/* Text View/Hypertext * * Usually, tags modify the appearance of text in the view, e.g. making it * bold or colored or underlined. But tags are not restricted to appearance. * They can also affect the behavior of mouse and key presses, as this demo * shows. */ #include #include /* Inserts a piece of text into the buffer, giving it the usual * appearance of a hyperlink in a web browser: blue and underlined. * Additionally, attaches some data on the tag, to make it recognizable * as a link. */ static void insert_link (GtkTextBuffer *buffer, GtkTextIter *iter, gchar *text, gint page) { GtkTextTag *tag; tag = gtk_text_buffer_create_tag (buffer, NULL, "foreground", "blue", "underline", PANGO_UNDERLINE_SINGLE, NULL); g_object_set_data (G_OBJECT (tag), "page", GINT_TO_POINTER (page)); gtk_text_buffer_insert_with_tags (buffer, iter, text, -1, tag, NULL); } /* Fills the buffer with text and interspersed links. In any real * hypertext app, this method would parse a file to identify the links. */ static void show_page (GtkTextBuffer *buffer, gint page) { GtkTextIter iter; gtk_text_buffer_set_text (buffer, "", 0); gtk_text_buffer_get_iter_at_offset (buffer, &iter, 0); if (page == 1) { gtk_text_buffer_insert (buffer, &iter, "Some text to show that simple ", -1); insert_link (buffer, &iter, "hyper text", 3); gtk_text_buffer_insert (buffer, &iter, " can easily be realized with ", -1); insert_link (buffer, &iter, "tags", 2); gtk_text_buffer_insert (buffer, &iter, ".", -1); } else if (page == 2) { gtk_text_buffer_insert (buffer, &iter, "A tag is an attribute that can be applied to some range of text. " "For example, a tag might be called \"bold\" and make the text inside " "the tag bold. However, the tag concept is more general than that; " "tags don't have to affect appearance. They can instead affect the " "behavior of mouse and key presses, \"lock\" a range of text so the " "user can't edit it, or countless other things.\n", -1); insert_link (buffer, &iter, "Go back", 1); } else if (page == 3) { GtkTextTag *tag; tag = gtk_text_buffer_create_tag (buffer, NULL, "weight", PANGO_WEIGHT_BOLD, NULL); gtk_text_buffer_insert_with_tags (buffer, &iter, "hypertext:\n", -1, tag, NULL); gtk_text_buffer_insert (buffer, &iter, "machine-readable text that is not sequential but is organized " "so that related items of information are connected.\n", -1); insert_link (buffer, &iter, "Go back", 1); } } /* Looks at all tags covering the position of iter in the text view, * and if one of them is a link, follow it by showing the page identified * by the data attached to it. */ static void follow_if_link (GtkWidget *text_view, GtkTextIter *iter) { GSList *tags = NULL, *tagp = NULL; tags = gtk_text_iter_get_tags (iter); for (tagp = tags; tagp != NULL; tagp = tagp->next) { GtkTextTag *tag = tagp->data; gint page = GPOINTER_TO_INT (g_object_get_data (G_OBJECT (tag), "page")); if (page != 0) { show_page (gtk_text_view_get_buffer (GTK_TEXT_VIEW (text_view)), page); break; } } if (tags) g_slist_free (tags); } /* Links can be activated by pressing Enter. */ static gboolean key_pressed (GtkEventController *controller, guint keyval, guint keycode, GdkModifierType modifiers, GtkWidget *text_view) { GtkTextIter iter; GtkTextBuffer *buffer; switch (keyval) { case GDK_KEY_Return: case GDK_KEY_KP_Enter: buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (text_view)); gtk_text_buffer_get_iter_at_mark (buffer, &iter, gtk_text_buffer_get_insert (buffer)); follow_if_link (text_view, &iter); break; default: break; } return GDK_EVENT_PROPAGATE; } static void