/*
 * QEMU graphical console
 *
 * Copyright (c) 2004 Fabrice Bellard
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "qemu/osdep.h"
#include "ui/console.h"
#include "hw/qdev-core.h"
#include "qapi/error.h"
#include "qapi/qapi-commands-ui.h"
#include "qapi/visitor.h"
#include "qemu/coroutine.h"
#include "qemu/error-report.h"
#include "qemu/main-loop.h"
#include "qemu/module.h"
#include "qemu/option.h"
#include "chardev/char.h"
#include "trace.h"
#include "system/memory.h"
#include "qom/object.h"
#include "qemu/memfd.h"

#include "console-priv.h"

OBJECT_DEFINE_ABSTRACT_TYPE(QemuConsole, qemu_console, QEMU_CONSOLE, OBJECT)

typedef struct QemuGraphicConsole {
    QemuConsole parent;

    Object *device;
    uint32_t head;

    QEMUCursor *cursor;
    int cursor_x, cursor_y;
    bool cursor_on;
} QemuGraphicConsole;

typedef QemuConsoleClass QemuGraphicConsoleClass;

OBJECT_DEFINE_TYPE(QemuGraphicConsole, qemu_graphic_console, QEMU_GRAPHIC_CONSOLE, QEMU_CONSOLE)

struct DisplayState {
    QEMUTimer *gui_timer;
    uint64_t last_update;
    uint64_t update_interval;
    bool refreshing;

    QLIST_HEAD(, DisplayChangeListener) listeners;
};

static DisplayState *display_state;
static QTAILQ_HEAD(, QemuConsole) consoles =
    QTAILQ_HEAD_INITIALIZER(consoles);

static void dpy_refresh(DisplayState *s);
static DisplayState *get_alloc_displaystate(void);
static bool displaychangelistener_has_dmabuf(DisplayChangeListener *dcl);
static bool console_compatible_with(QemuConsole *con,
                                    DisplayChangeListener *dcl, Error **errp);
static QemuConsole *qemu_graphic_console_lookup_unused(void);
static void dpy_set_ui_info_timer(void *opaque);

static void gui_update(void *opaque)
{
    uint64_t interval = GUI_REFRESH_INTERVAL_IDLE;
    uint64_t dcl_interval;
    DisplayState *ds = opaque;
    DisplayChangeListener *dcl;

    ds->refreshing = true;
    dpy_refresh(ds);
    ds->refreshing = false;

    QLIST_FOREACH(dcl, &ds->listeners, next) {
        dcl_interval = dcl->update_interval ?
            dcl->update_interval : GUI_REFRESH_INTERVAL_DEFAULT;
        if (interval > dcl_interval) {
            interval = dcl_interval;
        }
    }
    if (ds->update_interval != interval) {
        ds->update_interval = interval;
        trace_console_refresh(interval);
    }
    ds->last_update = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
    timer_mod(ds->gui_timer, ds->last_update + interval);
}

static void gui_setup_refresh(DisplayState *ds)
{
    DisplayChangeListener *dcl;
    bool need_timer = false;

    QLIST_FOREACH(dcl, &ds->listeners, next) {
        if (dcl->ops->dpy_refresh != NULL) {
            need_timer = true;
        }
    }

    if (need_timer && ds->gui_timer == NULL) {
        ds->gui_timer = timer_new_ms(QEMU_CLOCK_REALTIME, gui_update, ds);
        timer_mod(ds->gui_timer, qemu_clock_get_ms(QEMU_CLOCK_REALTIME));
    }
    if (!need_timer && ds->gui_timer != NULL) {
        timer_free(ds->gui_timer);
        ds->gui_timer = NULL;
    }
}

void graphic_hw_update_done(QemuConsole *con)
{
    if (con) {
        qemu_co_enter_all(&con->dump_queue, NULL);
    }
}

void graphic_hw_update(QemuConsole *con)
{
    bool async = false;
    if (!con) {
        return;
    }
    if (con->hw_ops->gfx_update) {
        con->hw_ops->gfx_update(con->hw);
        async = con->hw_ops->gfx_update_async;
    }
    if (!async) {
        graphic_hw_update_done(con);
    }
}

static void graphic_hw_update_bh(void *con)
{
    graphic_hw_update(con);
}

void qemu_console_co_wait_update(QemuConsole *con)
{
    if (qemu_co_queue_empty(&con->dump_queue)) {
        /* Defer the update, it will restart the pending coroutines */
        aio_bh_schedule_oneshot(qemu_get_aio_context(),
                                graphic_hw_update_bh, con);
    }
    qemu_co_queue_wait(&con->dump_queue, NULL);

}

static void graphic_hw_gl_unblock_timer(void *opaque)
{
    warn_report("console: no gl-unblock within one second");
}

void graphic_hw_gl_block(QemuConsole *con, bool block)
{
    uint64_t timeout;
    assert(con != NULL);

    if (block) {
        con->gl_block++;
    } else {
        con->gl_block--;
    }
    assert(con->gl_block >= 0);
    if (!con->hw_ops->gl_block) {
        return;
    }
    if ((block && con->gl_block != 1) || (!block && con->gl_block != 0)) {
        return;
    }
    con->hw_ops->gl_block(con->hw, block);

    if (block) {
        timeout = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
        timeout += 1000; /* one sec */
        timer_mod(con->gl_unblock_timer, timeout);
    } else {
        timer_del(con->gl_unblock_timer);
    }
}

int qemu_console_get_window_id(QemuConsole *con)
{
    return con->window_id;
}

void qemu_console_set_window_id(QemuConsole *con, int window_id)
{
    con->window_id = window_id;
}

void graphic_hw_invalidate(QemuConsole *con)
{
    if (con && con->hw_ops->invalidate) {
        con->hw_ops->invalidate(con->hw);
    }
}

void graphic_hw_text_update(QemuConsole *con, console_ch_t *chardata)
{
    if (con && con->hw_ops->text_update) {
        con->hw_ops->text_update(con->hw, chardata);
    }
}

static void displaychangelistener_gfx_switch(DisplayChangeListener *dcl,
                                             struct DisplaySurface *new_surface,
                                             bool update)
{
    if (dcl->ops->dpy_gfx_switch) {
        dcl->ops->dpy_gfx_switch(dcl, new_surface);
    }

