Re: redirecting stdout to gtk_text widget

[Claudio Polegato Junior <cpolegatojr_lsts pop com br>]

ashish gupta escreveu:
> hi,
> I need help on how to redirect stdout to a text widget.  I am writing 
> a gui using GTK libraries.I need to be able to redirect text that is 
> going to stdout through the printf's to my text widget.
> My application is in C and i am developing in Windows
> I could direct it all to a file, and then read the file,
>  but it seams there would be a better way. 
> thanks for ur help in advance
Hi,

 You can use pipe (maybe fifo or other file descriptor, but I prefer 
pipes) plus IO monitoring from GTK (or Glib Threads if you know about). 
I modify the "Hello Word" example a little and them, you can do like this:

#include <stdio.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <gtk/gtk.h>

/*
  Author: Claudio Polegato Junior + "Hello Word" authors example
    Date: 07 Feb 2006
 Program: pipe.c
 License: GPL

 Compilation Line: gcc pipe.c -o pipe `pkg-config --libs --cflags 
gtk+-2.0` && ./pipe
*/


/* The Text Buffer as a global variable*/
GtkTextBuffer *buffer;
/* File descriptors for pipe. */
int fds[2];

/* This is a callback function to watch data in standard output and 
write to a view text widget. */
void input_callback( gpointer          data,
                    gint              source,
                    GdkInputCondition condition )
{
   gchar buf[1024];
   gint chars_read;
   GtkTextIter iter;
   chars_read = 1024;
   gtk_text_buffer_get_end_iter(buffer, &iter);
   while (chars_read == 1024){
     chars_read = read(fds[0], buf, 1024);
     // fprintf(stderr, "%i chars: %s\n", chars_read, buf);
     gtk_text_buffer_insert (buffer, &iter, buf, chars_read);
   }
}

/* This is a callback function. The data arguments are ignored
* in this example. More on callbacks below. */
static void hello( GtkWidget *widget,
                  gpointer   data )
{
   g_print ("\nHello World\n");
}

static gboolean delete_event( GtkWidget *widget,
                             GdkEvent  *event,
                             gpointer   data )
{
   /* If you return FALSE in the "delete_event" signal handler,
    * GTK will emit the "destroy" signal. Returning TRUE means
    * you don't want the window to be destroyed.
    * This is useful for popping up 'are you sure you want to quit?'
    * type dialogs. */

   g_print ("\ndelete event occurred\n");
   g_print ("to destroy this window go to started terminal and them 
press CTRL+C\n");

   /* Change TRUE to FALSE and the main window will be destroyed with
    * a "delete_event". */

   return TRUE;
}

/* Another callback */
static void destroy( GtkWidget *widget,
                    gpointer   data )
{
   g_print ("destroy event occurred\n");
   gtk_main_quit ();
}

int main( int   argc,
         char *argv[] )
{
   /* GtkWidget is the storage type for widgets */
   GtkWidget     *window;
   GtkWidget     *vbox;
   GtkWidget     *button;
   GtkWidget     *view;

   // Create a pipe. File descriptors for the two ends of the pipe are 
placed in fds.
   pipe (fds);
   // Redirect fds[1] to be writed with the standard output.
   dup2 (fds[1], STDOUT_FILENO);

   /* This is called in all GTK applications. Arguments are parsed
    * from the command line and are returned to the application. */
   gtk_init (&argc, &argv);

   /* create a new window */
   window = gtk_window_new (GTK_WINDOW_TOPLEVEL);

   /* When the window is given the "delete_event" signal (this is given
    * by the window manager, usually by the "close" option, or on the
    * titlebar), we ask it to call the delete_event () function
    * as defined above. The data passed to the callback
    * function is NULL and is ignored in the callback function. */
   g_signal_connect (G_OBJECT (window), "delete_event",
             G_CALLBACK (delete_event), NULL);

