key_events.cpp

#include <assert.h>
#include <cerrno>
#include <fcntl.h>
#include <cstring>
#include <sys/mman.h>
#include <ctime>
#include <unistd.h>
#include <wayland-client.h>
#include <cstdio>
#include <xkbcommon/xkbcommon.h>
#include "xdg-shell-client-protocol.h"

/* Shared memory support code */
static void randname(char *buf) {
    struct timespec ts{};
    clock_gettime(CLOCK_REALTIME, &ts);
    long r = ts.tv_nsec;
    for (int i = 0; i < 6; ++i) {
        buf[i] = 'A' + (r & 15) + (r & 16) * 2;
        r >>= 5;
    }
}

static int create_shm_file() {
    int retries = 100;
    do {
        char name[] = "/wl_shm-XXXXXX";
        randname(name + sizeof(name) - 7);
        --retries;
        int fd = shm_open(name, O_RDWR | O_CREAT | O_EXCL, 0600);
        if (fd >= 0) {
            shm_unlink(name);
            return fd;
        }
    } while (retries > 0 && errno == EEXIST);
    return -1;
}

static int allocate_shm_file(size_t size) {
    int fd = create_shm_file();
    if (fd < 0)
        return -1;
    int ret;
    do {
        ret = ftruncate(fd, size);
    } while (ret < 0 && errno == EINTR);
    if (ret < 0) {
        close(fd);
        return -1;
    }
    return fd;
}

enum pointer_event_mask {
    POINTER_EVENT_ENTER = 1 << 0,
    POINTER_EVENT_LEAVE = 1 << 1,
    POINTER_EVENT_MOTION = 1 << 2,
    POINTER_EVENT_BUTTON = 1 << 3,
    POINTER_EVENT_AXIS = 1 << 4,
    POINTER_EVENT_AXIS_SOURCE = 1 << 5,
    POINTER_EVENT_AXIS_STOP = 1 << 6,
    POINTER_EVENT_AXIS_DISCRETE = 1 << 7,
};

struct pointer_event {
    uint32_t event_mask;
    wl_fixed_t surface_x, surface_y;
    uint32_t button, state;
    uint32_t time;
    uint32_t serial;
    struct {
        bool valid;
        wl_fixed_t value;
        int32_t discrete;
    } axes[2];
    uint32_t axis_source;
};

/* Wayland code */
struct client_state {
    /* Globals */
    struct wl_display *wl_display;
    struct wl_registry *wl_registry;
    struct wl_shm *wl_shm;
    struct wl_compositor *wl_compositor;
    struct xdg_wm_base *xdg_wm_base;
    struct wl_seat *wl_seat;
    /* Objects */
    struct wl_surface *wl_surface;
    struct xdg_surface *xdg_surface;
    struct xdg_toplevel *xdg_toplevel;
    struct wl_keyboard *wl_keyboard;
    struct wl_pointer *wl_pointer;
    struct wl_touch *wl_touch;
    /* State */
    float offset;
    uint32_t last_frame;

    struct pointer_event pointer_event;
    struct xkb_state *xkb_state;
    struct xkb_context *xkb_context;
    struct xkb_keymap *xkb_keymap;
};

static void
wl_buffer_release(void *data, struct wl_buffer *wl_buffer) {
    /* Sent by the compositor when it's no longer using this buffer */
    wl_buffer_destroy(wl_buffer);
}

static const struct wl_buffer_listener wl_buffer_listener = {
        .release = wl_buffer_release,
};

static struct wl_buffer *draw_frame(struct client_state *state) {
    const int width = 640, height = 480;
    int stride = width * 4;
    int size = stride * height;

    int fd = allocate_shm_file(size);
    if (fd == -1) {
        return nullptr;
    }

    uint32_t *data = static_cast<uint32_t *>(mmap(NULL, size,
                                                  PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0));
    if (data == MAP_FAILED) {
        close(fd);
        return NULL;
    }

    struct wl_shm_pool *pool = wl_shm_create_pool(state->wl_shm, fd, size);
    struct wl_buffer *buffer = wl_shm_pool_create_buffer(pool, 0,
                                                         width, height, stride, WL_SHM_FORMAT_XRGB8888);
    wl_shm_pool_destroy(pool);
    close(fd);

