try catch weird racey corner case where we try fallback to a window but it unmaps...

[chaz/openbox] / openbox / focus.c

/* -*- indent-tabs-mode: nil; tab-width: 4; c-basic-offset: 4; -*-

   focus.c for the Openbox window manager
   Copyright (c) 2006        Mikael Magnusson
   Copyright (c) 2003-2007   Dana Jansens

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   See the COPYING file for a copy of the GNU General Public License.
*/

#include "debug.h"
#include "event.h"
#include "openbox.h"
#include "grab.h"
#include "framerender.h"
#include "client.h"
#include "config.h"
#include "frame.h"
#include "screen.h"
#include "group.h"
#include "prop.h"
#include "focus.h"
#include "stacking.h"
#include "popup.h"
#include "render/render.h"

#include <X11/Xlib.h>
#include <glib.h>
#include <assert.h>

#define FOCUS_INDICATOR_WIDTH 6

ObClient *focus_client = NULL;
GList *focus_order = NULL;
ObClient *focus_cycle_target = NULL;

struct {
    InternalWindow top;
    InternalWindow left;
    InternalWindow right;
    InternalWindow bottom;
} focus_indicator;

RrAppearance *a_focus_indicator;
RrColor *color_white;

static ObIconPopup *focus_cycle_popup;

static gboolean valid_focus_target(ObClient *ft,
                                   gboolean all_desktops,
                                   gboolean dock_windows);
static void focus_cycle_destructor(ObClient *client, gpointer data);

static Window createWindow(Window parent, gulong mask,
                           XSetWindowAttributes *attrib)
{
    return XCreateWindow(ob_display, parent, 0, 0, 1, 1, 0,
                         RrDepth(ob_rr_inst), InputOutput,
                         RrVisual(ob_rr_inst), mask, attrib);
                       
}

void focus_startup(gboolean reconfig)
{
    focus_cycle_popup = icon_popup_new(TRUE);

    if (!reconfig) {
        XSetWindowAttributes attr;

        client_add_destructor(focus_cycle_destructor, NULL);

        /* start with nothing focused */
        focus_nothing();

        focus_indicator.top.obwin.type = Window_Internal;
        focus_indicator.left.obwin.type = Window_Internal;
        focus_indicator.right.obwin.type = Window_Internal;
        focus_indicator.bottom.obwin.type = Window_Internal;

        attr.override_redirect = True;
        attr.background_pixel = BlackPixel(ob_display, ob_screen);
        focus_indicator.top.win =
            createWindow(RootWindow(ob_display, ob_screen),
                         CWOverrideRedirect | CWBackPixel, &attr);
        focus_indicator.left.win =
            createWindow(RootWindow(ob_display, ob_screen),
                         CWOverrideRedirect | CWBackPixel, &attr);
        focus_indicator.right.win =
            createWindow(RootWindow(ob_display, ob_screen),
                         CWOverrideRedirect | CWBackPixel, &attr);
        focus_indicator.bottom.win =
            createWindow(RootWindow(ob_display, ob_screen),
                         CWOverrideRedirect | CWBackPixel, &attr);

        stacking_add(INTERNAL_AS_WINDOW(&focus_indicator.top));
        stacking_add(INTERNAL_AS_WINDOW(&focus_indicator.left));
        stacking_add(INTERNAL_AS_WINDOW(&focus_indicator.right));
        stacking_add(INTERNAL_AS_WINDOW(&focus_indicator.bottom));

        color_white = RrColorNew(ob_rr_inst, 0xff, 0xff, 0xff);

