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mutter/src/core/stack-tracker.c

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/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/*
* SECTION:stack-tracker
* @short_description: Track stacking order for compositor
*
* #MetaStackTracker maintains the most accurate view we have at a
* given point of time of the ordering of the children of the root
* window (including override-redirect windows.) This is used to order
* the windows when the compositor draws them.
*
* By contrast, #MetaStack is responsible for keeping track of how we
* think that windows *should* be ordered. For windows we manage
* (non-override-redirect windows), the two stacking orders will be
* the same.
*/
/*
* 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, see <http://www.gnu.org/licenses/>.
*/
#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;
MetaStackWindow window;
} any;
struct {
MetaStackOpType type;
gulong serial;
MetaStackWindow window;
} add;
struct {
MetaStackOpType type;
gulong serial;
MetaStackWindow window;
} remove;
struct {
MetaStackOpType type;
gulong serial;
MetaStackWindow window;
MetaStackWindow sibling;
} raise_above;
struct {
MetaStackOpType type;
gulong serial;
MetaStackWindow window;
MetaStackWindow 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 *xserver_stack;
/* This is the serial of the last request we made that was reflected
* in xserver_stack
*/
gulong xserver_serial;
/* A combined stack containing X and Wayland windows but without
* any unverified operations applied. */
GArray *verified_stack;
/* 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 *unverified_predictions;
/* This is how we think the stack is, based on verified_stack, and
* on the unverified_predictions we've made subsequent to
* verified_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 gboolean
meta_stack_window_is_set (const MetaStackWindow *window)
{
if (window->any.type == META_WINDOW_CLIENT_TYPE_X11)
return window->x11.xwindow == None ? FALSE : TRUE;
else
return window->wayland.meta_window ? TRUE : FALSE;
}
gboolean
meta_stack_window_equal (const MetaStackWindow *a,
const MetaStackWindow *b)
{
if (a->any.type == b->any.type)
{
if (a->any.type == META_WINDOW_CLIENT_TYPE_X11)
return a->x11.xwindow == b->x11.xwindow;
else
return a->wayland.meta_window == b->wayland.meta_window;
}
else
return FALSE;
}
static char *
get_window_id (MetaStackWindow *window)
{
if (window->any.type == META_WINDOW_CLIENT_TYPE_X11)
return g_strdup_printf ("X11:%lx", window->x11.xwindow);
else
return g_strdup_printf ("Wayland:%p", window->wayland.meta_window);
}
static void
meta_stack_op_dump (MetaStackOp *op,
const char *prefix,
const char *suffix)
{
char *window_id = get_window_id (&op->any.window);
switch (op->any.type)
{
case STACK_OP_ADD:
meta_topic (META_DEBUG_STACK, "%sADD(%s; %ld)%s",
prefix, window_id, op->any.serial, suffix);
break;
case STACK_OP_REMOVE:
meta_topic (META_DEBUG_STACK, "%sREMOVE(%s; %ld)%s",
prefix, window_id, op->any.serial, suffix);
break;
case STACK_OP_RAISE_ABOVE:
{
char *sibling_id = get_window_id (&op->raise_above.sibling);
meta_topic (META_DEBUG_STACK, "%sRAISE_ABOVE(%s, %s; %ld)%s",
prefix,
window_id, sibling_id,
op->any.serial,
suffix);
g_free (sibling_id);
break;
}
case STACK_OP_LOWER_BELOW:
{
char *sibling_id = get_window_id (&op->lower_below.sibling);
meta_topic (META_DEBUG_STACK, "%sLOWER_BELOW(%s, %s; %ld)%s",
prefix,
window_id, sibling_id,
op->any.serial,
suffix);
g_free (sibling_id);
break;
}
}
g_free (window_id);
}
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, " xserver_serial: %ld\n", tracker->xserver_serial);