set_cursor_if_appropriate (GtkTextView *text_view, gint x, gint y); /* Links can also be activated by clicking or tapping. */ static gboolean event_cb (GtkWidget *text_view, GdkEvent *ev) { GtkTextIter start, end, iter; GtkTextBuffer *buffer; gdouble ex, ey; int x, y; GdkEventType type; type = gdk_event_get_event_type (ev); gdk_event_get_coords (ev, &ex, &ey); gtk_text_view_window_to_buffer_coords (GTK_TEXT_VIEW (text_view), GTK_TEXT_WINDOW_WIDGET, ex, ey, &x, &y); if (type == GDK_BUTTON_RELEASE) { guint button; gdk_event_get_button (ev, &button); if (button != GDK_BUTTON_PRIMARY) return FALSE; } else if (type == GDK_MOTION_NOTIFY) { set_cursor_if_appropriate (GTK_TEXT_VIEW (text_view), x, y); return FALSE; } else if (type == GDK_TOUCH_END) { } else return FALSE; buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (text_view)); /* we shouldn't follow a link if the user has selected something */ gtk_text_buffer_get_selection_bounds (buffer, &start, &end); if (gtk_text_iter_get_offset (&start) != gtk_text_iter_get_offset (&end)) return FALSE; if (gtk_text_view_get_iter_at_location (GTK_TEXT_VIEW (text_view), &iter, x, y)) follow_if_link (text_view, &iter); return TRUE; } static gboolean hovering_over_link = FALSE; /* Looks at all tags covering the position (x, y) in the text view, * and if one of them is a link, change the cursor to the "hands" cursor * typically used by web browsers. */ static void set_cursor_if_appropriate (GtkTextView *text_view, gint x, gint y) { GSList *tags = NULL, *tagp = NULL; GtkTextIter iter; gboolean hovering = FALSE; if (gtk_text_view_get_iter_at_location (text_view, &iter, x, y)) { tags = gtk_text_iter_get_tags (&iter); for (tagp = tags; tagp != NULL; tagp = tagp->next) { GtkTextTag *tag = tagp->data; gint page = GPOINTER_TO_INT (g_object_get_data (G_OBJECT (tag), "page")); if (page != 0) { hovering = TRUE; break; } } } if (hovering != hovering_over_link) { hovering_over_link = hovering; if (hovering_over_link) gtk_widget_set_cursor_from_name (GTK_WIDGET (text_view), "pointer"); else gtk_widget_set_cursor_from_name (GTK_WIDGET (text_view), "text"); } if (tags) g_slist_free (tags); } GtkWidget * do_hypertext (GtkWidget *do_widget) { static GtkWidget *window = NULL; if (!window) { GtkWidget *view; GtkWidget *sw; GtkTextBuffer *buffer; GtkEventController *controller; window = gtk_window_new (GTK_WINDOW_TOPLEVEL); gtk_window_set_title (GTK_WINDOW (window), "Hypertext"); gtk_window_set_display (GTK_WINDOW (window), gtk_widget_get_display (do_widget)); gtk_window_set_default_size (GTK_WINDOW (window), 450, 450); g_signal_connect (window, "destroy", G_CALLBACK (gtk_widget_destroyed), &window); view = gtk_text_view_new (); gtk_text_view_set_wrap_mode (GTK_TEXT_VIEW (view), GTK_WRAP_WORD); gtk_text_view_set_left_margin (GTK_TEXT_VIEW (view), 20); gtk_text_view_set_right_margin (GTK_TEXT_VIEW (view), 20); controller = gtk_event_controller_key_new (view); g_object_set_data_full (G_OBJECT (view), "controller", controller, g_object_unref); g_signal_connect (controller, "key-pressed", G_CALLBACK (key_pressed), view); g_signal_connect (view, "event", G_CALLBACK (event_cb), NULL); buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (view)); sw = gtk_scrolled_window_new (NULL, NULL); gtk_scrolled_window_set_policy (GTK_SCROLLED_WINDOW (sw), GTK_POLICY_AUTOMATIC, GTK_POLICY_AUTOMATIC); gtk_container_add (GTK_CONTAINER (window), sw); gtk_container_add (GTK_CONTAINER (sw), view); show_page (buffer, 1); } if (!gtk_widget_get_visible (window)) gtk_widget_show (window); else gtk_widget_destroy (window); return window; }