        a_focus_indicator = RrAppearanceNew(ob_rr_inst, 4);
        a_focus_indicator->surface.grad = RR_SURFACE_SOLID;
        a_focus_indicator->surface.relief = RR_RELIEF_FLAT;
        a_focus_indicator->surface.primary = RrColorNew(ob_rr_inst,
                                                        0, 0, 0);
        a_focus_indicator->texture[0].type = RR_TEXTURE_LINE_ART;
        a_focus_indicator->texture[0].data.lineart.color = color_white;
        a_focus_indicator->texture[1].type = RR_TEXTURE_LINE_ART;
        a_focus_indicator->texture[1].data.lineart.color = color_white;
        a_focus_indicator->texture[2].type = RR_TEXTURE_LINE_ART;
        a_focus_indicator->texture[2].data.lineart.color = color_white;
        a_focus_indicator->texture[3].type = RR_TEXTURE_LINE_ART;
        a_focus_indicator->texture[3].data.lineart.color = color_white;
    }
}

void focus_shutdown(gboolean reconfig)
{
    icon_popup_free(focus_cycle_popup);

    if (!reconfig) {
        client_remove_destructor(focus_cycle_destructor);

        /* reset focus to root */
        XSetInputFocus(ob_display, PointerRoot, RevertToNone, CurrentTime);

        RrColorFree(color_white);

        RrAppearanceFree(a_focus_indicator);

        XDestroyWindow(ob_display, focus_indicator.top.win);
        XDestroyWindow(ob_display, focus_indicator.left.win);
        XDestroyWindow(ob_display, focus_indicator.right.win);
        XDestroyWindow(ob_display, focus_indicator.bottom.win);
    }
}

static void push_to_top(ObClient *client)
{
    focus_order = g_list_remove(focus_order, client);
    focus_order = g_list_prepend(focus_order, client);
}

void focus_set_client(ObClient *client)
{
    Window active;

    ob_debug_type(OB_DEBUG_FOCUS,
                  "focus_set_client 0x%lx\n", client ? client->window : 0);

    /* uninstall the old colormap, and install the new one */
    screen_install_colormap(focus_client, FALSE);
    screen_install_colormap(client, TRUE);

    /* in the middle of cycling..? kill it. CurrentTime is fine, time won't
       be used.
    */
    if (focus_cycle_target)
        focus_cycle(TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE);

    focus_client = client;

    if (client != NULL) {
        /* move to the top of the list */
        push_to_top(client);
        /* remove hiliting from the window when it gets focused */
        client_hilite(client, FALSE);
    }

    /* set the NET_ACTIVE_WINDOW hint, but preserve it on shutdown */
    if (ob_state() != OB_STATE_EXITING) {
        active = client ? client->window : None;
        PROP_SET32(RootWindow(ob_display, ob_screen),
                   net_active_window, window, active);
    }
}

ObClient* focus_fallback_target(gboolean allow_refocus, ObClient *old)
{
    GList *it;
    ObClient *target = NULL;
    ObClient *desktop = NULL;

    ob_debug_type(OB_DEBUG_FOCUS, "trying pointer stuff\n");
    if (config_focus_follow && !config_focus_last)
    {
        if ((target = client_under_pointer()))
            if (allow_refocus || target != old)
                if (client_normal(target) && client_can_focus(target)) {
                    ob_debug_type(OB_DEBUG_FOCUS, "found in pointer stuff\n");
                    return target;
                }
    }

#if 0
        /* try for group relations */
        if (old->group) {
            GSList *sit;

            for (it = focus_order[screen_desktop]; it; it = g_list_next(it))
                for (sit = old->group->members; sit; sit = g_slist_next(sit))
                    if (sit->data == it->data)
                        if (sit->data != old && client_normal(sit->data))
                            if (client_can_focus(sit->data))
                                return sit->data;
        }
#endif

    ob_debug_type(OB_DEBUG_FOCUS, "trying omnipresentness\n");
    if (allow_refocus && old && old->desktop == DESKTOP_ALL &&
        client_normal(old))
    {
        return old;
    }


    ob_debug_type(OB_DEBUG_FOCUS, "trying the focus order\n");
    for (it = focus_order; it; it = g_list_next(it))
        if (allow_refocus || it->data != old) {
            ObClient *c = it->data;
            /* fallback focus to a window if:
               1. it is actually focusable, cuz if it's not then we're sending
               focus off to nothing. this includes if it is visible right now
               2. it is on the current desktop. this ignores omnipresent
               windows, which are problematic in their own rite.
               3. it is a normal type window, don't fall back onto a dock or
               a splashscreen or a desktop window (save the desktop as a
               backup fallback though)
            */
            if (client_can_focus(c))
            {
                if (c->desktop == screen_desktop && client_normal(c)) {
                    ob_debug_type(OB_DEBUG_FOCUS, "found in focus order\n");
                    return it->data;
                } else if (c->type == OB_CLIENT_TYPE_DESKTOP && 
                           desktop == NULL)
                    desktop = c;
            }
        }

