6 ex_gui_combobox_items_8c example
gullradriel edited this page 2026-10-09 00:55:18 +02:00

ex_gui_combobox_items.c

n_gui combobox item count and removal A caller filling a combobox from data, and wanting to know whether a value is already in it, used to keep its own copy of the list: there was a text accessor but no count. n_gui_combobox_get_count() and n_gui_combobox_remove_item() complete the set the listbox already had, and the selection follows its item through a removal.

A second press on the combo box, or on a drop menu's button, while its list is open closes it and keeps the value it had, whatever the pointer highlighted on the way; a third opens it again.

Headless: the builtin font needs no display. ```c

#define ALLEGRO_UNSTABLE 1

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h>

#include "nilorea/n_common.h" #include "nilorea/n_log.h" #include "nilorea/n_gui.h"

static int log_level = LOG_ERR; static int failures = 0;

static void expect_true(const char* what, int ok) { if (!ok) { n_log(LOG_ERR, "FAIL: %s", what); failures++; } else { n_log(LOG_INFO, "ok: %s", what); } }

static int process_args(int argc, char** argv) { int opt = 0;

while ((opt = getopt(argc, argv, "V:")) != -1) {
    if (opt == 'V') {
        log_level = atoi(optarg);
    } else {
        return -1;
    }
}
return 0;

}

static void press_at(N_GUI_CTX* gui, float x, float y) { ALLEGRO_EVENT ev;

memset(&ev, 0, sizeof(ev));
ev.type = ALLEGRO_EVENT_MOUSE_AXES;
ev.mouse.x = (int)x;
ev.mouse.y = (int)y;
n_gui_process_event(gui, ev);
ev.type = ALLEGRO_EVENT_MOUSE_BUTTON_DOWN;
ev.mouse.button = 1;
n_gui_process_event(gui, ev);
ev.type = ALLEGRO_EVENT_MOUSE_BUTTON_UP;
n_gui_process_event(gui, ev);

}

static void move_to(N_GUI_CTX* gui, float x, float y) { ALLEGRO_EVENT ev;

memset(&ev, 0, sizeof(ev));
ev.type = ALLEGRO_EVENT_MOUSE_AXES;
ev.mouse.x = (int)x;
ev.mouse.y = (int)y;
n_gui_process_event(gui, ev);

}

static void add_once(N_GUI_CTX* gui, int combo, const char* text) { int i = 0;

for (i = 0; i < n_gui_combobox_get_count(gui, combo); i++) {
    if (strcmp(n_gui_combobox_get_item_text(gui, combo, i), text) == 0) return;
}
n_gui_combobox_add_item(gui, combo, text);

}

int main(int argc, char** argv) { set_log_level(LOG_ERR); if (process_args(argc, argv) != 0) { fprintf(stderr, "Usage: %s [-V LOG_LEVEL]\n", argv[0]); return 2; } set_log_level(log_level);

if (!al_init() || !al_init_font_addon()) {
    n_log(LOG_ERR, "allegro init failed");
    return 1;
}
ALLEGRO_FONT* font = al_create_builtin_font();
if (!font) return 1;
N_GUI_CTX* gui = n_gui_new_ctx(font);
if (!gui) {
    al_destroy_font(font);
    return 1;
}
n_gui_set_display_size(gui, 800.0f, 600.0f);
int win = n_gui_add_window(gui, "W", 0.0f, 0.0f, 300.0f, 200.0f);
int combo = n_gui_add_combobox(gui, win, 10.0f, 10.0f, 200.0f, 24.0f, NULL, NULL);
int label = n_gui_add_label(gui, win, "not a combobox", 10.0f, 40.0f, 200.0f, 20.0f, N_GUI_ALIGN_LEFT);

expect_true("an empty combobox counts zero", n_gui_combobox_get_count(gui, combo) == 0);
expect_true("a label is not a combobox", n_gui_combobox_get_count(gui, label) == 0);

add_once(gui, combo, "Canon EOS R6");
add_once(gui, combo, "Nikon Z6");
add_once(gui, combo, "Canon EOS R6");
add_once(gui, combo, "Fujifilm X-T4");
add_once(gui, combo, "Nikon Z6");
expect_true("values added once each, found by walking the combobox",
            n_gui_combobox_get_count(gui, combo) == 3);