meta_topic (META_DEBUG_STACK, " xserver_stack: ");
for (i = 0; i < tracker->xserver_stack->len; i++)
{
MetaStackWindow *window = &g_array_index (tracker->xserver_stack, MetaStackWindow, i);
char *window_id = get_window_id (window);
meta_topic (META_DEBUG_STACK, " %s", window_id);
g_free (window_id);
}
meta_topic (META_DEBUG_STACK, "\n verfied_stack: ");
for (i = 0; i < tracker->verified_stack->len; i++)
{
MetaStackWindow *window = &g_array_index (tracker->verified_stack, MetaStackWindow, i);
char *window_id = get_window_id (window);
meta_topic (META_DEBUG_STACK, " %s", window_id);
g_free (window_id);
}
meta_topic (META_DEBUG_STACK, "\n unverified_predictions: [");
for (l = tracker->unverified_predictions->head; l; l = l->next)
{
MetaStackOp *op = l->data;
meta_stack_op_dump (op, "", l->next ? ", " : "");
}
meta_topic (META_DEBUG_STACK, "]\n");
if (tracker->predicted_stack)
{
meta_topic (META_DEBUG_STACK, "\n predicted_stack: ");
for (i = 0; i < tracker->predicted_stack->len; i++)
{
MetaStackWindow *window = &g_array_index (tracker->predicted_stack, MetaStackWindow, i);
char *window_id = get_window_id (window);
meta_topic (META_DEBUG_STACK, " %s", window_id);
g_free (window_id);
}
}
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 *window_stack,
MetaStackWindow *window)
{
guint i;
for (i = 0; i < window_stack->len; i++)
{
MetaStackWindow *current = &g_array_index (window_stack, MetaStackWindow, i);
if (current->any.type == window->any.type)
{
if (current->any.type == META_WINDOW_CLIENT_TYPE_X11 &&
current->x11.xwindow == window->x11.xwindow)
return i;
else
if (current->wayland.meta_window == window->wayland.meta_window)
return i;
}
}
return -1;
}
/* Returns TRUE if stack was changed */
static gboolean
move_window_above (GArray *stack,
MetaStackWindow *window,
int old_pos,
int above_pos)
{
/* Copy the window by-value before we start shifting things around
* in the stack in case window points into the stack itself. */
MetaStackWindow window_val = *window;
int i;
if (old_pos < above_pos)
{
for (i = old_pos; i < above_pos; i++)
g_array_index (stack, MetaStackWindow, i) =
g_array_index (stack, MetaStackWindow, i + 1);
g_array_index (stack, MetaStackWindow, above_pos) = window_val;
return TRUE;
}
else if (old_pos > above_pos + 1)
{
for (i = old_pos; i > above_pos + 1; i--)
g_array_index (stack, MetaStackWindow, i) =
g_array_index (stack, MetaStackWindow, i - 1);
g_array_index (stack, MetaStackWindow, above_pos + 1) = window_val;
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)
{
char *window_id = get_window_id (&op->add.window);
g_warning ("STACK_OP_ADD: window %s already in stack",
window_id);
g_free (window_id);
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)
{
char *window_id = get_window_id (&op->remove.window);
g_warning ("STACK_OP_REMOVE: window %s not in stack",
window_id);
g_free (window_id);
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)
{
char *window_id = get_window_id (&op->raise_above.window);
g_warning ("STACK_OP_RAISE_ABOVE: window %s not in stack",
window_id);
g_free (window_id);
return FALSE;
}
if (meta_stack_window_is_set (&op->raise_above.sibling))
{
above_pos = find_window (stack, &op->raise_above.sibling);
if (above_pos < 0)
{
char *sibling_id = get_window_id (&op->raise_above.sibling);
g_warning ("STACK_OP_RAISE_ABOVE: sibling window %s not in stack",
sibling_id);
g_free (sibling_id);
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)
{
char *window_id = get_window_id (&op->lower_below.window);
g_warning ("STACK_OP_LOWER_BELOW: window %s not in stack",
window_id);
