Question

我正在编写的程序不显示树。该程序输出以下错误：

（gtk：3210）：Gtk-CRITICAL **：gtk_grid_attach_next_to：断言'gtk_widget_get_parent（child）== NULL'失败

代码显然在该功能上失败了，我不知道为什么。我设置的树与示例代码相同。唯一的区别是网格，但我想我可以像任何其他小部件一样附加树。有谁知道如何正确地附上它，还是我错过了什么？

int main (int argc, char** argv)
{
    // Main window
    GtkWidget*          window;
    GtkWidget*          grid;
    GtkWidget*          box;

    // Menubar
    GtkWidget*          menubar;
    GtkWidget*          filemenu;
    GtkWidget*          file;
    GtkWidget*          quit;

    // List
    GtkWidget*          tree;
    GtkTreeStore*       store;
    GtkTreeIter         iter;
    GtkCellRenderer*    renderer;
    GtkTreeViewColumn*  column;

    /*
     * Setup the window and the main grid.
     */
    gtk_init (&argc, &argv);

    window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
    gtk_window_set_title (GTK_WINDOW (window), "imgedit");
    gtk_window_set_default_size (GTK_WINDOW (window), 600, 400);

    grid = gtk_grid_new ();

    /*
     * Create the menubar, and all of it's menus.
     */
    box = gtk_box_new (GTK_ORIENTATION_VERTICAL, 0);
    menubar = gtk_menu_bar_new ();
    filemenu = gtk_menu_new ();
    file = gtk_menu_item_new_with_label ("File");
    quit = gtk_menu_item_new_with_label ("Quit");

    gtk_menu_item_set_submenu (GTK_MENU_ITEM (file), filemenu);
    gtk_menu_shell_append (GTK_MENU_SHELL (filemenu), quit);
    gtk_menu_shell_append (GTK_MENU_SHELL (menubar), file);
    gtk_box_pack_start (GTK_BOX (box), menubar, FALSE, FALSE, 3);

    /*
     * Setup the list with files.
     */
    store = gtk_tree_store_new (3, G_TYPE_STRING, G_TYPE_UINT, G_TYPE_UINT);
    gtk_tree_store_append (store, &iter, NULL);
    gtk_tree_store_set (store, &iter, FILE_NAME, "test name", FILE_OFFSET, 0, FILE_SIZE, 10, -1);

    tree = gtk_tree_view_new_with_model (GTK_TREE_MODEL (store));
    g_object_unref (G_OBJECT (store));
    renderer = gtk_cell_renderer_text_new ();

    column = gtk_tree_view_column_new_with_attributes ("Name", renderer, "text", FILE_NAME, NULL);
    gtk_tree_view_append_column (GTK_TREE_VIEW (tree), column);

    /*
     * Attach the grid to the main window and connect all signals.
     */
    gtk_container_add (GTK_CONTAINER (window), GTK_WIDGET (grid));
    gtk_grid_attach (GTK_GRID (grid), box, 1, 1, 1, 1);
    gtk_grid_attach_next_to (GTK_GRID (grid), box, tree, GTK_POS_BOTTOM, 1, 1);

    g_signal_connect (quit, "activate", G_CALLBACK (event_quit), GTK_WINDOW (window));
    g_signal_connect (window, "delete-event", G_CALLBACK (event_delete), GTK_WINDOW (window));
    g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);

    gtk_widget_show_all (window);

    gtk_main ();

    return 0;
}

Answer 1

检查gtk_grid_attach_next_to()的参数顺序。您告诉它将box附加到tree旁边而不是反之，但tree尚未附加且box已附加在上一行中。

虽然错误信息乍一看似乎很神秘，但您真的可以从中获取所需的所有信息：对于初学者来说，“断言失败”应该是您的第一个线索，即函数的输入无效。（许多GTK函数首先断言它们的输入是有效的。）

下一个线索是查看失败的断言：gtk_widget_get_parent (child) == NULL。换句话说，这是“child的父窗口小部件是NULL”或者用简单的英文“child窗口小部件没有父窗口（因此不在容器内）。）“断言失败，所以相反的情况必须如此。

查看对gtk_grid_attach_next_to()的来电，并注意您已将box作为child参数传递;因此断言告诉你，“box不应该已经在容器内，但它仍然在一个容器里面。”实际上，您使用gtk_grid_attach()将它放在上一行的容器中。

将树附加到网格

1 个答案: