mutter/src/core/stack-tracker.c

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/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/*
* Copyright (C) 2009 Red Hat, Inc.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA.
*/
#include <config.h>
#include <string.h>
#include "frame.h"
#include "screen-private.h"
#include "stack-tracker.h"
#include <meta/util.h>
#include <meta/compositor.h>
/* The complexity here comes from resolving two competing factors:
*
* - We need to have a view of the stacking order that takes into
* account everything we have done without waiting for events
* back from the X server; we don't want to draw intermediate
* partially-stacked stack states just because we haven't received
* some notification yet.
*
* - Only the X server has an accurate view of the complete stacking;
* when we make a request to restack windows, we don't know how
* it will affect override-redirect windows, because at any point
* applications may restack these windows without our involvement.
*
* The technique we use is that we keep three sets of information:
*
* - The stacking order on the server as known from the last
* event we received.
* - A queue of stacking requests that *we* made subsequent to
* that last event.
* - A predicted stacking order, derived from applying the queued
* requests to the last state from the server.
*
* When we receive a new event: a) we compare the serial in the event to
* the serial of the queued requests and remove any that are now
* no longer pending b) if necessary, drop the predicted stacking
* order to recompute it at the next opportunity.
*
* Possible optimizations:
* Keep the stacks as an array + reverse-mapping hash table to avoid
* linear lookups.
* Keep the stacks as a GList + reverse-mapping hash table to avoid
* linear lookups and to make restacking constant-time.
*/
typedef union _MetaStackOp MetaStackOp;
typedef enum {
STACK_OP_ADD,
STACK_OP_REMOVE,
STACK_OP_RAISE_ABOVE,
STACK_OP_LOWER_BELOW
} MetaStackOpType;
/* MetaStackOp represents a "stacking operation" - a change to
* apply to a window stack. Depending on the context, it could
* either reflect a request we have sent to the server, or a
* notification event we received from the X server.
*/
union _MetaStackOp
{
struct {
MetaStackOpType type;
gulong serial;
} any;
struct {
MetaStackOpType type;
gulong serial;
Window window;
} add;
struct {
MetaStackOpType type;
gulong serial;
Window window;
} remove;
struct {
MetaStackOpType type;
gulong serial;
Window window;
Window sibling;
} raise_above;
struct {
MetaStackOpType type;
gulong serial;
Window window;
Window sibling;
} lower_below;
};
struct _MetaStackTracker
{
MetaScreen *screen;
/* This is the last state of the stack as based on events received
* from the X server.
*/
GArray *server_stack;
/* This is the serial of the last request we made that was reflected
* in server_stack
*/
gulong server_serial;
/* This is a queue of requests we've made to change the stacking order,
* where we haven't yet gotten a reply back from the server.
*/
GQueue *queued_requests;
/* This is how we think the stack is, based on server_stack, and
* on requests we've made subsequent to server_stack
*/
GArray *predicted_stack;
/* Idle function used to sync the compositor's view of the window
* stack up with our best guess before a frame is drawn.