    /* as a last resort fallback to the desktop window if there is one.
       (if there's more than one, then the one most recently focused.)
    */
    ob_debug_type(OB_DEBUG_FOCUS, "found desktop: \n", !!desktop);
    return desktop;   
}

ObClient* focus_fallback(gboolean allow_refocus)
{
    ObClient *new;
    ObClient *old = focus_client;

    /* unfocus any focused clients.. they can be focused by Pointer events
       and such, and then when I try focus them, I won't get a FocusIn event
       at all for them.
    */
    focus_nothing();

    if ((new = focus_fallback_target(allow_refocus, old))) {
        client_focus(new);
        return new;
    } else
        return NULL;
}

void focus_nothing()
{
    /* Install our own colormap */
    if (focus_client != NULL) {
        screen_install_colormap(focus_client, FALSE);
        screen_install_colormap(NULL, TRUE);
    }

    focus_client = NULL;

    /* when nothing will be focused, send focus to the backup target */
    XSetInputFocus(ob_display, screen_support_win, RevertToPointerRoot,
                   event_curtime);
}

static gchar *popup_get_name(ObClient *c, ObClient **nametarget)
{
    ObClient *p;
    gchar *title = NULL;
    const gchar *desk = NULL;
    gchar *ret;

    /* find our highest direct parent, including non-normal windows */
    for (p = c; p->transient_for && p->transient_for != OB_TRAN_GROUP;
         p = p->transient_for);

    if (c->desktop != DESKTOP_ALL && c->desktop != screen_desktop)
        desk = screen_desktop_names[c->desktop];

    /* use the transient's parent's title/icon if we don't have one */
    if (p != c && !strcmp("", (c->iconic ? c->icon_title : c->title)))
        title = g_strdup(p->iconic ? p->icon_title : p->title);

    if (title == NULL)
        title = g_strdup(c->iconic ? c->icon_title : c->title);

    if (desk)
        ret = g_strdup_printf("%s [%s]", title, desk);
    else {
        ret = title;
        title = NULL;
    }
    g_free(title);

    /* set this only if we're returning true and they asked for it */
    if (ret && nametarget) *nametarget = p;
    return ret;
}

static void popup_cycle(ObClient *c, gboolean show,
                        gboolean all_desktops, gboolean dock_windows)
{
    gchar *showtext = NULL;
    ObClient *showtarget;

    if (!show) {
        icon_popup_hide(focus_cycle_popup);
        return;
    }

    /* do this stuff only when the dialog is first showing */
    if (!focus_cycle_popup->popup->mapped &&
        !focus_cycle_popup->popup->delay_mapped)
    {
        Rect *a;
        gchar **names;
        GList *targets = NULL, *it;
        gint n = 0, i;

        /* position the popup */
        a = screen_physical_area_monitor(0);
        icon_popup_position(focus_cycle_popup, CenterGravity,
                            a->x + a->width / 2, a->y + a->height / 2);
        icon_popup_height(focus_cycle_popup, POPUP_HEIGHT);
        icon_popup_min_width(focus_cycle_popup, POPUP_WIDTH);
        icon_popup_max_width(focus_cycle_popup,
                             MAX(a->width/3, POPUP_WIDTH));