    /* Draw checkerboxed background */
    int offset = (int) state->offset % 8;
    for (int y = 0; y < height; ++y) {
        for (int x = 0; x < width; ++x) {
            if (((x + offset) + (y + offset) / 8 * 8) % 16 < 8)
                data[y * width + x] = 0xFF666666;
            else
                data[y * width + x] = 0xFFEEEEEE;
        }
    }

    munmap(data, size);
    wl_buffer_add_listener(buffer, &wl_buffer_listener, NULL);
    return buffer;
}

static void
wl_surface_frame_done(void *data, struct wl_callback *cb, uint32_t time);

static const struct wl_callback_listener wl_surface_frame_listener = {
        .done = wl_surface_frame_done,
};

static void xdg_surface_configure(void *data,
                                  struct xdg_surface *xdg_surface, uint32_t serial) {
    struct client_state *state = static_cast<client_state *>(data);
    xdg_surface_ack_configure(xdg_surface, serial);


    struct wl_buffer *buffer = draw_frame(state);
    wl_surface_attach(state->wl_surface, buffer, 0, 0);
    wl_surface_commit(state->wl_surface);
}

static const struct xdg_surface_listener xdg_surface_listener = {
        .configure = xdg_surface_configure,
};

static void xdg_wm_base_ping(void *data, struct xdg_wm_base *xdg_wm_base, uint32_t serial) {
    xdg_wm_base_pong(xdg_wm_base, serial);
}

static const struct xdg_wm_base_listener xdg_wm_base_listener = {
        .ping = xdg_wm_base_ping,
};


static void
wl_surface_frame_done(void *data, struct wl_callback *cb, uint32_t time) {
    /* Destroy this callback */
    wl_callback_destroy(cb);

    /* Request another frame */
    struct client_state *state = static_cast<client_state *>(data);
    cb = wl_surface_frame(state->wl_surface);
    wl_callback_add_listener(cb, &wl_surface_frame_listener, state);

    /* Update scroll amount at 24 pixels per second */
    if (state->last_frame != 0) {
        int elapsed = time - state->last_frame;
        state->offset += elapsed / 1000.0 * 24;
    }

    /* Submit a frame for this event */
    struct wl_buffer *buffer = draw_frame(state);
    wl_surface_attach(state->wl_surface, buffer, 0, 0);
    wl_surface_damage_buffer(state->wl_surface, 0, 0, INT32_MAX, INT32_MAX);
    wl_surface_commit(state->wl_surface);

    state->last_frame = time;
}

static void
wl_pointer_enter(void *data, struct wl_pointer *wl_pointer,
                 uint32_t serial, struct wl_surface *surface,
                 wl_fixed_t surface_x, wl_fixed_t surface_y) {
    struct client_state *client_state = static_cast<struct client_state *>(data);
    client_state->pointer_event.event_mask |= POINTER_EVENT_ENTER;
    client_state->pointer_event.serial = serial;
    client_state->pointer_event.surface_x = surface_x,
            client_state->pointer_event.surface_y = surface_y;
}

static void wl_pointer_leave(void *data, struct wl_pointer *wl_pointer,
                             uint32_t serial, struct wl_surface *surface) {
    struct client_state *client_state = static_cast<struct client_state *>(data);
    client_state->pointer_event.serial = serial;
    client_state->pointer_event.event_mask |= POINTER_EVENT_LEAVE;
}

static void wl_pointer_motion(void *data, struct wl_pointer *wl_pointer, uint32_t time,
                              wl_fixed_t surface_x, wl_fixed_t surface_y) {
    struct client_state *client_state = static_cast<struct client_state *>(data);
    client_state->pointer_event.event_mask |= POINTER_EVENT_MOTION;
    client_state->pointer_event.time = time;
    client_state->pointer_event.surface_x = surface_x,
            client_state->pointer_event.surface_y = surface_y;
}

static void wl_pointer_button(void *data, struct wl_pointer *wl_pointer, uint32_t serial,
                              uint32_t time, uint32_t button, uint32_t state) {
    struct client_state *client_state = static_cast<struct client_state *>(data);
    client_state->pointer_event.event_mask |= POINTER_EVENT_BUTTON;
    client_state->pointer_event.time = time;
    client_state->pointer_event.serial = serial;
    client_state->pointer_event.button = button,
            client_state->pointer_event.state = state;
}

