feat(bar): bar item 扩展钩子功能 bar cell 添加 fixed_width 属性与操作接口

- item type 加入可为空的 after_layout 和 after_draw 钩子
- cell 加 fixed_width 属性， cell api 添加 cell_set_fixed_width 和
  cell_get_region 两个接口
- cell api 改为 const 避免外部修改

src/bar/bar.c

@@ -212,14 +212,16 @@ static void bar_output_layout(bar_output_t *bar_output, text_context_t *ctx) {
     item->region.start = start;
     for (size_t j = 0; j < item->count; ++j) {
       auto cell = &item->cells[j];
+      auto fixed_width = cell->fixed_width;
 
-      int32_t width = 0;
-      text_context_get_text_size(ctx, cell->text, &width, nullptr);
-
-      bar_x_region_t region = {
-        .start = start,
-        .end = start + width + item->cell_padding * 2,
-      };
+      bar_x_region_t region = {.start = start, .end = start};
+      if (fixed_width == 0) {
+        int32_t width = 0;
+        text_context_get_text_size(ctx, cell->text, &width, nullptr);
+        region.end += width + 2 * item->cell_padding;
+      } else if (fixed_width > 0) {
+        region.end += fixed_width;
+      }
       bar_cell_set_region(item, j, region);
 
       start = region.end;
@@ -240,14 +242,16 @@ static void bar_output_layout(bar_output_t *bar_output, text_context_t *ctx) {
     for (size_t j = item->count; j > 0; --j) {
       auto cell_index = j - 1;
       auto cell = &item->cells[cell_index];
+      auto fixed_width = cell->fixed_width;
 
-      int32_t width = 0;
-      text_context_get_text_size(ctx, cell->text, &width, nullptr);
-
-      bar_x_region_t region = {
-        .start = end - width - item->cell_padding * 2,
-        .end = end,
-      };
+      bar_x_region_t region = {.start = end, .end = end};
+      if (fixed_width == 0) {
+        int32_t width = 0;
+        text_context_get_text_size(ctx, cell->text, &width, nullptr);
+        region.start -= width + item->cell_padding * 2;
+      } else if (fixed_width > 0) {
+        region.start -= fixed_width;
+      }
       bar_cell_set_region(item, cell_index, region);
 
       end = region.start;
@@ -263,12 +267,30 @@ static void bar_output_layout(bar_output_t *bar_output, text_context_t *ctx) {
   if (center->count == 0) return;
   center->region = (bar_x_region_t){.start = start, .end = end};
 
-  auto width = (end - start) / (int32_t)center->count;
+  auto center_width = end - start;
+  auto center_count = center->count;
   for (size_t i = 0; i < center->count; ++i) {
-    bar_x_region_t region = {
-      .start = start,
-      .end = start + width + center->cell_padding * 2,
-    };
+    auto cell = &center->cells[i];
+    auto fixed_width = cell->fixed_width;
+    if (fixed_width > 0) {
+      center_width -= fixed_width;
+    } else if (fixed_width < 0) {
+      /* 隐藏的 cell 不占任何空间，平分宽度时不参与 */
+      --center_count;
+    }
+  }
+
+  auto width = center_width / (int32_t)center_count;
+  for (size_t i = 0; i < center->count; ++i) {
+    auto cell = &center->cells[i];
+    auto fixed_width = cell->fixed_width;
+
+    bar_x_region_t region = {.start = start, .end = start};
+    if (fixed_width == 0) {
+      region.end += width + center->cell_padding * 2;
+    } else if (fixed_width > 0) {
+      region.end += fixed_width;
+    }
     start = region.end;
     bar_cell_set_region(center, i, region);
   }
@@ -386,6 +408,42 @@ bar_output_draw(bar_output_t *bar_output, text_context_t *ctx, color_t *bg) {
   bar_item_draw(cr, &bar_output->center, ctx, bar_output->height);
 }
 