        /* make its width to be the width of all the possible titles */

        /* build a list of all the valid focus targets */
        for (it = focus_order; it; it = g_list_next(it)) {
            ObClient *ft = it->data;
            if (valid_focus_target(ft, all_desktops, dock_windows)) {
                targets = g_list_prepend(targets, ft);
                ++n;
            }
        }
        /* make it null terminated so we can use g_strfreev */
        names = g_new(char*, n+1);
        for (it = targets, i = 0; it; it = g_list_next(it), ++i) {
            ObClient *ft = it->data, *t;
            names[i] = popup_get_name(ft, &t);

            /* little optimization.. save this text and client, so we dont
               have to get it again */
            if (ft == c) {
                showtext = g_strdup(names[i]);
                showtarget = t;
            }
        }
        names[n] = NULL;

        icon_popup_text_width_to_strings(focus_cycle_popup, names, n);
        g_strfreev(names);
    }


    if (!showtext) showtext = popup_get_name(c, &showtarget);
    icon_popup_show(focus_cycle_popup, showtext,
                    client_icon(showtarget, 48, 48));
    g_free(showtext);
}

static void focus_cycle_destructor(ObClient *client, gpointer data)
{
    /* end cycling if the target disappears. CurrentTime is fine, time won't
       be used
    */
    if (focus_cycle_target == client)
        focus_cycle(TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE);
}

void focus_cycle_draw_indicator()
{
    if (!focus_cycle_target) {
        XUnmapWindow(ob_display, focus_indicator.top.win);
        XUnmapWindow(ob_display, focus_indicator.left.win);
        XUnmapWindow(ob_display, focus_indicator.right.win);
        XUnmapWindow(ob_display, focus_indicator.bottom.win);

        /* kill enter events cause by this unmapping */
        event_ignore_queued_enters();
    } else {
        /*
          if (focus_cycle_target)
              frame_adjust_focus(focus_cycle_target->frame, FALSE);
          frame_adjust_focus(focus_cycle_target->frame, TRUE);
        */
        gint x, y, w, h;
        gint wt, wl, wr, wb;

        wt = wl = wr = wb = FOCUS_INDICATOR_WIDTH;

        x = focus_cycle_target->frame->area.x;
        y = focus_cycle_target->frame->area.y;
        w = focus_cycle_target->frame->area.width;
        h = wt;

        XMoveResizeWindow(ob_display, focus_indicator.top.win,
                          x, y, w, h);
        a_focus_indicator->texture[0].data.lineart.x1 = 0;
        a_focus_indicator->texture[0].data.lineart.y1 = h-1;
        a_focus_indicator->texture[0].data.lineart.x2 = 0;
        a_focus_indicator->texture[0].data.lineart.y2 = 0;
        a_focus_indicator->texture[1].data.lineart.x1 = 0;
        a_focus_indicator->texture[1].data.lineart.y1 = 0;
        a_focus_indicator->texture[1].data.lineart.x2 = w-1;
        a_focus_indicator->texture[1].data.lineart.y2 = 0;
        a_focus_indicator->texture[2].data.lineart.x1 = w-1;
        a_focus_indicator->texture[2].data.lineart.y1 = 0;
        a_focus_indicator->texture[2].data.lineart.x2 = w-1;
        a_focus_indicator->texture[2].data.lineart.y2 = h-1;
        a_focus_indicator->texture[3].data.lineart.x1 = (wl-1);
        a_focus_indicator->texture[3].data.lineart.y1 = h-1;
        a_focus_indicator->texture[3].data.lineart.x2 = w - wr;
        a_focus_indicator->texture[3].data.lineart.y2 = h-1;
        RrPaint(a_focus_indicator, focus_indicator.top.win,
                w, h);

        x = focus_cycle_target->frame->area.x;
        y = focus_cycle_target->frame->area.y;
        w = wl;
        h = focus_cycle_target->frame->area.height;

