How does one set the background of a GtkWindow to an image?

c, gtk

Solution

My questions are:

1- How do I derive a GdkWindow from the codes main window ( GtkWindow )? 2- Do I need to use a Drawing Area at all? 3- What do I need to do get the background.gif image displayed as the background on the main >window?

If you want set a image like a background in you gtk window, you should do: 1 - Load the image to a GdkPixbuf or variant. (gdk_pixbuf_new_from_file) 2 - Create a pixmap and a mask bitmap. (gdk_pixbuf_render_pixmap_and_mask () ) 3 - Create a GtkStyle that hold style information for widgets. 4 - Load the render pixmap to the style. 5 - Set the GtkStyle to the main window.

An example:

#include <gtk/gtk.h>
#include <stdio.h>
#include <stdlib.h>

GdkPixbuf *load_pixbuf_from_file (const char *filename)
{
    GError *error = NULL;
    GdkPixbuf *pixbuf = gdk_pixbuf_new_from_file (filename, &error);

    if (pixbuf == NULL)
    {
        g_print ("Error loading file: %d : %s\n", error->code, error->message);
        g_error_free (error);
        exit (1);
    }
    return pixbuf;
}

GdkPixbufAnimation *load_pixbuf_animation_from_file (const char *filename)
{
    GError *error = NULL;
    GdkPixbufAnimation *pixbuf = gdk_pixbuf_animation_new_from_file (filename, &error);

    if (pixbuf == NULL)
    {
        g_print ("Error loading file: %d : %s\n", error->code, error->message);
        g_error_free (error);
        exit (1);   
    }
    return pixbuf;
}

int main (int argc, char **argv)
{
    GtkWidget *window = NULL;
    GdkPixbuf *image = NULL;
    GdkPixbufAnimation * anim = NULL;
    GtkWidget *widget = NULL;
    GdkPixmap *background = NULL;
    GtkStyle *style = NULL;

    gtk_init (&argc, &argv);
    /* Load a non animated gif */
    image = load_pixbuf_from_file ("/home/midnigther/Desktop/pict.gif");
    //  widget = gtk_image_new_from_pixbuf (image);
    gdk_pixbuf_render_pixmap_and_mask (image, &background, NULL, 0);
    style = gtk_style_new ();
    style->bg_pixmap [0] = background;
    window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
    gtk_window_set_title (GTK_WINDOW(window), "Load Image");
    gtk_window_set_default_size (GTK_WINDOW (window), 400, 300);
    gtk_widget_set_style (GTK_WIDGET(window), GTK_STYLE (style));
    gtk_window_set_transient_for (GTK_WINDOW (window), NULL);

    GtkWidget *hbox = NULL;
    hbox = gtk_hbox_new (0, FALSE);
    gtk_container_add (GTK_CONTAINER(window), hbox);

    GtkWidget *button = NULL;
    button = gtk_button_new_with_label ("Sonic");
    gtk_box_pack_start (GTK_BOX (hbox), button, FALSE, FALSE, 0);

    gtk_widget_show_all (window);
    gtk_main ();
    return 0;
}

Problem

I've got a simple `C` `GTK` Linux application that needs to set the background of the main window to an image from a `GIF` file. I done some reading and it appears that I should be able to do the following: 1- stuff the background image into a `GdkPixbuf` using `gdk_pixbuf_new_from_file()` 2- use `gdk_pixbuf_render_pixmap_and_mask()` to render the `GdkPixbuf` into a `GdkPixMap` 3- set the background of the `GtkWindow` using `gdk_window_set_back_pixmap()` The call to `gdk_window_set_back_pixmap()` appears to require a `GdKWindow` instead of a `GtkWindow`. My code that isn't working is below followed by my specific questions. ``` /* * Compile me with: * gcc -o reels reels.c $(pkg-config --cflags --libs gtk+-2.0 gmodule-2.0) */ #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> #include <string.h> #include <stdlib.h> #include <errno.h> #include <time.h> /* GTK */ #include <gdk/gdkx.h> #include <gtk/gtk.h> /**** prototypes ****/ static void destroy (GtkWidget*, gpointer); GdkPixbuf *create_pixbuf(const gchar * filename); /********************/ GtkWidget *images[3][5]; static void destroy (GtkWidget *window, gpointer data) { gtk_main_quit (); } GdkPixbuf *create_pixbuf(const gchar * filename) { GdkPixbuf *pixbuf; GError *error = NULL; pixbuf = gdk_pixbuf_new_from_file(filename, &error); if(!pixbuf) { fprintf(stderr, "%s\n", error->message); g_error_free(error); } return pixbuf; } int main (int argc, char *argv[]) { GtkWidget *window, *table; GdkPixbufAnimation *animation; GtkWidget *image; int x,y; GdkPixbuf *pixBuf; GdkPixmap *pixMap; gtk_init (&argc, &argv); window = gtk_window_new (GTK_WINDOW_TOPLEVEL); gtk_window_set_default_size (GTK_WINDOW (window), 628, 530); gtk_window_set_title (GTK_WINDOW (window), "Demo"); gtk_container_set_border_width (GTK_CONTAINER (window), 10); //gtk_window_set_decorated( GTK_WINDOW(window), FALSE ); pixBuf = create_pixbuf("background.gif"); gdk_pixbuf_render_pixmap_and_mask(pixBuf, &pixMap, NULL, 255); gdk_window_set_back_pixmap( GDK_WINDOW (window), pixMap, (gboolean) TRUE); #if 0 /* some code I found that is supposed to create a background image.. Can't seem to get it converted correctly into 'C' */ area=gtk.Drawingarea() pixbuf=gtk.gdk.pixbuf_new_from_file('background.png') pixmap, mask=pixbuf.render_pixmap_and_mask() area.window.set_back_pixmap(pixmap, False) #endif g_signal_connect (G_OBJECT (window), "destroy", G_CALLBACK (destroy), NULL); table = gtk_table_new (3, 5, TRUE); /* setup animated gifs */ for( y = 0; y < 3; y++ ) { for( x = 0; x < 5; x++ ) { /* set each Image widget to spin GIF */ images[y][x] = gtk_image_new_from_file("spinning.gif");; gtk_table_attach (GTK_TABLE (table), images[y][x], x, x+1, y, y+1, GTK_EXPAND, GTK_SHRINK, 0, 0); } } /* Add five pixels of spacing between every row and every column. */ gtk_table_set_row_spacings (GTK_TABLE (table), 5); gtk_table_set_col_spacings (GTK_TABLE (table), 5); gtk_container_add (GTK_CONTAINER (window), table); gtk_widget_show_all (window); gtk_main (); return 0; } ``` The code compiles and runs but I get the following runtime errors ( which I expected since I don't know how to derive a `GdkWindow` from a `GtkWindow`: (reels:10951): GLib-GObject-WARNING **: invalid cast from `GtkWindow' to`GdkWindow' (reels:10951): Gdk-CRITICAL **: gdk_window_set_back_pixmap: assertion `GDK_IS_WINDOW (window)' failed My questions are: 1- How do I derive a `GdkWindow` from the codes main window ( `GtkWindow` )? 2- Do I need to use a Drawing Area at all? 3- What do I need to do get the `background.gif` image displayed as the background on the main window? Any help would be greatly appreciated. I've seen many snippets of code, but I'm having a hard time putting it all together, and I'm fairly new to `Gtk` still.

Original source