cam: Add a parser for capture scripts

Add a parser class to the cam test application to control the capture
operations through a yaml script.

The capture script currently allow to specify a list of controls and
their associated values to be applied per-frame.

Also add a trivial capture script example to showcase the intended
script structure.

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

4 files changed, 446 insertions, 0 deletions

diff --git a/src/cam/capture-script.yaml b/src/cam/capture-script.yaml
new file mode 100644
index 00000000..6a749bc6
--- /dev/null
+++ b/src/cam/capture-script.yaml
@@ -0,0 +1,46 @@
+# SPDX-License-Identifier: CC0-1.0
+
+# Capture script example
+#
+# A capture script allows to associate a list of controls and their values
+# to frame numbers.
+
+# \todo Formally define the capture script structure with a schema
+
+# Notes:
+# - Controls have to be specified by name, as defined in the
+#   libcamera::controls:: enumeration
+# - Controls not supported by the camera currently operated are ignored
+# - Frame numbers shall be monotonically incrementing, gaps are allowed
+
+# Example:
+frames:
+  - 1:
+      Brightness: 0.0
+
+  - 40:
+      Brightness: 0.2
+
+  - 80:
+      Brightness: 0.4
+
+  - 120:
+      Brightness: 0.8
+
+  - 160:
+      Brightness: 0.4
+
+  - 200:
+      Brightness: 0.2
+
+  - 240:
+      Brightness: 0.0
+
+  - 280:
+      Brightness: -0.2
+
+  - 300:
+      Brightness: -0.4
+
+  - 340:
+      Brightness: -0.8
diff --git a/src/cam/capture_script.cpp b/src/cam/capture_script.cpp
new file mode 100644
index 00000000..9f22d5f7
--- /dev/null
+++ b/src/cam/capture_script.cpp
@@ -0,0 +1,336 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2022, Ideas on Board Oy
+ *
+ * capture_script.cpp - Capture session configuration script
+ */
+
+#include "capture_script.h"
+
+#include <iostream>
+#include <stdio.h>
+#include <stdlib.h>
+
+using namespace libcamera;
+
+CaptureScript::CaptureScript(std::shared_ptr<Camera> camera,
+			     const std::string &fileName)
+	: camera_(camera), valid_(false)
+{
+	FILE *fh = fopen(fileName.c_str(), "r");
+	if (!fh) {
+		int ret = -errno;
+		std::cerr << "Failed to open capture script " << fileName
+			  << ": " << strerror(-ret) << std::endl;
+		return;
+	}
+
+	/*
+	 * Map the camera's controls to their name so that they can be
+	 * easily identified when parsing the script file.
+	 */
+	for (const auto &[control, info] : camera_->controls())
+		controls_[control->name()] = control;
+
+	int ret = parseScript(fh);
+	fclose(fh);
+	if (ret)
+		return;
+
+	valid_ = true;
+}
+
+/* Retrieve the control list associated with a frame number. */
+const ControlList &CaptureScript::frameControls(unsigned int frame)
+{
+	static ControlList controls{};
+
+	auto it = frameControls_.find(frame);
+	if (it == frameControls_.end())
+		return controls;
+
+	return it->second;
+}
+
+CaptureScript::EventPtr CaptureScript::nextEvent(yaml_event_type_t expectedType)
+{
+	EventPtr event(new yaml_event_t);
+
+	if (!yaml_parser_parse(&parser_, event.get()))
+		return nullptr;
+
+	if (expectedType != YAML_NO_EVENT && !checkEvent(event, expectedType))
+		return nullptr;
+
+	return event;
+}
+
+bool CaptureScript::checkEvent(const EventPtr &event, yaml_event_type_t expectedType) const
+{
+	if (event->type != expectedType) {
+		std::cerr << "Capture script error on line " << event->start_mark.line
+			  << " column " << event->start_mark.column << ": "
+			  << "Expected " << eventTypeName(expectedType)
+			  << " event, got " << eventTypeName(event->type)
+			  << std::endl;
+		return false;
+	}
+
+	return true;
+}
+
+std::string CaptureScript::eventScalarValue(const EventPtr &event)
+{
+	return std::string(reinterpret_cast<char *>(event->data.scalar.value),
+			   event->data.scalar.length);
+}
+
+std::string CaptureScript::eventTypeName(yaml_event_type_t type)
+{
+	static const std::map<yaml_event_type_t, std::string> typeNames = {
+		{ YAML_STREAM_START_EVENT, "stream-start" },
+		{ YAML_STREAM_END_EVENT, "stream-end" },
+		{ YAML_DOCUMENT_START_EVENT, "document-start" },
+		{ YAML_DOCUMENT_END_EVENT, "document-end" },
+		{ YAML_ALIAS_EVENT, "alias" },
+		{ YAML_SCALAR_EVENT, "scalar" },
+		{ YAML_SEQUENCE_START_EVENT, "sequence-start" },
+		{ YAML_SEQUENCE_END_EVENT, "sequence-end" },
+		{ YAML_MAPPING_START_EVENT, "mapping-start" },
+		{ YAML_MAPPING_END_EVENT, "mapping-end" },
+	};
+
+	auto it = typeNames.find(type);
+	if (it == typeNames.end())
+		return "[type " + std::to_string(type) + "]";
+
+	return it->second;
+}
+
+int CaptureScript::parseScript(FILE *script)
+{
+	int ret = yaml_parser_initialize(&parser_);
+	if (!ret) {
+		std::cerr << "Failed to initialize yaml parser" << std::endl;
+		return ret;
+	}
+
+	/* Delete the parser upon function exit. */
+	struct ParserDeleter {
+		ParserDeleter(yaml_parser_t *parser) : parser_(parser) { }
+		~ParserDeleter() { yaml_parser_delete(parser_); }
+		yaml_parser_t *parser_;
+	} deleter(&parser_);
+
+	yaml_parser_set_input_file(&parser_, script);
+
+	EventPtr event = nextEvent(YAML_STREAM_START_EVENT);
+	if (!event)
+		return -EINVAL;
+
+	event = nextEvent(YAML_DOCUMENT_START_EVENT);
+	if (!event)
+		return -EINVAL;
+
+	event = nextEvent(YAML_MAPPING_START_EVENT);
+	if (!event)
+		return -EINVAL;
+
+	while (1) {
+		event = nextEvent();
+		if (!event)
+			return -EINVAL;
+
+		if (event->type == YAML_MAPPING_END_EVENT)
+			return 0;
+
+		if (!checkEvent(event, YAML_SCALAR_EVENT))
+			return -EINVAL;
+
+		std::string section = eventScalarValue(event);
+
+		if (section == "frames") {
+			parseFrames();
+		} else {
+			std::cerr << "Unsupported section '" << section << "'"
+				  << std::endl;
+			return -EINVAL;
+		}
+	}
+}
+
+int CaptureScript::parseFrames()
+{
+	EventPtr event = nextEvent(YAML_SEQUENCE_START_EVENT);
+	if (!event)
+		return -EINVAL;
+
+	while (1) {
+		event = nextEvent();
+		if (!event)
+			return -EINVAL;
+
+		if (event->type == YAML_SEQUENCE_END_EVENT)
+			return 0;
+
+		int ret = parseFrame(std::move(event));
+		if (ret)
+			return ret;
+	}
+}
+
+int CaptureScript::parseFrame(EventPtr event)
+{
+	if (!checkEvent(event, YAML_MAPPING_START_EVENT))
+		return -EINVAL;
+
+	std::string key = parseScalar();
+	if (key.empty())
+		return -EINVAL;
+
+	unsigned int frameId = atoi(key.c_str());
+
+	event = nextEvent(YAML_MAPPING_START_EVENT);
+	if (!event)
+		return -EINVAL;
+
+	ControlList controls{};
+
+	while (1) {
+		event = nextEvent();
+		if (!event)
+			return -EINVAL;
+
+		if (event->type == YAML_MAPPING_END_EVENT)
+			break;
+
+		int ret = parseControl(std::move(event), controls);
+		if (ret)
+			return ret;
+	}
+
+	frameControls_[frameId] = std::move(controls);
+
+	event = nextEvent(YAML_MAPPING_END_EVENT);
+	if (!event)
+		return -EINVAL;
+
+	return 0;
+}
+
+int CaptureScript::parseControl(EventPtr event, ControlList &controls)
+{
+	/* We expect a value after a key. */
+	std::string name = eventScalarValue(event);
+	if (name.empty())
+		return -EINVAL;
+
+	/* If the camera does not support the control just ignore it. */
+	auto it = controls_.find(name);
+	if (it == controls_.end()) {
+		std::cerr << "Unsupported control '" << name << "'" << std::endl;
+		return -EINVAL;
+	}
+
+	std::string value = parseScalar();
+	if (value.empty())
+		return -EINVAL;
+
+	const ControlId *controlId = it->second;
+	ControlValue val = unpackControl(controlId, value);
+	controls.set(controlId->id(), val);
+
+	return 0;
+}
+
+std::string CaptureScript::parseScalar()
+{
+	EventPtr event = nextEvent(YAML_SCALAR_EVENT);
+	if (!event)
+		return "";
+
+	return eventScalarValue(event);
+}
+
+void CaptureScript::unpackFailure(const ControlId *id, const std::string &repr)
+{
+	static const std::map<unsigned int, const char *> typeNames = {
+		{ ControlTypeNone, "none" },
+		{ ControlTypeBool, "bool" },
+		{ ControlTypeByte, "byte" },
+		{ ControlTypeInteger32, "int32" },
+		{ ControlTypeInteger64, "int64" },
