GUI: some fixes of help

* moved the help file to the application folder
 * use absolute path instead of relative path for helpfile
 * show warning messages if help file doesn't exist or fails to be loaded

gui/helpwindow.cpp

@@ -52,12 +52,17 @@ HelpWindow::HelpWindow(QWidget *parent) :
     m_ui(new Ui::HelpWindow)
 {
     m_ui->setupUi(this);
+    helpEngine = NULL;
+}
 
-    setVisible(true);
-
-    helpEngine = new QHelpEngine("help/online-help.qhc", this);
-    if (helpEngine->setupData())
+bool HelpWindow::load(const QString &helpFile)
 {
+    helpEngine = new QHelpEngine(helpFile, this);
+    if (!helpEngine->setupData())
+    {
+        return false;
+    }
+
     QSplitter *helpPanel = new QSplitter(Qt::Horizontal);
     HelpBrowser *helpBrowser = new HelpBrowser(helpEngine, this);
 
@@ -75,7 +80,8 @@ HelpWindow::HelpWindow(QWidget *parent) :
     connect(m_ui->homeButton, SIGNAL(clicked()), helpBrowser, SLOT(home()));
     //connect(m_ui->zoomInButton, SIGNAL(clicked()), helpBrowser, SLOT(zoomIn()));
     //connect(m_ui->zoomOutButton, SIGNAL(clicked()), helpBrowser, SLOT(zoomOut()));
-    }
+
+    return true;
 }
 
 HelpWindow::~HelpWindow()

gui/helpwindow.h

@@ -41,6 +41,12 @@ public:
     HelpWindow(QWidget *parent = 0);
     ~HelpWindow();
 
+    /**
+     * load a *.qhc file and setup GUI. the file must exist.
+     * @return false if loading failed
+     */
+    bool load(const QString &helpFile);
+
 private:
     Ui::HelpWindow *m_ui;
 

gui/mainwindow.cpp

@@ -684,7 +684,23 @@ void MainWindow::OpenHelpContents()
 void MainWindow::OpenHtmlHelpContents()
 {
     if (mHelpWindow == NULL)
+    {
+        const QString fname = qApp->applicationDirPath() + "/online-help.qhc";
+        if (!QFileInfo(fname).exists())
+        {
+            QMessageBox::warning(this, tr("Cppcheck Help"), tr("Failed to load help file (not found)"));
+            return;
+        }
+
         mHelpWindow = new HelpWindow;
+        if (!mHelpWindow->load(fname))
+        {
+            delete mHelpWindow;
+            mHelpWindow = NULL;
+            QMessageBox::warning(this, tr("Cppcheck Help"), tr("Failed to load help file"));
+            return;
+        }
+    }
 
     mHelpWindow->show();
     if (!mHelpWindow->isActiveWindow())