    if (update && dcl->ops->dpy_gfx_update) {
        dcl->ops->dpy_gfx_update(dcl, 0, 0,
                                 surface_width(new_surface),
                                 surface_height(new_surface));
    }
}

static void dpy_gfx_create_texture(QemuConsole *con, DisplaySurface *surface)
{
    if (con->gl && con->gl->ops->dpy_gl_ctx_create_texture) {
        con->gl->ops->dpy_gl_ctx_create_texture(con->gl, surface);
    }
}

static void dpy_gfx_destroy_texture(QemuConsole *con, DisplaySurface *surface)
{
    if (con->gl && con->gl->ops->dpy_gl_ctx_destroy_texture) {
        con->gl->ops->dpy_gl_ctx_destroy_texture(con->gl, surface);
    }
}

static void dpy_gfx_update_texture(QemuConsole *con, DisplaySurface *surface,
                                   int x, int y, int w, int h)
{
    if (con->gl && con->gl->ops->dpy_gl_ctx_update_texture) {
        con->gl->ops->dpy_gl_ctx_update_texture(con->gl, surface, x, y, w, h);
    }
}

static void displaychangelistener_display_console(DisplayChangeListener *dcl,
                                                  Error **errp)
{
    static const char nodev[] =
        "This VM has no graphic display device.";
    static DisplaySurface *dummy;
    QemuConsole *con = dcl->con;

    if (!con || !console_compatible_with(con, dcl, errp)) {
        if (!dummy) {
            dummy = qemu_create_placeholder_surface(640, 480, nodev);
        }
        if (con) {
            dpy_gfx_create_texture(con, dummy);
        }
        displaychangelistener_gfx_switch(dcl, dummy, TRUE);
        return;
    }

    dpy_gfx_create_texture(con, con->surface);
    displaychangelistener_gfx_switch(dcl, con->surface,
                                     con->scanout.kind == SCANOUT_SURFACE);

    if (con->scanout.kind == SCANOUT_DMABUF &&
        displaychangelistener_has_dmabuf(dcl)) {
        dcl->ops->dpy_gl_scanout_dmabuf(dcl, con->scanout.dmabuf);
    } else if (con->scanout.kind == SCANOUT_TEXTURE &&
               dcl->ops->dpy_gl_scanout_texture) {
        dcl->ops->dpy_gl_scanout_texture(dcl,
                                         con->scanout.texture.backing_id,
                                         con->scanout.texture.backing_y_0_top,
                                         con->scanout.texture.backing_width,
                                         con->scanout.texture.backing_height,
                                         con->scanout.texture.x,
                                         con->scanout.texture.y,
                                         con->scanout.texture.width,
                                         con->scanout.texture.height,
                                         con->scanout.texture.d3d_tex2d);
    }
}

void qemu_text_console_put_keysym(QemuTextConsole *s, int keysym)
{
    qemu_text_console_handle_keysym(s, keysym);
}

static const int qcode_to_keysym[Q_KEY_CODE__MAX] = {
    [Q_KEY_CODE_UP]     = QEMU_KEY_UP,
    [Q_KEY_CODE_DOWN]   = QEMU_KEY_DOWN,
    [Q_KEY_CODE_RIGHT]  = QEMU_KEY_RIGHT,
    [Q_KEY_CODE_LEFT]   = QEMU_KEY_LEFT,
    [Q_KEY_CODE_HOME]   = QEMU_KEY_HOME,
    [Q_KEY_CODE_END]    = QEMU_KEY_END,
    [Q_KEY_CODE_PGUP]   = QEMU_KEY_PAGEUP,
    [Q_KEY_CODE_PGDN]   = QEMU_KEY_PAGEDOWN,
    [Q_KEY_CODE_DELETE] = QEMU_KEY_DELETE,
    [Q_KEY_CODE_TAB]    = QEMU_KEY_TAB,
    [Q_KEY_CODE_BACKSPACE] = QEMU_KEY_BACKSPACE,
};

static const int ctrl_qcode_to_keysym[Q_KEY_CODE__MAX] = {
    [Q_KEY_CODE_UP]     = QEMU_KEY_CTRL_UP,
    [Q_KEY_CODE_DOWN]   = QEMU_KEY_CTRL_DOWN,
    [Q_KEY_CODE_RIGHT]  = QEMU_KEY_CTRL_RIGHT,
    [Q_KEY_CODE_LEFT]   = QEMU_KEY_CTRL_LEFT,
    [Q_KEY_CODE_HOME]   = QEMU_KEY_CTRL_HOME,
    [Q_KEY_CODE_END]    = QEMU_KEY_CTRL_END,
    [Q_KEY_CODE_PGUP]   = QEMU_KEY_CTRL_PAGEUP,
    [Q_KEY_CODE_PGDN]   = QEMU_KEY_CTRL_PAGEDOWN,
};

bool qemu_text_console_put_qcode(QemuTextConsole *s, int qcode, bool ctrl)
{
    int keysym;

    keysym = ctrl ? ctrl_qcode_to_keysym[qcode] : qcode_to_keysym[qcode];
    if (keysym == 0) {
        return false;
    }
    qemu_text_console_put_keysym(s, keysym);
    return true;
}

void qemu_text_console_put_string(QemuTextConsole *s, const char *str, int len)
{
    int i;

    for (i = 0; i < len && str[i]; i++) {
        qemu_text_console_put_keysym(s, str[i]);
    }
}

static void
qemu_console_register(QemuConsole *c)
{
    int i;

    if (QTAILQ_EMPTY(&consoles)) {
        c->index = 0;
        QTAILQ_INSERT_TAIL(&consoles, c, next);
    } else if (!QEMU_IS_GRAPHIC_CONSOLE(c) || phase_check(PHASE_MACHINE_READY)) {
        QemuConsole *last = QTAILQ_LAST(&consoles);
        c->index = last->index + 1;
        QTAILQ_INSERT_TAIL(&consoles, c, next);
    } else {
        /*
         * HACK: Put graphical consoles before text consoles.
         *
         * Only do that for coldplugged devices.  After initial device
         * initialization we will not renumber the consoles any more.
         */
        QemuConsole *it = QTAILQ_FIRST(&consoles);

        while (QTAILQ_NEXT(it, next) != NULL && QEMU_IS_GRAPHIC_CONSOLE(it)) {
            it = QTAILQ_NEXT(it, next);
        }
        if (QEMU_IS_GRAPHIC_CONSOLE(it)) {
            /* have no text consoles */
            c->index = it->index + 1;
            QTAILQ_INSERT_AFTER(&consoles, it, c, next);
        } else {
            c->index = it->index;
            QTAILQ_INSERT_BEFORE(it, c, next);
            /* renumber text consoles */
            for (i = c->index + 1; it != NULL; it = QTAILQ_NEXT(it, next), i++) {
                it->index = i;
            }
        }
    }
}

static void
qemu_console_finalize(Object *obj)
{
    QemuConsole *c = QEMU_CONSOLE(obj);

