I’m currently making a line-per-line text editor in C using GTK 4.8.3. It’s my first program ever using GTK 4 so I’m not comfortable with it.

To begin with, a text file is parsed into the following structures :

typedef struct Line {
    char *text;
    int id;
} Line;

typedef struct LineNode {
    Line *line;
    struct LineNode *next;
} LineNode;

typedef struct File {
    char *filename;
    Client *host_client;    // not needed for this question
    LineNode *lines;
    int line_count;        
    ClientNode *clients;    // not needed for this question
    int client_count;       // not needed for this question
} File;

The main part of my GUI is composed of a GtkListBox in which each row contains a GtkTextView that displays the text of the corresponding line. I would like to retrieve a pointer to the corresponding LineNode when I select a row.

I tried using GtkListStore and GtkMapListModel to associate each row with a LineNode but I couldn’t manage to make it work. The problem I encountered with GtkListStore is that I couldn’t bind my store with my box since gtk_list_box_bind_model() is only for GListModel. Then, the issue I had with GtkMapListModel is that I couldn’t manage to add data to the model.

I “bypassed” this issue by making using a function that gets a pointer to a LineNode of a row by text. This “solution” is stupid because it doesn’t work as inteded when fetching an empty line or if the text is the same on multiple lines.

Here are the 2 most important functions :

void on_row_selected(GtkListBox *listbox, GtkListBoxRow *row, FileEditorWindow *win)
{
    GtkLabel *lineSelectedLabel;
    GtkWidget *textView;

    File *file_struct = get_file_struct_from_filename(gtk_stack_get_visible_child_name(GTK_STACK(win->stack)));

    lineSelectedLabel = GTK_LABEL(gtk_grid_get_child_at(GTK_GRID(win->grid), 0, 0));

    if(row){
        int index = gtk_list_box_row_get_index(row);
        char *label_text = g_strdup_printf("Line selected: %d", index);
        gtk_label_set_text(lineSelectedLabel, label_text);
        g_free(label_text);
    }
    else{
        lineSelectedLabel = GTK_LABEL(gtk_label_new("No line selected"));
    }

    // test : get LineNode from text
    textView = gtk_widget_get_first_child(GTK_WIDGET(row));

    // there's only one child in the row so we can safely cast it to a GtkTextView
    if(GTK_IS_TEXT_VIEW(textView)) {
        GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(textView));
        GtkTextIter start, end;
        gtk_text_buffer_get_start_iter(buffer, &start);
        gtk_text_buffer_get_end_iter(buffer, &end);
        gchar *text = gtk_text_buffer_get_text(buffer, &start, &end, FALSE);
        LineNode *lineNode = get_line_node_from_text(file_struct, text); // calling the dumb function - NOT GOOD
        if(lineNode) {
            g_print("Line found: %sn", lineNode->line->text);
            selected_line = lineNode->line;
        }
        else {
            g_print("Line not foundn");
        }
    }
}

void file_editor_window_open(FileEditorWindow *win, GFile *file)
{
    char *filepath;
    GtkWidget *scrolled;
    GtkTextBuffer *buffer;
    char *contents;
    gsize length;
    GtkTextTag *tag;
    GtkButton *add_btn, *edit_btn, *delete_btn;

    // BUTTONS

    add_btn = GTK_BUTTON(gtk_grid_get_child_at(GTK_GRID(win->grid), 1, 0));
    edit_btn = GTK_BUTTON(gtk_grid_get_child_at(GTK_GRID(win->grid), 2, 0));
    delete_btn = GTK_BUTTON(gtk_grid_get_child_at(GTK_GRID(win->grid), 3, 0));

    gtk_widget_set_visible(GTK_WIDGET(add_btn), TRUE);
    gtk_widget_set_visible(GTK_WIDGET(edit_btn), TRUE);
    gtk_widget_set_visible(GTK_WIDGET(delete_btn), TRUE);

    // g_signal_connect(add_btn, "clicked", G_CALLBACK(on_add_clicked), win);
    // g_signal_connect(edit_btn, "clicked", G_CALLBACK(on_edit_clicked), win);
    g_signal_connect(delete_btn, "clicked", G_CALLBACK(on_delete_clicked), win);

    // FILE

    filepath = g_file_get_path(file);

    File *file_struct;

    int i;

    for(i = 0; i < MAX_FILES; i++) {
        if(!open_files[i]) {
            file_struct = open_files[i] = open_local_file(filepath);
            break;
        }

        if(i == MAX_FILES - 1) {
            // dialog error
            GtkWidget *dialog = gtk_message_dialog_new(GTK_WINDOW(win), GTK_DIALOG_MODAL, GTK_MESSAGE_ERROR, GTK_BUTTONS_CLOSE, "Too many files opened");
            
            gtk_window_present(GTK_WINDOW(dialog));

            g_free(filepath);
            return;
        }
    }

    // LISTBOX STUFF

    scrolled = gtk_scrolled_window_new();
    gtk_widget_set_hexpand(scrolled, TRUE);
    gtk_widget_set_vexpand(scrolled, TRUE);

    gtk_scrolled_window_set_policy(GTK_SCROLLED_WINDOW(scrolled), GTK_POLICY_AUTOMATIC, GTK_POLICY_AUTOMATIC);

    GtkWidget *listbox = gtk_list_box_new();
    gtk_list_box_set_selection_mode(GTK_LIST_BOX(listbox), GTK_SELECTION_SINGLE);
    g_signal_connect(listbox, "row-selected", G_CALLBACK(on_row_selected), win);
    listboxes[i] = GTK_LIST_BOX(listbox);

    LineNode *curr = file_struct->lines;

    while(curr) {
        Line *line = curr->line;

        buffer = gtk_text_buffer_new(NULL);
        gtk_text_buffer_set_text(buffer, line->text, -1);

        tag = gtk_text_buffer_create_tag(buffer, NULL, NULL);
        g_settings_bind(win->settings, "font", tag, "font", G_SETTINGS_BIND_DEFAULT);

        GtkWidget *view = gtk_text_view_new_with_buffer(buffer);
        gtk_text_view_set_editable(GTK_TEXT_VIEW(view), FALSE);
        gtk_text_view_set_cursor_visible(GTK_TEXT_VIEW(view), FALSE);

        GtkWidget *row = gtk_list_box_row_new();
        gtk_widget_set_hexpand(view, TRUE);
        gtk_widget_set_vexpand(view, FALSE);
        gtk_list_box_row_set_child(GTK_LIST_BOX_ROW(row), view);
        gtk_list_box_append(GTK_LIST_BOX(listbox), row);

        g_object_unref(buffer);

        curr = curr->next;
    }

    gtk_scrolled_window_set_child(GTK_SCROLLED_WINDOW(scrolled), listbox);
    gtk_stack_add_titled(GTK_STACK(win->stack), scrolled, file_struct->filename, file_struct->filename);

    g_free(filepath);
}

I’ve browsed the documentation and multiple forum posts but I’m still so confused. That would be great if some of you could explain how GtkListBox works in that case. Thank you very much!