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state: Add support for group latch action
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Surprisingly, the latch group action was not yet implemented.

Added tests to ensure we get the tricky bits right.
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@wismill
wismill committed Aug 28, 2024
1 parent ce32dec commit e9bd7de
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Showing 5 changed files with 490 additions and 41 deletions.
1 change: 1 addition & 0 deletions changes/api/455.group-latch.feature.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Implement the `GroupLatch` action, usually activated with the keysym `ISO_Group_Latch`.
212 changes: 171 additions & 41 deletions src/state.c
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Original file line number Diff line number Diff line change
Expand Up @@ -240,11 +240,13 @@ xkb_filter_new(struct xkb_state *state)
darray_foreach(iter, state->filters) {
if (iter->func)
continue;
/* Use available slot */
filter = iter;
break;
}

if (!filter) {
/* No available slot: resize the filters array */
darray_resize0(state->filters, darray_size(state->filters) + 1);
filter = &darray_item(state->filters, darray_size(state->filters) -1);
}
Expand All @@ -270,14 +272,23 @@ enum xkb_filter_result {
XKB_FILTER_CONTINUE,
};

/* Modify a group component, depending on the ACTION_ABSOLUTE_SWITCH flag */
#define apply_group_delta(filter_, state_, component_) \
if (filter_->action.group.flags & ACTION_ABSOLUTE_SWITCH) \
state_->components.component_ = filter_->action.group.group; \
else \
state_->components.component_ += filter_->action.group.group

#define compute_group_delta(filter_, state_) \
(filter_->action.group.flags & ACTION_ABSOLUTE_SWITCH) \
? filter_->action.group.group - state_->components.base_group \
: filter_->action.group.group

static void
xkb_filter_group_set_new(struct xkb_state *state, struct xkb_filter *filter)
{
filter->priv = state->components.base_group;
if (filter->action.group.flags & ACTION_ABSOLUTE_SWITCH)
state->components.base_group = filter->action.group.group;
else
state->components.base_group += filter->action.group.group;
apply_group_delta(filter, state, base_group);
}

static bool
Expand Down Expand Up @@ -311,10 +322,7 @@ xkb_filter_group_set_func(struct xkb_state *state,
static void
xkb_filter_group_lock_new(struct xkb_state *state, struct xkb_filter *filter)
{
if (filter->action.group.flags & ACTION_ABSOLUTE_SWITCH)
state->components.locked_group = filter->action.group.group;
else
state->components.locked_group += filter->action.group.group;
apply_group_delta(filter, state, locked_group);
}

static bool
Expand All @@ -337,6 +345,144 @@ xkb_filter_group_lock_func(struct xkb_state *state,
return XKB_FILTER_CONTINUE;
}

static bool
xkb_action_breaks_latch(const union xkb_action *action)
{
switch (action->type) {
case ACTION_TYPE_NONE:
case ACTION_TYPE_PTR_BUTTON:
case ACTION_TYPE_PTR_LOCK:
case ACTION_TYPE_CTRL_SET:
case ACTION_TYPE_CTRL_LOCK:
case ACTION_TYPE_SWITCH_VT:
case ACTION_TYPE_TERMINATE:
return true;
default:
return false;
}
}

enum xkb_key_latch_state {
NO_LATCH = 0,
LATCH_KEY_DOWN,
LATCH_PENDING,
_KEY_LATCH_STATE_NUM_ENTRIES
};

#define MAX_XKB_KEY_LATCH_STATE_LOG2 2
#if (_KEY_LATCH_STATE_NUM_ENTRIES > (1 << MAX_XKB_KEY_LATCH_STATE_LOG2)) || \
(-XKB_MAX_GROUPS) < (INT32_MIN >> MAX_XKB_KEY_LATCH_STATE_LOG2) || \
XKB_MAX_GROUPS > (INT32_MAX >> MAX_XKB_KEY_LATCH_STATE_LOG2)
#error "Cannot represent priv field of the group latch filter"
#endif

/* Hold the latch state *and* the group delta */
union group_latch_priv {
uint32_t priv;
struct {
/* The type is really: enum xkb_key_latch_state, but it is problematic
* on Windows, because it is interpreted as signed and leads to wrong
* negative values. */
unsigned int latch:MAX_XKB_KEY_LATCH_STATE_LOG2;
int32_t group_delta:(32 - MAX_XKB_KEY_LATCH_STATE_LOG2);
};
};

static void
xkb_filter_group_latch_new(struct xkb_state *state, struct xkb_filter *filter)
{
const union group_latch_priv priv = {
.latch = LATCH_KEY_DOWN,
.group_delta = compute_group_delta(filter, state)
};
filter->priv = priv.priv;
/* Like group set */
apply_group_delta(filter, state, base_group);
}