    /* TODO: check this code path, and unregister from consoles */
    g_clear_pointer(&c->surface, qemu_free_displaysurface);
    g_clear_pointer(&c->gl_unblock_timer, timer_free);
    g_clear_pointer(&c->ui_timer, timer_free);
}

static void
qemu_console_class_init(ObjectClass *oc, const void *data)
{
}

static void
qemu_console_init(Object *obj)
{
    QemuConsole *c = QEMU_CONSOLE(obj);
    DisplayState *ds = get_alloc_displaystate();

    qemu_co_queue_init(&c->dump_queue);
    c->ds = ds;
    c->window_id = -1;
    c->ui_timer = timer_new_ms(QEMU_CLOCK_REALTIME,
                               dpy_set_ui_info_timer, c);
    qemu_console_register(c);
}

static void
qemu_graphic_console_finalize(Object *obj)
{
    QemuGraphicConsole *c = QEMU_GRAPHIC_CONSOLE(obj);

    g_clear_pointer(&c->device, object_unref);
}

static void
qemu_graphic_console_prop_get_head(Object *obj, Visitor *v, const char *name,
                                   void *opaque, Error **errp)
{
    QemuGraphicConsole *c = QEMU_GRAPHIC_CONSOLE(obj);

    visit_type_uint32(v, name, &c->head, errp);
}

static void
qemu_graphic_console_class_init(ObjectClass *oc, const void *data)
{
    object_class_property_add_link(oc, "device", TYPE_DEVICE,
                                   offsetof(QemuGraphicConsole, device),
                                   object_property_allow_set_link,
                                   OBJ_PROP_LINK_STRONG);
    object_class_property_add(oc, "head", "uint32",
                              qemu_graphic_console_prop_get_head,
                              NULL, NULL, NULL);
}

static void
qemu_graphic_console_init(Object *obj)
{
}

void qemu_displaysurface_set_share_handle(DisplaySurface *surface,
                                          qemu_pixman_shareable handle,
                                          uint32_t offset)
{
    assert(surface->share_handle == SHAREABLE_NONE);

    surface->share_handle = handle;
    surface->share_handle_offset = offset;

}

DisplaySurface *qemu_create_displaysurface(int width, int height)
{
    trace_displaysurface_create(width, height);

    return qemu_create_displaysurface_from(
        width, height,
        PIXMAN_x8r8g8b8,
        width * 4, NULL
    );
}

DisplaySurface *qemu_create_displaysurface_from(int width, int height,
                                                pixman_format_code_t format,
                                                int linesize, uint8_t *data)
{
    DisplaySurface *surface = g_new0(DisplaySurface, 1);

    trace_displaysurface_create_from(surface, width, height, format);
    surface->share_handle = SHAREABLE_NONE;

    if (data) {
        surface->image = pixman_image_create_bits(format,
                                                  width, height,
                                                  (void *)data, linesize);
    } else {
        qemu_pixman_image_new_shareable(&surface->image,
                                        &surface->share_handle,
                                        "displaysurface",
                                        format,
                                        width,
                                        height,
                                        linesize,
                                        &error_abort);
        surface->flags = QEMU_ALLOCATED_FLAG;
    }

    assert(surface->image != NULL);
    return surface;
}

DisplaySurface *qemu_create_displaysurface_pixman(pixman_image_t *image)
{
    DisplaySurface *surface = g_new0(DisplaySurface, 1);

    trace_displaysurface_create_pixman(surface);
    surface->share_handle = SHAREABLE_NONE;
    surface->image = pixman_image_ref(image);

    return surface;
}

DisplaySurface *qemu_create_placeholder_surface(int w, int h,
                                                const char *msg)
{
    DisplaySurface *surface = qemu_create_displaysurface(w, h);
#ifdef CONFIG_PIXMAN
    pixman_color_t bg = QEMU_PIXMAN_COLOR_BLACK;
    pixman_color_t fg = QEMU_PIXMAN_COLOR_GRAY;
    pixman_image_t *glyph;
    int len, x, y, i;

    len = strlen(msg);
    x = (w / FONT_WIDTH  - len) / 2;
    y = (h / FONT_HEIGHT - 1)   / 2;
    for (i = 0; i < len; i++) {
        glyph = qemu_pixman_glyph_from_vgafont(FONT_HEIGHT, vgafont16, msg[i]);
        qemu_pixman_glyph_render(glyph, surface->image, &fg, &bg,
                                 x+i, y, FONT_WIDTH, FONT_HEIGHT);
        qemu_pixman_image_unref(glyph);
    }
#endif
    surface->flags |= QEMU_PLACEHOLDER_FLAG;
    return surface;
}

void qemu_free_displaysurface(DisplaySurface *surface)
{
    if (surface == NULL) {
        return;
    }
    trace_displaysurface_free(surface);
    qemu_pixman_image_unref(surface->image);
    g_free(surface);
}

bool console_has_gl(QemuConsole *con)
{
    return con->gl != NULL;
}

static bool displaychangelistener_has_dmabuf(DisplayChangeListener *dcl)
{
    if (dcl->ops->dpy_has_dmabuf) {
        return dcl->ops->dpy_has_dmabuf(dcl);
    }

    if (dcl->ops->dpy_gl_scanout_dmabuf) {
        return true;
    }

    return false;
}

static bool console_compatible_with(QemuConsole *con,
                                    DisplayChangeListener *dcl, Error **errp)
{
    int flags;

    flags = con->hw_ops->get_flags ? con->hw_ops->get_flags(con->hw) : 0;

    if (console_has_gl(con) &&
        !con->gl->ops->dpy_gl_ctx_is_compatible_dcl(con->gl, dcl)) {
        error_setg(errp, "Display %s is incompatible with the GL context",
                   dcl->ops->dpy_name);
        return false;
    }

    if (flags & GRAPHIC_FLAGS_GL &&
        !console_has_gl(con)) {
        error_setg(errp, "The console requires a GL context.");
        return false;