static void
wl_pointer_axis(void *data, struct wl_pointer *wl_pointer, uint32_t time,
                uint32_t axis, wl_fixed_t value) {
    struct client_state *client_state = static_cast<struct client_state *>(data);
    client_state->pointer_event.event_mask |= POINTER_EVENT_AXIS;
    client_state->pointer_event.time = time;
    client_state->pointer_event.axes[axis].valid = true;
    client_state->pointer_event.axes[axis].value = value;
}

static void wl_pointer_axis_source(void *data, struct wl_pointer *wl_pointer,
                                   uint32_t axis_source) {
    struct client_state *client_state = static_cast<struct client_state *>(data);
    client_state->pointer_event.event_mask |= POINTER_EVENT_AXIS_SOURCE;
    client_state->pointer_event.axis_source = axis_source;
}

static void wl_pointer_axis_stop(void *data, struct wl_pointer *wl_pointer,
                                 uint32_t time, uint32_t axis) {
    struct client_state *client_state = static_cast<struct client_state *>(data);
    client_state->pointer_event.time = time;
    client_state->pointer_event.event_mask |= POINTER_EVENT_AXIS_STOP;
    client_state->pointer_event.axes[axis].valid = true;
}

static void wl_pointer_axis_discrete(void *data, struct wl_pointer *wl_pointer,
                                     uint32_t axis, int32_t discrete) {
    struct client_state *client_state = static_cast<struct client_state *>(data);
    client_state->pointer_event.event_mask |= POINTER_EVENT_AXIS_DISCRETE;
    client_state->pointer_event.axes[axis].valid = true;
    client_state->pointer_event.axes[axis].discrete = discrete;
}

static void
wl_pointer_frame(void *data, struct wl_pointer *wl_pointer) {
    struct client_state *client_state = static_cast<struct client_state *>(data);
    struct pointer_event *event = &client_state->pointer_event;
    fprintf(stderr, "pointer frame @ %d: ", event->time);

    if (event->event_mask & POINTER_EVENT_ENTER) {
        fprintf(stderr, "entered %f, %f ",
                wl_fixed_to_double(event->surface_x),
                wl_fixed_to_double(event->surface_y));
    }

    if (event->event_mask & POINTER_EVENT_LEAVE) {
        fprintf(stderr, "leave");
    }

    if (event->event_mask & POINTER_EVENT_MOTION) {
        fprintf(stderr, "motion %f, %f ",
                wl_fixed_to_double(event->surface_x),
                wl_fixed_to_double(event->surface_y));
    }

    if (event->event_mask & POINTER_EVENT_BUTTON) {
        char *state = const_cast<char *>(event->state == WL_POINTER_BUTTON_STATE_RELEASED ?
                                         "released" : "pressed");
        fprintf(stderr, "button %d %s ", event->button, state);
    }

    uint32_t axis_events = POINTER_EVENT_AXIS
                           | POINTER_EVENT_AXIS_SOURCE
                           | POINTER_EVENT_AXIS_STOP
                           | POINTER_EVENT_AXIS_DISCRETE;
    char *axis_name[2] = {
            [WL_POINTER_AXIS_VERTICAL_SCROLL] = "vertical",
            [WL_POINTER_AXIS_HORIZONTAL_SCROLL] = "horizontal",
    };
    char *axis_source[4] = {
            [WL_POINTER_AXIS_SOURCE_WHEEL] = "wheel",
            [WL_POINTER_AXIS_SOURCE_FINGER] = "finger",
            [WL_POINTER_AXIS_SOURCE_CONTINUOUS] = "continuous",
            [WL_POINTER_AXIS_SOURCE_WHEEL_TILT] = "wheel tilt",
    };
    if (event->event_mask & axis_events) {
        for (size_t i = 0; i < 2; ++i) {
            if (!event->axes[i].valid) {
                continue;
            }
            fprintf(stderr, "%s axis ", axis_name[i]);
            if (event->event_mask & POINTER_EVENT_AXIS) {
                fprintf(stderr, "value %f ", wl_fixed_to_double(
                        event->axes[i].value));
            }
            if (event->event_mask & POINTER_EVENT_AXIS_DISCRETE) {
                fprintf(stderr, "discrete %d ",
                        event->axes[i].discrete);
            }
            if (event->event_mask & POINTER_EVENT_AXIS_SOURCE) {
                fprintf(stderr, "via %s ",
                        axis_source[event->axis_source]);
            }
            if (event->event_mask & POINTER_EVENT_AXIS_STOP) {
                fprintf(stderr, "(stopped) ");
            }
        }
    }

