/* Images * * GtkImage is used to display an image; the image can be in a number of formats. * Typically, you load an image into a GdkPixbuf, then display the pixbuf. * * This demo code shows some of the more obscure cases, in the simple * case a call to gtk_image_new_from_file() is all you need. * * If you want to put image data in your program as a C variable, * use the make-inline-pixbuf program that comes with GTK+. */ #include #include #include static GtkWidget *window = NULL; static GdkPixbufLoader *pixbuf_loader = NULL; static guint load_timeout = 0; static FILE* image_stream = NULL; static void progressive_prepared_callback (GdkPixbufLoader* loader, gpointer data) { GdkPixbuf* pixbuf; GtkWidget* image; image = GTK_WIDGET (data); pixbuf = gdk_pixbuf_loader_get_pixbuf (loader); /* Avoid displaying random memory contents, since the pixbuf * isn't filled in yet. */ gdk_pixbuf_fill (pixbuf, 0xaaaaaaff); gtk_image_set_from_pixbuf (GTK_IMAGE (image), pixbuf); } static void progressive_updated_callback (GdkPixbufLoader* loader, guint x, guint y, guint width, guint height, gpointer data) { GtkWidget* image; image = GTK_WIDGET (data); /* We know the pixbuf inside the image has changed, but the image * itself doesn't know this; so queue a redraw. If we wanted to be * really efficient, we could use a drawing area or something * instead of a GtkImage, so we could control the exact position of * the pixbuf on the display, then we could queue a draw for only * the updated area of the image. */ gtk_widget_queue_draw (image); } static gint progressive_timeout (gpointer data) { GtkWidget *image; image = GTK_WIDGET (data); /* This shows off fully-paranoid error handling, so looks scary. * You could factor out the error handling code into a nice separate * function to make things nicer. */ if (image_stream) { size_t bytes_read; guchar buf[256]; GError *error = NULL; bytes_read = fread (buf, 1, 256, image_stream); if (ferror (image_stream)) { GtkWidget *dialog; dialog = gtk_message_dialog_new (GTK_WINDOW (window), GTK_DIALOG_DESTROY_WITH_PARENT, GTK_MESSAGE_ERROR, GTK_BUTTONS_CLOSE, "Failure reading image file 'gtk-logo-rgb.gif': %s", g_strerror (errno)); gtk_signal_connect (GTK_OBJECT (dialog), "response", GTK_SIGNAL_FUNC (gtk_widget_destroy), NULL); fclose (image_stream); image_stream = NULL; gtk_widget_show (dialog); load_timeout = 0; return FALSE; /* uninstall the timeout */ } if (!gdk_pixbuf_loader_write (pixbuf_loader, buf, bytes_read, &error)) { GtkWidget *dialog; dialog = gtk_message_dialog_new (GTK_WINDOW (window), GTK_DIALOG_DESTROY_WITH_PARENT, GTK_MESSAGE_ERROR, GTK_BUTTONS_CLOSE, "Failed to load image: %s", error->message); g_error_free (error); gtk_signal_connect (GTK_OBJECT (dialog), "response", GTK_SIGNAL_FUNC (gtk_widget_destroy), NULL); fclose (image_stream); image_stream = NULL; gtk_widget_show (dialog); load_timeout = 0; return FALSE; /* uninstall the timeout */ } if (feof (image_stream)) { fclose (image_stream); image_stream = NULL; /* Errors can happen on close, e.g. if the image * file was truncated we'll know on close that * it was incomplete. */ error = NULL; if (!gdk_pixbuf_loader_close (pixbuf_loader, &error)) { GtkWidget *dialog; dialog = gtk_message_dialog_new (GTK_WINDOW (window), GTK_DIALOG_DESTROY_WITH_PARENT, GTK_MESSAGE_ERROR, GTK_BUTTONS_CLOSE, "Failed to load image: %s", error->message); g_error_free (error); gtk_signal_connect (GTK_OBJECT (dialog), "response", GTK_SIGNAL_FUNC (gtk_widget_destroy), NULL); gtk_widget_show (dialog); g_object_unref (G_OBJECT (pixbuf_loader)); pixbuf_loader = NULL; load_timeout = 0; return FALSE; /* uninstall the timeout */ } g_object_unref (G_OBJECT (pixbuf_loader)); pixbuf_loader = NULL; } } else { const gchar *filename; if (g_file_test ("./gtk-logo-rgb.gif", G_FILE_TEST_EXISTS)) filename = "./gtk-logo-rgb.gif"; else filename = DEMOCODEDIR"/gtk-log-rgb.gif"; image_stream = fopen (filename, "r"); if (image_stream == NULL) { GtkWidget *dialog; dialog = gtk_message_dialog_new (GTK_WINDOW (window), GTK_DIALOG_DESTROY_WITH_PARENT, GTK_MESSAGE_ERROR, GTK_BUTTONS_CLOSE, "Unable to open image file 'gtk-logo-rgb.gif': %s", g_strerror (errno)); gtk_signal_connect (GTK_OBJECT (dialog), "response", GTK_SIGNAL_FUNC (gtk_widget_destroy), NULL); gtk_widget_show (dialog); load_timeout = 0; return FALSE; /* uninstall the timeout */ } if (pixbuf_loader) { gdk_pixbuf_loader_close (pixbuf_loader, NULL); g_object_unref (G_OBJECT (pixbuf_loader)); pixbuf_loader = NULL; } pixbuf_loader = gdk_pixbuf_loader_new (); g_signal_connect_data (G_OBJECT (pixbuf_loader), "area_prepared", G_CALLBACK (progressive_prepared_callback), image, NULL, FALSE, FALSE); g_signal_connect_data (G_OBJECT (pixbuf_loader), "area_updated", G_CALLBACK (progressive_updated_callback), image, NULL, FALSE, FALSE); } /* leave timeout installed */ return TRUE; } static void start_progressive_loading (GtkWidget *image) { /* This is obviously totally contrived (we slow down loading * on purpose to show how incremental loading works). * The real purpose of incremental loading is the case where * you are reading data from a slow source such as the network. * The timeout simply simulates a slow data source by inserting * pauses in the reading process. */ load_timeout = g_timeout_add (300, progressive_timeout, image); } static void cleanup_callback (GtkObject *object, gpointer data) { if (load_timeout) { g_source_remove (load_timeout); load_timeout = 0; } if (pixbuf_loader) { gdk_pixbuf_loader_close (pixbuf_loader, NULL); g_object_unref (G_OBJECT (pixbuf_loader)); pixbuf_loader = NULL; } if (image_stream) fclose (image_stream); image_stream = NULL; } GtkWidget * do_images (void) { GtkWidget *frame; GtkWidget *vbox; GtkWidget *image; GtkWidget *label; GtkWidget *align; if (!window) { window = gtk_window_new (GTK_WINDOW_TOPLEVEL); gtk_window_set_title (GTK_WINDOW (window), "Images"); gtk_signal_connect (GTK_OBJECT (window), "destroy", GTK_SIGNAL_FUNC (gtk_widget_destroyed), &window); gtk_signal_connect (GTK_OBJECT (window), "destroy", GTK_SIGNAL_FUNC (cleanup_callback), NULL); gtk_container_set_border_width (GTK_CONTAINER (window), 8); vbox = gtk_vbox_new (FALSE, 8); gtk_container_set_border_width (GTK_CONTAINER (vbox), 8); gtk_container_add (GTK_CONTAINER (window), vbox); label = gtk_label_new (NULL); gtk_label_set_markup (GTK_LABEL (label), "Image loaded from a file"); gtk_box_pack_start (GTK_BOX (vbox), label, FALSE, FALSE, 0); frame = gtk_frame_new (NULL); gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_IN); /* The alignment keeps the frame from growing when users resize * the window */ align = gtk_alignment_new (0.5, 0.5, 0, 0); gtk_container_add (GTK_CONTAINER (align), frame); gtk_box_pack_start (GTK_BOX (vbox), align, FALSE, FALSE, 0); /* We look for the image in the current directory first, * so you can run gtk-demo without installing GTK */ if (g_file_test ("./gtk-logo-rgb.gif", G_FILE_TEST_EXISTS)) { /* This code shows off error handling. You can just use * gtk_image_new_from_file() instead if you don't want to report * errors to the user. If the file doesn't load when using * gtk_image_new_from_file(), a "missing image" icon will * be displayed instead. */ GdkPixbuf *pixbuf; GError *error = NULL; pixbuf = gdk_pixbuf_new_from_file ("./gtk-logo-rgb.gif", &error); if (error) { GtkWidget *dialog; dialog = gtk_message_dialog_new (GTK_WINDOW (window), GTK_DIALOG_DESTROY_WITH_PARENT, GTK_MESSAGE_ERROR, GTK_BUTTONS_CLOSE, "Unable to open image file 'gtk-logo-rgb.gif': %s", error->message); g_error_free (error); gtk_signal_connect (GTK_OBJECT (dialog), "response", GTK_SIGNAL_FUNC (gtk_widget_destroy), NULL); gtk_widget_show (dialog); } image = gtk_image_new_from_pixbuf (pixbuf); } else { /* This is the simpler code, with no error handling. * Here we're loading the installed gtk-logo-rgb.gif instead * of the one in the current directory. */ image = gtk_image_new_from_file (DEMOCODEDIR"/gtk-logo-rgb.gif"); } gtk_container_add (GTK_CONTAINER (frame), image); label = gtk_label_new (NULL); gtk_label_set_markup (GTK_LABEL (label), "Progressive image loading"); gtk_box_pack_start (GTK_BOX (vbox), label, FALSE, FALSE, 0); frame = gtk_frame_new (NULL); gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_IN); /* The alignment keeps the frame from growing when users resize * the window */ align = gtk_alignment_new (0.5, 0.5, 0, 0); gtk_container_add (GTK_CONTAINER (align), frame); gtk_box_pack_start (GTK_BOX (vbox), align, FALSE, FALSE, 0); /* Create an empty image for now; the progressive loader * will create the pixbuf and fill it in. */ image = gtk_image_new_from_pixbuf (NULL); gtk_container_add (GTK_CONTAINER (frame), image); start_progressive_loading (image); } if (!GTK_WIDGET_VISIBLE (window)) { gtk_widget_show_all (window); } else { gtk_widget_destroy (window); window = NULL; } return window; }