    }

    if (flags & GRAPHIC_FLAGS_DMABUF &&
        !displaychangelistener_has_dmabuf(dcl)) {
        error_setg(errp, "The console requires display DMABUF support.");
        return false;
    }

    return true;
}

void console_handle_touch_event(QemuConsole *con,
                                struct touch_slot touch_slots[INPUT_EVENT_SLOTS_MAX],
                                uint64_t num_slot,
                                int width, int height,
                                double x, double y,
                                InputMultiTouchType type,
                                Error **errp)
{
    struct touch_slot *slot;
    bool needs_sync = false;
    int update;
    int i;

    if (num_slot >= INPUT_EVENT_SLOTS_MAX) {
        error_setg(errp,
                   "Unexpected touch slot number: % " PRId64" >= %d",
                   num_slot, INPUT_EVENT_SLOTS_MAX);
        return;
    }

    slot = &touch_slots[num_slot];
    slot->x = x;
    slot->y = y;

    if (type == INPUT_MULTI_TOUCH_TYPE_BEGIN) {
        slot->tracking_id = num_slot;
    }

    for (i = 0; i < INPUT_EVENT_SLOTS_MAX; ++i) {
        if (i == num_slot) {
            update = type;
        } else {
            update = INPUT_MULTI_TOUCH_TYPE_UPDATE;
        }

        slot = &touch_slots[i];

        if (slot->tracking_id == -1) {
            continue;
        }

        if (update == INPUT_MULTI_TOUCH_TYPE_END) {
            slot->tracking_id = -1;
            qemu_input_queue_mtt(con, update, i, slot->tracking_id);
            needs_sync = true;
        } else {
            qemu_input_queue_mtt(con, update, i, slot->tracking_id);
            qemu_input_queue_btn(con, INPUT_BUTTON_TOUCH, true);
            qemu_input_queue_mtt_abs(con,
                                    INPUT_AXIS_X, (int) slot->x,
                                    0, width,
                                    i, slot->tracking_id);
            qemu_input_queue_mtt_abs(con,
                                    INPUT_AXIS_Y, (int) slot->y,
                                    0, height,
                                    i, slot->tracking_id);
            needs_sync = true;
        }
    }

    if (needs_sync) {
        qemu_input_event_sync();
    }
}

void qemu_console_set_display_gl_ctx(QemuConsole *con, DisplayGLCtx *gl)
{
    /* display has opengl support */
    assert(con);
    if (con->gl) {
        error_report("The console already has an OpenGL context.");
        exit(1);
    }
    con->gl = gl;
}

static void
dcl_set_graphic_cursor(DisplayChangeListener *dcl, QemuGraphicConsole *con)
{
    if (con && con->cursor && dcl->ops->dpy_cursor_define) {
        dcl->ops->dpy_cursor_define(dcl, con->cursor);
    }
    if (con && dcl->ops->dpy_mouse_set) {
        dcl->ops->dpy_mouse_set(dcl, con->cursor_x, con->cursor_y, con->cursor_on);
    }
}

void register_displaychangelistener(DisplayChangeListener *dcl)
{
    assert(!dcl->ds);

    trace_displaychangelistener_register(dcl, dcl->ops->dpy_name);
    dcl->ds = get_alloc_displaystate();
    QLIST_INSERT_HEAD(&dcl->ds->listeners, dcl, next);
    gui_setup_refresh(dcl->ds);
    if (dcl->con) {
        dcl->con->dcls++;
    }
    displaychangelistener_display_console(dcl, &error_fatal);
    if (QEMU_IS_GRAPHIC_CONSOLE(dcl->con)) {
        dcl_set_graphic_cursor(dcl, QEMU_GRAPHIC_CONSOLE(dcl->con));
    } else if (QEMU_IS_TEXT_CONSOLE(dcl->con)) {
        qemu_text_console_update_size(QEMU_TEXT_CONSOLE(dcl->con));
    }
    qemu_text_console_update_cursor();
}

void update_displaychangelistener(DisplayChangeListener *dcl,
                                  uint64_t interval)
{
    DisplayState *ds = dcl->ds;

    dcl->update_interval = interval;
    if (!ds->refreshing && ds->update_interval > interval) {
        timer_mod(ds->gui_timer, ds->last_update + interval);
    }
}

void unregister_displaychangelistener(DisplayChangeListener *dcl)
{
    DisplayState *ds = dcl->ds;
    trace_displaychangelistener_unregister(dcl, dcl->ops->dpy_name);
    if (dcl->con) {
        dcl->con->dcls--;
    }
    QLIST_REMOVE(dcl, next);
    dcl->ds = NULL;
    gui_setup_refresh(ds);
}

static void dpy_set_ui_info_timer(void *opaque)
{
    QemuConsole *con = opaque;
    uint32_t head = qemu_console_get_head(con);

    con->hw_ops->ui_info(con->hw, head, &con->ui_info);
}

bool dpy_ui_info_supported(const QemuConsole *con)
{
    if (con == NULL) {
        return false;
    }

    return con->hw_ops->ui_info != NULL;
}

const QemuUIInfo *dpy_get_ui_info(const QemuConsole *con)
{
    assert(dpy_ui_info_supported(con));

    return &con->ui_info;
}

int dpy_set_ui_info(QemuConsole *con, QemuUIInfo *info, bool delay)
{
    if (!dpy_ui_info_supported(con)) {
        return -1;
    }
    if (memcmp(&con->ui_info, info, sizeof(con->ui_info)) == 0) {
        /* nothing changed -- ignore */
        return 0;
    }

