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# Using Qt Standard Dialogs

We start by using two of the Qt Standard Dialogs: QFileDialog and QMessageBox. Both of these classes provide useful static convenience functions.

QFileDialog::getOpenFileName() | replacement for the Open dialog
QFileDialog::getSaveFileName() | replacement for the Save As dialog
QMessageBox::information() | replacement for Page Delete dialog
QMessageBox::warning() | replacement for IO Error dialog.

Each of these functions takes a QWidget *parent argument. If we pass zero as the parent argument, then we will have dialogs that are centered on the screen, instead of being centered over our main window. We can have QMotifWidget create our `XmMainWindow`, and we can then use this class as the parent for both Motif dialogs and Qt dialogs.

We need to include the appropriate headers for QMotifWidget and QFileDialog in `todo.cpp`.

        // Qt includes
        #include <qapplication.h>
        #include <qfiledialog.h>
        #include <qmotif.h>
        #include <qmotifwidget.h>

Next, we make a few modifications to how the application is initialized. We could initialize Xt/Motif and create the `XtAppContext` ourselves, but QMotif can do this for us. We also let QApplication open the connection to the X server. Next, we create a QMotifWidget, passing `xmMainWindowWidgetClass` as the widgetclass argument. We can now use the QMotifWidget::motifWidget() function to access the Motif widget. The shell widget is created automatically by QMotifWidget. We use `XtParent()` to access it. The top-level window is now a QMotifWidget, which means we can use it as the parent for the Qt Standard Dialogs.

          QMotif integrator( APP_CLASS, NULL,
                             optionDesc, XtNumber(optionDesc) );
          QApplication app( argc, argv );
          QMotifWidget toplevel( 0, xmMainWindowWidgetClass,
                                 NULL, 0, "mainw" );
          app.setMainWidget( &toplevel );

          mainw         = toplevel.motifWidget();
          shell         = XtParent( mainw );
          XtGetApplicationResources(shell, (XtPointer) &options,
                                    resources, XtNumber(resources),
                                    (Arg *) NULL, 0);

          XtManageChild(mainw);

## Replacing the Open and Save As Dialogs

First, we completely remove all use of the existing Motif file selection dialog. We remove the `Xm/FileSB.h` include, the global `file_dialog` variable, and the code to create the dialog. We also remove the `PresentFDialog()` callback function. None of this code is needed to use QFileDialog.

After removing the `PresentFDialog()` callback function, we need to make Open and Save As popup-menu callbacks call the `Open()` and `Save()` functions.

First we must change the declaration of these two functions.

            // void Open(Widget, char*, XmFileSelectionBoxCallbackStruct *);
            void Open(Widget, XtPointer, XmPushButtonCallbackStruct *);
            // void Save(Widget, char*, XmFileSelectionBoxCallbackStruct *);
            void Save(Widget, XtPointer, XmPushButtonCallbackStruct *);

We also change the arguments to the callbacks. We pass the top-level QMotifWidget as the `client_data` to these functions, since we will be using it as the parent for the QFileDialog.

          // XtAddCallback(file_menu[FILE_OPEN], XmNactivateCallback,
          //               (XtCallbackProc) PresentFDialog, (XtPointer) Open);
          XtAddCallback(file_menu[FILE_OPEN], XmNactivateCallback,
                        (XtCallbackProc) Open, (XtPointer) &toplevel);
            ...
          // XtAddCallback(file_menu[FILE_SAVE_AS], XmNactivateCallback,
          //               (XtCallbackProc) PresentFDialog, (XtPointer) Save);
          XtAddCallback(file_menu[FILE_SAVE_AS], XmNactivateCallback,
                        (XtCallbackProc) Save, (XtPointer) &toplevel);

Next, we modify the `Save()` function to use QFileDialog::getSaveFileName().

        void
        Save(Widget /*unused*/, XtPointer client_data,
             XmPushButtonCallbackStruct */*unused*/)
        {
          QWidget *toplevel = (QWidget *) client_data;
          QString filename =
              QFileDialog::getSaveFileName( QString::null,
                                            QString::null,
                                            toplevel );

          if ( ! filename.isEmpty() ) {
            char *str = qstrdup( filename.local8Bit() );
            SaveDB(str);

... and the `Open()` function to use QFileDialog::getOpenFileName().

        void
        Open(Widget /*unused*/, XtPointer client_data,
             XmPushButtonCallbackStruct */*unused*/)
        {
          QWidget *toplevel = (QWidget *) client_data;
          QString filename =
              QFileDialog::getOpenFileName( QString::null,
                                            QString::null,
                                            toplevel );

          if ( ! filename.isEmpty() ) {
            char *str = qstrdup( filename.local8Bit() );
            ReadDB(str);

After we build the project, the application runs and operates as expected. The difference is that the Open and Save As dialogs now use QFileDialog.

