move(queuedRequests_.front());
 		queuedRequests_.pop();
 	}
@@ -408,6 +417,8 @@ gst_libcamera_src_open(GstLibcameraSrc *self)
 		return false;
 	}
 
+	self->state->controls_.setCamera(cam);
+
 	cam->requestCompleted.connect(self->state, &GstLibcameraSrcState::requestCompleted);
 
 	/* No need to lock here, we didn't start our threads yet. */
@@ -722,6 +733,7 @@ gst_libcamera_src_set_property(GObject *object, guint prop_id,
 {
 	GLibLocker lock(GST_OBJECT(object));
 	GstLibcameraSrc *self = GST_LIBCAMERA_SRC(object);
+	GstLibcameraSrcState *state = self->state;
 
 	switch (prop_id) {
 	case PROP_CAMERA_NAME:
@@ -729,7 +741,8 @@ gst_libcamera_src_set_property(GObject *object, guint prop_id,
 		self->camera_name = g_value_dup_string(value);
 		break;
 	default:
-		G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
+		if (!state->controls_.setProperty(prop_id - PROP_LAST, value, pspec))
+			G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
 		break;
 	}
 }
@@ -740,13 +753,15 @@ gst_libcamera_src_get_property(GObject *object, guint prop_id, GValue *value,
 {
 	GLibLocker lock(GST_OBJECT(object));
 	GstLibcameraSrc *self = GST_LIBCAMERA_SRC(object);
+	GstLibcameraSrcState *state = self->state;
 
 	switch (prop_id) {
 	case PROP_CAMERA_NAME:
 		g_value_set_string(value, self->camera_name);
 		break;
 	default:
-		G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
+		if (!state->controls_.getProperty(prop_id - PROP_LAST, value, pspec))
+			G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
 		break;
 	}
 }
@@ -947,6 +962,7 @@ gst_libcamera_src_class_init(GstLibcameraSrcClass *klass)
 							     | G_PARAM_STATIC_STRINGS));
 	g_object_class_install_property(object_class, PROP_CAMERA_NAME, spec);
 
+	GstCameraControls::installProperties(object_class, PROP_LAST);
 }
 
 /* GstChildProxy implementation */
diff --git a/src/gstreamer/meson.build b/src/gstreamer/meson.build
index c2a01e7b..6b7e53b5 100644
--- a/src/gstreamer/meson.build
+++ b/src/gstreamer/meson.build
@@ -25,6 +25,16 @@ libcamera_gst_sources = [
     'gstlibcamerasrc.cpp',
 ]
 
+# Generate gstreamer control properties
+
+gen_gst_controls_template = files('gstlibcamera-controls.cpp.in')
+libcamera_gst_sources += custom_target('gstlibcamera-controls.cpp',
+                                       input : controls_files,
+                                       output : 'gstlibcamera-controls.cpp',
+                                       command : [gen_gst_controls, '-o', '@OUTPUT@',
+                                                  '-t', gen_gst_controls_template, '@INPUT@'],
+                                       env : py_build_env)
+
 libcamera_gst_cpp_args = [
     '-DVERSION="@0@"'.format(libcamera_git_version),
     '-DPACKAGE="@0@"'.format(meson.project_name()),