    /*
     * Typically we get a flood of these as the user resizes the window.
     * Wait until the dust has settled (one second without updates), then
     * go notify the guest.
     */
    con->ui_info = *info;
    timer_mod(con->ui_timer,
              qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + (delay ? 1000 : 0));
    return 0;
}

void dpy_gfx_update(QemuConsole *con, int x, int y, int w, int h)
{
    DisplayState *s = con->ds;
    DisplayChangeListener *dcl;
    int width = qemu_console_get_width(con, x + w);
    int height = qemu_console_get_height(con, y + h);

    x = MAX(x, 0);
    y = MAX(y, 0);
    x = MIN(x, width);
    y = MIN(y, height);
    w = MIN(w, width - x);
    h = MIN(h, height - y);

    if (!qemu_console_is_visible(con)) {
        return;
    }
    dpy_gfx_update_texture(con, con->surface, x, y, w, h);
    QLIST_FOREACH(dcl, &s->listeners, next) {
        if (con != dcl->con) {
            continue;
        }
        if (dcl->ops->dpy_gfx_update) {
            dcl->ops->dpy_gfx_update(dcl, x, y, w, h);
        }
    }
}

void dpy_gfx_update_full(QemuConsole *con)
{
    int w = qemu_console_get_width(con, 0);
    int h = qemu_console_get_height(con, 0);

    dpy_gfx_update(con, 0, 0, w, h);
}

void dpy_gfx_replace_surface(QemuConsole *con,
                             DisplaySurface *surface)
{
    static const char placeholder_msg[] = "Display output is not active.";
    DisplayState *s = con->ds;
    DisplaySurface *old_surface = con->surface;
    DisplaySurface *new_surface = surface;
    DisplayChangeListener *dcl;
    int width;
    int height;

    if (!surface) {
        if (old_surface) {
            width = surface_width(old_surface);
            height = surface_height(old_surface);
        } else {
            width = 640;
            height = 480;
        }

        new_surface = qemu_create_placeholder_surface(width, height, placeholder_msg);
    }

    assert(old_surface != new_surface);

    con->scanout.kind = SCANOUT_SURFACE;
    con->surface = new_surface;
    dpy_gfx_create_texture(con, new_surface);
    QLIST_FOREACH(dcl, &s->listeners, next) {
        if (con != dcl->con) {
            continue;
        }
        displaychangelistener_gfx_switch(dcl, new_surface, surface ? FALSE : TRUE);
    }
    dpy_gfx_destroy_texture(con, old_surface);
    qemu_free_displaysurface(old_surface);
}

bool dpy_gfx_check_format(QemuConsole *con,
                          pixman_format_code_t format)
{
    DisplayChangeListener *dcl;
    DisplayState *s = con->ds;

    QLIST_FOREACH(dcl, &s->listeners, next) {
        if (dcl->con && dcl->con != con) {
            /* dcl bound to another console -> skip */
            continue;
        }
        if (dcl->ops->dpy_gfx_check_format) {
            if (!dcl->ops->dpy_gfx_check_format(dcl, format)) {
                return false;
            }
        } else {
            /* default is to allow native 32 bpp only */
            if (format != qemu_default_pixman_format(32, true)) {
                return false;
            }
        }
    }
    return true;
}

static void dpy_refresh(DisplayState *s)
{
    DisplayChangeListener *dcl;

    QLIST_FOREACH(dcl, &s->listeners, next) {
        if (dcl->ops->dpy_refresh) {
            dcl->ops->dpy_refresh(dcl);
        }
    }
}

void dpy_text_cursor(QemuConsole *con, int x, int y)
{
    DisplayState *s = con->ds;
    DisplayChangeListener *dcl;

    if (!qemu_console_is_visible(con)) {
        return;
    }
    QLIST_FOREACH(dcl, &s->listeners, next) {
        if (con != dcl->con) {
            continue;
        }
        if (dcl->ops->dpy_text_cursor) {
            dcl->ops->dpy_text_cursor(dcl, x, y);
        }
    }
}

void dpy_text_update(QemuConsole *con, int x, int y, int w, int h)
{
    DisplayState *s = con->ds;
    DisplayChangeListener *dcl;

    if (!qemu_console_is_visible(con)) {
        return;
    }
    QLIST_FOREACH(dcl, &s->listeners, next) {
        if (con != dcl->con) {
            continue;
        }
        if (dcl->ops->dpy_text_update) {
            dcl->ops->dpy_text_update(dcl, x, y, w, h);
        }
    }
}

void dpy_text_resize(QemuConsole *con, int w, int h)
{
    DisplayState *s = con->ds;
    DisplayChangeListener *dcl;

    if (!qemu_console_is_visible(con)) {
        return;
    }
    QLIST_FOREACH(dcl, &s->listeners, next) {
        if (con != dcl->con) {
            continue;
        }
        if (dcl->ops->dpy_text_resize) {
            dcl->ops->dpy_text_resize(dcl, w, h);
        }
    }
}

void dpy_mouse_set(QemuConsole *c, int x, int y, bool on)
{
    QemuGraphicConsole *con = QEMU_GRAPHIC_CONSOLE(c);
    DisplayState *s = c->ds;
    DisplayChangeListener *dcl;

    con->cursor_x = x;
    con->cursor_y = y;
    con->cursor_on = on;
    if (!qemu_console_is_visible(c)) {
        return;
    }
    QLIST_FOREACH(dcl, &s->listeners, next) {
        if (c != dcl->con) {
            continue;
        }
        if (dcl->ops->dpy_mouse_set) {
            dcl->ops->dpy_mouse_set(dcl, x, y, on);
        }
    }
}

void dpy_cursor_define(QemuConsole *c, QEMUCursor *cursor)
{
    QemuGraphicConsole *con = QEMU_GRAPHIC_CONSOLE(c);
    DisplayState *s = c->ds;
    DisplayChangeListener *dcl;

    cursor_unref(con->cursor);
    con->cursor = cursor_ref(cursor);
    if (!qemu_console_is_visible(c)) {
        return;
    }
    QLIST_FOREACH(dcl, &s->listeners, next) {
        if (c != dcl->con) {
            continue;
        }
        if (dcl->ops->dpy_cursor_define) {
            dcl->ops->dpy_cursor_define(dcl, cursor);
        }
    }
}

