[libcamera-devel] [PATCH 3/3] qcam: Make log less verbose by default

[Laurent Pinchart]

The qcam log prints one message per frame, which is pretty verbose. This
feature is useful for debugging, but not necessarily as a default
option. Silence it by default, and add a -v/--verbose command line
parameter to make the log verbose.

While this could have been handled manually by checking a verbose flag
when printing the message, the feature is instead integrated with the Qt
log infrastructure to make it more flexible. Messages printed by
qDebug() are now silenced by default and controlled by the -v/--verbose
argument.

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 src/qcam/main.cpp            |  5 +++++
 src/qcam/main_window.cpp     |  2 +-
 src/qcam/main_window.h       |  2 ++
 src/qcam/meson.build         |  1 +
 src/qcam/message_handler.cpp | 27 +++++++++++++++++++++++++++
 src/qcam/message_handler.h   | 26 ++++++++++++++++++++++++++
 6 files changed, 62 insertions(+), 1 deletion(-)
 create mode 100644 src/qcam/message_handler.cpp
 create mode 100644 src/qcam/message_handler.h

diff --git a/src/qcam/main.cpp b/src/qcam/main.cpp
index 5505a5d88ef6..5eff90a3fa66 100644
--- a/src/qcam/main.cpp
+++ b/src/qcam/main.cpp
@@ -16,6 +16,7 @@
 #include "../cam/options.h"
 #include "../cam/stream_options.h"
 #include "main_window.h"
+#include "message_handler.h"
 
 void signalHandler([[maybe_unused]] int signal)
 {
@@ -38,6 +39,8 @@ OptionsParser::Options parseOptions(int argc, char *argv[])
 			 "renderer", ArgumentRequired, "renderer");
 	parser.addOption(OptStream, &streamKeyValue,
 			 "Set configuration of a camera stream", "stream", true);
+	parser.addOption(OptVerbose, OptionNone,
+			 "Print verbose log messages", "verbose");
 
 	OptionsParser::Options options = parser.parse(argc, argv);
 	if (options.isSet(OptHelp))
@@ -57,6 +60,8 @@ int main(int argc, char **argv)
 	if (options.isSet(OptHelp))
 		return 0;
 
+	MessageHandler msgHandler(options.isSet(OptVerbose));
+
 	struct sigaction sa = {};
 	sa.sa_handler = &signalHandler;
 	sigaction(SIGINT, &sa, nullptr);
diff --git a/src/qcam/main_window.cpp b/src/qcam/main_window.cpp
index 2502ecd40abe..39d034de6bb2 100644
--- a/src/qcam/main_window.cpp
+++ b/src/qcam/main_window.cpp
@@ -746,7 +746,7 @@ void MainWindow::processViewfinder(FrameBuffer *buffer)
 	fps = lastBufferTime_ && fps ? 1000000000.0 / fps : 0.0;
 	lastBufferTime_ = metadata.timestamp;
 
-	qInfo().noquote()
+	qDebug().noquote()
 		<< QString("seq: %1").arg(metadata.sequence, 6, 10, QLatin1Char('0'))
 		<< "bytesused:" << metadata.planes[0].bytesused
 		<< "timestamp:" << metadata.timestamp
diff --git a/src/qcam/main_window.h b/src/qcam/main_window.h
index 64bcfebc7dbd..a9aa8ffcd8fd 100644
--- a/src/qcam/main_window.h
+++ b/src/qcam/main_window.h
@@ -41,6 +41,7 @@ enum {
 	OptHelp = 'h',
 	OptRenderer = 'r',
 	OptStream = 's',
+	OptVerbose = 'v',
 };
 
 class MainWindow : public QMainWindow
@@ -98,6 +99,7 @@ private:
 
 	/* Options */
 	const OptionsParser::Options &options_;
+	bool verbose_;
 
 	/* Camera manager, camera, configuration and buffers */
 	CameraManager *cm_;
diff --git a/src/qcam/meson.build b/src/qcam/meson.build
index 9bb48c0d06c5..ebcd5ca010cf 100644
--- a/src/qcam/meson.build
+++ b/src/qcam/meson.build
@@ -6,6 +6,7 @@ qcam_sources = files([
     'format_converter.cpp',
     'main.cpp',
     'main_window.cpp',
+    'message_handler.cpp',
     'viewfinder_qt.cpp',
 ])
 
diff --git a/src/qcam/message_handler.cpp b/src/qcam/message_handler.cpp
new file mode 100644
index 000000000000..261623e19ca9
--- /dev/null
+++ b/src/qcam/message_handler.cpp
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2020, Laurent Pinchart <laurent.pinchart at ideasonboard.com>
+ *
+ * message_handler.cpp - qcam - Log message handling
+ */
+
+#include "message_handler.h"
+
+QtMessageHandler MessageHandler::handler_ = nullptr;
+bool MessageHandler::verbose_ = false;
+
+MessageHandler::MessageHandler(bool verbose)
+{
+	verbose_ = verbose;
+	handler_ = qInstallMessageHandler(&MessageHandler::handleMessage);
+}
+
+void MessageHandler::handleMessage(QtMsgType type,
+				   const QMessageLogContext &context,
+				   const QString &msg)
+{
+	if (type == QtDebugMsg && !verbose_)
+		return;
+
+	handler_(type, context, msg);
+}
diff --git a/src/qcam/message_handler.h b/src/qcam/message_handler.h
new file mode 100644
index 000000000000..4534db9d93f7
--- /dev/null
+++ b/src/qcam/message_handler.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2020, Laurent Pinchart <laurent.pinchart at ideasonboard.com>
+ *
+ * message_handler.cpp - qcam - Log message handling
+ */
+#ifndef __QCAM_MESSAGE_HANDLER_H__
+#define __QCAM_MESSAGE_HANDLER_H__
+
+#include <QtGlobal>
+
+class MessageHandler
+{
+public:
+	MessageHandler(bool verbose);
+
+private:
+	static void handleMessage(QtMsgType type,
+				  const QMessageLogContext &context,
+				  const QString &msg);
+
+	static QtMessageHandler handler_;
+	static bool verbose_;
+};
+
+#endif /* __QCAM_MESSAGE_HANDLER_H__ */
-- 
Regards,

Laurent Pinchart