Wayland monitor size and position

main.c

// gcc -o main main.c -std=gnu23 -lwayland-client

#include <assert.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <wayland-client-protocol.h>

#define MAX_NAME_SIZE 512
#define MAX_MONITORS 42

typedef struct {
    int x, y, w, h;
    int scale;
    char name[MAX_NAME_SIZE];
    struct wl_output *wl_output;
} monitor_t;


monitor_t monitors[MAX_MONITORS];
size_t monitor_count = 0;

static void geometry(void *data, struct wl_output *wl_output, int32_t x, int32_t y, int32_t physical_width, int32_t physical_height, int32_t subpixel, const char *make, const char *model, int32_t transform) {
    monitors[monitor_count].x = x;
    monitors[monitor_count].y = y;
}

static void pixel_contexts(void *data, struct wl_output *wl_output, uint32_t flags, int32_t width, int32_t height, int32_t refresh) {
    monitors[monitor_count].w = width;
    monitors[monitor_count].h = height;
}

static void done(void *data, struct wl_output *wl_output) {
    monitors[monitor_count].wl_output = wl_output;
    monitor_count++;
    assert(monitor_count < MAX_MONITORS);
}

static void scale(void *data, struct wl_output *wl_output, int32_t factor) {
    monitors[monitor_count].scale = factor;
}

static void name(void *data, struct wl_output *wl_output, const char *name) {
    strncpy(monitors[monitor_count].name, name, MAX_NAME_SIZE);
}

static void description(void *data, struct wl_output *wl_output, const char *description) {
    // nop
}

const struct wl_output_listener listener = {
    geometry,
    pixel_contexts,
    done,
    scale,
    name,
    description
};

static void interface_added(void *data, struct wl_registry *registry, uint32_t name, const char *interface, uint32_t version) {
    if (strcmp(interface, wl_output_interface.name) == 0) {
        struct wl_output *wl_output = wl_registry_bind(registry, name, &wl_output_interface, version);
        wl_output_add_listener(wl_output, &listener, NULL);
    }
}

static const struct wl_registry_listener registry_listener = {
    interface_added,
};

int moncmp(const void *a, const void *b) {
    const monitor_t *ma = a, *mb = b;
    return strcmp(ma->name, mb->name);
}

int main(void) {
    struct wl_display *display = wl_display_connect(NULL);

    struct wl_registry *registry = wl_display_get_registry(display);
    wl_registry_add_listener(registry, &registry_listener, nullptr);
    wl_display_roundtrip(display);
    while (wl_display_dispatch(display) == -1) {}
    for (size_t i = 0; i < monitor_count; i++) {
        wl_output_release(monitors[i].wl_output);
    }
    wl_registry_destroy(registry);
    wl_display_disconnect(display);

    printf("Monitor count: %zu\n", monitor_count);

    qsort(monitors, monitor_count, sizeof(monitors[0]), moncmp);

    for (size_t i = 0; i < monitor_count; i++) {
        monitor_t m = monitors[i];
        printf("\"%s\": %dx%d at (%d,%d) (scaled by %d)\n", m.name, m.w / m.scale, m.h / m.scale, m.x, m.y, m.scale);
    }

    return 0;
}