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// Copyright (C) 2022 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
#include <QCoreApplication>
#include <QLoggingCategory>
//![1]
// in a header
Q_DECLARE_LOGGING_CATEGORY(driverUsb)
// in one source file
Q_LOGGING_CATEGORY(driverUsb, "driver.usb")
//![1]
//![5]
Q_LOGGING_CATEGORY(driverUsbEvents, "driver.usb.events", QtWarningMsg)
//![5]
// Completely made up example, inspired by en.wikipedia.org/wiki/USB :)
struct UsbEntry {
int id;
int classtype;
};
QDebug operator<<(QDebug &debug, const UsbEntry &entry)
{
QDebugStateSaver saver(debug);
debug.nospace() << "" << entry.id << " (" << entry.classtype << ')';
return debug;
}
QList<UsbEntry> usbEntries() {
QList<UsbEntry> entries;
return entries;
}
//![20]
void myCategoryFilter(QLoggingCategory *);
//![20]
//![21]
static QLoggingCategory::CategoryFilter oldCategoryFilter = nullptr;
void myCategoryFilter(QLoggingCategory *category)
{
// For a category set up after this filter is installed, we first set it up
// with the old filter. This ensures that any driver.usb logging configured
// by the user is kept, aside from the one level we override; and any new
// categories we're not interested in get configured by the old filter.
if (oldCategoryFilter)
oldCategoryFilter(category);
// Tweak driver.usb's logging, over-riding the default filter:
if (qstrcmp(category->categoryName(), "driver.usb") == 0)
category->setEnabled(QtDebugMsg, true);
}
//![21]
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
//![2]
QLoggingCategory::setFilterRules(QStringLiteral("driver.usb.debug=true"));
//![2]
//![22]
oldCategoryFilter = QLoggingCategory::installFilter(myCategoryFilter);
//![22]
//![3]
qSetMessagePattern("%{category} %{message}");
//![3]
//![4]
// usbEntries() will only be called if driverUsb category is enabled
qCDebug(driverUsb) << "devices: " << usbEntries();
//![4]
{
//![10]
QLoggingCategory category("driver.usb");
qCDebug(category) << "a debug message";
//![10]
}
//![qcinfo_stream]
QLoggingCategory category("driver.usb");
qCInfo(category) << "an informational message";
//![qcinfo_stream]
{
//![11]
QLoggingCategory category("driver.usb");
qCWarning(category) << "a warning message";
//![11]
}
{
//![12]
QLoggingCategory category("driver.usb");
qCCritical(category) << "a critical message";
//![12]
}
{
//![13]
QLoggingCategory category("driver.usb");
qCDebug(category, "a debug message logged into category %s", category.categoryName());
//![13]
}
{
//![qcinfo_printf]
QLoggingCategory category("driver.usb");
qCInfo(category, "an informational message logged into category %s", category.categoryName());
//![qcinfo_printf]
}
{
//![14]
QLoggingCategory category("driver.usb");
qCWarning(category, "a warning message logged into category %s", category.categoryName());
//![14]
}
{
//![15]
QLoggingCategory category("driver.usb");
qCCritical(category, "a critical message logged into category %s", category.categoryName());
//![15]
}
{
//![16]
QLoggingCategory category("driver.usb");
qCFatal(category) << "a fatal message. Program will be terminated!";
//![16]
}
{
//![17]
QLoggingCategory category("driver.usb");
qCFatal(category, "a fatal message. Program will be terminated!");
//![17]
}
return 0;
}
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