QEMUGLContext dpy_gl_ctx_create(QemuConsole *con,
                                struct QEMUGLParams *qparams)
{
    assert(con->gl);
    return con->gl->ops->dpy_gl_ctx_create(con->gl, qparams);
}

void dpy_gl_ctx_destroy(QemuConsole *con, QEMUGLContext ctx)
{
    assert(con->gl);
    con->gl->ops->dpy_gl_ctx_destroy(con->gl, ctx);
}

int dpy_gl_ctx_make_current(QemuConsole *con, QEMUGLContext ctx)
{
    assert(con->gl);
    return con->gl->ops->dpy_gl_ctx_make_current(con->gl, ctx);
}

void dpy_gl_scanout_disable(QemuConsole *con)
{
    DisplayState *s = con->ds;
    DisplayChangeListener *dcl;

    if (con->scanout.kind != SCANOUT_SURFACE) {
        con->scanout.kind = SCANOUT_NONE;
    }
    QLIST_FOREACH(dcl, &s->listeners, next) {
        if (con != dcl->con) {
            continue;
        }
        if (dcl->ops->dpy_gl_scanout_disable) {
            dcl->ops->dpy_gl_scanout_disable(dcl);
        }
    }
}

void dpy_gl_scanout_texture(QemuConsole *con,
                            uint32_t backing_id,
                            bool backing_y_0_top,
                            uint32_t backing_width,
                            uint32_t backing_height,
                            uint32_t x, uint32_t y,
                            uint32_t width, uint32_t height,
                            void *d3d_tex2d)
{
    DisplayState *s = con->ds;
    DisplayChangeListener *dcl;

    con->scanout.kind = SCANOUT_TEXTURE;
    con->scanout.texture = (ScanoutTexture) {
        backing_id, backing_y_0_top, backing_width, backing_height,
        x, y, width, height, d3d_tex2d,
    };
    QLIST_FOREACH(dcl, &s->listeners, next) {
        if (con != dcl->con) {
            continue;
        }
        if (dcl->ops->dpy_gl_scanout_texture) {
            dcl->ops->dpy_gl_scanout_texture(dcl, backing_id,
                                             backing_y_0_top,
                                             backing_width, backing_height,
                                             x, y, width, height,
                                             d3d_tex2d);
        }
    }
}

void dpy_gl_scanout_dmabuf(QemuConsole *con,
                           QemuDmaBuf *dmabuf)
{
    DisplayState *s = con->ds;
    DisplayChangeListener *dcl;

    con->scanout.kind = SCANOUT_DMABUF;
    con->scanout.dmabuf = dmabuf;
    QLIST_FOREACH(dcl, &s->listeners, next) {
        if (con != dcl->con) {
            continue;
        }
        if (dcl->ops->dpy_gl_scanout_dmabuf) {
            dcl->ops->dpy_gl_scanout_dmabuf(dcl, dmabuf);
        }
    }
}

void dpy_gl_cursor_dmabuf(QemuConsole *con, QemuDmaBuf *dmabuf,
                          bool have_hot, uint32_t hot_x, uint32_t hot_y)
{
    DisplayState *s = con->ds;
    DisplayChangeListener *dcl;

    QLIST_FOREACH(dcl, &s->listeners, next) {
        if (con != dcl->con) {
            continue;
        }
        if (dcl->ops->dpy_gl_cursor_dmabuf) {
            dcl->ops->dpy_gl_cursor_dmabuf(dcl, dmabuf,
                                           have_hot, hot_x, hot_y);
        }
    }
}

void dpy_gl_cursor_position(QemuConsole *con,
                            uint32_t pos_x, uint32_t pos_y)
{
    DisplayState *s = con->ds;
    DisplayChangeListener *dcl;

    QLIST_FOREACH(dcl, &s->listeners, next) {
        if (con != dcl->con) {
            continue;
        }
        if (dcl->ops->dpy_gl_cursor_position) {
            dcl->ops->dpy_gl_cursor_position(dcl, pos_x, pos_y);
        }
    }
}

void dpy_gl_release_dmabuf(QemuConsole *con,
                          QemuDmaBuf *dmabuf)
{
    DisplayState *s = con->ds;
    DisplayChangeListener *dcl;

    QLIST_FOREACH(dcl, &s->listeners, next) {
        if (con != dcl->con) {
            continue;
        }
        if (dcl->ops->dpy_gl_release_dmabuf) {
            dcl->ops->dpy_gl_release_dmabuf(dcl, dmabuf);
        }
    }
}

void dpy_gl_update(QemuConsole *con,
                   uint32_t x, uint32_t y, uint32_t w, uint32_t h)
{
    DisplayState *s = con->ds;
    DisplayChangeListener *dcl;

    assert(con->gl);

    graphic_hw_gl_block(con, true);
    QLIST_FOREACH(dcl, &s->listeners, next) {
        if (con != dcl->con) {
            continue;
        }
        if (dcl->ops->dpy_gl_update) {
            dcl->ops->dpy_gl_update(dcl, x, y, w, h);
        }
    }
    graphic_hw_gl_block(con, false);
}

/***********************************************************/
/* register display */

/* console.c internal use only */
static DisplayState *get_alloc_displaystate(void)
{
    if (!display_state) {
        display_state = g_new0(DisplayState, 1);
    }
    return display_state;
}

/*
 * Called by main(), after creating QemuConsoles
 * and before initializing ui (sdl/vnc/...).
 */
DisplayState *init_displaystate(void)
{
    gchar *name;
    QemuConsole *con;

    QTAILQ_FOREACH(con, &consoles, next) {
        /* Hook up into the qom tree here (not in object_new()), once
         * all QemuConsoles are created and the order / numbering
         * doesn't change any more */
        name = g_strdup_printf("console[%d]", con->index);
        object_property_add_child(object_get_container("backend"),
                                  name, OBJECT(con));
        g_free(name);
    }

    return display_state;
}

void graphic_console_set_hwops(QemuConsole *con,
                               const GraphicHwOps *hw_ops,
                               void *opaque)
{
    con->hw_ops = hw_ops;
    con->hw = opaque;
}