*/
guint sync_stack_later;
};
static void
meta_stack_op_dump (MetaStackOp *op,
const char *prefix,
const char *suffix)
{
switch (op->any.type)
{
case STACK_OP_ADD:
meta_topic (META_DEBUG_STACK, "%sADD(%#lx; %ld)%s",
prefix, op->add.window, op->any.serial, suffix);
break;
case STACK_OP_REMOVE:
meta_topic (META_DEBUG_STACK, "%sREMOVE(%#lx; %ld)%s",
prefix, op->add.window, op->any.serial, suffix);
break;
case STACK_OP_RAISE_ABOVE:
meta_topic (META_DEBUG_STACK, "%sRAISE_ABOVE(%#lx, %#lx; %ld)%s",
prefix,
op->raise_above.window, op->raise_above.sibling,
op->any.serial,
suffix);
break;
case STACK_OP_LOWER_BELOW:
meta_topic (META_DEBUG_STACK, "%sLOWER_BELOW(%#lx, %#lx; %ld)%s",
prefix,
op->lower_below.window, op->lower_below.sibling,
op->any.serial,
suffix);
break;
}
}
static void
meta_stack_tracker_dump (MetaStackTracker *tracker)
{
guint i;
GList *l;
meta_topic (META_DEBUG_STACK, "MetaStackTracker state (screen=%d)\n", tracker->screen->number);
meta_push_no_msg_prefix ();
meta_topic (META_DEBUG_STACK, " server_serial: %ld\n", tracker->server_serial);
meta_topic (META_DEBUG_STACK, " server_stack: ");
for (i = 0; i < tracker->server_stack->len; i++)
meta_topic (META_DEBUG_STACK, " %#lx", g_array_index (tracker->server_stack, Window, i));
if (tracker->predicted_stack)
{
meta_topic (META_DEBUG_STACK, "\n predicted_stack: ");
for (i = 0; i < tracker->predicted_stack->len; i++)
meta_topic (META_DEBUG_STACK, " %#lx", g_array_index (tracker->predicted_stack, Window, i));
}
meta_topic (META_DEBUG_STACK, "\n queued_requests: [");
for (l = tracker->queued_requests->head; l; l = l->next)
{
MetaStackOp *op = l->data;
meta_stack_op_dump (op, "", l->next ? ", " : "");
}
meta_topic (META_DEBUG_STACK, "]\n");
meta_pop_no_msg_prefix ();
}
static void
meta_stack_op_free (MetaStackOp *op)
{
g_slice_free (MetaStackOp, op);
}
static int
find_window (GArray *stack,
Window window)
{
guint i;
for (i = 0; i < stack->len; i++)
if (g_array_index (stack, Window, i) == window)
return i;
return -1;
}
/* Returns TRUE if stack was changed */
static gboolean
move_window_above (GArray *stack,
Window window,
int old_pos,
int above_pos)
{
int i;
if (old_pos < above_pos)
{
for (i = old_pos; i < above_pos; i++)
g_array_index (stack, Window, i) = g_array_index (stack, Window, i + 1);
g_array_index (stack, Window, above_pos) = window;
return TRUE;
}
else if (old_pos > above_pos + 1)
{
for (i = old_pos; i > above_pos + 1; i--)
g_array_index (stack, Window, i) = g_array_index (stack, Window, i - 1);
g_array_index (stack, Window, above_pos + 1) = window;
return TRUE;
}
else
return FALSE;
}
/* Returns TRUE if stack was changed */
static gboolean
meta_stack_op_apply (MetaStackOp *op,
GArray *stack)
{
switch (op->any.type)
{
case STACK_OP_ADD:
{
int old_pos = find_window (stack, op->add.window);
if (old_pos >= 0)
{
g_warning ("STACK_OP_ADD: window %#lx already in stack",
op->add.window);
return FALSE;
}
g_array_append_val (stack, op->add.window);
return TRUE;
}
case STACK_OP_REMOVE:
{
int old_pos = find_window (stack, op->remove.window);
if (old_pos < 0)
{
g_warning ("STACK_OP_REMOVE: window %#lx not in stack",
op->remove.window);
return FALSE;
}
g_array_remove_index (stack, old_pos);
return TRUE;
}
case STACK_OP_RAISE_ABOVE:
{
int old_pos = find_window (stack, op->raise_above.window);
int above_pos;
if (old_pos < 0)
{
g_warning ("STACK_OP_RAISE_ABOVE: window %#lx not in stack",