static bool
xkb_filter_group_latch_func(struct xkb_state *state,
struct xkb_filter *filter,
const struct xkb_key *key,
enum xkb_key_direction direction)
{
union group_latch_priv priv = {.priv = filter->priv};
enum xkb_key_latch_state latch = priv.latch;

if (direction == XKB_KEY_DOWN && latch == LATCH_PENDING) {
/* If this is a new keypress and we're awaiting our single latched
* keypress, then either break the latch if any random key is pressed,
* or promote it to a lock or plain base set if it's the same
* group delta & flags. */
const union xkb_action *action = xkb_key_get_action(state, key);
if (action->type == ACTION_TYPE_GROUP_LATCH &&
action->group.group == filter->action.group.group &&
action->group.flags == filter->action.group.flags) {
filter->action = *action;
if (filter->action.group.flags & ACTION_LATCH_TO_LOCK &&
filter->action.group.group != 0) {
/* Promote to lock */
filter->action.type = ACTION_TYPE_GROUP_LOCK;
filter->func = xkb_filter_group_lock_func;
xkb_filter_group_lock_new(state, filter);
}
else {
/* Degrade to plain set */
filter->action.type = ACTION_TYPE_GROUP_SET;
filter->func = xkb_filter_group_set_func;
xkb_filter_group_set_new(state, filter);
}
filter->key = key;
state->components.latched_group -= priv.group_delta;
/* XXX beep beep! */
return XKB_FILTER_CONSUME;
}
else if (xkb_action_breaks_latch(action)) {
/* Breaks the latch */
state->components.latched_group = 0;
filter->func = NULL;
return XKB_FILTER_CONTINUE;
}
}
else if (direction == XKB_KEY_UP && key == filter->key) {
/* Our key got released. If we've set it to clear locks, and we
* currently have a group locked, then release it and
* don't actually latch. Else we've actually hit the latching
* stage, so set PENDING and move our group from base to
* latched. */
if (latch == NO_LATCH ||
((filter->action.group.flags & ACTION_LOCK_CLEAR) &&
state->components.locked_group)) {
if (latch == LATCH_PENDING)
state->components.latched_group -= priv.group_delta;
else
state->components.base_group -= priv.group_delta;
if (filter->action.group.flags & ACTION_LOCK_CLEAR)
state->components.locked_group = 0;
filter->func = NULL;
}
else {
latch = LATCH_PENDING;
/* Switch from set to latch */
state->components.base_group -= priv.group_delta;
state->components.latched_group += priv.group_delta;
/* XXX beep beep! */
}
}
else if (direction == XKB_KEY_DOWN && latch == LATCH_KEY_DOWN) {
/* Another key was pressed while we've still got the latching
* key held down, so keep the base group active (from
* xkb_filter_group_latch_new), but don't trip the latch, just clear
* it as soon as the group key gets released. */
latch = NO_LATCH;
}

priv.latch = latch;
filter->priv = priv.priv;

return XKB_FILTER_CONTINUE;
}

static void
xkb_filter_mod_set_new(struct xkb_state *state, struct xkb_filter *filter)
{
Expand Down Expand Up @@ -404,29 +550,6 @@ xkb_filter_mod_lock_func(struct xkb_state *state,
return XKB_FILTER_CONTINUE;
}

enum xkb_key_latch_state {
NO_LATCH,
LATCH_KEY_DOWN,
LATCH_PENDING,
};

static bool
xkb_action_breaks_latch(const union xkb_action *action)
{
switch (action->type) {
case ACTION_TYPE_NONE:
case ACTION_TYPE_PTR_BUTTON:
case ACTION_TYPE_PTR_LOCK:
case ACTION_TYPE_CTRL_SET:
case ACTION_TYPE_CTRL_LOCK:
case ACTION_TYPE_SWITCH_VT:
case ACTION_TYPE_TERMINATE:
return true;
default:
return false;
}
}

static void
xkb_filter_mod_latch_new(struct xkb_state *state, struct xkb_filter *filter)
{
Expand Down Expand Up @@ -520,16 +643,18 @@ static const struct {
bool (*func)(struct xkb_state *state, struct xkb_filter *filter,
const struct xkb_key *key, enum xkb_key_direction direction);
} filter_action_funcs[_ACTION_TYPE_NUM_ENTRIES] = {
[ACTION_TYPE_MOD_SET] = { xkb_filter_mod_set_new,
xkb_filter_mod_set_func },
[ACTION_TYPE_MOD_LATCH] = { xkb_filter_mod_latch_new,
xkb_filter_mod_latch_func },
[ACTION_TYPE_MOD_LOCK] = { xkb_filter_mod_lock_new,
xkb_filter_mod_lock_func },
[ACTION_TYPE_GROUP_SET] = { xkb_filter_group_set_new,
xkb_filter_group_set_func },
[ACTION_TYPE_GROUP_LOCK] = { xkb_filter_group_lock_new,
xkb_filter_group_lock_func },
[ACTION_TYPE_MOD_SET] = { xkb_filter_mod_set_new,
xkb_filter_mod_set_func },
[ACTION_TYPE_MOD_LATCH] = { xkb_filter_mod_latch_new,
xkb_filter_mod_latch_func },
[ACTION_TYPE_MOD_LOCK] = { xkb_filter_mod_lock_new,
xkb_filter_mod_lock_func },
[ACTION_TYPE_GROUP_SET] = { xkb_filter_group_set_new,
xkb_filter_group_set_func },
[ACTION_TYPE_GROUP_LATCH] = { xkb_filter_group_latch_new,
xkb_filter_group_latch_func },
[ACTION_TYPE_GROUP_LOCK] = { xkb_filter_group_lock_new,
xkb_filter_group_lock_func },
};