## Replacing the Page Delete and IO Error Dialogs

The Page Delete dialog is created and used in `actions.c`. We need to migrate this file to C++. We rename it to `actions.cpp`, modify the project file and regenerate the `Makefile`.

The changes required to make `actions.cpp` compile are minimal. We need to wrap more C header files and global variables in an `extern "C"` block.

        extern "C" {
        #include <Exm/TabB.h>
        #include "page.h"

        extern Page pages[];
        // Widget editDialog = 0, deleteDialog = 0;

        void SetPage(int);
        void AdjustPages(int, int);
        void FixPages();
        void PageChange(Widget w, XtPointer i, XmNotebookCallbackStruct *cs);
        Page AllocPage();
        char* Trim(char*);
        extern void SaveDB(char*);

        extern Widget shell, textw, labelw, notebook;
        extern int maxpages, currentPage, modified;

We need to forward declare the `NewPage()`, `DeletePage()`, `EditPage()` and `SaveIt()` functions so that the compiler generates the correct symbols for these functions.

        void NewPage(Widget, XtPointer, XmPushButtonCallbackStruct *);
        void DeletePage(Widget, XtPointer, XmPushButtonCallbackStruct *);
        void EditPage(Widget, XtPointer, XmPushButtonCallbackStruct *);
        void SaveIt(Widget, char *, XmPushButtonCallbackStruct *);
        } // extern "C"

We need to fix a single invalid pointer cast.

And we need to change the variable named new to newstr in the `Trim()` function.

We can now change the `DeletePage()` function to use QMessageBox::information().

First, we need to make sure we include the proper header for QMessageBox.

        // Qt includes
        #include <qmessagebox.h>

The code for `DeletePage()` looks like this:

        void
        DeletePage(Widget, XtPointer client_data,
                   XmPushButtonCallbackStruct *)
        {
          QWidget *toplevel = (QWidget *) client_data;
          int result =
            QMessageBox::information( toplevel, "Page Delete Dialog",
                                      "Do you want to delete this page?",
                                      QMessageBox::Yes, QMessageBox::No );
          if ( result != QMessageBox::Yes )
              return;

At this point in the code, the page should be deleted. The code to do this is in the `DoDeletePage()` function. We move the contents of `DoDeletePage()` to this point and remove the `DoDeletePage()` function completely.

Next, we change `todo.cpp` to pass the top-level QMotifWidget as the `client_data` tot he `DeletePage()` function.

          // XtAddCallback(selected_menu[SELECTED_DELETE], XmNactivateCallback,
          //               (XtCallbackProc) DeletePage, NULL);
          XtAddCallback(selected_menu[SELECTED_DELETE], XmNactivateCallback,
                        (XtCallbackProc) DeletePage, (XtPointer) &toplevel);

The IO Error dialog is created and used in `io.c`. We need to migrate this file to C++. We rename it to `io.cpp`, modify the project file and regenerate the `Makefile`.

The changes required to make `io.cpp` compile are minimal. We need to wrap more C header files and global variables in an `extern "C"` block.

        extern "C" {
        #include <Exm/TabB.h>
        #include "page.h"

        extern Widget notebook, textw, shell;
        Page pages[MAXPAGES];

        extern int currentPage;
        extern int modified;
        int maxpages;
        Page AllocPage();

We need to forward declare the `ReadDB()` and `SaveDB()` functions so that the compiler generates the correct symbols for these functions.

        void ReadDB(char*);
        void SaveDB(char*);
        } // extern "C"

The `ParseNewLines()` function needs to be converted to proper C++.

        /*
        void ParseNewLines(char *label)
        char * label;
        */
        void ParseNewLines(char *label)
        {
            /* look for "\n" and change in '\n' and compact */

The `PrintWithNewLines()` function also needs to be converted to proper C++.

        /*
        static void PrintWithNewLines(output, label)
        FILE * output;
        char * label;
        */
        static void PrintWithNewLines(FILE *output, char *label)
        {
            /* look for '\n' and print "\n" */

We can now change the `ReadDB()` and `SaveDB()` functions to use QMessageBox::warning().

First, we need to make sure we include the proper header for QMessageBox.

The code for `ReadDB()` looks like this:

          input = fopen(filename, "r");

          if (input == NULL && strncmp(filename,"untitled",8) != 0) {
            QString message = "Cannot access (%1) for reading";
            QMessageBox::warning( 0, "IO Error", message.arg(filename) );
          }

          /* Destroy current pages on reread */
            ...

The code for `SaveDB()` looks like this:

          if (access(filename, F_OK) == 0 &&
              access(filename, W_OK) != 0) {
            QString message = "Cannot access (%1) for writing";
            QMessageBox::warning( 0, "IO Error", message.arg(filename) );
            return;
          }

          /* Append a ~ to make the old filename */
            ...

After we build the project, the application runs and operates as expected. The difference is that the Page Delete and IO Error dialogs now use QMessageBox.

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