QemuConsole *graphic_console_init(DeviceState *dev, uint32_t head,
                                  const GraphicHwOps *hw_ops,
                                  void *opaque)
{
    static const char noinit[] =
        "Guest has not initialized the display (yet).";
    int width = 640;
    int height = 480;
    QemuConsole *s;
    DisplaySurface *surface;

    s = qemu_graphic_console_lookup_unused();
    if (s) {
        trace_console_gfx_reuse(s->index);
        width = qemu_console_get_width(s, 0);
        height = qemu_console_get_height(s, 0);
    } else {
        trace_console_gfx_new();
        s = (QemuConsole *)object_new(TYPE_QEMU_GRAPHIC_CONSOLE);
    }
    QEMU_GRAPHIC_CONSOLE(s)->head = head;
    graphic_console_set_hwops(s, hw_ops, opaque);
    if (dev) {
        object_property_set_link(OBJECT(s), "device", OBJECT(dev),
                                 &error_abort);
    }

    surface = qemu_create_placeholder_surface(width, height, noinit);
    dpy_gfx_replace_surface(s, surface);
    s->gl_unblock_timer = timer_new_ms(QEMU_CLOCK_REALTIME,
                                       graphic_hw_gl_unblock_timer, s);
    return s;
}

static const GraphicHwOps unused_ops = {
    /* no callbacks */
};

void graphic_console_close(QemuConsole *con)
{
    static const char unplugged[] =
        "Guest display has been unplugged";
    DisplaySurface *surface;
    int width = qemu_console_get_width(con, 640);
    int height = qemu_console_get_height(con, 480);

    trace_console_gfx_close(con->index);
    object_property_set_link(OBJECT(con), "device", NULL, &error_abort);
    graphic_console_set_hwops(con, &unused_ops, NULL);

    if (con->gl) {
        dpy_gl_scanout_disable(con);
    }
    surface = qemu_create_placeholder_surface(width, height, unplugged);
    dpy_gfx_replace_surface(con, surface);
}

QemuConsole *qemu_console_lookup_default(void)
{
    QemuConsole *con;

    QTAILQ_FOREACH(con, &consoles, next) {
        if (QEMU_IS_GRAPHIC_CONSOLE(con)) {
            return con;
        }
    }
    return QTAILQ_FIRST(&consoles);
}

QemuConsole *qemu_console_lookup_by_index(unsigned int index)
{
    QemuConsole *con;

    QTAILQ_FOREACH(con, &consoles, next) {
        if (con->index == index) {
            return con;
        }
    }
    return NULL;
}

QemuConsole *qemu_console_lookup_by_device(DeviceState *dev, uint32_t head)
{
    QemuConsole *con;
    Object *obj;
    uint32_t h;

    QTAILQ_FOREACH(con, &consoles, next) {
        obj = object_property_get_link(OBJECT(con),
                                       "device", &error_abort);
        if (DEVICE(obj) != dev) {
            continue;
        }
        h = object_property_get_uint(OBJECT(con),
                                     "head", &error_abort);
        if (h != head) {
            continue;
        }
        return con;
    }
    return NULL;
}

QemuConsole *qemu_console_lookup_by_device_name(const char *device_id,
                                                uint32_t head, Error **errp)
{
    DeviceState *dev;
    QemuConsole *con;

    dev = qdev_find_recursive(sysbus_get_default(), device_id);
    if (dev == NULL) {
        error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
                  "Device '%s' not found", device_id);
        return NULL;
    }

    con = qemu_console_lookup_by_device(dev, head);
    if (con == NULL) {
        error_setg(errp, "Device %s (head %d) is not bound to a QemuConsole",
                   device_id, head);
        return NULL;
    }

    return con;
}

static QemuConsole *qemu_graphic_console_lookup_unused(void)
{
    QemuConsole *con;
    Object *obj;

    QTAILQ_FOREACH(con, &consoles, next) {
        if (!QEMU_IS_GRAPHIC_CONSOLE(con) || con->hw_ops != &unused_ops) {
            continue;
        }
        obj = object_property_get_link(OBJECT(con),
                                       "device", &error_abort);
        if (obj != NULL) {
            continue;
        }
        return con;
    }
    return NULL;
}

QEMUCursor *qemu_console_get_cursor(QemuConsole *con)
{
    return QEMU_IS_GRAPHIC_CONSOLE(con) ? QEMU_GRAPHIC_CONSOLE(con)->cursor : NULL;
}

bool qemu_console_is_visible(QemuConsole *con)
{
    return con->dcls > 0;
}

bool qemu_console_is_graphic(QemuConsole *con)
{
    return con && QEMU_IS_GRAPHIC_CONSOLE(con);
}

bool qemu_console_is_fixedsize(QemuConsole *con)
{
    return con && (QEMU_IS_GRAPHIC_CONSOLE(con) || QEMU_IS_FIXED_TEXT_CONSOLE(con));
}

bool qemu_console_is_gl_blocked(QemuConsole *con)
{
    assert(con != NULL);
    return con->gl_block;
}

static bool qemu_graphic_console_is_multihead(QemuGraphicConsole *c)
{
    QemuConsole *con;

    QTAILQ_FOREACH(con, &consoles, next) {
        QemuGraphicConsole *candidate;

        if (!QEMU_IS_GRAPHIC_CONSOLE(con)) {
            continue;
        }

        candidate = QEMU_GRAPHIC_CONSOLE(con);
        if (candidate->device != c->device) {
            continue;
        }

        if (candidate->head != c->head) {
            return true;
        }
    }
    return false;
}

char *qemu_console_get_label(QemuConsole *con)
{
    if (QEMU_IS_GRAPHIC_CONSOLE(con)) {
        QemuGraphicConsole *c = QEMU_GRAPHIC_CONSOLE(con);
        if (c->device) {
            DeviceState *dev;
            bool multihead;

            dev = DEVICE(c->device);
            multihead = qemu_graphic_console_is_multihead(c);
            if (multihead) {
                return g_strdup_printf("%s.%d", dev->id ?
                                       dev->id :
                                       object_get_typename(c->device),
                                       c->head);
            } else {
                return g_strdup(dev->id ? : object_get_typename(c->device));
            }
        }
        return g_strdup("VGA");
    } else if (QEMU_IS_TEXT_CONSOLE(con)) {
        const char *label = qemu_text_console_get_label(QEMU_TEXT_CONSOLE(con));
        if (label) {
            return g_strdup(label);
        }
    }

