8 files changed, 91 insertions, 21 deletions
diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
index bf991d59..c7c9b3fd 100644
--- a/src/android/camera_device.cpp
+++ b/src/android/camera_device.cpp
@@ -640,7 +640,7 @@ int CameraDevice::configureStreams(camera3_stream_configuration_t *stream_list)
 			       << ", direction: " << stream->stream_type
 			       << ", width: " << stream->width
 			       << ", height: " << stream->height
-			       << ", format: " << std::hex << stream->format;
+			       << ", format: " << utils::hex(stream->format);
 	}
 
 	/* Hardcode viewfinder role, collecting sizes from the stream config. */
diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
index 9e8b44a2..1b8e8c0e 100644
--- a/src/libcamera/camera_sensor.cpp
+++ b/src/libcamera/camera_sensor.cpp
@@ -14,6 +14,7 @@
 #include <math.h>
 
 #include "formats.h"
+#include "utils.h"
 #include "v4l2_subdevice.h"
 
 /**
@@ -79,9 +80,8 @@ int CameraSensor::init()
 
 	if (entity_->function() != MEDIA_ENT_F_CAM_SENSOR) {
 		LOG(CameraSensor, Error)
-			<< "Invalid sensor function 0x"
-			<< std::hex << std::setfill('0') << std::setw(8)
-			<< entity_->function();
+			<< "Invalid sensor function "
+			<< utils::hex(entity_->function());
 		return -EINVAL;
 	}
 
diff --git a/src/libcamera/controls.cpp b/src/libcamera/controls.cpp
index e46aa438..6a0301f3 100644
--- a/src/libcamera/controls.cpp
+++ b/src/libcamera/controls.cpp
@@ -549,8 +549,7 @@ const ControlValue &ControlList::get(unsigned int id) const
 	const auto ctrl = idmap_->find(id);
 	if (ctrl == idmap_->end()) {
 		LOG(Controls, Error)
-			<< std::hex << std::setfill('0')
-			<< "Control 0x" << std::setw(8) << id
+			<< "Control " << utils::hex(id)
 			<< " is not supported";
 		return zero;
 	}
@@ -579,8 +578,7 @@ void ControlList::set(unsigned int id, const ControlValue &value)
 	const auto ctrl = idmap_->find(id);
 	if (ctrl == idmap_->end()) {
 		LOG(Controls, Error)
-			<< std::hex << std::setfill('0')
-			<< "Control 0x" << std::setw(8) << id
+			<< "Control 0x" << utils::hex(id)
 			<< " is not supported";
 		return;
 	}
diff --git a/src/libcamera/include/utils.h b/src/libcamera/include/utils.h
index 52eee8ac..3efb11c1 100644
--- a/src/libcamera/include/utils.h
+++ b/src/libcamera/include/utils.h
@@ -10,6 +10,7 @@
 #include <algorithm>
 #include <chrono>
 #include <memory>
+#include <ostream>
 #include <string>
 #include <sys/time.h>
 
@@ -63,6 +64,45 @@ using time_point = std::chrono::steady_clock::time_point;
 struct timespec duration_to_timespec(const duration &value);
 std::string time_point_to_string(const time_point &time);
 
+#ifndef __DOXYGEN__
+struct _hex {
+	uint64_t v;
+	unsigned int w;
+};
+
+std::basic_ostream<char, std::char_traits<char>> &
+operator<<(std::basic_ostream<char, std::char_traits<char>> &stream, const _hex &h);
+#endif
+
+template<typename T>
+_hex hex(T value, unsigned int width = 0);
+
+#ifndef __DOXYGEN__
+template<>
+inline _hex hex<int32_t>(int32_t value, unsigned int width)
+{
+	return { static_cast<uint64_t>(value), width ? width : 8 };
+}
+
+template<>
+inline _hex hex<uint32_t>(uint32_t value, unsigned int width)
+{
+	return { static_cast<uint64_t>(value), width ? width : 8 };
+}
+
+template<>
+inline _hex hex<int64_t>(int64_t value, unsigned int width)
+{
+	return { static_cast<uint64_t>(value), width ? width : 16 };
+}
+
+template<>
+inline _hex hex<uint64_t>(uint64_t value, unsigned int width)
+{
+	return { static_cast<uint64_t>(value), width ? width : 16 };
+}
+#endif
+
 } /* namespace utils */
 