op->raise_above.window);
return FALSE;
}
if (op->raise_above.sibling != None)
{
above_pos = find_window (stack, op->raise_above.sibling);
if (above_pos < 0)
{
g_warning ("STACK_OP_RAISE_ABOVE: sibling window %#lx not in stack",
op->raise_above.sibling);
return FALSE;
}
}
else
{
above_pos = -1;
}
return move_window_above (stack, op->raise_above.window, old_pos, above_pos);
}
case STACK_OP_LOWER_BELOW:
{
int old_pos = find_window (stack, op->lower_below.window);
int above_pos;
if (old_pos < 0)
{
g_warning ("STACK_OP_LOWER_BELOW: window %#lx not in stack",
op->lower_below.window);
return FALSE;
}
if (op->lower_below.sibling != None)
{
int below_pos = find_window (stack, op->lower_below.sibling);
if (below_pos < 0)
{
g_warning ("STACK_OP_LOWER_BELOW: sibling window %#lx not in stack",
op->lower_below.sibling);
return FALSE;
}
above_pos = below_pos - 1;
}
else
{
above_pos = stack->len - 1;
}
return move_window_above (stack, op->lower_below.window, old_pos, above_pos);
}
}
g_assert_not_reached ();
return FALSE;
}
static GArray *
copy_stack (Window *windows,
guint n_windows)
{
GArray *stack = g_array_new (FALSE, FALSE, sizeof (Window));
g_array_set_size (stack, n_windows);
memcpy (stack->data, windows, sizeof (Window) * n_windows);
return stack;
}
MetaStackTracker *
meta_stack_tracker_new (MetaScreen *screen)
{
MetaStackTracker *tracker;
Window ignored1, ignored2;
Window *children;
guint n_children;
tracker = g_new0 (MetaStackTracker, 1);
tracker->screen = screen;
tracker->server_serial = XNextRequest (screen->display->xdisplay);
XQueryTree (screen->display->xdisplay,
screen->xroot,
&ignored1, &ignored2, &children, &n_children);
tracker->server_stack = copy_stack (children, n_children);
XFree (children);
tracker->queued_requests = g_queue_new ();
return tracker;
}
void
meta_stack_tracker_free (MetaStackTracker *tracker)
{
if (tracker->sync_stack_later)
meta_later_remove (tracker->sync_stack_later);
g_array_free (tracker->server_stack, TRUE);
if (tracker->predicted_stack)
g_array_free (tracker->predicted_stack, TRUE);
g_queue_foreach (tracker->queued_requests, (GFunc)meta_stack_op_free, NULL);
g_queue_free (tracker->queued_requests);
tracker->queued_requests = NULL;
g_free (tracker);
}
static void
stack_tracker_queue_request (MetaStackTracker *tracker,
MetaStackOp *op)
{
meta_stack_op_dump (op, "Queueing: ", "\n");
g_queue_push_tail (tracker->queued_requests, op);
if (!tracker->predicted_stack ||
meta_stack_op_apply (op, tracker->predicted_stack))
meta_stack_tracker_queue_sync_stack (tracker);
meta_stack_tracker_dump (tracker);
}
void
meta_stack_tracker_record_add (MetaStackTracker *tracker,
Window window,
gulong serial)
{
MetaStackOp *op = g_slice_new (MetaStackOp);
op->any.type = STACK_OP_ADD;
op->any.serial = serial;
op->add.window = window;
stack_tracker_queue_request (tracker, op);
}
void
meta_stack_tracker_record_remove (MetaStackTracker *tracker,
Window window,
gulong serial)
{
MetaStackOp *op = g_slice_new (MetaStackOp);
op->any.type = STACK_OP_REMOVE;
op->any.serial = serial;
op->remove.window = window;
stack_tracker_queue_request (tracker, op);
}
void
meta_stack_tracker_record_restack_windows (MetaStackTracker *tracker,
Window *windows,
int n_windows,
gulong serial)
{
int i;
/* XRestackWindows() isn't actually a X requests - it's broken down
* by XLib into a series of XConfigureWindow(StackMode=below); we
* mirror that exactly here.
