Hmmmm.

src/updater/formupdater.cpp

@@ -19,12 +19,17 @@
 #include <QTimer>
 
 
+FormUpdater *FormUpdater::s_instance;
+
 FormUpdater::FormUpdater(QWidget *parent)
   : QMainWindow(parent, Qt::Dialog | Qt::WindowStaysOnTopHint),
     m_state(NoState),
     m_txtOutput(new QTextEdit(this)),
     m_parsedArguments(QHash<QString, QString>())  {
 
+  // Initialize singleton.
+  s_instance = this;
+
   m_txtOutput->setAutoFormatting(QTextEdit::AutoNone);
   m_txtOutput->setAcceptRichText(true);
   m_txtOutput->setFontPointSize(10.0);
@@ -47,6 +52,8 @@ FormUpdater::~FormUpdater() {
 }
 
 void FormUpdater::startUpgrade() {
+  qDebug("Started...");
+
   printHeading("Welcome to RSS Guard updater");
   printText("Analyzing updater arguments.");
 
@@ -101,6 +108,70 @@ void FormUpdater::executeMainApplication() {
   }
 }
 
+
+#if QT_VERSION >= 0x050000
+void FormUpdater::debugHandler(QtMsgType type,
+                               const QMessageLogContext &placement,
+                               const QString &message) {
+#ifndef QT_NO_DEBUG_OUTPUT
+  Q_UNUSED(placement)
+
+  switch (type) {
+    case QtDebugMsg:
+      s_instance->printText(QString("DEBUG: %1").arg(message));
+      break;
+
+    case QtWarningMsg:
+      s_instance->printText(QString("WARNING: %1").arg(message));
+      break;
+
+    case QtCriticalMsg:
+      s_instance->printText(QString("CRITICAL: %1").arg(message));
+      break;
+
+    case QtFatalMsg:
+      s_instance->printText(QString("FATAL: %1").arg(message));
+      qApp->exit(EXIT_FAILURE);
+
+    default:
+      break;
+  }
+#else
+  Q_UNUSED(type)
+  Q_UNUSED(placement)
+  Q_UNUSED(message)
+#endif
+}
+#else
+void FormUpdater::debugHandler(QtMsgType type, const char *message) {
+#ifndef QT_NO_DEBUG_OUTPUT
+  switch (type) {
+    case QtDebugMsg:
+      s_instance->printText(QString("DEBUG: %1").arg(message));
+      break;
+
+    case QtWarningMsg:
+      s_instance->printText(QString("WARNING: %1").arg(message));
+      break;
+
+    case QtCriticalMsg:
+      s_instance->printText(QString("CRITICAL: %1").arg(message));
+      break;
+
+    case QtFatalMsg:
+      s_instance->printText(QString("FATAL: %1").arg(message));
+      qApp->exit(EXIT_FAILURE);
+
+    default:
+      break;
+  }
+#else
+  Q_UNUSED(type)
+  Q_UNUSED(message)
+#endif
+}
+#endif
+
 void FormUpdater::printArguments() {
   printNewline();
   printHeading("Arguments");

src/updater/formupdater.h

@@ -3,6 +3,7 @@
 
 #include <QMainWindow>
 
+#include <QtGlobal>
 #include <QHash>
 
 
@@ -13,6 +14,7 @@ class FormUpdater : public QMainWindow {
     Q_OBJECT
 
   public:
+    // Describes the state of updater.
     enum UpdaterState {
       NoState,
       ExitNormal,
@@ -23,6 +25,11 @@ class FormUpdater : public QMainWindow {
     explicit FormUpdater(QWidget *parent = 0);
     virtual ~FormUpdater();
 
+    // Prints various texts.
+    void printText(const QString &text);
+    void printNewline();
+    void printHeading(const QString &header);
+
     // Starts the whole update process.
     void startUpgrade();
 
@@ -35,16 +42,20 @@ class FormUpdater : public QMainWindow {
     bool doFinalCleanup();
     void executeMainApplication();
 
+    // Debug handlers for messages.
+#if QT_VERSION >= 0x050000
+    static void debugHandler(QtMsgType type,
+                             const QMessageLogContext &placement,
+                             const QString &message);
+#else
+    static void debugHandler(QtMsgType type,
+                             const char *message);
+#endif
+
   protected:
     // Catch the "press any key event" to exit the updater.
     void keyPressEvent(QKeyEvent *event);
 
-  private:
-    // Prints various texts.
-    void printText(const QString &text);
-    void printNewline();
-    void printHeading(const QString &header);
-
     // Moves the window into the center of the screen and resizes it.
     void moveToCenterAndResize();
 
@@ -57,8 +68,9 @@ class FormUpdater : public QMainWindow {
   private:
     UpdaterState m_state;
     QTextEdit *m_txtOutput;
-
     QHash<QString, QString> m_parsedArguments;
+
+    static FormUpdater *s_instance;
 };
 
 #endif // FORMUPDATER_H

src/updater/main.cpp

@@ -29,6 +29,7 @@
 #include <iostream>
 #include <limits>
 
+
 // Main entry point to "rssguard_updater.exe".
 // It expects 4 ARGUMENTS:
 //  0) - the actual path of this process,
@@ -39,11 +40,13 @@
 int main(int argc, char *argv[]) {
   // Instantiate base application object.
   QtSingleApplication application(APP_LOW_NAME, argc, argv);
-
   application.setQuitOnLastWindowClosed(true);
 
   FormUpdater main_form;
 
+  // Setup message handler after main_form is created.
+  qInstallMessageHandler(FormUpdater::debugHandler);
+
   main_form.show();
   main_form.startUpgrade();