libcamera: PixelFormat: Turn into a class

Create a class to represent a pixel format. This is done to add support
for modifiers for the formats. So far no modifiers are added by any
pipeline handler, all plumbing to deal with them is however in place.

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

8 files changed, 126 insertions, 17 deletions

diff --git a/include/libcamera/pixelformats.h b/include/libcamera/pixelformats.h
index 544363af..eb40e55a 100644
--- a/include/libcamera/pixelformats.h
+++ b/include/libcamera/pixelformats.h
@@ -7,13 +7,36 @@
 #ifndef __LIBCAMERA_PIXEL_FORMATS_H__
 #define __LIBCAMERA_PIXEL_FORMATS_H__
 
+#include <set>
 #include <stdint.h>
+#include <string>
 
 #include <linux/drm_fourcc.h>
 
 namespace libcamera {
 
-using PixelFormat = uint32_t;
+class PixelFormat
+{
+public:
+	PixelFormat();
+	PixelFormat(uint32_t fourcc, const std::set<uint64_t> &modifiers = {});
+
+	bool operator==(const PixelFormat &other) const;
+	bool operator!=(const PixelFormat &other) const { return !(*this == other); }
+	bool operator<(const PixelFormat &other) const;
+
+	bool isValid() const { return fourcc_ != 0; }
+
+	operator uint32_t() const { return fourcc_; }
+	uint32_t fourcc() const { return fourcc_; }
+	const std::set<uint64_t> &modifiers() const { return modifiers_; }
+
+	std::string toString() const;
+
+private:
+	uint32_t fourcc_;
+	std::set<uint64_t> modifiers_;
+};
 
 } /* namespace libcamera */
 
diff --git a/src/cam/main.cpp b/src/cam/main.cpp
index af516f1c..f73e77f3 100644
--- a/src/cam/main.cpp
+++ b/src/cam/main.cpp
@@ -253,7 +253,7 @@ int CamApp::prepareConfig()
 
 			/* TODO: Translate 4CC string to ID. */
 			if (opt.isSet("pixelformat"))
-				cfg.pixelFormat = opt["pixelformat"];
+				cfg.pixelFormat = PixelFormat(opt["pixelformat"]);
 		}
 	}
 
@@ -304,8 +304,8 @@ int CamApp::infoConfiguration()
 
 		const StreamFormats &formats = cfg.formats();
 		for (PixelFormat pixelformat : formats.pixelformats()) {
-			std::cout << " * Pixelformat: 0x" << std::hex
-				  << std::setw(8) << pixelformat << " "
+			std::cout << " * Pixelformat: "
+				  << pixelformat.toString() << " "
 				  << formats.range(pixelformat).toString()
 				  << std::endl;
 
diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
index 5ff29240..9876d8c9 100644
--- a/src/libcamera/pipeline/uvcvideo.cpp
+++ b/src/libcamera/pipeline/uvcvideo.cpp
@@ -115,8 +115,9 @@ CameraConfiguration::Status UVCCameraConfiguration::validate()
 	if (iter == pixelFormats.end()) {
 		cfg.pixelFormat = pixelFormats.front();
 		LOG(UVC, Debug)
-			<< "Adjusting pixel format from " << pixelFormat
-			<< " to " << cfg.pixelFormat;
+			<< "Adjusting pixel format from "
+			<< pixelFormat.toString() << " to "
+			<< cfg.pixelFormat.toString();
 		status = Adjusted;
 	}
 
diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
index 82649952..00cb7389 100644
--- a/src/libcamera/pipeline/vimc.cpp
+++ b/src/libcamera/pipeline/vimc.cpp
@@ -105,7 +105,7 @@ private:
 
 namespace {
 
-constexpr std::array<PixelFormat, 3> pixelformats{
+static const std::array<PixelFormat, 3> pixelformats{
 	DRM_FORMAT_RGB888,
 	DRM_FORMAT_BGR888,
 	DRM_FORMAT_BGRA8888,
diff --git a/src/libcamera/pixelformats.cpp b/src/libcamera/pixelformats.cpp
index c0333540..87557d98 100644
--- a/src/libcamera/pixelformats.cpp
+++ b/src/libcamera/pixelformats.cpp
@@ -15,14 +15,102 @@
 namespace libcamera {
 