*
* Aside: Having a separate StackOp for this would be possible to
* get some extra efficiency in memory allocation and in applying
* the op, at the expense of a code complexity. Implementation hint
* for that - keep op->restack_window.n_complete, and when receiving
* events with intermediate serials, set n_complete rather than
* removing the op from the queue.
*/
for (i = 0; i < n_windows - 1; i++)
meta_stack_tracker_record_lower_below (tracker, windows[i + 1], windows[i],
serial + i);
}
void
meta_stack_tracker_record_raise_above (MetaStackTracker *tracker,
Window window,
Window sibling,
gulong serial)
{
MetaStackOp *op = g_slice_new (MetaStackOp);
op->any.type = STACK_OP_RAISE_ABOVE;
op->any.serial = serial;
op->raise_above.window = window;
op->raise_above.sibling = sibling;
stack_tracker_queue_request (tracker, op);
}
void
meta_stack_tracker_record_lower_below (MetaStackTracker *tracker,
Window window,
Window sibling,
gulong serial)
{
MetaStackOp *op = g_slice_new (MetaStackOp);
op->any.type = STACK_OP_LOWER_BELOW;
op->any.serial = serial;
op->lower_below.window = window;
op->lower_below.sibling = sibling;
stack_tracker_queue_request (tracker, op);
}
void
meta_stack_tracker_record_lower (MetaStackTracker *tracker,
Window window,
gulong serial)
{
meta_stack_tracker_record_raise_above (tracker, window, None, serial);
}
static void
stack_tracker_event_received (MetaStackTracker *tracker,
MetaStackOp *op)
{
gboolean need_sync = FALSE;
meta_stack_op_dump (op, "Stack op event received: ", "\n");
if (op->any.serial < tracker->server_serial)
return;
tracker->server_serial = op->any.serial;
if (meta_stack_op_apply (op, tracker->server_stack))
need_sync = TRUE;
while (tracker->queued_requests->head)
{
MetaStackOp *queued_op = tracker->queued_requests->head->data;
if (queued_op->any.serial > op->any.serial)
break;
g_queue_pop_head (tracker->queued_requests);
meta_stack_op_free (queued_op);
need_sync = TRUE;
}
if (need_sync)
{
if (tracker->predicted_stack)
{
g_array_free (tracker->predicted_stack, TRUE);
tracker->predicted_stack = NULL;
}
meta_stack_tracker_queue_sync_stack (tracker);
}
meta_stack_tracker_dump (tracker);
}
void
meta_stack_tracker_create_event (MetaStackTracker *tracker,
XCreateWindowEvent *event)
{
MetaStackOp op;
op.any.type = STACK_OP_ADD;
op.any.serial = event->serial;
op.add.window = event->window;
stack_tracker_event_received (tracker, &op);
}
void
meta_stack_tracker_destroy_event (MetaStackTracker *tracker,
XDestroyWindowEvent *event)
{
MetaStackOp op;
op.any.type = STACK_OP_REMOVE;
op.any.serial = event->serial;
op.remove.window = event->window;
stack_tracker_event_received (tracker, &op);
}
void
meta_stack_tracker_reparent_event (MetaStackTracker *tracker,
XReparentEvent *event)
{
if (event->parent == event->event)
{
MetaStackOp op;
op.any.type = STACK_OP_ADD;
op.any.serial = event->serial;
op.add.window = event->window;
stack_tracker_event_received (tracker, &op);
}
else
{
MetaStackOp op;
op.any.type = STACK_OP_REMOVE;
op.any.serial = event->serial;
op.remove.window = event->window;
stack_tracker_event_received (tracker, &op);
}
}
void
meta_stack_tracker_configure_event (MetaStackTracker *tracker,
XConfigureEvent *event)
{
MetaStackOp op;
op.any.type = STACK_OP_RAISE_ABOVE;
op.any.serial = event->serial;
op.raise_above.window = event->window;
op.raise_above.sibling = event->above;
stack_tracker_event_received (tracker, &op);
}
/**
* meta_stack_tracker_get_stack:
* @tracker: a #MetaStackTracker
* @windows: location to store list of windows, or %NULL
* @n_windows: location to store count of windows, or %NULL
*
* Returns the most current view we have of the stacking order
* of the children of the root window. The returned array contains
* everything: InputOnly windows, override-redirect windows,
* hidden windows, etc. Some of these will correspond to MetaWindow
* objects, others won't.