g_free (window_id);
return FALSE;
}
if (meta_stack_window_is_set (&op->lower_below.sibling))
{
int below_pos = find_window (stack, &op->lower_below.sibling);
if (below_pos < 0)
{
char *sibling_id = get_window_id (&op->lower_below.sibling);
g_warning ("STACK_OP_LOWER_BELOW: sibling window %s not in stack",
sibling_id);
g_free (sibling_id);
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 (GArray *stack)
{
GArray *copy = g_array_sized_new (FALSE, FALSE, sizeof (MetaStackWindow), stack->len);
g_array_set_size (copy, stack->len);
memcpy (copy->data, stack->data, sizeof (MetaStackWindow) * stack->len);
return copy;
}
static void
requery_xserver_stack (MetaStackTracker *tracker)
{
MetaScreen *screen = tracker->screen;
Window ignored1, ignored2;
Window *children;
guint n_children;
guint i;
if (tracker->xserver_stack)
g_array_free (tracker->xserver_stack, TRUE);
tracker->xserver_serial = XNextRequest (screen->display->xdisplay);
XQueryTree (screen->display->xdisplay,
screen->xroot,
&ignored1, &ignored2, &children, &n_children);
tracker->xserver_stack =
g_array_sized_new (FALSE, FALSE, sizeof (MetaStackWindow), n_children);
g_array_set_size (tracker->xserver_stack, n_children);
for (i = 0; i < n_children; i++)
{
MetaStackWindow *window =
&g_array_index (tracker->xserver_stack, MetaStackWindow, i);
window->any.type = META_WINDOW_CLIENT_TYPE_X11;
window->x11.xwindow = children[i];
}
XFree (children);
}
MetaStackTracker *
meta_stack_tracker_new (MetaScreen *screen)
{
MetaStackTracker *tracker;
tracker = g_new0 (MetaStackTracker, 1);
tracker->screen = screen;
requery_xserver_stack (tracker);
tracker->verified_stack = copy_stack (tracker->xserver_stack);
tracker->unverified_predictions = g_queue_new ();
meta_stack_tracker_dump (tracker);
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->xserver_stack, TRUE);
g_array_free (tracker->verified_stack, TRUE);
if (tracker->predicted_stack)
g_array_free (tracker->predicted_stack, TRUE);
g_queue_foreach (tracker->unverified_predictions, (GFunc)meta_stack_op_free, NULL);
g_queue_free (tracker->unverified_predictions);
tracker->unverified_predictions = NULL;
g_free (tracker);
}
static void
stack_tracker_apply_prediction (MetaStackTracker *tracker,
MetaStackOp *op)
{
/* If this is a wayland operation then it's implicitly verified so
* we can apply it immediately so long as it doesn't depend on any
* unverified X operations...
*/
if (op->any.window.any.type == META_WINDOW_CLIENT_TYPE_WAYLAND &&
tracker->unverified_predictions->length == 0)
{
if (meta_stack_op_apply (op, tracker->verified_stack))
meta_stack_tracker_queue_sync_stack (tracker);
}
else
{
meta_stack_op_dump (op, "Predicting: ", "\n");
g_queue_push_tail (tracker->unverified_predictions, 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,
const MetaStackWindow *window,
gulong serial)
{
MetaStackOp *op = g_slice_new (MetaStackOp);
op->any.type = STACK_OP_ADD;
op->any.serial = serial;
op->any.window = *window;
stack_tracker_apply_prediction (tracker, op);
}
void
meta_stack_tracker_record_remove (MetaStackTracker *tracker,
const MetaStackWindow *window,
gulong serial)
{
MetaStackOp *op = g_slice_new (MetaStackOp);
op->any.type = STACK_OP_REMOVE;
op->any.serial = serial;
op->any.window = *window;
stack_tracker_apply_prediction (tracker, op);
}
void
meta_stack_tracker_record_restack_windows (MetaStackTracker *tracker,
const MetaStackWindow *windows,
int n_windows,
gulong serial)
{
int i;
int n_x_windows = 0;
/* XRestackWindows() isn't actually a X requests - it's broken down
* by XLib into a series of XConfigureWindow(StackMode=below); we
* mirror that here.