        XMoveResizeWindow(ob_display, focus_indicator.left.win,
                          x, y, w, h);
        a_focus_indicator->texture[0].data.lineart.x1 = w-1;
        a_focus_indicator->texture[0].data.lineart.y1 = 0;
        a_focus_indicator->texture[0].data.lineart.x2 = 0;
        a_focus_indicator->texture[0].data.lineart.y2 = 0;
        a_focus_indicator->texture[1].data.lineart.x1 = 0;
        a_focus_indicator->texture[1].data.lineart.y1 = 0;
        a_focus_indicator->texture[1].data.lineart.x2 = 0;
        a_focus_indicator->texture[1].data.lineart.y2 = h-1;
        a_focus_indicator->texture[2].data.lineart.x1 = 0;
        a_focus_indicator->texture[2].data.lineart.y1 = h-1;
        a_focus_indicator->texture[2].data.lineart.x2 = w-1;
        a_focus_indicator->texture[2].data.lineart.y2 = h-1;
        a_focus_indicator->texture[3].data.lineart.x1 = w-1;
        a_focus_indicator->texture[3].data.lineart.y1 = wt-1;
        a_focus_indicator->texture[3].data.lineart.x2 = w-1;
        a_focus_indicator->texture[3].data.lineart.y2 = h - wb;
        RrPaint(a_focus_indicator, focus_indicator.left.win,
                w, h);

        x = focus_cycle_target->frame->area.x +
            focus_cycle_target->frame->area.width - wr;
        y = focus_cycle_target->frame->area.y;
        w = wr;
        h = focus_cycle_target->frame->area.height ;

        XMoveResizeWindow(ob_display, focus_indicator.right.win,
                          x, y, w, h);
        a_focus_indicator->texture[0].data.lineart.x1 = 0;
        a_focus_indicator->texture[0].data.lineart.y1 = 0;
        a_focus_indicator->texture[0].data.lineart.x2 = w-1;
        a_focus_indicator->texture[0].data.lineart.y2 = 0;
        a_focus_indicator->texture[1].data.lineart.x1 = w-1;
        a_focus_indicator->texture[1].data.lineart.y1 = 0;
        a_focus_indicator->texture[1].data.lineart.x2 = w-1;
        a_focus_indicator->texture[1].data.lineart.y2 = h-1;
        a_focus_indicator->texture[2].data.lineart.x1 = w-1;
        a_focus_indicator->texture[2].data.lineart.y1 = h-1;
        a_focus_indicator->texture[2].data.lineart.x2 = 0;
        a_focus_indicator->texture[2].data.lineart.y2 = h-1;
        a_focus_indicator->texture[3].data.lineart.x1 = 0;
        a_focus_indicator->texture[3].data.lineart.y1 = wt-1;
        a_focus_indicator->texture[3].data.lineart.x2 = 0;
        a_focus_indicator->texture[3].data.lineart.y2 = h - wb;
        RrPaint(a_focus_indicator, focus_indicator.right.win,
                w, h);

        x = focus_cycle_target->frame->area.x;
        y = focus_cycle_target->frame->area.y +
            focus_cycle_target->frame->area.height - wb;
        w = focus_cycle_target->frame->area.width;
        h = wb;

        XMoveResizeWindow(ob_display, focus_indicator.bottom.win,
                          x, y, w, h);
        a_focus_indicator->texture[0].data.lineart.x1 = 0;
        a_focus_indicator->texture[0].data.lineart.y1 = 0;
        a_focus_indicator->texture[0].data.lineart.x2 = 0;
        a_focus_indicator->texture[0].data.lineart.y2 = h-1;
        a_focus_indicator->texture[1].data.lineart.x1 = 0;
        a_focus_indicator->texture[1].data.lineart.y1 = h-1;
        a_focus_indicator->texture[1].data.lineart.x2 = w-1;
        a_focus_indicator->texture[1].data.lineart.y2 = h-1;
        a_focus_indicator->texture[2].data.lineart.x1 = w-1;
        a_focus_indicator->texture[2].data.lineart.y1 = h-1;
        a_focus_indicator->texture[2].data.lineart.x2 = w-1;
        a_focus_indicator->texture[2].data.lineart.y2 = 0;
        a_focus_indicator->texture[3].data.lineart.x1 = wl-1;
        a_focus_indicator->texture[3].data.lineart.y1 = 0;
        a_focus_indicator->texture[3].data.lineart.x2 = w - wr;
        a_focus_indicator->texture[3].data.lineart.y2 = 0;
        RrPaint(a_focus_indicator, focus_indicator.bottom.win,
                w, h);