   /* Here we connect the "destroy" event to a signal handler.
    * This event occurs when we call gtk_widget_destroy() on the window,
    * or if we return FALSE in the "delete_event" callback. */
   g_signal_connect (G_OBJECT (window), "destroy",
             G_CALLBACK (destroy), NULL);

   /* Sets the border width of the window. */
   gtk_container_set_border_width (GTK_CONTAINER (window), 10);

   /* Creates a new button with the label "Hello World". */
   button = gtk_button_new_with_label ("Hello World");

   /* When the button receives the "clicked" signal, it will call the
    * function hello() passing it NULL as its argument.  The hello()
    * function is defined above. */
   g_signal_connect (G_OBJECT (button), "clicked",
             G_CALLBACK (hello), NULL);

   /* This will cause the window to be destroyed by calling
    * gtk_widget_destroy(window) when "clicked".  Again, the destroy
    * signal could come from here, or the window manager. */
/*
   g_signal_connect_swapped (G_OBJECT (button), "clicked",
                 G_CALLBACK (gtk_widget_destroy),
                             G_OBJECT (window));

   /* Creates a new text view with a text buffer "Hello, this is some 
text". */
   view = gtk_text_view_new ();
   buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (view));
   gtk_text_buffer_set_text (buffer, "Hello, this is some text", -1);

   /* Creates a new vertical box. */
   vbox = gtk_vbox_new (FALSE, 10);

   /* This packs the vbox into the window (a gtk container). */
   gtk_container_add (GTK_CONTAINER (window), vbox);

   /* This packs the text view into the vbox. */
   gtk_box_pack_start (GTK_BOX (vbox), view, TRUE, TRUE, 0);

   /* This packs the button into the vbox. */
   gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);

   /* This is the singnal connection to call input_callback when we 
have data in standard output read end pipe. */
   gdk_input_add(fds[0], GDK_INPUT_READ, input_callback, NULL);

   /* The final step is to display this newly created widget. */
   gtk_widget_show (button);
   gtk_widget_show (view);
   gtk_widget_show (vbox);

   /* and the window */
   gtk_widget_show (window);

   /* All GTK applications must have a gtk_main(). Control ends here
    * and waits for an event to occur (like a key press or
    * mouse event). */
   gtk_main ();

   return 0;
}


--

[]'s

Claudio Polegato Junior

Um peregrino de Problemas; Um pergaminho de Soluções.

#include <stdio.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <gtk/gtk.h>

/*
   Author: Claudio Polegato Junior + "Hellow Word" authors example
     Date: 07 Feb 2006
  Program: pipe.c
  Licence: GPL

  Compilation Line: gcc pipe.c -o pipe `pkg-config --libs --cflags gtk+-2.0` && ./pipe
*/


/* The Text Buffer as a global variabel*/
GtkTextBuffer *buffer;
/* File descriptors for pipe. */
int fds[2];

/* This is a callback function to watch data in standard output and write to a view text widget. */
void input_callback( gpointer          data,
                     gint              source,
                     GdkInputCondition condition )
{
    gchar buf[1024];
    gint chars_read;
    GtkTextIter iter;
    chars_read = 1024;
    gtk_text_buffer_get_end_iter(buffer, &iter);
    while (chars_read == 1024){
      chars_read = read(fds[0], buf, 1024);
      // fprintf(stderr, "%i chars: %s\n", chars_read, buf);
      gtk_text_buffer_insert (buffer, &iter, buf, chars_read);
    }
}

/* This is a callback function. The data arguments are ignored
 * in this example. More on callbacks below. */
static void hello( GtkWidget *widget,
                   gpointer   data )
{
    g_print ("\nHello World\n");
}

static gboolean delete_event( GtkWidget *widget,
                              GdkEvent  *event,
                              gpointer   data )
{
    /* If you return FALSE in the "delete_event" signal handler,
     * GTK will emit the "destroy" signal. Returning TRUE means
     * you don't want the window to be destroyed.
     * This is useful for popping up 'are you sure you want to quit?'
     * type dialogs. */

    g_print ("\ndelete event occurred\n");
    g_print ("to destroy this window go to started terminal and them press CTRL+C\n");