    return g_strdup_printf("vc%d", con->index);
}

int qemu_console_get_index(QemuConsole *con)
{
    return con ? con->index : -1;
}

uint32_t qemu_console_get_head(QemuConsole *con)
{
    if (con == NULL) {
        return -1;
    }
    if (QEMU_IS_GRAPHIC_CONSOLE(con)) {
        return QEMU_GRAPHIC_CONSOLE(con)->head;
    }
    return 0;
}

int qemu_console_get_width(QemuConsole *con, int fallback)
{
    if (con == NULL) {
        return fallback;
    }
    switch (con->scanout.kind) {
    case SCANOUT_DMABUF:
        return qemu_dmabuf_get_width(con->scanout.dmabuf);
    case SCANOUT_TEXTURE:
        return con->scanout.texture.width;
    case SCANOUT_SURFACE:
        return surface_width(con->surface);
    default:
        return fallback;
    }
}

int qemu_console_get_height(QemuConsole *con, int fallback)
{
    if (con == NULL) {
        return fallback;
    }
    switch (con->scanout.kind) {
    case SCANOUT_DMABUF:
        return qemu_dmabuf_get_height(con->scanout.dmabuf);
    case SCANOUT_TEXTURE:
        return con->scanout.texture.height;
    case SCANOUT_SURFACE:
        return surface_height(con->surface);
    default:
        return fallback;
    }
}

int qemu_invalidate_text_consoles(void)
{
    QemuConsole *s;
    int count = 0;

    QTAILQ_FOREACH(s, &consoles, next) {
        if (qemu_console_is_graphic(s) ||
            !qemu_console_is_visible(s)) {
            continue;
        }
        count++;
        graphic_hw_invalidate(s);
    }

    return count;
}

void qemu_console_resize(QemuConsole *s, int width, int height)
{
    DisplaySurface *surface = qemu_console_surface(s);

    assert(QEMU_IS_GRAPHIC_CONSOLE(s));

    if ((s->scanout.kind != SCANOUT_SURFACE ||
         (surface && surface_is_allocated(surface) &&
                     !surface_is_placeholder(surface))) &&
        qemu_console_get_width(s, -1) == width &&
        qemu_console_get_height(s, -1) == height) {
        return;
    }

    surface = qemu_create_displaysurface(width, height);
    dpy_gfx_replace_surface(s, surface);
}

DisplaySurface *qemu_console_surface(QemuConsole *console)
{
    switch (console->scanout.kind) {
    case SCANOUT_SURFACE:
        return console->surface;
    default:
        return NULL;
    }
}

PixelFormat qemu_default_pixelformat(int bpp)
{
    pixman_format_code_t fmt = qemu_default_pixman_format(bpp, true);
    PixelFormat pf = qemu_pixelformat_from_pixman(fmt);
    return pf;
}

static QemuDisplay *dpys[DISPLAY_TYPE__MAX];

void qemu_display_register(QemuDisplay *ui)
{
    assert(ui->type < DISPLAY_TYPE__MAX);
    dpys[ui->type] = ui;
}

bool qemu_display_find_default(DisplayOptions *opts)
{
    static DisplayType prio[] = {
#if defined(CONFIG_GTK)
        DISPLAY_TYPE_GTK,
#endif
#if defined(CONFIG_SDL)
        DISPLAY_TYPE_SDL,
#endif
#if defined(CONFIG_COCOA)
        DISPLAY_TYPE_COCOA
#endif
    };
    int i;

    for (i = 0; i < (int)ARRAY_SIZE(prio); i++) {
        if (dpys[prio[i]] == NULL) {
            Error *local_err = NULL;
            int rv = ui_module_load(DisplayType_str(prio[i]), &local_err);
            if (rv < 0) {
                error_report_err(local_err);
            }
        }
        if (dpys[prio[i]] == NULL) {
            continue;
        }
        opts->type = prio[i];
        return true;
    }
    return false;
}

void qemu_display_early_init(DisplayOptions *opts)
{
    assert(opts->type < DISPLAY_TYPE__MAX);
    if (opts->type == DISPLAY_TYPE_NONE) {
        return;
    }
    if (dpys[opts->type] == NULL) {
        Error *local_err = NULL;
        int rv = ui_module_load(DisplayType_str(opts->type), &local_err);
        if (rv < 0) {
            error_report_err(local_err);
        }
    }
    if (dpys[opts->type] == NULL) {
        error_report("Display '%s' is not available.",
                     DisplayType_str(opts->type));
        exit(1);
    }
    if (dpys[opts->type]->early_init) {
        dpys[opts->type]->early_init(opts);
    }
}

void qemu_display_init(DisplayState *ds, DisplayOptions *opts)
{
    assert(opts->type < DISPLAY_TYPE__MAX);
    if (opts->type == DISPLAY_TYPE_NONE) {
        return;
    }
    assert(dpys[opts->type] != NULL);
    dpys[opts->type]->init(ds, opts);
}

const char *qemu_display_get_vc(DisplayOptions *opts)
{
#ifdef CONFIG_PIXMAN
    const char *vc = "vc:80Cx24C";
#else
    const char *vc = NULL;
#endif

    assert(opts->type < DISPLAY_TYPE__MAX);
    if (dpys[opts->type] && dpys[opts->type]->vc) {
        vc = dpys[opts->type]->vc;
    }
    return vc;
}

void qemu_display_help(void)
{
    int idx;

    printf("Available display backend types:\n");
    printf("none\n");
    for (idx = DISPLAY_TYPE_NONE; idx < DISPLAY_TYPE__MAX; idx++) {
        if (!dpys[idx]) {
            Error *local_err = NULL;
            int rv = ui_module_load(DisplayType_str(idx), &local_err);
            if (rv < 0) {
                error_report_err(local_err);
            }
        }
        if (dpys[idx]) {
            printf("%s\n",  DisplayType_str(dpys[idx]->type));
        }
    }
    printf("\n"
           "Some display backends support suboptions, which can be set with\n"
           "   -display backend,option=value,option=value...\n"
           "For a short list of the suboptions for each display, see the "
           "top-level -help output; more detail is in the documentation.\n");
}