libcamera: Add BayerFormat type

This type encodes BayerFormats in an explicit way, that makes them
easier to use than some of the other more opaque type formats. This
makes the BayerFormat useful for editing or manipulating Bayer types
more easily.

Signed-off-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

2 files changed, 269 insertions, 0 deletions

diff --git a/src/libcamera/bayer_format.cpp b/src/libcamera/bayer_format.cpp
new file mode 100644
index 00000000..c42792ff
--- /dev/null
+++ b/src/libcamera/bayer_format.cpp
@@ -0,0 +1,268 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2020, Raspberry Pi (Trading) Limited
+ *
+ * bayer_format.cpp - Class to represent Bayer formats
+ */
+
+#include "libcamera/internal/bayer_format.h"
+
+#include <map>
+
+#include <libcamera/transform.h>
+
+/**
+ * \file bayer_format.h
+ * \brief Class to represent Bayer formats and manipulate them
+ */
+
+namespace libcamera {
+
+/**
+ * \class BayerFormat
+ * \brief Class to represent a raw image Bayer format
+ *
+ * This class encodes the different Bayer formats in such a way that they can
+ * be easily manipulated. For example, the bit depth or Bayer order can be
+ * easily altered - the Bayer order can even be "transformed" in the same
+ * manner as happens in many sensors when their horizontal or vertical "flip"
+ * controls are set.
+ */
+
+/**
+ * \enum BayerFormat::Order
+ * \brief The order of the colour channels in the Bayer pattern
+ *
+ * \var BayerFormat::BGGR
+ * \brief B then G on the first row, G then R on the second row.
+ * \var BayerFormat::GBRG
+ * \brief G then B on the first row, R then G on the second row.
+ * \var BayerFormat::GRBG
+ * \brief G then R on the first row, B then G on the second row.
+ * \var BayerFormat::RGGB
+ * \brief R then G on the first row, G then B on the second row.
+ */
+
+/**
+ * \enum BayerFormat::Packing
+ * \brief Different types of packing that can be applied to a BayerFormat
+ *
+ * \var BayerFormat::None
+ * \brief No packing
+ * \var BayerFormat::CSI2Packed
+ * \brief Format uses MIPI CSI-2 style packing
+ * \var BayerFormat::IPU3Packed
+ * \brief Format uses IPU3 style packing
+ */
+
+namespace {
+
+const std::map<V4L2PixelFormat, BayerFormat> v4l2ToBayer{
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SBGGR8), { BayerFormat::BGGR, 8, BayerFormat::None } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SGBRG8), { BayerFormat::GBRG, 8, BayerFormat::None } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SGRBG8), { BayerFormat::GRBG, 8, BayerFormat::None } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SRGGB8), { BayerFormat::RGGB, 8, BayerFormat::None } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SBGGR10), { BayerFormat::BGGR, 10, BayerFormat::None } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SGBRG10), { BayerFormat::GBRG, 10, BayerFormat::None } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SGRBG10), { BayerFormat::GRBG, 10, BayerFormat::None } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SRGGB10), { BayerFormat::RGGB, 10, BayerFormat::None } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SBGGR10P), { BayerFormat::BGGR, 10, BayerFormat::CSI2Packed } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SGBRG10P), { BayerFormat::GBRG, 10, BayerFormat::CSI2Packed } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SGRBG10P), { BayerFormat::GRBG, 10, BayerFormat::CSI2Packed } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SRGGB10P), { BayerFormat::RGGB, 10, BayerFormat::CSI2Packed } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_IPU3_SBGGR10), { BayerFormat::BGGR, 10, BayerFormat::IPU3Packed } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_IPU3_SGBRG10), { BayerFormat::GBRG, 10, BayerFormat::IPU3Packed } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_IPU3_SGRBG10), { BayerFormat::GRBG, 10, BayerFormat::IPU3Packed } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_IPU3_SRGGB10), { BayerFormat::RGGB, 10, BayerFormat::IPU3Packed } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SBGGR12), { BayerFormat::BGGR, 