Using Qt Standard 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.

        // XtFree((XtPointer) pages[currentPage]);
        XtFree((char *) pages[currentPage]);

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.

    // Qt includes
    #include <qmessagebox.h>

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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