C++ program with blank UI with GTK+ 2.0 - c++

Question

I wrote a C++ software using GTK library (2.0 version) for UI.
The compilation (with makefile) gave no errors but when I execute the program the window appears empty.
I think I've done some error in the code that create the interface.
In particular I have some doubts about the widgets positioning and sizing.
The .h interface file is composed from the declaration of the struct widgets_t (that contains all the pointers to widgets of the interface) and the declaration of the function build_interface (that create and initialize the UI).
the .cpp interface file is
#include <gtk/gtk.h>
#include "interface.h"
void build_interface (widgets_t *widgets)
{
//window
widgets->W = gtk_window_new(GTK_WINDOW_TOPLEVEL);
gtk_window_set_title(GTK_WINDOW(widgets->W), "myNavigator");
gtk_window_set_default_size(GTK_WINDOW(widgets->W),800,600);
gtk_window_set_position(GTK_WINDOW(widgets->W), GTK_WIN_POS_NONE);
//menu bar
widgets->MB = gtk_menu_bar_new();
widgets->IF = gtk_menu_item_new_with_mnemonic("File");
gtk_menu_bar_append(GTK_MENU_BAR(widgets->MB), widgets->IF);
widgets->MF = gtk_menu_new();
gtk_menu_item_set_submenu(GTK_MENU_ITEM(widgets->IF), widgets->MF);
widgets->IQ = gtk_menu_item_new_with_mnemonic("Close");
gtk_menu_shell_append (GTK_MENU_SHELL (widgets->MF), widgets->IQ);
widgets->IM = gtk_menu_item_new_with_mnemonic("Map");
gtk_menu_bar_append(GTK_MENU_BAR(widgets->MB), widgets->IM);
widgets->MM = gtk_menu_new();
gtk_menu_item_set_submenu(GTK_MENU_ITEM(widgets->IM), widgets->MM);
widgets->ILM = gtk_menu_item_new_with_mnemonic("Load");
gtk_menu_shell_append (GTK_MENU_SHELL (widgets->MM), widgets->ILM);
widgets->IP = gtk_menu_item_new_with_mnemonic("Path");
gtk_menu_bar_append(GTK_MENU_BAR(widgets->MB), widgets->IP);
widgets->MP = gtk_menu_new();
gtk_menu_item_set_submenu(GTK_MENU_ITEM(widgets->IP), widgets->MP);
widgets->ICP = gtk_menu_item_new_with_mnemonic("Calculate");
gtk_menu_shell_append (GTK_MENU_SHELL (widgets->MP), widgets->ICP);
//image to display a map
widgets->I = gtk_image_new();
//widgets for input
widgets->LF = gtk_label_new("Origin:");
widgets->SBF = gtk_spin_button_new_with_range(0,0,1);
widgets->LT = gtk_label_new("Destination:");
widgets->SBT = gtk_spin_button_new_with_range(0,0,1);
//button to perform software elaboration
widgets->BCP = gtk_button_new_with_mnemonic("Calculate Path");
//containers
//vertical box
widgets->VB = gtk_vbox_new(false, 0);
gtk_box_pack_start(GTK_BOX(widgets->VB), widgets->LF, FALSE, FALSE, 0);
gtk_box_pack_start(GTK_BOX(widgets->VB), widgets->SBF, FALSE, FALSE, 0);
gtk_box_pack_start(GTK_BOX(widgets->VB), widgets->LT, FALSE, FALSE, 0);
gtk_box_pack_start(GTK_BOX(widgets->VB), widgets->SBT, FALSE, FALSE, 0);
gtk_box_pack_start(GTK_BOX(widgets->VB), widgets->BCP, FALSE, FALSE, 0);
//horizontal box
widgets->HB = gtk_hbox_new(false, 0);
gtk_box_pack_start(GTK_BOX(widgets->HB), widgets->MB, FALSE, FALSE, 0);
gtk_box_pack_start(GTK_BOX(widgets->HB), widgets->I, FALSE, FALSE, 0);
gtk_box_pack_start(GTK_BOX(widgets->HB), widgets->VB, FALSE, FALSE, 0);
//add vertical box to the window
gtk_container_add(GTK_CONTAINER(widgets->W), widgets->VB);
//display widgets
gtk_widget_show_all(widgets->W);
}
someone sees something wrong and helps me to appear the UI? :)
thank you all in advance!

Answer 1

As the comment says you failed parenting the widgets:
widgets->W should contain widgets->HB and not widgets->VB.
If you can run your program from a terminal (if you are on windows "cmd" should work), GTK should have warned you about wrong parenting when you added "VB" to "W".
Note also that you may want to use local declaration for intermediate objects like "vboxes", and also for objects that will not change during your program execution.
Also note that you can build the interface also in XML using glade or by hand through the GtkBuilder Interface.
IMHO programmatically built GUIs should be used only when the interface will need to change dinamically during the program execution.