libcamera: Add event notification infrastructure

Add three new classes, EventDispatcher, EventNotifier and Timer, that
define APIs for file descriptor event notification and timers. The
implementation of the EventDispatcher is meant to be provided to
libcamera by the application.

The event dispatcher is integrated twith the camera manager to implement
automatic registration of timers and events.

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

1 files changed, 42 insertions, 0 deletions

diff --git a/include/libcamera/event_notifier.h b/include/libcamera/event_notifier.h
new file mode 100644
index 00000000..1e9b6da1
--- /dev/null
+++ b/include/libcamera/event_notifier.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * event_notifier.h - File descriptor event notifier
+ */
+#ifndef __LIBCAMERA_EVENT_NOTIFIER_H__
+#define __LIBCAMERA_EVENT_NOTIFIER_H__
+
+#include <libcamera/signal.h>
+
+namespace libcamera {
+
+class EventNotifier
+{
+public:
+	enum Type {
+		Read,
+		Write,
+		Exception,
+	};
+
+	EventNotifier(int fd, Type type);
+	virtual ~EventNotifier();
+
+	Type type() const { return type_; }
+	int fd() const { return fd_; }
+
+	bool enabled() const { return enabled_; }
+	void setEnabled(bool enable);
+
+	Signal<EventNotifier *> activated;
+
+private:
+	int fd_;
+	Type type_;
+	bool enabled_;
+};
+
+} /* namespace libcamera */
+
+#endif /* __LIBCAMERA_EVENT_NOTIFIER_H__ */