[libcamera-devel,v3,02/10] libcamera: camera: Introduce Orientation
diff mbox series

Message ID 20230718105210.83558-3-jacopo.mondi@ideasonboard.com
State Superseded
Headers show
Series
  • libcamera: Replace CameraConfiguration::transform
Related show

Commit Message

Jacopo Mondi July 18, 2023, 10:52 a.m. UTC
Introduce the Orientation enumeration which describes the possible 2D
transformations that can be applied to an image using two basic plane
transformations.

Add to the CameraConfiguration class a new member 'orientation' which is
used to specify the image orientation in the memory buffers delivered to
applications.

The enumeration values follow the ones defined by the EXIF specification at
revision 2.32, Tag 274 'orientation'.

The newly introduced field is meant to replace
CameraConfiguration::transform which is not removed yet not to break
compilation.

Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: David Plowman <david.plowman@raspberrypi.com>
---
 include/libcamera/camera.h      |  2 +
 include/libcamera/meson.build   |  1 +
 include/libcamera/orientation.h | 28 ++++++++++++
 src/libcamera/camera.cpp        | 18 +++++++-
 src/libcamera/meson.build       |  1 +
 src/libcamera/orientation.cpp   | 78 +++++++++++++++++++++++++++++++++
 6 files changed, 127 insertions(+), 1 deletion(-)
 create mode 100644 include/libcamera/orientation.h
 create mode 100644 src/libcamera/orientation.cpp

Patch
diff mbox series

diff --git a/include/libcamera/camera.h b/include/libcamera/camera.h
index 004bc89455f5..6e9342773962 100644
--- a/include/libcamera/camera.h
+++ b/include/libcamera/camera.h
@@ -19,6 +19,7 @@ 
 #include <libcamera/base/signal.h>
 
 #include <libcamera/controls.h>
+#include <libcamera/orientation.h>
 #include <libcamera/request.h>
 #include <libcamera/stream.h>
 #include <libcamera/transform.h>
@@ -67,6 +68,7 @@  public:
 	std::size_t size() const;
 
 	Transform transform;
+	Orientation orientation;
 
 protected:
 	CameraConfiguration();
diff --git a/include/libcamera/meson.build b/include/libcamera/meson.build
index 408b7acf152c..a24c50d66a82 100644
--- a/include/libcamera/meson.build
+++ b/include/libcamera/meson.build
@@ -12,6 +12,7 @@  libcamera_public_headers = files([
     'framebuffer_allocator.h',
     'geometry.h',
     'logging.h',
+    'orientation.h',
     'pixel_format.h',
     'request.h',
     'stream.h',
diff --git a/include/libcamera/orientation.h b/include/libcamera/orientation.h
new file mode 100644
index 000000000000..63ac4aba07ce
--- /dev/null
+++ b/include/libcamera/orientation.h
@@ -0,0 +1,28 @@ 
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2023, Ideas On Board Oy
+ *
+ * orientation.h - Image orientation
+ */
+
+#pragma once
+
+#include <iostream>
+
+namespace libcamera {
+
+enum class Orientation {
+	/* EXIF tag 274 starts from '1' */
+	rotate0 = 1,
+	rotate0Flip,
+	rotate180,
+	rotate180Flip,
+	rotate90Flip,
+	rotate270,
+	rotate270Flip,
+	rotate90,
+};
+
+std::ostream &operator<<(std::ostream &out, const Orientation &orientation);
+
+} /* namespace libcamera */
diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
index 0eecee766f00..d4ad4a553752 100644
--- a/src/libcamera/camera.cpp
+++ b/src/libcamera/camera.cpp
@@ -160,7 +160,8 @@  LOG_DECLARE_CATEGORY(Camera)
  * \brief Create an empty camera configuration
  */
 CameraConfiguration::CameraConfiguration()
-	: transform(Transform::Identity), config_({})
+	: transform(Transform::Identity), orientation(Orientation::rotate0),
+	  config_({})
 {
 }
 
@@ -404,6 +405,21 @@  CameraConfiguration::Status CameraConfiguration::validateColorSpaces(ColorSpaceF
  * may adjust this field at its discretion if the selection is not supported.
  */
 