 /**
- * \typedef PixelFormat
+ * \class PixelFormat
  * \brief libcamera image pixel format
  *
  * The PixelFormat type describes the format of images in the public libcamera
- * API. It stores a FourCC value as a 32-bit unsigned integer. The values are
- * defined in the Linux kernel DRM/KMS API (see linux/drm_fourcc.h).
+ * API. It stores a FourCC value as a 32-bit unsigned integer and a set of
+ * modifiers. The FourCC and modifiers values are defined in the Linux kernel
+ * DRM/KMS API (see linux/drm_fourcc.h).
+ */
+
+/**
+ * \brief Construct a PixelFormat with an invalid format
+ *
+ * PixelFormat instances constructed with the default constructor are
+ * invalid, calling the isValid() function returns false.
+ */
+PixelFormat::PixelFormat()
+	: fourcc_(0)
+{
+}
+
+/**
+ * \brief Construct a PixelFormat from a DRM FourCC and a set of modifiers
+ * \param[in] fourcc A DRM FourCC
+ * \param[in] modifiers A set of DRM FourCC modifiers
+ */
+PixelFormat::PixelFormat(uint32_t fourcc, const std::set<uint64_t> &modifiers)
+	: fourcc_(fourcc), modifiers_(modifiers)
+{
+}
+
+/**
+ * \brief Compare pixel formats for equality
+ * \return True if the two pixel formats are equal, false otherwise
+ */
+bool PixelFormat::operator==(const PixelFormat &other) const
+{
+	return fourcc_ == other.fourcc() && modifiers_ == other.modifiers_;
+}
+
+/**
+ * \fn bool PixelFormat::operator!=(const PixelFormat &other) const
+ * \brief Compare pixel formats for inequality
+ * \return True if the two pixel formats are not equal, false otherwise
+ */
+
+/**
+ * \brief Compare pixel formats for smaller than order
+ * \return True if \a this is smaller than \a other, false otherwise
+ */
+bool PixelFormat::operator<(const PixelFormat &other) const
+{
+	if (fourcc_ < other.fourcc_)
+		return true;
+	if (fourcc_ > other.fourcc_)
+		return false;
+	return modifiers_ < modifiers_;
+}
+
+/**
+ * \fn bool PixelFormat::isValid() const
+ * \brief Check if the pixel format is valid
+ *
+ * PixelFormat instances constructed with the default constructor are
+ * invalid. Instances constructed with a FourCC defined in the DRM API
+ * are valid. The behaviour is undefined otherwise.
  *
- * \todo Add support for format modifiers
+ * \return True if the pixel format is valid, false otherwise
+ */
+
+/**
+ * \fn PixelFormat::operator uint32_t() const
+ * \brief Convert the the pixel format numerical value
+ * \return The pixel format numerical value
+ */
+
+/**
+ * \fn PixelFormat::fourcc() const
+ * \brief Retrieve the pixel format FourCC
+ * \return DRM FourCC
+ */
+
+/**
+ * \fn PixelFormat::modifiers() const
+ * \brief Retrieve the pixel format modifiers
+ * \return Set of DRM modifiers
+ */
+
+/**
+ * \brief Assemble and return a string describing the pixel format
+ * \return A string describing the pixel format
  */
+std::string PixelFormat::toString() const
+{
+	char str[11];
+	snprintf(str, 11, "0x%08x", fourcc_);
+	return str;
+}
 
 } /* namespace libcamera */
diff --git a/src/libcamera/stream.cpp b/src/libcamera/stream.cpp
index 13789e9e..0716de38 100644
--- a/src/libcamera/stream.cpp
+++ b/src/libcamera/stream.cpp
@@ -347,9 +347,7 @@ StreamConfiguration::StreamConfiguration(const StreamFormats &formats)
  */
 std::string StreamConfiguration::toString() const
 {
-	std::stringstream ss;
-	ss << size.toString() << "-" << utils::hex(pixelFormat);
-	return ss.str();
+	return size.toString() + "-" + pixelFormat.toString();
 }
 
 /**
diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
index ca0d147f..ce67e04c 100644
--- a/src/libcamera/v4l2_videodevice.cpp
+++ b/src/libcamera/v4l2_videodevice.cpp
@@ -1551,8 +1551,7 @@ uint32_t V4L2VideoDevice::toV4L2Fourcc(PixelFormat pixelFormat, bool multiplanar
 	 * class. Until we fix the logger, work around it.
 	 */
 	libcamera::_log(__FILE__, __LINE__, _LOG_CATEGORY(V4L2)(), LogError).stream()
-		<< "Unsupported V4L2 pixel format "
-		<< utils::hex(pixelFormat);
+		<< "Unsupported V4L2 pixel format " << pixelFormat.toString();
 	return 0;
 }
 
diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp
index e349fbdd..3bc1c1aa 100644
--- a/src/v4l2/v4l2_camera_proxy.cpp
+++ b/src/v4l2/v4l2_camera_proxy.cpp
@@ -533,7 +533,7 @@ struct PixelFormatInfo {
 
 namespace {
 
-constexpr std::array<PixelFormatInfo, 13> pixelFormatInfo = {{
+static const std::array<PixelFormatInfo, 13> pixelFormatInfo = {{
 	/* RGB formats. */
 	{ DRM_FORMAT_RGB888,	V4L2_PIX_FMT_BGR24,	1, {{ { 24, 1, 1 }, {  0, 0, 0 }, {  0, 0, 0 } }} },
 	{ DRM_FORMAT_BGR888,	V4L2_PIX_FMT_RGB24,	1, {{ { 24, 1, 1 }, {  0, 0, 0 }, {  0, 0, 0 } }} },