*
* Since there may be a mixture of X and wayland windows in the
* stack it's ambiguous which operations we should associate with an
* X serial number. One thing we do know though is that there will
* be (n_x_window - 1) X requests made.
*
* 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.
*/
if (n_windows && windows[0].any.type == META_WINDOW_CLIENT_TYPE_X11)
n_x_windows++;
for (i = 0; i < n_windows - 1; i++)
{
const MetaStackWindow *lower = &windows[i + 1];
gboolean involves_x = FALSE;
if (lower->any.type == META_WINDOW_CLIENT_TYPE_X11)
{
n_x_windows++;
/* Since the first X window is a reference point we only
* assoicate a serial number with the operations involving
* later X windows. */
if (n_x_windows > 1)
involves_x = TRUE;
}
meta_stack_tracker_record_lower_below (tracker, lower, &windows[i],
involves_x ? serial++ : 0);
}
}
void
meta_stack_tracker_record_raise_above (MetaStackTracker *tracker,
const MetaStackWindow *window,
const MetaStackWindow *sibling,
gulong serial)
{
MetaStackOp *op = g_slice_new (MetaStackOp);
op->any.type = STACK_OP_RAISE_ABOVE;
op->any.serial = serial;
op->any.window = *window;
if (sibling)
op->raise_above.sibling = *sibling;
else
{
op->raise_above.sibling.any.type = META_WINDOW_CLIENT_TYPE_X11;
op->raise_above.sibling.x11.xwindow = None;
}
stack_tracker_apply_prediction (tracker, op);
}
void
meta_stack_tracker_record_lower_below (MetaStackTracker *tracker,
const MetaStackWindow *window,
const MetaStackWindow *sibling,
gulong serial)
{
MetaStackOp *op = g_slice_new (MetaStackOp);
op->any.type = STACK_OP_LOWER_BELOW;
op->any.serial = serial;
op->any.window = *window;
if (sibling)
op->lower_below.sibling = *sibling;
else
{
op->lower_below.sibling.any.type = META_WINDOW_CLIENT_TYPE_X11;
op->lower_below.sibling.x11.xwindow = None;
}
stack_tracker_apply_prediction (tracker, op);
}
void
meta_stack_tracker_record_lower (MetaStackTracker *tracker,
const MetaStackWindow *window,
gulong serial)
{
meta_stack_tracker_record_raise_above (tracker, window, NULL, serial);
}
/* @op is an operation derived from an X event from the server and we
* want to verify that our predicted operations are consistent with
* what's being reported by the X server.
*
* NB: Since our stack may actually be a mixture of X and Wayland
* clients we can't simply apply these operations derived from X
* events onto our stack and discard old predictions because these
* operations aren't aware of wayland windows.
*
* This function applies all the unverified predicted operations up to
* the given @serial onto the verified_stack so that we can check the
* stack for consistency with the given X operation.
*
* Return value: %TRUE if the predicted state is consistent with
* receiving the given @op from X, else %FALSE.
*
* @modified will be set to %TRUE if tracker->verified_stack is
* changed by applying any newly validated operations, else %FALSE.