+static inline void bar_item_run_hook(
+  zdwm_bar_item_t *item,
+  void (*hook)(const zdwm_bar_item_hook_params_t *params)
+) {
+  if (!hook) return;
+
+  zdwm_bar_item_hook_params_t params = {
+    .item = item,
+    .cell_api = &bar_cell_api,
+    .region = item->region,
+    .state = item->state
+  };
+  hook(&params);
+}
+
+static void visitor_after_layout(zdwm_bar_item_t *item) {
+  bar_item_run_hook(item, item->api.after_layout);
+}
+
+static void visitor_after_draw(zdwm_bar_item_t *item) {
+  bar_item_run_hook(item, item->api.after_draw);
+}
+
+typedef void (*bar_item_visitor_t)(zdwm_bar_item_t *item);
+
+static void
+bar_output_foreach_item(bar_output_t *bar_output, bar_item_visitor_t visit) {
+  for (size_t i = 0; i < bar_output->left.count; ++i) {
+    visit(&bar_output->left.items[i]);
+  }
+  visit(&bar_output->center);
+  for (size_t i = 0; i < bar_output->right.count; ++i) {
+    visit(&bar_output->right.items[i]);
+  }
+}
+
 bool bar_draw(bar_t *bar) {
   auto ctx = bar->ctx;
 
@@ -396,7 +454,9 @@ bool bar_draw(bar_t *bar) {
     if (!bar_output_is_dirty(bar_output)) continue;
 
     bar_output_layout(bar_output, ctx);
+    bar_output_foreach_item(bar_output, visitor_after_layout);
     bar_output_draw(bar_output, ctx, &bar->palette.bg);
+    bar_output_foreach_item(bar_output, visitor_after_draw);
     changed = true;
   }
 

src/bar/cell.c

@@ -2,6 +2,7 @@
 
 #include <assert.h>
 #include <stddef.h>
+#include <stdint.h>
 #include <string.h>
 #include <strings.h>
 #include <zdwm/types.h>
@@ -119,15 +120,37 @@ bar_cell_set_indicator(zdwm_bar_item_t *item, size_t index, bool show) {
   item->dirty = true;
 }
 
+static void
+bar_cell_set_fixed_width(zdwm_bar_item_t *item, size_t index, int32_t width) {
+  if (index >= item->count) return;
+
+  auto cell = &item->cells[index];
+  if (cell->fixed_width == width) return;
+
+  cell->fixed_width = width;
+
+  cell->dirty = true;
+  item->dirty = true;
+}
+
+static bar_x_region_t bar_cell_get_region(zdwm_bar_item_t *item, size_t index) {
+  if (index >= item->count) return (bar_x_region_t){0};
+
+  auto cell = &item->cells[index];
+  return cell->region;
+}
+
 /* clang-format off */
-zdwm_bar_cell_api_t bar_cell_api = {
-  .get_cell_count     = bar_cell_get_count,
-  .set_cell_count     = bar_cell_set_count,
-  .cell_set_text      = bar_cell_set_text,
-  .cell_set_bg        = bar_cell_set_bg,
-  .cell_set_fg        = bar_cell_set_fg,
-  .cell_set_icon      = bar_cell_set_icon,
-  .cell_set_indicator = bar_cell_set_indicator,
+const zdwm_bar_cell_api_t bar_cell_api = {
+  .get_cell_count       = bar_cell_get_count,
+  .set_cell_count       = bar_cell_set_count,
+  .cell_set_text        = bar_cell_set_text,
+  .cell_set_bg          = bar_cell_set_bg,
+  .cell_set_fg          = bar_cell_set_fg,
+  .cell_set_icon        = bar_cell_set_icon,
+  .cell_set_indicator   = bar_cell_set_indicator,
+  .cell_set_fixed_width = bar_cell_set_fixed_width,
+  .cell_get_region      = bar_cell_get_region,
 };
 /* clang-format on */
 

src/bar/cell.h

@@ -12,4 +12,4 @@ void bar_cell_set_region(
   bar_x_region_t region
 );
 
-extern zdwm_bar_cell_api_t bar_cell_api;
+extern const zdwm_bar_cell_api_t bar_cell_api;

src/bar/types.h

@@ -7,10 +7,7 @@
 
 #include "base/color.h"
 
-typedef struct bar_x_region_t {
-  int32_t start;
-  int32_t end;
-} bar_x_region_t;
+typedef struct zdwm_bar_x_region_t bar_x_region_t;
 
 typedef struct bar_cell_t {
   zdwm_icon_t icon;
@@ -20,6 +17,7 @@ typedef struct bar_cell_t {
   color_t fg;
   color_t bg;
   bar_x_region_t region;
+  int32_t fixed_width;
   bool show_indicator;
   bool dirty;
 } bar_cell_t;