    fprintf(stderr, "\n");
    memset(event, 0, sizeof(*event));
}

static const struct wl_pointer_listener wl_pointer_listener = {
        .enter = wl_pointer_enter,
        .leave = wl_pointer_leave,
        .motion = wl_pointer_motion,
        .button = wl_pointer_button,
        .axis = wl_pointer_axis,
        .frame = wl_pointer_frame,
        .axis_source = wl_pointer_axis_source,
        .axis_stop = wl_pointer_axis_stop,
        .axis_discrete = wl_pointer_axis_discrete,
};


static void wl_keyboard_keymap(void *data, struct wl_keyboard *wl_keyboard,
                               uint32_t format, int32_t fd, uint32_t size) {
    struct client_state *client_state = static_cast<struct client_state *>(data);
    assert(format == WL_KEYBOARD_KEYMAP_FORMAT_XKB_V1);

    char *map_shm = static_cast<char *>(mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0));
    assert(map_shm != MAP_FAILED);

    struct xkb_keymap *xkb_keymap = xkb_keymap_new_from_string(
            client_state->xkb_context, map_shm,
            XKB_KEYMAP_FORMAT_TEXT_V1, XKB_KEYMAP_COMPILE_NO_FLAGS);
    munmap(map_shm, size);
    close(fd);

    struct xkb_state *xkb_state = xkb_state_new(xkb_keymap);
    xkb_keymap_unref(client_state->xkb_keymap);
    xkb_state_unref(client_state->xkb_state);
    client_state->xkb_keymap = xkb_keymap;
    client_state->xkb_state = xkb_state;
}

static void wl_keyboard_enter(void *data, struct wl_keyboard *wl_keyboard,
                              uint32_t serial, struct wl_surface *surface,
                              struct wl_array *keys) {
    struct client_state *client_state = static_cast<struct client_state *>(data);
    fprintf(stderr, "keyboard enter; keys pressed are:\n");
    uint32_t *key;
    wl_array_for_each(key, keys) {
        char buf[128];
        xkb_keysym_t sym = xkb_state_key_get_one_sym(
                client_state->xkb_state, *key + 8);
        xkb_keysym_get_name(sym, buf, sizeof(buf));
        fprintf(stderr, "sym: %-12s (%d), ", buf, sym);
        xkb_state_key_get_utf8(client_state->xkb_state,
                               *key + 8, buf, sizeof(buf));
        fprintf(stderr, "utf8: '%s'\n", buf);
    }
}

static void wl_keyboard_key(void *data, struct wl_keyboard *wl_keyboard,
                            uint32_t serial, uint32_t time, uint32_t key, uint32_t state) {
    struct client_state *client_state = static_cast<struct client_state *>(data);
    char buf[128];
    uint32_t keycode = key + 8;
    xkb_keysym_t sym = xkb_state_key_get_one_sym(
            client_state->xkb_state, keycode);
    xkb_keysym_get_name(sym, buf, sizeof(buf));
    const char *action =
            state == WL_KEYBOARD_KEY_STATE_PRESSED ? "press" : "release";
    fprintf(stderr, "key %s: sym: %-12s (%d), ", action, buf, sym);
    xkb_state_key_get_utf8(client_state->xkb_state, keycode,
                           buf, sizeof(buf));
    fprintf(stderr, "utf8: '%s'\n", buf);
}

static void wl_keyboard_leave(void *data, struct wl_keyboard *wl_keyboard,
                              uint32_t serial, struct wl_surface *surface) {
    fprintf(stderr, "keyboard leave\n");
}

static void wl_keyboard_modifiers(void *data, struct wl_keyboard *wl_keyboard,
                                  uint32_t serial, uint32_t mods_depressed,
                                  uint32_t mods_latched, uint32_t mods_locked,
                                  uint32_t group) {
    struct client_state *client_state = static_cast<struct client_state *>(data);
    xkb_state_update_mask(client_state->xkb_state,
                          mods_depressed, mods_latched, mods_locked, 0, 0, group);
}

static void wl_keyboard_repeat_info(void *data, struct wl_keyboard *wl_keyboard,
                                    int32_t rate, int32_t delay) {
    /* Left as an exercise for the reader */
}

static const struct wl_keyboard_listener wl_keyboard_listener = {
        .keymap = wl_keyboard_keymap,
        .enter = wl_keyboard_enter,
        .leave = wl_keyboard_leave,
        .key = wl_keyboard_key,
        .modifiers = wl_keyboard_modifiers,
        .repeat_info = wl_keyboard_repeat_info,
        };