*/
static gboolean
stack_tracker_verify_predictions (MetaStackTracker *tracker,
MetaStackOp *op,
gboolean *modified)
{
GArray *tmp_predicted_stack = NULL;
GArray *predicted_stack;
gboolean modified_stack = FALSE;
/* Wayland operations don't need to be verified and shouldn't end up
* passed to this api. */
g_return_val_if_fail (op->any.window.any.type == META_WINDOW_CLIENT_TYPE_X11, FALSE);
if (tracker->unverified_predictions->length)
{
GList *l;
tmp_predicted_stack = predicted_stack = copy_stack (tracker->verified_stack);
for (l = tracker->unverified_predictions->head; l; l = l->next)
{
MetaStackOp *current_op = l->data;
if (current_op->any.serial > op->any.serial)
break;
modified_stack |= meta_stack_op_apply (current_op, predicted_stack);
}
}
else
predicted_stack = tracker->verified_stack;
switch (op->any.type)
{
case STACK_OP_ADD:
if (!find_window (predicted_stack, &op->any.window))
{
char *window_id = get_window_id (&op->any.window);
meta_topic (META_DEBUG_STACK, "Verify STACK_OP_ADD: window %s not found\n",
window_id);
g_free (window_id);
goto not_verified;
}
break;
case STACK_OP_REMOVE:
if (find_window (predicted_stack, &op->any.window))
{
char *window_id = get_window_id (&op->any.window);
meta_topic (META_DEBUG_STACK, "Verify STACK_OP_REMOVE: window %s was unexpectedly found\n",
window_id);
g_free (window_id);
goto not_verified;
}
break;
case STACK_OP_RAISE_ABOVE:
{
Window last_xwindow = None;
char *window_id;
unsigned int i;
/* This code is only intended for verifying operations based
* on XEvents where we can assume the sibling refers to
* another X window... */
g_return_val_if_fail (op->raise_above.sibling.any.type ==
META_WINDOW_CLIENT_TYPE_X11, FALSE);
for (i = 0; i < predicted_stack->len; i++)
{
MetaStackWindow *window = &g_array_index (predicted_stack, MetaStackWindow, i);
if (meta_stack_window_equal (window, &op->any.window))
{
if (last_xwindow == op->raise_above.sibling.x11.xwindow)
goto verified;
else
goto not_verified;
}
if (window->any.type == META_WINDOW_CLIENT_TYPE_X11)
last_xwindow = window->x11.xwindow;
}
window_id = get_window_id (&op->any.window);
meta_topic (META_DEBUG_STACK, "Verify STACK_OP_RAISE_ABOVE: window %s not found\n",
window_id);
g_free (window_id);
goto not_verified;
}
case STACK_OP_LOWER_BELOW:
g_warn_if_reached (); /* No X events currently lead to this path */
goto not_verified;
}
verified:
/* We can free the operations which we have now verified... */
while (tracker->unverified_predictions->head)
{
MetaStackOp *queued_op = tracker->unverified_predictions->head->data;
if (queued_op->any.serial > op->any.serial)
break;
g_queue_pop_head (tracker->unverified_predictions);
meta_stack_op_free (queued_op);
}
*modified = modified_stack;
if (modified_stack)
{
g_array_free (tracker->verified_stack, TRUE);
tracker->verified_stack = predicted_stack;
}
else if (tmp_predicted_stack)
g_array_free (tmp_predicted_stack, TRUE);
return TRUE;
not_verified:
if (tmp_predicted_stack)
g_array_free (tmp_predicted_stack, TRUE);
if (tracker->predicted_stack)
{
g_array_free (tracker->predicted_stack, TRUE);
tracker->predicted_stack = NULL;
}
*modified = FALSE;
return FALSE;
}
/* If we find that our predicted state is not consistent with what the
* X server is reporting to us then this function can re-query and
* re-synchronize verified_stack with the X server stack while
* hopefully not disrupting the relative stacking of Wayland windows.
*
* Return value: %TRUE if the verified stack was modified with respect
* to the predicted stack else %FALSE.
*
* Note: ->predicted_stack will be cleared by this function if
* ->verified_stack had to be modified when re-synchronizing.
*/
static gboolean
resync_verified_stack_with_xserver_stack (MetaStackTracker *tracker)
{
GList *l;
unsigned int i, j;
MetaStackWindow *expected_xwindow;
gboolean modified_stack;
/* Overview of the algorithm:
*
* - Re-query the complete X window stack from the X server via
* XQueryTree() and update xserver_stack.