        XMapWindow(ob_display, focus_indicator.top.win);
        XMapWindow(ob_display, focus_indicator.left.win);
        XMapWindow(ob_display, focus_indicator.right.win);
        XMapWindow(ob_display, focus_indicator.bottom.win);
    }
}

static gboolean has_valid_group_siblings_on_desktop(ObClient *ft,
                                                    gboolean all_desktops)
                                                         
{
    GSList *it;

    if (!ft->group) return FALSE;

    for (it = ft->group->members; it; it = g_slist_next(it)) {
        ObClient *c = it->data;
        /* check that it's not a helper window to avoid infinite recursion */
        if (c != ft && !client_helper(c) &&
            valid_focus_target(c, all_desktops, FALSE))
        {
            return TRUE;
        }
    }
    return FALSE;
}

/*! @param allow_helpers This is used for calling itself recursively while
                         checking helper windows. */
static gboolean valid_focus_target(ObClient *ft,
                                   gboolean all_desktops,
                                   gboolean dock_windows)
{
    gboolean ok = FALSE;

    /* it's on this desktop unless you want all desktops.

       do this check first because it will usually filter out the most
       windows */
    ok = (all_desktops || ft->desktop == screen_desktop ||
          ft->desktop == DESKTOP_ALL);

    /* the window can receive focus somehow */
    ok = ok && (ft->can_focus || ft->focus_notify);

    /* it's the right type of window */
    if (dock_windows)
        ok = ok && ft->type == OB_CLIENT_TYPE_DOCK;
    else
        /* normal non-helper windows are valid targets */
        ok = ok &&
            ((client_normal(ft) && !client_helper(ft))
             ||
             /* helper windows are valid targets it... */
             (client_helper(ft) &&
              /* ...a window in its group already has focus ... */
              ((focus_client && ft->group == focus_client->group) ||
               /* ... or if there are no other windows in its group 
                  that can be cycled to instead */
               !has_valid_group_siblings_on_desktop(ft, all_desktops))));

    /* it's not set to skip the taskbar (unless it is a type that would be
       expected to set this hint */
    ok = ok && ((ft->type == OB_CLIENT_TYPE_DOCK ||
                 ft->type == OB_CLIENT_TYPE_TOOLBAR ||
                 ft->type == OB_CLIENT_TYPE_MENU ||
                 ft->type == OB_CLIENT_TYPE_UTILITY) ||
                !ft->skip_taskbar);

    /* it's not going to just send fous off somewhere else (modal window) */
    ok = ok && ft == client_focus_target(ft);

    return ok;
}

void focus_cycle(gboolean forward, gboolean all_desktops,
                 gboolean dock_windows,
                 gboolean linear, gboolean interactive,
                 gboolean dialog, gboolean done, gboolean cancel)
{
    static ObClient *first = NULL;
    static ObClient *t = NULL;
    static GList *order = NULL;
    GList *it, *start, *list;
    ObClient *ft = NULL;

    if (interactive) {
        if (cancel) {
            focus_cycle_target = NULL;
            goto done_cycle;
        } else if (done)
            goto done_cycle;

        if (!focus_order)
            goto done_cycle;

        if (!first) first = focus_client;

        if (linear) list = client_list;
        else        list = focus_order;
    } else {
        if (!focus_order)
            goto done_cycle;
        list = client_list;
    }
    if (!focus_cycle_target) focus_cycle_target = focus_client;

    start = it = g_list_find(list, focus_cycle_target);
    if (!start) /* switched desktops or something? */
        start = it = forward ? g_list_last(list) : g_list_first(list);
    if (!start) goto done_cycle;