 } /* namespace libcamera */
diff --git a/src/libcamera/stream.cpp b/src/libcamera/stream.cpp
index c28b4cd6..610920d1 100644
--- a/src/libcamera/stream.cpp
+++ b/src/libcamera/stream.cpp
@@ -16,6 +16,7 @@
 #include <libcamera/request.h>
 
 #include "log.h"
+#include "utils.h"
 
 /**
  * \file stream.h
@@ -367,11 +368,7 @@ StreamConfiguration::StreamConfiguration(const StreamFormats &formats)
 std::string StreamConfiguration::toString() const
 {
 	std::stringstream ss;
-
-	ss.fill(0);
-	ss << size.toString() << "-0x" << std::hex << std::setw(8)
-	   << pixelFormat;
-
+	ss << size.toString() << "-" << utils::hex(pixelFormat);
 	return ss.str();
 }
 
diff --git a/src/libcamera/utils.cpp b/src/libcamera/utils.cpp
index 928db254..d632f6e6 100644
--- a/src/libcamera/utils.cpp
+++ b/src/libcamera/utils.cpp
@@ -143,6 +143,45 @@ std::string time_point_to_string(const time_point &time)
 	return ossTimestamp.str();
 }
 
+std::basic_ostream<char, std::char_traits<char>> &
+operator<<(std::basic_ostream<char, std::char_traits<char>> &stream, const _hex &h)
+{
+	stream << "0x";
+
+	std::ostream::fmtflags flags = stream.setf(std::ios_base::hex,
+						   std::ios_base::basefield);
+	std::streamsize width = stream.width(h.w);
+	char fill = stream.fill('0');
+
+	stream << h.v;
+
+	stream.flags(flags);
+	stream.width(width);
+	stream.fill(fill);
+
+	return stream;
+}
+
+/**
+ * \fn hex(T value, unsigned int width)
+ * \brief Write an hexadecimal value to an output string
+ * \param value The value
+ * \param width The width
+ *
+ * Return an object of unspecified type such that, if \a os is the name of an
+ * output stream of type std::ostream, and T is an integer type, then the
+ * expression
+ *
+ * \code{.cpp}
+ * os << utils::hex(value)
+ * \endcode
+ *
+ * will output the \a value to the stream in hexadecimal form with the base
+ * prefix and the filling character set to '0'. The field width is set to \a
+ * width if specified to a non-zero value, or to the native width of type T
+ * otherwise. The \a os stream configuration is not modified.
+ */
+
 } /* namespace utils */
 
 } /* namespace libcamera */
diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp
index a188298d..f2bcd7f7 100644
--- a/src/libcamera/v4l2_subdevice.cpp
+++ b/src/libcamera/v4l2_subdevice.cpp
@@ -21,6 +21,7 @@
 #include "log.h"
 #include "media_device.h"
 #include "media_object.h"
+#include "utils.h"
 
 /**
  * \file v4l2_subdevice.h
@@ -76,10 +77,7 @@ LOG_DECLARE_CATEGORY(V4L2)
 const std::string V4L2SubdeviceFormat::toString() const
 {
 	std::stringstream ss;
-
-	ss.fill(0);
-	ss << size.toString() << "-0x" << std::hex << std::setw(4) << mbus_code;
-
+	ss << size.toString() << "-" << utils::hex(mbus_code, 4);
 	return ss.str();
 }
 
diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
index eb4e44de..208ab541 100644
--- a/src/libcamera/v4l2_videodevice.cpp
+++ b/src/libcamera/v4l2_videodevice.cpp
@@ -23,6 +23,7 @@
 #include "log.h"
 #include "media_device.h"
 #include "media_object.h"
+#include "utils.h"
 
 /**
  * \file v4l2_videodevice.h
@@ -239,10 +240,7 @@ LOG_DECLARE_CATEGORY(V4L2)
 const std::string V4L2DeviceFormat::toString() const
 {
 	std::stringstream ss;
-
-	ss.fill(0);
-	ss << size.toString() << "-0x" << std::hex << std::setw(8) << fourcc;
-
+	ss << size.toString() << "-" << utils::hex(fourcc);
 	return ss.str();
 }