ex_gui_label_lines.c

labels honour a line break, in every alignment A label drew one line for every alignment but JUSTIFIED, which wrapped to its width and treated a line break as a space: two lines meant two widgets and a computed line height. Now "\n" is a hard break everywhere: a LEFT, CENTER or RIGHT label draws one line under another, each aligned on its own, and a JUSTIFIED one breaks there and does not stretch the line before it. n_gui_label_fits() counts the lines.

Headless: the builtin font and a memory bitmap. What is drawn is checked by counting the bands of rows that have ink in them. ```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 int colour_distance(ALLEGRO_COLOR a, ALLEGRO_COLOR b) { unsigned char ar, ag, ab, br, bg, bb; al_unmap_rgb(a, &ar, &ag, &ab); al_unmap_rgb(b, &br, &bg, &bb); return abs(ar - br) + abs(ag - bg) + abs(ab - bb); }

static void ink(N_GUI_CTX* gui, int x0, int y0, int w, int h, int* bands, int* widest_gap, int* first_right) { ALLEGRO_BITMAP* target = NULL; int old = al_get_new_bitmap_flags(); int x, y, in_band = 0, gap = 0, band_no = 0;

al_set_new_bitmap_flags(ALLEGRO_MEMORY_BITMAP);
target = al_create_bitmap(400, 300);
al_set_new_bitmap_flags(old);
al_set_target_bitmap(target);
al_clear_to_color(al_map_rgb(0, 0, 0));
n_gui_draw(gui);
/* The background is what the label's box holds in its bottom right
 * corner, which no text reaches. */
ALLEGRO_COLOR bg = al_get_pixel(target, x0 + w - 2, y0 + h - 2);
*bands = 0;
*widest_gap = 0;
*first_right = -1;
for (y = y0; y < y0 + h; y++) {
    int row_ink = 0;
    for (x = x0; x < x0 + w - 3; x++) {
        if (colour_distance(al_get_pixel(target, x, y), bg) > 60) {
            row_ink = 1;
            if (band_no <= 1 && x > *first_right && (in_band || band_no == 0)) *first_right = x;
        }
    }
    if (row_ink && !in_band) {
        (*bands)++;
        band_no = *bands;
        if (*bands > 1 && gap > *widest_gap) *widest_gap = gap;
        in_band = 1;
    } else if (!row_ink && in_band) {
        in_band = 0;
        gap = 0;
    }
    if (!row_ink) gap++;
}
al_set_target_bitmap(NULL);
al_destroy_bitmap(target);

}

int main(int argc, char** argv) { int bands = 0, gap = 0, right = 0; float nw = 0.0f, nh = 0.0f;

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) 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);
float fh = (float)al_get_font_line_height(font);
float pad = gui->style.label_padding;
int win = n_gui_add_window(gui, "W", 0.0f, 0.0f, 400.0f, 300.0f);
n_gui_window_set_flags(gui, win, N_GUI_WIN_FRAMELESS);
n_gui_open_window(gui, win);

/* Plain labels. */
int left = n_gui_add_label(gui, win, "one\ntwo\nthree", 10.0f, 10.0f, 150.0f, 60.0f, N_GUI_ALIGN_LEFT);
expect_true("fits counts every line",
            n_gui_label_fits(gui, left, &nw, &nh) == 1 && nh == 3.0f * fh &&
                nw == (float)al_get_text_width(font, "three") + 2.0f * pad);
ink(gui, 10, 10, 150, 60, &bands, &gap, &right);
expect_true("a LEFT label draws each line under the one before", bands == 3);

n_gui_label_set_text(gui, left, "above\n\nbelow");
ink(gui, 10, 10, 150, 60, &bands, &gap, &right);
expect_true("a blank line is a line", bands == 2 && gap >= (int)fh);

n_gui_label_set_text(gui, left, "no break here");
expect_true("a label with no break measures as it always did",
            n_gui_label_fits(gui, left, &nw, &nh) == 1 && nh == fh);

int centre = n_gui_add_label(gui, win, "a\nwide line", 10.0f, 80.0f, 150.0f, 40.0f, N_GUI_ALIGN_CENTER);
ink(gui, 10, 80, 150, 40, &bands, &gap, &right);
expect_true("a CENTER label draws its lines", bands == 2);
(void)centre;

/* Not fitting, and cut at its box rather than drawn over what is below:
   nothing of its fourth line may reach the label under it. */
expect_true("a box too short for the lines does not fit",
            n_gui_label_fits(gui, n_gui_add_label(gui, win, "1\n2\n3\n4", 10.0f, 130.0f, 100.0f, 20.0f, N_GUI_ALIGN_LEFT), &nw, &nh) == 0 &&
                nh == 4.0f * fh);

/* Justified: a break, and the line before it is not stretched. */
n_gui_label_set_text(gui, left, "");
int just = n_gui_add_label(gui, win, "aa bb\ncc", 10.0f, 160.0f, 300.0f, 60.0f, N_GUI_ALIGN_JUSTIFIED);
ink(gui, 10, 160, 300, 60, &bands, &gap, &right);
expect_true("a JUSTIFIED label breaks at a line break", bands == 2);
expect_true("and does not stretch the line before it across the box",
            right >= 0 && right < 10 + (int)pad + al_get_text_width(font, "aa bb") + 4);
expect_true("its content height counts the break",
            n_gui_label_fits(gui, just, &nw, &nh) == 1 && nh == 2.0f * fh + pad);

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

}

_Filename: ex_gui_label_lines.c_