static void wl_seat_capabilities(void *data, struct wl_seat *wl_seat, uint32_t capabilities) {
    struct client_state *state = static_cast<client_state *>(data);

    bool have_pointer = capabilities & WL_SEAT_CAPABILITY_POINTER;

    if (have_pointer && state->wl_pointer == NULL) {
        state->wl_pointer = wl_seat_get_pointer(state->wl_seat);
        wl_pointer_add_listener(state->wl_pointer,
                                &wl_pointer_listener, state);
    } else if (!have_pointer && state->wl_pointer != NULL) {
        wl_pointer_release(state->wl_pointer);
        state->wl_pointer = NULL;
    }
    bool have_keyboard = capabilities & WL_SEAT_CAPABILITY_KEYBOARD;
    if (have_keyboard && state->wl_keyboard == NULL) {
        state->wl_keyboard = wl_seat_get_keyboard(state->wl_seat);
        wl_keyboard_add_listener(state->wl_keyboard,
                                 &wl_keyboard_listener, state);
    } else if (!have_keyboard && state->wl_keyboard != NULL) {
        wl_keyboard_release(state->wl_keyboard);
        state->wl_keyboard = NULL;
    }
}

static void wl_seat_name(void *data, struct wl_seat *wl_seat, const char *name) {
    fprintf(stderr, "seat name: %s\n", name);
}

static const struct wl_seat_listener wl_seat_listener = {
        .capabilities = wl_seat_capabilities,
        .name = wl_seat_name,
};

static void registry_global(void *data, struct wl_registry *wl_registry,
                            uint32_t name, const char *interface, uint32_t version) {
    struct client_state *state = static_cast<client_state *>(data);
    if (strcmp(interface, wl_shm_interface.name) == 0) {
        state->wl_shm = static_cast<wl_shm *>(wl_registry_bind(
                wl_registry, name, &wl_shm_interface, 1));
    } else if (strcmp(interface, wl_compositor_interface.name) == 0) {
        state->wl_compositor = static_cast<wl_compositor *>(wl_registry_bind(
                wl_registry, name, &wl_compositor_interface, 4));
    } else if (strcmp(interface, xdg_wm_base_interface.name) == 0) {
        state->xdg_wm_base = static_cast<xdg_wm_base *>(wl_registry_bind(
                wl_registry, name, &xdg_wm_base_interface, 1));
        xdg_wm_base_add_listener(state->xdg_wm_base,
                                 &xdg_wm_base_listener, state);
    } else if (strcmp(interface, wl_seat_interface.name) == 0) {
        state->wl_seat = static_cast<wl_seat *>(wl_registry_bind(
                wl_registry, name, &wl_seat_interface, 5/*7*/));
        wl_seat_add_listener(state->wl_seat, &wl_seat_listener, state);
    }
    
}

static void registry_global_remove(void *data,
                                   struct wl_registry *wl_registry, uint32_t name) {
    /* This space deliberately left blank */
}

static const struct wl_registry_listener wl_registry_listener = {
        .global = registry_global,
        .global_remove = registry_global_remove,
};

int main(int argc, char *argv[]) {
    struct client_state state = {0};
    state.wl_display = wl_display_connect(NULL);
    state.wl_registry = wl_display_get_registry(state.wl_display);
    state.xkb_context = xkb_context_new(XKB_CONTEXT_NO_FLAGS);
    wl_registry_add_listener(state.wl_registry, &wl_registry_listener, &state);
    wl_display_roundtrip(state.wl_display);

    state.wl_surface = wl_compositor_create_surface(state.wl_compositor);
    state.xdg_surface = xdg_wm_base_get_xdg_surface(
            state.xdg_wm_base, state.wl_surface);
    xdg_surface_add_listener(state.xdg_surface, &xdg_surface_listener, &state);
    state.xdg_toplevel = xdg_surface_get_toplevel(state.xdg_surface);
    xdg_toplevel_set_title(state.xdg_toplevel, "Example client");
    wl_surface_commit(state.wl_surface);

    struct wl_callback *cb = wl_surface_frame(state.wl_surface);
    wl_callback_add_listener(cb, &wl_surface_frame_listener, &state);

    while (wl_display_dispatch(state.wl_display)) {
        /* This space deliberately left blank */
    }
    return 0;
}