/* The selection names an item: removing one before it moves it up. */
n_gui_combobox_set_selected(gui, combo, 2);
expect_true("removing an item before the selection succeeds",
            n_gui_combobox_remove_item(gui, combo, 0) == 0);
expect_true("and the count drops", n_gui_combobox_get_count(gui, combo) == 2);
expect_true("the selection follows its item",
            n_gui_combobox_get_selected(gui, combo) == 1 &&
                strcmp(n_gui_combobox_get_item_text(gui, combo, 1), "Fujifilm X-T4") == 0);

/* Removing the selected item clears the selection rather than moving it
 * to a neighbour nobody chose. */
expect_true("removing the selected item succeeds", n_gui_combobox_remove_item(gui, combo, 1) == 0);
expect_true("and leaves nothing selected", n_gui_combobox_get_selected(gui, combo) == -1);
expect_true("the other item is still there",
            n_gui_combobox_get_count(gui, combo) == 1 &&
                strcmp(n_gui_combobox_get_item_text(gui, combo, 0), "Nikon Z6") == 0);

expect_true("a bad index is refused", n_gui_combobox_remove_item(gui, combo, 5) == -1 &&
                                          n_gui_combobox_remove_item(gui, combo, -1) == -1);
expect_true("a label cannot have an item removed", n_gui_combobox_remove_item(gui, label, 0) == -1);
expect_true("the last item goes", n_gui_combobox_remove_item(gui, combo, 0) == 0 &&
                                      n_gui_combobox_get_count(gui, combo) == 0);

/* A second press on it closes an open list, keeping the value. */
{
    float x = 0.0f, y = 0.0f, w = 0.0f, h = 0.0f;
    int menu = n_gui_add_dropmenu(gui, win, "Menu", 220.0f, 10.0f, 60.0f, 24.0f, NULL, NULL);

    add_once(gui, combo, "Canon EOS R6");
    add_once(gui, combo, "Nikon Z6");
    add_once(gui, combo, "Fujifilm X-T4");
    n_gui_combobox_set_selected(gui, combo, 1);
    n_gui_dropmenu_add_entry(gui, menu, "One", 1, NULL, NULL);
    n_gui_dropmenu_add_entry(gui, menu, "Two", 2, NULL, NULL);
    if (!n_gui_widget_screen_rect(gui, combo, &x, &y, &w, &h)) {
        expect_true("the combobox is on screen", 0);
    } else {
        press_at(gui, x + w * 0.5f, y + h * 0.5f);
        expect_true("a press opens the list", n_gui_menu_is_open(gui));
        /* the pointer passes over the third item on its way back */
        move_to(gui, x + w * 0.5f, y + h + h * 2.5f);
        press_at(gui, x + w * 0.5f, y + h * 0.5f);
        expect_true("a second press on it closes the list", !n_gui_menu_is_open(gui));
        expect_true("keeping the value it had", n_gui_combobox_get_selected(gui, combo) == 1);
        press_at(gui, x + w * 0.5f, y + h * 0.5f);
        expect_true("a third opens it again", n_gui_menu_is_open(gui));
        press_at(gui, x + w * 0.5f, y + h * 0.5f);
    }
    if (menu < 0 || !n_gui_widget_screen_rect(gui, menu, &x, &y, &w, &h)) {
        expect_true("the drop menu is on screen", 0);
    } else {
        press_at(gui, x + w * 0.5f, y + h * 0.5f);
        expect_true("a press opens the drop menu", n_gui_dropmenu_is_open(gui, menu));
        press_at(gui, x + w * 0.5f, y + h * 0.5f);
        expect_true("a second press on its button closes it", !n_gui_dropmenu_is_open(gui, menu));
    }
}

n_gui_destroy_ctx(&gui);
al_destroy_font(font);
if (failures) {
    fprintf(stderr, "ex_gui_combobox_items: %d failure(s)\n", failures);
    return 1;
}
printf("ex_gui_combobox_items: ok\n");
return 0;

}


_Filename: ex_gui_combobox_items.c_