12, BayerFormat::None } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SGBRG12), { BayerFormat::GBRG, 12, BayerFormat::None } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SGRBG12), { BayerFormat::GRBG, 12, BayerFormat::None } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SRGGB12), { BayerFormat::RGGB, 12, BayerFormat::None } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SBGGR12P), { BayerFormat::BGGR, 12, BayerFormat::CSI2Packed } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SGBRG12P), { BayerFormat::GBRG, 12, BayerFormat::CSI2Packed } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SGRBG12P), { BayerFormat::GRBG, 12, BayerFormat::CSI2Packed } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SRGGB12P), { BayerFormat::RGGB, 12, BayerFormat::CSI2Packed } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SBGGR16), { BayerFormat::BGGR, 16, BayerFormat::None } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SGBRG16), { BayerFormat::GBRG, 16, BayerFormat::None } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SGRBG16), { BayerFormat::GRBG, 16, BayerFormat::None } },
+	{ V4L2PixelFormat(V4L2_PIX_FMT_SRGGB16), { BayerFormat::RGGB, 16, BayerFormat::None } },
+};
+
+/* Define a slightly arbitrary ordering so that we can use a std::map. */
+struct BayerFormatComparator {
+	constexpr bool operator()(const BayerFormat &lhs, const BayerFormat &rhs) const
+	{
+		if (lhs.bitDepth < rhs.bitDepth)
+			return true;
+		else if (lhs.bitDepth > rhs.bitDepth)
+			return false;
+
+		if (lhs.order < rhs.order)
+			return true;
+		else if (lhs.order > rhs.order)
+			return false;
+
+		if (lhs.packing < rhs.packing)
+			return true;
+		else
+			return false;
+	}
+};
+
+const std::map<BayerFormat, V4L2PixelFormat, BayerFormatComparator> bayerToV4l2{
+	{ { BayerFormat::BGGR, 8, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SBGGR8) },
+	{ { BayerFormat::GBRG, 8, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SGBRG8) },
+	{ { BayerFormat::GRBG, 8, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SGRBG8) },
+	{ { BayerFormat::RGGB, 8, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SRGGB8) },
+	{ { BayerFormat::BGGR, 10, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SBGGR10) },
+	{ { BayerFormat::GBRG, 10, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SGBRG10) },
+	{ { BayerFormat::GRBG, 10, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SGRBG10) },
+	{ { BayerFormat::RGGB, 10, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SRGGB10) },
+	{ { BayerFormat::BGGR, 10, BayerFormat::CSI2Packed }, V4L2PixelFormat(V4L2_PIX_FMT_SBGGR10P) },
+	{ { BayerFormat::GBRG, 10, BayerFormat::CSI2Packed }, V4L2PixelFormat(V4L2_PIX_FMT_SGBRG10P) },
+	{ { BayerFormat::GRBG, 10, BayerFormat::CSI2Packed }, V4L2PixelFormat(V4L2_PIX_FMT_SGRBG10P) },
+	{ { BayerFormat::RGGB, 10, BayerFormat::CSI2Packed }, V4L2PixelFormat(V4L2_PIX_FMT_SRGGB10P) },
+	{ { BayerFormat::BGGR, 10, BayerFormat::IPU3Packed }, V4L2PixelFormat(V4L2_PIX_FMT_IPU3_SBGGR10) },
+	{ { BayerFormat::GBRG, 10, BayerFormat::IPU3Packed }, V4L2PixelFormat(V4L2_PIX_FMT_IPU3_SGBRG10) },
+	{ { BayerFormat::GRBG, 10, BayerFormat::IPU3Packed }, V4L2PixelFormat(V4L2_PIX_FMT_IPU3_SGRBG10) },
+	{ { BayerFormat::RGGB, 10, BayerFormat::IPU3Packed }, V4L2PixelFormat(V4L2_PIX_FMT_IPU3_SRGGB10) },
+	{ { BayerFormat::BGGR, 12, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SBGGR12) },
+	{ { BayerFormat::GBRG, 12, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SGBRG12) },
+	{ { BayerFormat::GRBG, 12, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SGRBG12) },
+	{ { BayerFormat::RGGB, 12, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SRGGB12) },
+	{ { BayerFormat::BGGR, 12, BayerFormat::CSI2Packed }, V4L2PixelFormat(V4L2_PIX_FMT_SBGGR12P) },
+	{ { BayerFormat::GBRG, 12, BayerFormat::CSI2Packed }, V4L2PixelFormat(V4L2_PIX_FMT_SGBRG12P) },
+	{ { BayerFormat::GRBG, 12, BayerFormat::CSI2Packed }, V4L2PixelFormat(V4L2_PIX_FMT_SGRBG12P) },
+	{ { BayerFormat::RGGB, 12, BayerFormat::CSI2Packed }, V4L2PixelFormat(V4L2_PIX_FMT_SRGGB12P) },