    do {
        if (forward) {
            it = it->next;
            if (it == NULL) it = g_list_first(list);
        } else {
            it = it->prev;
            if (it == NULL) it = g_list_last(list);
        }
        ft = it->data;
        if (valid_focus_target(ft, all_desktops, dock_windows)) {
            if (interactive) {
                if (ft != focus_cycle_target) { /* prevents flicker */
                    focus_cycle_target = ft;
                    focus_cycle_draw_indicator();
                }
                /* same arguments as valid_focus_target */
                popup_cycle(ft, dialog, all_desktops, dock_windows);
                return;
            } else if (ft != focus_cycle_target) {
                focus_cycle_target = ft;
                done = TRUE;
                break;
            }
        }
    } while (it != start);

done_cycle:
    if (done && focus_cycle_target)
        client_activate(focus_cycle_target, FALSE, TRUE);

    t = NULL;
    first = NULL;
    focus_cycle_target = NULL;
    g_list_free(order);
    order = NULL;

    if (interactive) {
        focus_cycle_draw_indicator();
        popup_cycle(ft, FALSE, FALSE, FALSE);
    }

    return;
}

/* this be mostly ripped from fvwm */
static ObClient *focus_find_directional(ObClient *c, ObDirection dir,
                                 gboolean dock_windows) 
{
    gint my_cx, my_cy, his_cx, his_cy;
    gint offset = 0;
    gint distance = 0;
    gint score, best_score;
    ObClient *best_client, *cur;
    GList *it;

    if(!client_list)
        return NULL;

    /* first, find the centre coords of the currently focused window */
    my_cx = c->frame->area.x + c->frame->area.width / 2;
    my_cy = c->frame->area.y + c->frame->area.height / 2;

    best_score = -1;
    best_client = NULL;

    for(it = g_list_first(client_list); it; it = g_list_next(it)) {
        cur = it->data;

        /* the currently selected window isn't interesting */
        if(cur == c)
            continue;
        if (!dock_windows && !client_normal(cur))
            continue;
        if (dock_windows && cur->type != OB_CLIENT_TYPE_DOCK)
            continue;
        /* using c->desktop instead of screen_desktop doesn't work if the
         * current window was omnipresent, hope this doesn't have any other
         * side effects */
        if(screen_desktop != cur->desktop && cur->desktop != DESKTOP_ALL)
            continue;
        if(cur->iconic)
            continue;
        if(!(client_focus_target(cur) == cur &&
             client_can_focus(cur)))
            continue;

        /* find the centre coords of this window, from the
         * currently focused window's point of view */
        his_cx = (cur->frame->area.x - my_cx)
            + cur->frame->area.width / 2;
        his_cy = (cur->frame->area.y - my_cy)
            + cur->frame->area.height / 2;

        if(dir == OB_DIRECTION_NORTHEAST || dir == OB_DIRECTION_SOUTHEAST ||
           dir == OB_DIRECTION_SOUTHWEST || dir == OB_DIRECTION_NORTHWEST) {
            gint tx;
            /* Rotate the diagonals 45 degrees counterclockwise.
             * To do this, multiply the matrix /+h +h\ with the
             * vector (x y).                   \-h +h/
             * h = sqrt(0.5). We can set h := 1 since absolute
             * distance doesn't matter here. */
            tx = his_cx + his_cy;
            his_cy = -his_cx + his_cy;
            his_cx = tx;
        }

        switch(dir) {
        case OB_DIRECTION_NORTH:
        case OB_DIRECTION_SOUTH:
        case OB_DIRECTION_NORTHEAST:
        case OB_DIRECTION_SOUTHWEST:
            offset = (his_cx < 0) ? -his_cx : his_cx;
            distance = ((dir == OB_DIRECTION_NORTH ||
                         dir == OB_DIRECTION_NORTHEAST) ?
                        -his_cy : his_cy);
            break;
        case OB_DIRECTION_EAST:
        case OB_DIRECTION_WEST:
        case OB_DIRECTION_SOUTHEAST:
        case OB_DIRECTION_NORTHWEST:
            offset = (his_cy < 0) ? -his_cy : his_cy;
            distance = ((dir == OB_DIRECTION_WEST ||
                         dir == OB_DIRECTION_NORTHWEST) ?
                        -his_cx : his_cx);
            break;
        }