*
* Assuming that no other clients have made requests that change
* the stacking order since we last received a notification, the
* returned list of windows is exactly that you'd get as the
* children when calling XQueryTree() on the root window.
*/
void
meta_stack_tracker_get_stack (MetaStackTracker *tracker,
Window **windows,
int *n_windows)
{
GArray *stack;
if (tracker->queued_requests->length == 0)
{
stack = tracker->server_stack;
}
else
{
if (tracker->predicted_stack == NULL)
{
GList *l;
tracker->predicted_stack = copy_stack ((Window *)tracker->server_stack->data,
tracker->server_stack->len);
for (l = tracker->queued_requests->head; l; l = l->next)
{
MetaStackOp *op = l->data;
meta_stack_op_apply (op, tracker->predicted_stack);
}
}
stack = tracker->predicted_stack;
}
if (windows)
*windows = (Window *)stack->data;
if (n_windows)
*n_windows = stack->len;
}
/**
* meta_stack_tracker_sync_stack:
* @tracker: a #MetaStackTracker
*
* Informs the compositor of the current stacking order of windows,
* based on the predicted view maintained by the #MetaStackTracker.
*/
void
meta_stack_tracker_sync_stack (MetaStackTracker *tracker)
{
GList *meta_windows;
Window *windows;
int n_windows;
int i;
if (tracker->sync_stack_later)
{
meta_later_remove (tracker->sync_stack_later);
tracker->sync_stack_later = 0;
}
meta_stack_tracker_get_stack (tracker, &windows, &n_windows);
meta_windows = NULL;
for (i = 0; i < n_windows; i++)
{
MetaWindow *meta_window;
meta_window = meta_display_lookup_x_window (tracker->screen->display,
windows[i]);
/* When mapping back from xwindow to MetaWindow we have to be a bit careful;
* children of the root could include unmapped windows created by toolkits
* for internal purposes, including ones that we have registered in our
* XID => window table. (Wine uses a toplevel for _NET_WM_USER_TIME_WINDOW;
* see window-prop.c:reload_net_wm_user_time_window() for registration.)
*/
if (meta_window &&
(windows[i] == meta_window->xwindow ||
(meta_window->frame && windows[i] == meta_window->frame->xwindow)))
meta_windows = g_list_prepend (meta_windows, meta_window);
}
if (tracker->screen->display->compositor)
meta_compositor_sync_stack (tracker->screen->display->compositor,
tracker->screen,
meta_windows);
g_list_free (meta_windows);
meta_screen_restacked (tracker->screen);
}
static gboolean
stack_tracker_sync_stack_later (gpointer data)
{
meta_stack_tracker_sync_stack (data);
return FALSE;
}
/**
* meta_stack_tracker_queue_sync_stack:
* @tracker: a #MetaStackTracker
*
* Queue informing the compositor of the new stacking order before the
* next redraw. (See meta_stack_tracker_sync_stack()). This is called
* internally when the stack of X windows changes, but also needs be
* called directly when we an undecorated window is first shown or
* withdrawn since the compositor's stacking order (which contains only
* the windows that have a corresponding MetaWindow) will change without
* any change to the stacking order of the X windows, if we are creating
* or destroying MetaWindows.
*/
void
meta_stack_tracker_queue_sync_stack (MetaStackTracker *tracker)
{
if (tracker->sync_stack_later == 0)
{
tracker->sync_stack_later = meta_later_add (META_LATER_BEFORE_REDRAW,
stack_tracker_sync_stack_later,
tracker, NULL);
}
}