*
* - Apply all operations in unverified_predictions to
* verified_stack so we have a predicted stack including Wayland
* windows and free the queue of unverified_predictions.
*
* - Iterate through the x windows listed in verified_stack at the
* same time as iterating the windows in xserver_list. (Stop
* when we reach the end of the xserver_list)
* - If the window found doesn't match the window expected
* according to the order of xserver_list then:
* - Look ahead for the window we were expecting and restack
* that above the previous X window. If we fail to find the
* expected window then create a new entry for it and stack
* that.
*
* - Continue to iterate through verified_stack for any remaining
* X windows that we now know aren't in the xserver_list and
* remove them.
*
* - Free ->predicted_stack if any.
*/
meta_topic (META_DEBUG_STACK, "Fully re-synchronizing X stack with verified stack\n");
requery_xserver_stack (tracker);
for (l = tracker->unverified_predictions->head; l; l = l->next)
meta_stack_op_apply (l->data, tracker->verified_stack);
g_queue_clear (tracker->unverified_predictions);
j = 0;
expected_xwindow =
&g_array_index (tracker->xserver_stack, MetaStackWindow, j);
for (i = 0;
i < tracker->verified_stack->len;
)
{
MetaStackWindow *current =
&g_array_index (tracker->verified_stack, MetaStackWindow, i);
if (current->any.type != META_WINDOW_CLIENT_TYPE_X11)
{
/* Progress i but not j */
i++;
continue;
}
if (current->x11.xwindow != expected_xwindow->x11.xwindow)
{
MetaStackWindow new;
MetaStackWindow *expected;
int expected_index;
/* If the current window corresponds to a window that's not
* in xserver_stack any more then the least disruptive thing
* we can do is to simply remove it and take another look at
* the same index.
*
* Note: we didn't used to do this and instead relied on
* removed windows getting pushed to the end of the list so
* they could all be removed together but this also resulted
* in pushing Wayland windows to the end too, disrupting
* their positioning relative to X windows too much.
*
* Technically we only need to look forward from j if we
* wanted to optimize this a bit...
*/
if (find_window (tracker->xserver_stack, current) < 0)
{
g_array_remove_index (tracker->verified_stack, i);
continue;
}
/* Technically we only need to look forward from i if we
* wanted to optimize this a bit... */
expected_index =
find_window (tracker->verified_stack, expected_xwindow);
if (expected_index >= 0)
{
expected = &g_array_index (tracker->verified_stack,
MetaStackWindow, expected_index);
}
else
{
new.any.type = META_WINDOW_CLIENT_TYPE_X11;
new.x11.xwindow = expected_xwindow->x11.xwindow;
g_array_append_val (tracker->verified_stack, new);
expected = &new;
expected_index = tracker->verified_stack->len - 1;
}
/* Note: that this move will effectively bump the index of
* the current window.
*
* We want to continue by re-checking this window against
* the next expected window though so we don't have to
* update i to compensate here.
