6 ex_gui_display_fallback_8c example
gullradriel edited this page 2026-10-09 00:55:18 +02:00

ex_gui_display_fallback.c

n_gui takes the display size from the draw target until one is set A context starts believing the display is zero by zero. A caller that never calls n_gui_set_display_size() used to get tooltips wrapped to one word per line and dropdowns clamped to nothing, with nothing pointing at the cause. Now n_gui_draw() takes the size of its target bitmap on every pass until a size is set, and the caller's size stands once it is.

Headless: the builtin font and memory bitmaps need no display. ```c

#define ALLEGRO_UNSTABLE 1

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

#include <allegro5/allegro_primitives.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 draw_into(N_GUI_CTX* gui, int w, int h) { int old_flags = al_get_new_bitmap_flags();

al_set_new_bitmap_flags(ALLEGRO_MEMORY_BITMAP);
ALLEGRO_BITMAP* target = al_create_bitmap(w, h);
al_set_new_bitmap_flags(old_flags);
if (!target) {
    expect_true("a memory bitmap to draw into", 0);
    return;
}
al_set_target_bitmap(target);
al_clear_to_color(al_map_rgb(0, 0, 0));
n_gui_draw(gui);
al_set_target_bitmap(NULL);
al_destroy_bitmap(target);

}

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() || !al_init_primitives_addon()) {
    n_log(LOG_ERR, "allegro init failed");
    return 1;
}
ALLEGRO_FONT* font = al_create_builtin_font();
if (!font) {
    n_log(LOG_ERR, "al_create_builtin_font failed");
    return 1;
}
N_GUI_CTX* gui = n_gui_new_ctx(font);
if (!gui) {
    al_destroy_font(font);
    return 1;
}
int win = n_gui_add_window(gui, "W", 10.0f, 10.0f, 200.0f, 100.0f);
n_gui_add_label(gui, win, "a label", 10.0f, 10.0f, 150.0f, 20.0f, N_GUI_ALIGN_LEFT);
n_gui_open_window(gui, win);

expect_true("a new context has no display size", gui->display_w == 0.0f && gui->display_h == 0.0f);

draw_into(gui, 640, 400);
expect_true("with none set, a draw takes the target's size",
            gui->display_w == 640.0f && gui->display_h == 400.0f);

draw_into(gui, 1024, 300);
expect_true("and follows it when the target changes, as a resize would",
            gui->display_w == 1024.0f && gui->display_h == 300.0f);

n_gui_set_display_size(gui, 800.0f, 600.0f);
draw_into(gui, 640, 400);
expect_true("once a size is set, the target no longer overrides it",
            gui->display_w == 800.0f && gui->display_h == 600.0f);

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

}


_Filename: ex_gui_display_fallback.c_