Browser for QDebug output/de

This article may require cleanup to meet the Qt Wiki's quality standards. Reason: Auto-imported from ExpressionEngine. Please improve this article if you can. Remove the {{cleanup}} tag and add this page to Updated pages list after it's clean.

En Ar Bg De El Es Fa Fi Fr Hi Hu It Ja Kn Ko Ms Nl Pl Pt Ru Sq Th Tr Uk Zh

Ein Browser für QDebug-Log-Ausgaben

Der folgende Code-Schnipsel zeigt, wie man einen einfachen Log-Browser zu einem Programm hinzufügen kann.

Der Schnipsel besteht aus dem eigentlichen Log-Browser (Klasse LogBrowserDialog in logbrowserdialog.h und logbrowserdialog.h) und einem kleinen Wrapper (Klasse LogBrowser in logbrowser.h und logbrowser.h). Der Wrapper wird in der

main()

-Funktion des Programms instantiiert und erzeugt das Browser-Fenster. Er fungiert darüber hinaus auch als Zwischenstück und wandelt die const char* -basierten Nachrichten des Debug-Systems in QString-basierte Nachrichten. Mit diesem Trick können die Debug-Nachrichten an den eigentlichen Browser mittels Signal-Slot-Verbindungen gesendet werden. Dadurch kann der Browser auch in einem Programm mit mehreren Threads verwendet werden.

logbrowser.pro

QT ''= core gui

TARGET = DebugWindow
TEMPLATE = app

SOURCES''= main.cpp logbrowserdialog.cpp logbrowser.cpp
HEADERS += logbrowserdialog.h logbrowser.h

logbrowser.h

#ifndef LOGBROWSER_H
#define LOGBROWSER_H

#include <QObject>

class LogBrowserDialog;

class LogBrowser : public QObject
{
 Q_OBJECT
public:
 explicit LogBrowser(QObject *parent = 0);
 ~LogBrowser();

public slots:
 void outputMessage( QtMsgType type, const QString &msg );

signals:
 void sendMessage( QtMsgType type, const QString &msg );

private:
 LogBrowserDialog *browserDialog;

};

#endif // LOGBROWSER_H

logbrowser.cpp

#include "logbrowser.h"

#include <QMetaType>

#include "logbrowserdialog.h"

LogBrowser::LogBrowser(QObject *parent) :
 QObject(parent)
{
 qRegisterMetaType<QtMsgType>("QtMsgType");
 browserDialog = new LogBrowserDialog;
 connect(this, SIGNAL (sendMessage(QtMsgType,QString)), browserDialog, SLOT (outputMessage(QtMsgType,QString)), Qt::QueuedConnection);
 browserDialog->show();
}

LogBrowser::~LogBrowser()
{
 delete browserDialog;
}

void LogBrowser::outputMessage(QtMsgType type, const QString &msg)
{
 emit sendMessage( type, msg );
}

logbrowserdialog.h

#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>

class QTextBrowser;
class QPushButton;

class LogBrowserDialog : public QDialog
{
 Q_OBJECT

public:
 LogBrowserDialog(QWidget *parent = 0);
 ~LogBrowserDialog();

public slots:
 void outputMessage( QtMsgType type, const QString &msg );

protected slots:
 void save();

protected:
 virtual void keyPressEvent( QKeyEvent *e );
 virtual void closeEvent( QCloseEvent *e );

QTextBrowser *browser;
 QPushButton *clearButton;
 QPushButton *saveButton;
};

#endif // DIALOG_H

logbrowserdialog.cpp

#include "logbrowserdialog.h"

#include <QVBoxLayout>
#include <QHBoxLayout>
#include <QTextBrowser>
#include <QPushButton>
#include <QFileDialog>
#include <QDir>
#include <QFile>
#include <QMessageBox>
#include <QTextStream>
#include <QCloseEvent>
#include <QKeyEvent>

LogBrowserDialog::LogBrowserDialog(QWidget *parent)
 : QDialog(parent)
{
 QVBoxLayout *layout = new QVBoxLayout;
 setLayout(layout);

browser = new QTextBrowser(this);
 layout->addWidget(browser);

QHBoxLayout '''buttonLayout = new QHBoxLayout;
 buttonLayout->setContentsMargins(0, 0, 0, 0);
 layout->addLayout(buttonLayout);

 buttonLayout->addStretch(10);

 clearButton = new QPushButton(this);
 clearButton->setText("clear");
 buttonLayout->addWidget(clearButton);
 connect(clearButton, SIGNAL (clicked()), browser, SLOT (clear()));

 saveButton = new QPushButton(this);
 saveButton->setText("save output");
 buttonLayout->addWidget(saveButton);
 connect(saveButton, SIGNAL (clicked()), this, SLOT (save()));

 resize(200, 400);
}


LogBrowserDialog::~LogBrowserDialog()
{

}


void LogBrowserDialog::outputMessage(QtMsgType type, const QString &msg)
{
 switch (type) {
 case QtDebugMsg:
 browser->append(msg);
 break;

 case QtWarningMsg:
 browser->append(tr("— WARNING: %1").arg(msg));
 break;

 case QtCriticalMsg:
 browser->append(tr("— CRITICAL: %1").arg(msg));
 break;

 case QtFatalMsg:
 browser->append(tr("— FATAL: %1").arg(msg));
 break;
 }
}


void LogBrowserDialog::save()
{
 QString saveFileName = QFileDialog::getSaveFileName(
 this,
 tr("Save Log Output"),
 tr("%1/logfile.txt").arg(QDir::homePath()),
 tr("Text Files ('''.txt);;All Files (*)")
 );

if(saveFileName.isEmpty())
 return;

QFile file(saveFileName);
 if(!file.open(QIODevice::WriteOnly)) {
 QMessageBox::warning(
 this,
 tr("Error"),
 QString(tr("<nobr>File '%1'<br/>cannot be opened for writing.<br/><br/>"
 "The log output could <b>not</b> be saved!</nobr>"))
 .arg(saveFileName));
 return;
 }

QTextStream stream(&file);
 stream << browser->toPlainText();
 file.close();
}

void LogBrowserDialog::closeEvent(QCloseEvent *e)
{
 QMessageBox::StandardButton answer = QMessageBox::question(
 this,
 tr("Close Log Browser?"),
 tr("Do you really want to close the log browser?"),
 QMessageBox::Yes | QMessageBox::No
 );

if (answer == QMessageBox::Yes)
 e->accept();
 else
 e->ignore();
}

void LogBrowserDialog::keyPressEvent(QKeyEvent *e)
{
 // ignore all keyboard events
 // protects against accidentally closing of the dialog
 // without asking the user
 e->ignore();
}

main.cpp

#include <QApplication>
#include <QPointer>
#include <QDebug>
#include "logbrowser.h"

QPointer<LogBrowser> logBrowser;

void myMessageOutput(QtMsgType type, const char *msg)
{
 if(logBrowser)
 logBrowser->outputMessage( type, msg );
}

int main(int argc, char *argv[])
{
 QApplication a(argc, argv);

logBrowser = new LogBrowser;
 qInstallMsgHandler(myMessageOutput);

qDebug() << "test for debug";
 int result = a.exec();
 qDebug() << "application exec return result =" << result;

delete logBrowser;
 return result;
}