6 ex_gui_tree_lazy_8c example
gullradriel edited this page 2026-10-09 00:55:18 +02:00

ex_gui_tree_lazy.c

a tree filled one node at a time, as it is opened A folder tree cannot be built before it is shown: reading every directory under a home directory is what makes a file chooser take a second to appear. n_gui_tree_set_expandable() gives a node an expander before it has children, and the expand callback set with n_gui_tree_set_expand_callback() fills it the first time it is opened. n_gui_tree_expand() opens a node from code the same way, for a caller revealing a path one level at a time.

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 int fills = 0; static int last_filled = -1; static int empty_node = -1;

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 on_expand(int node, void* user_data) { N_GUI_TREE* tree = (N_GUI_TREE*)user_data; int a = -1, b = -1;

fills++;
last_filled = node;
if (node == empty_node) return;
a = n_gui_tree_add_node(tree, "photos", node, NULL);
b = n_gui_tree_add_node(tree, "empty", node, NULL);
n_gui_tree_set_expandable(tree, a, 1);
n_gui_tree_set_expandable(tree, b, 1);
if (empty_node < 0) empty_node = b;

}

static const char* row(N_GUI_TREE* tree, int index) { return n_gui_listbox_get_item_text(tree->ctx, tree->listbox_id, index); }

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, 400.0f, 300.0f); int win = n_gui_add_window(gui, "Folders", 0.0f, 0.0f, 300.0f, 200.0f); N_GUI_TREE* tree = n_gui_tree_create(gui, win, 0.0f, 0.0f, 200.0f, 160.0f, NULL, NULL); if (!tree) return 1; n_gui_tree_set_expand_callback(tree, on_expand, tree);

int home = n_gui_tree_add_node(tree, "home", -1, NULL);
expect_true("a node with no children has no expander", strncmp(row(tree, 0), "  ", 2) == 0);
n_gui_tree_set_expandable(tree, home, 1);
expect_true("an expandable node has one before it has children", strncmp(row(tree, 0), "> ", 2) == 0);
expect_true("and nothing has been read yet", fills == 0 && tree->nb_nodes == 1);

n_gui_tree_toggle_expand(tree, home);
expect_true("opening it fills it, once", fills == 1 && last_filled == home && tree->nb_nodes == 3);
expect_true("and shows what was added, in the same rebuild",
            tree->nb_visible == 3 && strncmp(row(tree, 0), "v ", 2) == 0);

n_gui_tree_toggle_expand(tree, home);
expect_true("closing it hides the children", tree->nb_visible == 1);
n_gui_tree_toggle_expand(tree, home);
expect_true("reopening it does not fill it again", fills == 1 && tree->nb_nodes == 3 && tree->nb_visible == 3);

/* An empty folder: the callback runs and adds nothing. */
n_gui_tree_expand(tree, empty_node);
expect_true("opening an empty one asks once", fills == 2 && last_filled == empty_node);
expect_true("and it loses its expander and stays shut",
            !tree->nodes[empty_node].expanded && !tree->nodes[empty_node].expandable);
n_gui_tree_toggle_expand(tree, empty_node);
expect_true("after which it cannot be opened again", fills == 2);

/* Opening from code, as a caller revealing a path does. */
int photos = 1;
n_gui_tree_expand(tree, photos);
expect_true("n_gui_tree_expand fills and opens", fills == 3 && tree->nodes[photos].expanded);
n_gui_tree_expand(tree, photos);
expect_true("and on an open node does nothing", fills == 3 && tree->nodes[photos].expanded);

/* A refresh: the view saved, the tree rebuilt from nothing, the view put
 * back. Only the top node exists after the rebuild, so the state has to
 * fill each expanded level before the next one can be found. */
N_GUI_TREE_STATE state;
memset(&state, 0, sizeof(state));
expect_true("the view is saved", n_gui_tree_state_save(tree, &state) == 0);
n_gui_tree_clear(tree);
home = n_gui_tree_add_node(tree, "home", -1, NULL);
n_gui_tree_set_expandable(tree, home, 1);
n_gui_tree_state_apply(tree, &state);
n_gui_tree_state_free(&state);
expect_true("both expanded levels come back, each filled once more",
            fills == 5 && tree->nodes[home].expanded && tree->nodes[photos].expanded &&
                tree->nb_nodes == 5);

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

}


_Filename: ex_gui_tree_lazy.c_