+		{ ControlTypeFloat, "float" },
+		{ ControlTypeString, "string" },
+		{ ControlTypeRectangle, "Rectangle" },
+		{ ControlTypeSize, "Size" },
+	};
+
+	const char *typeName;
+	auto it = typeNames.find(id->type());
+	if (it != typeNames.end())
+		typeName = it->second;
+	else
+		typeName = "unknown";
+
+	std::cerr << "Unsupported control '" << repr << "' for "
+		  << typeName << " control " << id->name() << std::endl;
+}
+
+ControlValue CaptureScript::unpackControl(const ControlId *id,
+					  const std::string &repr)
+{
+	ControlValue value{};
+
+	switch (id->type()) {
+	case ControlTypeNone:
+		break;
+	case ControlTypeBool: {
+		bool val;
+
+		if (repr == "true") {
+			val = true;
+		} else if (repr == "false") {
+			val = false;
+		} else {
+			unpackFailure(id, repr);
+			return value;
+		}
+
+		value.set<bool>(val);
+		break;
+	}
+	case ControlTypeByte: {
+		uint8_t val = strtol(repr.c_str(), NULL, 10);
+		value.set<uint8_t>(val);
+		break;
+	}
+	case ControlTypeInteger32: {
+		int32_t val = strtol(repr.c_str(), NULL, 10);
+		value.set<int32_t>(val);
+		break;
+	}
+	case ControlTypeInteger64: {
+		int64_t val = strtoll(repr.c_str(), NULL, 10);
+		value.set<int64_t>(val);
+		break;
+	}
+	case ControlTypeFloat: {
+		float val = strtof(repr.c_str(), NULL);
+		value.set<float>(val);
+		break;
+	}
+	case ControlTypeString: {
+		value.set<std::string>(repr);
+		break;
+	}
+	case ControlTypeRectangle:
+		/* \todo Parse rectangles. */
+		break;
+	case ControlTypeSize:
+		/* \todo Parse Sizes. */
+		break;
+	}
+
+	return value;
+}
diff --git a/src/cam/capture_script.h b/src/cam/capture_script.h
new file mode 100644
index 00000000..8b4f8f62
--- /dev/null
+++ b/src/cam/capture_script.h
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2022, Ideas on Board Oy
+ *
+ * capture_script.h - Capture session configuration script
+ */
+
+#pragma once
+
+#include <map>
+#include <memory>
+#include <string>
+
+#include <libcamera/camera.h>
+#include <libcamera/controls.h>
+
+#include <yaml.h>
+
+class CaptureScript
+{
+public:
+	CaptureScript(std::shared_ptr<libcamera::Camera> camera,
+		      const std::string &fileName);
+
+	bool valid() const { return valid_; }
+
+	const libcamera::ControlList &frameControls(unsigned int frame);
+
+private:
+	struct EventDeleter {
+		void operator()(yaml_event_t *event) const
+		{
+			yaml_event_delete(event);
+			delete event;
+		}
+	};
+	using EventPtr = std::unique_ptr<yaml_event_t, EventDeleter>;
+
+	std::map<std::string, const libcamera::ControlId *> controls_;
+	std::map<unsigned int, libcamera::ControlList> frameControls_;
+	std::shared_ptr<libcamera::Camera> camera_;
+	yaml_parser_t parser_;
+	bool valid_;
+
+	EventPtr nextEvent(yaml_event_type_t expectedType = YAML_NO_EVENT);
+	bool checkEvent(const EventPtr &event, yaml_event_type_t expectedType) const;
+	static std::string eventScalarValue(const EventPtr &event);
+	static std::string eventTypeName(yaml_event_type_t type);
+
+	int parseScript(FILE *script);
+
+	int parseFrames();
+	int parseFrame(EventPtr event);
+	int parseControl(EventPtr event, libcamera::ControlList &controls);
+
+	std::string parseScalar();
+
+	void unpackFailure(const libcamera::ControlId *id,
+			   const std::string &repr);
+	libcamera::ControlValue unpackControl(const libcamera::ControlId *id,
+					      const std::string &repr);
+};
diff --git a/src/cam/meson.build b/src/cam/meson.build
index 5bab8c9e..c47a8559 100644
--- a/src/cam/meson.build
+++ b/src/cam/meson.build
@@ -11,6 +11,7 @@ cam_enabled = true
 
 cam_sources = files([
     'camera_session.cpp',
+    'capture_script.cpp',
     'event_loop.cpp',
     'file_sink.cpp',
     'frame_sink.cpp',
@@ -38,6 +39,7 @@ cam  = executable('cam', cam_sources,
                       libcamera_public,
                       libdrm,
                       libevent,
+                      libyaml,
                   ],
                   cpp_args : cam_cpp_args,
                   install : true)