    /* Change TRUE to FALSE and the main window will be destroyed with
     * a "delete_event". */

    return TRUE;
}

/* Another callback */
static void destroy( GtkWidget *widget,
                     gpointer   data )
{
    g_print ("destroy event occurred\n");
    gtk_main_quit ();
}

int main( int   argc,
          char *argv[] )
{
    /* GtkWidget is the storage type for widgets */
    GtkWidget     *window;
    GtkWidget     *vbox;
    GtkWidget     *button;
    GtkWidget     *view;

    // Create a pipe. File descriptors for the two ends of the pipe are placed in fds.
    pipe (fds);
    // Redirect fds[1] to be writed with the standard output.
    dup2 (fds[1], STDOUT_FILENO);

    /* This is called in all GTK applications. Arguments are parsed
     * from the command line and are returned to the application. */
    gtk_init (&argc, &argv);

    /* create a new window */
    window = gtk_window_new (GTK_WINDOW_TOPLEVEL);

    /* When the window is given the "delete_event" signal (this is given
     * by the window manager, usually by the "close" option, or on the
     * titlebar), we ask it to call the delete_event () function
     * as defined above. The data passed to the callback
     * function is NULL and is ignored in the callback function. */
    g_signal_connect (G_OBJECT (window), "delete_event",
		      G_CALLBACK (delete_event), NULL);

    /* Here we connect the "destroy" event to a signal handler.
     * This event occurs when we call gtk_widget_destroy() on the window,
     * or if we return FALSE in the "delete_event" callback. */
    g_signal_connect (G_OBJECT (window), "destroy",
		      G_CALLBACK (destroy), NULL);

    /* Sets the border width of the window. */
    gtk_container_set_border_width (GTK_CONTAINER (window), 10);

    /* Creates a new button with the label "Hello World". */
    button = gtk_button_new_with_label ("Hello World");

    /* When the button receives the "clicked" signal, it will call the
     * function hello() passing it NULL as its argument.  The hello()
     * function is defined above. */
    g_signal_connect (G_OBJECT (button), "clicked",
		      G_CALLBACK (hello), NULL);

    /* This will cause the window to be destroyed by calling
     * gtk_widget_destroy(window) when "clicked".  Again, the destroy
     * signal could come from here, or the window manager. */
/*
    g_signal_connect_swapped (G_OBJECT (button), "clicked",
			      G_CALLBACK (gtk_widget_destroy),
                              G_OBJECT (window));

    /* Creates a new text view with a text buffer "Hello, this is some text". */
    view = gtk_text_view_new ();
    buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (view));
    gtk_text_buffer_set_text (buffer, "Hello, this is some text", -1);

    /* Creates a new vertical box. */
    vbox = gtk_vbox_new (FALSE, 10);

    /* This packs the vbox into the window (a gtk container). */
    gtk_container_add (GTK_CONTAINER (window), vbox);

    /* This packs the text view into the vbox. */
    gtk_box_pack_start (GTK_BOX (vbox), view, TRUE, TRUE, 0);

    /* This packs the button into the vbox. */
    gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);

    /* This is the singnal connection to call input_callback when we have data in standard output read end pipe. */
    gdk_input_add(fds[0], GDK_INPUT_READ, input_callback, NULL);

    /* The final step is to display this newly created widget. */
    gtk_widget_show (button);
    gtk_widget_show (view);
    gtk_widget_show (vbox);

    /* and the window */
    gtk_widget_show (window);

    /* All GTK applications must have a gtk_main(). Control ends here
     * and waits for an event to occur (like a key press or
     * mouse event). */
    gtk_main ();

    return 0;
}