+	{ { BayerFormat::BGGR, 16, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SBGGR16) },
+	{ { BayerFormat::GBRG, 16, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SGBRG16) },
+	{ { BayerFormat::GRBG, 16, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SGRBG16) },
+	{ { BayerFormat::RGGB, 16, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SRGGB16) },
+};
+
+} /* namespace */
+
+/**
+ * \fn BayerFormat::BayerFormat()
+ * \brief Construct an empty (and invalid) BayerFormat
+ */
+
+/**
+ * \fn BayerFormat::BayerFormat(Order o, uint8_t b, Packing p)
+ * \brief Construct a BayerFormat from explicit values
+ * \param[in] o The order of the Bayer pattern
+ * \param[in] b The bit depth of the Bayer samples
+ * \param[in] p The type of packing applied to the pixel values
+ */
+
+/**
+ * \brief Construct a BayerFormat from a V4L2PixelFormat
+ * \param[in] v4l2Format The raw format to convert into a BayerFormat
+ */
+BayerFormat::BayerFormat(V4L2PixelFormat v4l2Format)
+	: order(BGGR), packing(None)
+{
+	const auto it = v4l2ToBayer.find(v4l2Format);
+	if (it == v4l2ToBayer.end())
+		bitDepth = 0;
+	else
+		*this = it->second;
+}
+
+/**
+ * \fn BayerFormat::isValid()
+ * \brief Return whether a BayerFormat is valid
+ */
+
+/**
+ * \brief Assemble and return a readable string representation of the
+ * BayerFormat
+ * \return A string describing the BayerFormat
+ */
+std::string BayerFormat::toString() const
+{
+	std::string result;
+
+	static const char *orderStrings[] = {
+		"BGGR",
+		"GBRG",
+		"GRBG",
+		"RGGB"
+	};
+	if (isValid() && order <= RGGB)
+		result = orderStrings[order];
+	else
+		return "INVALID";
+
+	result += "-" + std::to_string(bitDepth);
+
+	if (packing == CSI2Packed)
+		result += "-CSI2P";
+	else if (packing == IPU3Packed)
+		result += "-IPU3P";
+
+	return result;
+}
+
+/**
+ * \brief Convert a BayerFormat into the corresponding V4L2PixelFormat
+ * \return The V4L2PixelFormat corresponding to this BayerFormat
+ */
+V4L2PixelFormat BayerFormat::toV4L2PixelFormat() const
+{
+	const auto it = bayerToV4l2.find(*this);
+	if (it != bayerToV4l2.end())
+		return it->second;
+
+	return V4L2PixelFormat();
+}
+
+/**
+ * \brief Apply a transform to this BayerFormat
+ * \param[in] t The transform to apply
+ *
+ * Appplying a transform to an image stored in a Bayer format affects the Bayer
+ * order. For example, performing a horizontal flip on the Bayer pattern
+ * RGGB causes the RG rows of pixels to become GR, and the GB rows to become BG.
+ * The transformed image would have a GRBG order. The bit depth and modifiers
+ * are not affected.
+ *
+ * Note that transpositions are ignored as the order of a transpose with
+ * respect to the flips would have to be defined, and sensors are not expected
+ * to support transposition.
+ *
+ * \return The transformed Bayer format
+ */
+BayerFormat BayerFormat::transform(Transform t) const
+{
+	BayerFormat result = *this;
+
+	/*
+	 * Observe that flipping bit 0 of the Order enum performs a horizontal
+	 * mirror on the Bayer pattern (e.g. RGGB goes to GRBG). Similarly,
+	 * flipping bit 1 performs a vertical mirror operation on it. Hence:
+	 */
+	if (!!(t & Transform::HFlip))
+		result.order = static_cast<Order>(result.order ^ 1);
+	if (!!(t & Transform::VFlip))
+		result.order = static_cast<Order>(result.order ^ 2);
+
+	return result;
+}
+
+/**
+ * \var BayerFormat::order
+ * \brief The order of the colour channels in the Bayer pattern
+ */
+
+/**
+ * \var BayerFormat::bitDepth
+ * \brief The bit depth of the samples in the Bayer pattern
+ */
+
+/**
+ * \var BayerFormat::packing
+ * \brief Any packing scheme applied to this BayerFormat
+ */
+
+} /* namespace libcamera */
diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
index 1351dbba..07711b5f 100644
--- a/src/libcamera/meson.build
+++ b/src/libcamera/meson.build
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: CC0-1.0
 
 libcamera_sources = files([
+    'bayer_format.cpp',
     'bound_method.cpp',
     'buffer.cpp',
     'byte_stream_buffer.cpp',