/**
Expand Down Expand Up @@ -559,6 +684,7 @@ xkb_filter_apply_all(struct xkb_state *state,
if (consumed || direction == XKB_KEY_UP)
return;

/* No filter consumed this event, so proceed with the key action */
action = xkb_key_get_action(state, key);

/*
Expand All @@ -571,9 +697,11 @@ xkb_filter_apply_all(struct xkb_state *state,
if (action->type >= _ACTION_TYPE_NUM_ENTRIES)
return;

/* Return if no corresponding action */
if (!filter_action_funcs[action->type].new)
return;

/* Add a new filter and run the corresponding initial action */
filter = xkb_filter_new(state);
filter->key = key;
filter->func = filter_action_funcs[action->type].func;
Expand Down Expand Up @@ -689,12 +817,14 @@ xkb_state_update_derived(struct xkb_state *state)

/* TODO: Use groups_wrap control instead of always RANGE_WRAP. */

/* Lock group must be adjusted, but not base nor latched groups */
wrapped = XkbWrapGroupIntoRange(state->components.locked_group,
state->keymap->num_groups,
RANGE_WRAP, 0);
state->components.locked_group =
(wrapped == XKB_LAYOUT_INVALID ? 0 : wrapped);

/* Effective group must be adjusted */
wrapped = XkbWrapGroupIntoRange(state->components.base_group +
state->components.latched_group +
state->components.locked_group,
Expand Down
6 changes: 6 additions & 0 deletions test/data/rules/evdev
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Original file line number Diff line number Diff line change
Expand Up @@ -1016,6 +1016,12 @@
grp:alt_shift_toggle = +group(alt_shift_toggle)
grp:alt_shift_toggle_bidir = +group(alt_shift_toggle_bidir)
grp:lctrl_lwin_toggle = +group(lctrl_lwin_toggle)
grp:menu_latch_group2 = +group(menu_latch_group2)
grp:menu_latch_group2_lock = +group(menu_latch_group2_lock)
grp:menu_latch = +group(menu_latch)
grp:menu_latch_lock = +group(menu_latch_lock)
grp:menu_latch_negative = +group(menu_latch_negative)
grp:menu_latch_negative_lock = +group(menu_latch_negative_lock)
lv3:switch = +level3(switch)
lv3:ralt_switch = +level3(ralt_switch)
lv3:ralt_switch_multikey = +level3(ralt_switch_multikey)
Expand Down
48 changes: 48 additions & 0 deletions test/data/symbols/group
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Original file line number Diff line number Diff line change
Expand Up @@ -466,3 +466,51 @@ xkb_symbols "lctrl_lwin_toggle" {
symbols[ Group1 ] = [ Super_L, ISO_Next_Group ]
};
};

partial modifier_keys
xkb_symbols "menu_latch_group2" {
key <MENU> {
symbols[1] = [ ISO_Group_Latch ],
actions[1] = [ LatchGroup(group=2) ]
};
};

partial modifier_keys
xkb_symbols "menu_latch_group2_lock" {
key <MENU> {
symbols[1] = [ ISO_Group_Latch ],
actions[1] = [ LatchGroup(group=2, latchToLock=yes) ]
};
};

partial modifier_keys
xkb_symbols "menu_latch" {
key <MENU> {
symbols[1] = [ ISO_Group_Latch ],
actions[1] = [ LatchGroup(group=+1) ]
};
};

partial modifier_keys
xkb_symbols "menu_latch_lock" {
key <MENU> {
symbols[1] = [ ISO_Group_Latch ],
actions[1] = [ LatchGroup(group=+1, latchToLock=yes) ]
};
};

partial modifier_keys
xkb_symbols "menu_latch_negative" {
key <MENU> {
symbols[1] = [ ISO_Group_Latch ],
actions[1] = [ LatchGroup(group=-1) ]
};
};

partial modifier_keys
xkb_symbols "menu_latch_negative_lock" {
key <MENU> {
symbols[1] = [ ISO_Group_Latch ],
actions[1] = [ LatchGroup(group=-1, latchToLock=yes) ]
};
};
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