*/
move_window_above (tracker->verified_stack, expected,
expected_index, /* current index */
i - 1); /* above */
modified_stack = TRUE;
}
/* NB: we want to make sure that if we break the loop because j
* reaches the end of xserver_stack that i has also been
* incremented already so that we can run a final loop to remove
* remaining windows based on the i index. */
i++;
j++;
expected_xwindow =
&g_array_index (tracker->xserver_stack, MetaStackWindow, j);
if (j >= tracker->xserver_stack->len)
break;
}
/* We now know that any remaining X windows aren't listed in the
* xserver_stack and so we can remove them. */
while (i < tracker->verified_stack->len)
{
MetaStackWindow *current =
&g_array_index (tracker->verified_stack, MetaStackWindow, i);
if (current->any.type == META_WINDOW_CLIENT_TYPE_X11)
g_array_remove_index (tracker->verified_stack, i);
else
i++;
modified_stack = TRUE;
}
/* If we get to the end of verified_list and there are any remaining
* entries in xserver_list then append them all to the end */
for (; j < tracker->xserver_stack->len; j++)
{
MetaStackWindow *current =
&g_array_index (tracker->xserver_stack, MetaStackWindow, j);
g_array_append_val (tracker->verified_stack, *current);
modified_stack = TRUE;
}
if (modified_stack)
{
if (tracker->predicted_stack)
{
g_array_free (tracker->predicted_stack, TRUE);
tracker->predicted_stack = NULL;
}
meta_stack_tracker_queue_sync_stack (tracker);
}
return modified_stack;
}
static void
stack_tracker_event_received (MetaStackTracker *tracker,
MetaStackOp *op)
{
gboolean need_sync = FALSE;
gboolean verified;
meta_stack_op_dump (op, "Stack op event received: ", "\n");
if (op->any.serial < tracker->xserver_serial)
{
g_warning ("Spurious X event received affecting stack; doing full re-query");
resync_verified_stack_with_xserver_stack (tracker);
meta_stack_tracker_dump (tracker);
return;
}
tracker->xserver_serial = op->any.serial;
/* XXX: With the design we have ended up with it looks like we've
* ended up making it unnecessary to maintain tracker->xserver_stack
* since we only need an xserver_stack during the
* resync_verified_stack_with_xserver_stack() at which point we are
* going to query the full stack from the X server using
* XQueryTree() anyway.
*
* TODO: remove tracker->xserver_stack.
*/
meta_stack_op_apply (op, tracker->xserver_stack);
verified = stack_tracker_verify_predictions (tracker, op, &need_sync);
if (!verified)
{
resync_verified_stack_with_xserver_stack (tracker);
meta_stack_tracker_dump (tracker);
return;
}
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.any.type = META_WINDOW_CLIENT_TYPE_X11;
op.add.window.x11.xwindow = 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.any.type = META_WINDOW_CLIENT_TYPE_X11;
op.remove.window.x11.xwindow = 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.any.type = META_WINDOW_CLIENT_TYPE_X11;
op.add.window.x11.xwindow = 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.any.type = META_WINDOW_CLIENT_TYPE_X11;
op.remove.window.x11.xwindow = 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.any.type = META_WINDOW_CLIENT_TYPE_X11;
op.raise_above.window.x11.xwindow = event->window;
op.raise_above.sibling.any.type = META_WINDOW_CLIENT_TYPE_X11;
op.raise_above.sibling.x11.xwindow = 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
*
* @windows will contain 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,
MetaStackWindow **windows,
int *n_windows)
{
GArray *stack;
if (tracker->unverified_predictions->length == 0)
{
stack = tracker->verified_stack;
}
else
{
if (tracker->predicted_stack == NULL)
{
GList *l;
tracker->predicted_stack = copy_stack (tracker->verified_stack);
for (l = tracker->unverified_predictions->head; l; l = l->next)
{
MetaStackOp *op = l->data;
meta_stack_op_apply (op, tracker->predicted_stack);
}
}
stack = tracker->predicted_stack;
}
meta_topic (META_DEBUG_STACK, "Get Stack\n");
meta_stack_tracker_dump (tracker);
if (windows)
*windows = (MetaStackWindow *)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)
{
MetaStackWindow *windows;
GList *meta_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++)
{
MetaStackWindow *window = &windows[i];
if (window->any.type == META_WINDOW_CLIENT_TYPE_X11)
{
MetaWindow *meta_window =
meta_display_lookup_x_window (tracker->screen->display, windows[i].x11.xwindow);
/* 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].x11.xwindow == meta_window->xwindow ||
(meta_window->frame && windows[i].x11.xwindow == meta_window->frame->xwindow)))
meta_windows = g_list_prepend (meta_windows, meta_window);
}
else
meta_windows = g_list_prepend (meta_windows, window->wayland.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_SYNC_STACK,
stack_tracker_sync_stack_later,
tracker, NULL);
}
}
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