ex_gui_cursor.c

The application's mouse cursor, kept by the GUI (headless).

The application's mouse cursor, kept by the GUI (headless). A picking tool wants a crosshair while the pointer is over what it picks from. The GUI sets the display's cursor itself, a resize cursor over a split pane divider and the default elsewhere, so a cursor the application set with Allegro was put back to the default on the next pointer move. n_gui_set_cursor() makes the application's cursor the GUI's "elsewhere": this checks it survives pointer moves, gives way to the resize cursor over a divider and comes back after, waits while a press is held, and hands back to the GUI's own behaviour when set to the default.

Author

Castagnier Mickael

Version

1.0

Date

25/09/2026

/*
 * Nilorea Library
 * Copyright (C) 2005-2026 Castagnier Mickael
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * permissions and limitations under the License.
 *
 * SPDX-License-Identifier: Apache-2.0
 */

 
#define ALLEGRO_UNSTABLE 1
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#include "nilorea/n_common.h"
#include "nilorea/n_gui.h"
#include "nilorea/n_log.h"

static int failures = 0;

static void expect_true(const char* label, int cond) {
    if (!cond) {
        n_log(LOG_ERR, "%s: FAILED", label);
        failures++;
    } else {
        n_log(LOG_INFO, "%s: OK", label);
    }
}

static void mouse(N_GUI_CTX* gui, int type, int x, int y) {
    ALLEGRO_EVENT ev;
    memset(&ev, 0, sizeof(ev));
    ev.type = (unsigned int)type;
    ev.mouse.x = x;
    ev.mouse.y = y;
    ev.mouse.button = 1;
    n_gui_process_event(gui, ev);
}
 
int main(void) {
    ALLEGRO_FONT* font;
    N_GUI_CTX* gui;
    int win, sp;
    ALLEGRO_MOUSE_CURSOR* custom = (ALLEGRO_MOUSE_CURSOR*)1;
 
    set_log_level(LOG_ERR);
    if (!al_init() || !al_init_font_addon()) {
        n_log(LOG_ERR, "allegro init failed");
        return 1;
    }
    font = al_create_builtin_font(); /* no display needed */
    if (!font) {
        n_log(LOG_ERR, "al_create_builtin_font failed");
        return 1;
    }
    gui = n_gui_new_ctx(font);
    if (!gui) {
        n_log(LOG_ERR, "n_gui_new_ctx failed");
        al_destroy_font(font);
        return 1;
    }
    n_gui_set_display_size(gui, 800.0f, 600.0f);
    /* A window with a vertical split pane down the middle of its left half,
       and nothing of the GUI's on the right: the right is "the application's
       own area", where its picking tool would be. */
    win = n_gui_add_window(gui, "W", 0.0f, 0.0f, 400.0f, 600.0f);
    n_gui_window_set_flags(gui, win, N_GUI_WIN_FRAMELESS);
    sp = n_gui_add_splitpane(gui, win, 0.0f, 0.0f, 400.0f, 600.0f, N_GUI_SPLIT_VERTICAL, 0.5f, NULL, NULL);
    n_gui_open_window(gui, win);
    expect_true("split pane created", sp >= 0);
 
    n_gui_get_cursor(gui, &custom);
    expect_true("the default until asked", n_gui_get_cursor(gui, NULL) == ALLEGRO_SYSTEM_MOUSE_CURSOR_DEFAULT && custom == NULL);
 
    n_gui_set_cursor(gui, ALLEGRO_SYSTEM_MOUSE_CURSOR_PRECISION, NULL);
    expect_true("applied at once", n_gui_get_cursor(gui, NULL) == ALLEGRO_SYSTEM_MOUSE_CURSOR_PRECISION);
    mouse(gui, ALLEGRO_EVENT_MOUSE_AXES, 600, 300);
    expect_true("kept over the application's area", n_gui_get_cursor(gui, NULL) == ALLEGRO_SYSTEM_MOUSE_CURSOR_PRECISION);
 
    /* Over the divider the GUI's own resize cursor wins, and the
       application's comes back when the pointer leaves it. */
    mouse(gui, ALLEGRO_EVENT_MOUSE_AXES, 200, 300);
    expect_true("the divider shows its resize cursor", n_gui_get_cursor(gui, NULL) == ALLEGRO_SYSTEM_MOUSE_CURSOR_RESIZE_E);
    mouse(gui, ALLEGRO_EVENT_MOUSE_AXES, 600, 300);
    expect_true("and the application's comes back", n_gui_get_cursor(gui, NULL) == ALLEGRO_SYSTEM_MOUSE_CURSOR_PRECISION);
 
    /* A press held is a drag, which keeps the cursor it started with. */
    mouse(gui, ALLEGRO_EVENT_MOUSE_BUTTON_DOWN, 600, 300);
    n_gui_set_cursor(gui, ALLEGRO_SYSTEM_MOUSE_CURSOR_MOVE, NULL);
    expect_true("not changed under a held press", n_gui_get_cursor(gui, NULL) == ALLEGRO_SYSTEM_MOUSE_CURSOR_PRECISION);
    mouse(gui, ALLEGRO_EVENT_MOUSE_BUTTON_UP, 600, 300);
    mouse(gui, ALLEGRO_EVENT_MOUSE_AXES, 601, 300);
    expect_true("changed once it is let go", n_gui_get_cursor(gui, NULL) == ALLEGRO_SYSTEM_MOUSE_CURSOR_MOVE);
 
    n_gui_set_cursor(gui, ALLEGRO_SYSTEM_MOUSE_CURSOR_DEFAULT, NULL);
    mouse(gui, ALLEGRO_EVENT_MOUSE_AXES, 600, 300);
    n_gui_get_cursor(gui, &custom);
    expect_true("the default hands back to the GUI", n_gui_get_cursor(gui, NULL) == ALLEGRO_SYSTEM_MOUSE_CURSOR_DEFAULT && custom == NULL);
 
    n_gui_destroy_ctx(&gui);
    al_destroy_font(font);
    if (failures) {
        n_log(LOG_ERR, "ex_gui_cursor: %d failure(s)", failures);
        return 1;
    }
    n_log(LOG_NOTICE, "ex_gui_cursor: all checks passed");
    return 0;
}