feat(bar): 新增绑定模式指示器显示当前 binding mode

- 新增 bar/binding: 监听 binding mode 变更，显示当前模式名
- 支持点击单元循环切换绑定模式（binding_mode_cycle）
- 默认模式下按 show_default 配置决定是否隐藏单元
- 补充 binding 相关默认配置（颜色、内边距、是否显示默认模式）

CMakeLists.txt

@@ -30,6 +30,7 @@ add_executable(${APP_NAME}
     ${SOURCE_DIR}/backend/x11/window.c
 
     ${SOURCE_DIR}/bar/bar.c
+    ${SOURCE_DIR}/bar/binding.c
     ${SOURCE_DIR}/bar/cell.c
     ${SOURCE_DIR}/bar/text.c
     ${SOURCE_DIR}/bar/workspaces.c

include/zdwm/bar.h

@@ -33,8 +33,12 @@ typedef struct zdwm_bar_config_t {
 
   const char *layout_bg;
   const char *layout_fg;
+
+  bool binding_show_default;
+  uint32_t binding_padding_x;
   const char *binding_mode_bg;
   const char *binding_mode_fg;
+
   const char *window_bg;
   const char *window_fg;
   const char *window_focused_bg;

src/bar/bar.c

@@ -8,6 +8,7 @@
 #include <zdwm/bar.h>
 #include <zdwm/types.h>
 
+#include "bar/binding.h"
 #include "bar/cell.h"
 #include "bar/text.h"
 #include "bar/types.h"
@@ -78,6 +79,28 @@ void bar_output_add_workspace(
   bar_workspace_add_listeners(listeners, item->state);
 }
 
+static void bar_output_add_binding(
+  bar_output_t *bar_output,
+  zdwm_bar_config_t *config,
+  listeners_t *listeners
+) {
+  bar_binding_config_t binding_config = {
+    .show_default = config->binding_show_default,
+    .cell_padding = VALUE(config->binding_padding_x, config->padding_x),
+    .bg           = VALUE(config->binding_mode_bg, config->bg),
+    .fg           = VALUE(config->binding_mode_fg, config->fg),
+  };
+  auto item = bar_add_item(
+    bar_output->output_id,
+    &bar_output->left,
+    bar_binding,
+    &binding_config
+  );
+  item->cell_padding = binding_config.cell_padding;
+
+  bar_binding_add_listeners(listeners, item->state);
+}
+
 void bar_init(bar_t *bar, listeners_t *listeners) {
   auto c   = &bar->config;
   bar->ctx = text_context_create(c->font_family, c->font_size, c->dpi);
@@ -87,6 +110,7 @@ void bar_init(bar_t *bar, listeners_t *listeners) {
 
     bar_output->height = bar->config.height;
     bar_output_add_workspace(bar_output, &bar->config, listeners);
+    bar_output_add_binding(bar_output, &bar->config, listeners);
   }
 
   bar->timerfd = time_create_monotonic_timerfd_by_fps(bar->config.fps);

src/bar/binding.c

@@ -0,0 +1,104 @@
+#include "bar/binding.h"
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <zdwm/action.h>
+#include <zdwm/bar.h>
+#include <zdwm/listeners.h>
+#include <zdwm/types.h>
+
+#include "base/memory.h"
+#include "core/listeners.h"
+
+typedef struct bar_binding_state_t {
+  zdwm_binding_mode_notify_t mode;
+
+  bar_binding_config_t config;
+
+  bool inited;
+  bool dirty;
+} bar_binding_state_t;
+
+static void *
+bar_binding_create_state(zdwm_output_id_t output_id, void *config) {
+  const bar_binding_config_t *bar_config = config;
+  assert(bar_config);
+
+  auto state    = p_new(bar_binding_state_t, 1);
+  state->config = *bar_config;
+
+  return state;
+}
+
+static void bar_binding_update(
+  zdwm_bar_item_t *item,
+  const zdwm_bar_cell_api_t *cells,
+  void *state
+) {
+  auto data = (bar_binding_state_t *)state;
+  if (!data->inited || !data->dirty) return;
+
+  auto config = &data->config;
+  auto mode   = &data->mode;
+
+  if (!config->show_default && mode->is_default_mode) {
+    cells->set_cell_count(item, 0);
+  } else {
+    constexpr auto index = 0;
+    cells->set_cell_count(item, 1);
+    cells->cell_set_text(item, index, mode->name);
+    cells->cell_set_bg(item, index, config->bg);
+    cells->cell_set_fg(item, index, config->fg);
+  }
+
+  data->dirty = false;
+}
+
+static zdwm_action_t bar_binding_on_click(
+  zdwm_bar_item_t *item,
+  size_t cell_index,
+  int32_t x,
+  void *state
+) {
+  return (zdwm_action_t){
+    .type                  = ZDWM_ACTION_BINDING_MODE_CYCLE,
+    .as.binding_mode_cycle = {.delta = 1},
+  };
+}
+
+static void bar_binding_destroy_state(void *state) {
+  if (!state) return;
+
+  auto data = (bar_binding_state_t *)state;
+  p_delete(&data);
+}
+
+zdwm_bar_item_type_t bar_binding = {
+  .create_state       = bar_binding_create_state,
+  .update             = bar_binding_update,
+  .on_click           = bar_binding_on_click,
+  .destroy_state      = bar_binding_destroy_state,
+  .update_interval_ms = 0,
+};
+
+static void
+bar_binding_mode_notify(zdwm_binding_mode_notify_t mode, void *user_data) {
+  auto state = (bar_binding_state_t *)user_data;
+  if (!state->inited) {
+    state->mode = mode;
+
+    state->inited = true;
+    state->dirty  = true;
+    return;
+  }
+
+  if (state->mode.id == mode.id) return;
+  state->mode = mode;
+
+  state->dirty = true;
+}
+
+void bar_binding_add_listeners(listeners_t *listeners, void *state) {
+  listeners_add_binding_mode_notify(listeners, bar_binding_mode_notify, state);
+}

src/bar/binding.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <stdint.h>
+#include <zdwm/bar.h>
+
+#include "core/listeners.h"
+
+typedef struct bar_binding_config_t {
+  bool show_default;
+  uint32_t cell_padding;
+  const char *bg;
+  const char *fg;
+} bar_binding_config_t;
+
+extern zdwm_bar_item_type_t bar_binding;
+
+void bar_binding_add_listeners(listeners_t *listeners, void *state);

src/config/defaults.c

@@ -189,6 +189,11 @@ bool config_defaults_build(
     .tag_urgent_fg       = "#ff0000",
     .layout_bg           = "#222222",
     .layout_fg           = "#bbbbbb",
+
+    .binding_show_default = true,
+    .binding_padding_x    = 2,
+    .binding_mode_bg      = "#900000",
+    .binding_mode_fg      = "#ffffff",
   };
   api->set_bar_config(builder, bar_config);