        /* the target must be in the requested direction */
        if(distance <= 0)
            continue;

        /* Calculate score for this window.  The smaller the better. */
        score = distance + offset;

        /* windows more than 45 degrees off the direction are
         * heavily penalized and will only be chosen if nothing
         * else within a million pixels */
        if(offset > distance)
            score += 1000000;

        if(best_score == -1 || score < best_score)
            best_client = cur,
                best_score = score;
    }

    return best_client;
}

void focus_directional_cycle(ObDirection dir, gboolean dock_windows,
                             gboolean interactive,
                             gboolean dialog, gboolean done, gboolean cancel)
{
    static ObClient *first = NULL;
    ObClient *ft = NULL;

    if (!interactive)
        return;

    if (cancel) {
        focus_cycle_target = NULL;
        goto done_cycle;
    } else if (done)
        goto done_cycle;

    if (!focus_order)
        goto done_cycle;

    if (!first) first = focus_client;
    if (!focus_cycle_target) focus_cycle_target = focus_client;

    if (focus_cycle_target)
        ft = focus_find_directional(focus_cycle_target, dir, dock_windows);
    else {
        GList *it;

        for (it = focus_order; it; it = g_list_next(it))
            if (valid_focus_target(it->data, FALSE, dock_windows))
                ft = it->data;
    }
        
    if (ft) {
        if (ft != focus_cycle_target) {/* prevents flicker */
            focus_cycle_target = ft;
            focus_cycle_draw_indicator();
        }
    }
    if (focus_cycle_target) {
        /* same arguments as valid_focus_target */
        popup_cycle(focus_cycle_target, dialog, FALSE, dock_windows);
        if (dialog)
            return;
    }


done_cycle:
    if (done && focus_cycle_target)
        client_activate(focus_cycle_target, FALSE, TRUE);

    first = NULL;
    focus_cycle_target = NULL;

    focus_cycle_draw_indicator();
    popup_cycle(ft, FALSE, FALSE, FALSE);

    return;
}

void focus_order_add_new(ObClient *c)
{
    if (c->iconic)
        focus_order_to_top(c);
    else {
        g_assert(!g_list_find(focus_order, c));
        /* if there are any iconic windows, put this above them in the order,
           but if there are not, then put it under the currently focused one */
        if (focus_order && ((ObClient*)focus_order->data)->iconic)
            focus_order = g_list_insert(focus_order, c, 0);
        else
            focus_order = g_list_insert(focus_order, c, 1);
    }
}

void focus_order_remove(ObClient *c)
{
    focus_order = g_list_remove(focus_order, c);
}

void focus_order_to_top(ObClient *c)
{
    focus_order = g_list_remove(focus_order, c);
    if (!c->iconic) {
        focus_order = g_list_prepend(focus_order, c);
    } else {
        GList *it;

        /* insert before first iconic window */
        for (it = focus_order;
             it && !((ObClient*)it->data)->iconic; it = g_list_next(it));
        focus_order = g_list_insert_before(focus_order, it, c);
    }
}

void focus_order_to_bottom(ObClient *c)
{
    focus_order = g_list_remove(focus_order, c);
    if (c->iconic) {
        focus_order = g_list_append(focus_order, c);
    } else {
        GList *it;

        /* insert before first iconic window */
        for (it = focus_order;
             it && !((ObClient*)it->data)->iconic; it = g_list_next(it));
        focus_order = g_list_insert_before(focus_order, it, c);
    }
}

ObClient *focus_order_find_first(guint desktop)
{
    GList *it;
    for (it = focus_order; it; it = g_list_next(it)) {
        ObClient *c = it->data;
        if (c->desktop == desktop || c->desktop == DESKTOP_ALL)
            return c;
    }
    return NULL;
}