+/**
+ * \var CameraConfiguration::orientation
+ * \brief The desired orientation of the images produced by the camera
+ *
+ * The orientation field is a user-specified 2D plane transformation that
+ * specifies how the application wants the camera images to be rotated in
+ * the memory buffers.
+ *
+ * If the application requested orientation cannot be obtained the validate()
+ * function will Adjust this field to the actual orientation of the images
+ * as produced by the camera pipeline.
+ *
+ * By default the orientation field is set to Orientation::rotate0.
+ */
+
 /**
  * \var CameraConfiguration::config_
  * \brief The vector of stream configurations
diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
index b24f82965764..d0e26f6b4141 100644
--- a/src/libcamera/meson.build
+++ b/src/libcamera/meson.build
@@ -34,6 +34,7 @@  libcamera_sources = files([
     'mapped_framebuffer.cpp',
     'media_device.cpp',
     'media_object.cpp',
+    'orientation.cpp',
     'pipeline_handler.cpp',
     'pixel_format.cpp',
     'process.cpp',
diff --git a/src/libcamera/orientation.cpp b/src/libcamera/orientation.cpp
new file mode 100644
index 000000000000..f2ee14dd4182
--- /dev/null
+++ b/src/libcamera/orientation.cpp
@@ -0,0 +1,78 @@ 
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2023, Ideas On Board Oy
+ *
+ * orientation.cpp - Image orientation
+ */
+
+#include <libcamera/orientation.h>
+
+#include <array>
+#include <string>
+
+/**
+ * \file libcamera/orientation.h
+ * \brief Image orientation definition
+ */
+
+namespace libcamera {
+
+/**
+ * \enum Orientation
+ * \brief The image orientation in a memory buffer
+ *
+ * The Orientation enumeration describes the orientation of the images
+ * produced by the camera pipeline as they get received by the application
+ * inside memory buffers.
+ *
+ * All the possible 2D plane transformations of an image are expressed as the
+ * combination of two basic operations:
+ *
+ *   'a': rotate the image 90 degrees clockwise
+ *   'b': flip the image horizontally (mirroring)
+ *
+ * plus an identity operator 'e'.
+ *
+ * The composition of operations 'a' and 'b' according to the canonical function
+ * composition notion 'b * a' (where 'a' is applied first, then 'b' is applied
+ * next) gives origin to a symmetric group of order 8, or dihedral group.
+ *
+ * See https://en.wikipedia.org/wiki/Dihedral_group#/media/File:Dih4_cycle_graph.svg
+ * as an example of the 2D plane transformation and how they originate from
+ * the composition of the 'a' and 'b' operations.
+ *
+ * The image orientation expressed using the Orientation enumeration can be
+ * then inferred by applying a multiple of a 90 degrees rotation from the origin
+ * and then applying any horizontal mirroring to a base image assume to be
+ * naturally oriented (no rotation and no mirroring applied).
+ *
+ * The enumeration numerical values follow the ones defined by the EXIF
+ * Specification version 2.32, Tag 274 "Orientation", while the names of the
+ * enumerated values report the rotation and mirroring operations performed.
+ *
+ * In example Orientation::rotate90Flip describes the image transformation
+ * obtained by rotating 90 degrees clockwise first and then applying an
+ * horizontal mirroring.
+ */
+
+/**
+ * \brief Prints human-friendly names for Orientation items
+ * \param[in] out The output stream
+ * \param[in] orientation The Orientation item
+ * \return The output stream \a out
+ */
+std::ostream &operator<<(std::ostream &out, const Orientation &orientation)
+{
+	constexpr std::array<const char *, 9> orientationNames = {
+		"", /* Orientation starts counting from 1. */
+		"rotate0", "rotate0Flip",
+		"rotate180", "rotate180Flip",
+		"rotate90Flip", "rotate270",
+		"rotate270Flip", "rotate90",
+	};
+
+	out << orientationNames[static_cast<unsigned int>(orientation)];
+	return out;
+}
+
+} /* namespace libcamera */