chore: add alt-tab navigation with update_mru flag and MRU-based taskbar rendering

include/client.h

@@ -18,7 +18,7 @@ void client_unmanage(Client *client);
 Client *client_find_by_window(Window window);
 Client *client_find_by_frame(Window frame);
 
-void client_focus(Client *client);
+void client_focus(Client *client, bool update_mru);
 void client_unfocus(Client *client);
 void client_raise(Client *client);
 void client_lower(Client *client);

include/dwn.h

@@ -171,6 +171,9 @@ typedef struct {
 
     Client *pending_focus_client;
     long pending_focus_time;
+
+    bool is_alt_tabbing;
+    Client *alt_tab_client;
 } DWNState;
 
 extern DWNState *dwn;

include/workspace.h

@@ -50,6 +50,10 @@ void workspace_focus_next(void);
 void workspace_focus_prev(void);
 void workspace_focus_master(void);
 
+void workspace_alt_tab_next(void);
+void workspace_alt_tab_prev(void);
+void workspace_end_alt_tab(void);
+
 void workspace_mru_push(int workspace, Client *client);
 void workspace_mru_remove(int workspace, Client *client);
 Client *workspace_mru_get_previous(int workspace, Client *current);

src/api.c

@@ -111,7 +111,7 @@ static void handle_command(struct mg_connection *c, cJSON *json) {
                 if (cl->workspace != (unsigned int)dwn->current_workspace) {
                     workspace_switch(cl->workspace);
                 }
-                client_focus(cl);
+                client_focus(cl, true);
                 handle_get_status(c);
             }
         }

src/client.c

@@ -232,7 +232,7 @@ Client *client_manage(Window window)
     client_show(client);
 
     client_sync_log("client_manage: focusing");
-    client_focus(client);
+    client_focus(client, true);
 
     client_sync_log("client_manage: DONE");
     return client;
@@ -249,6 +249,10 @@ void client_unmanage(Client *client)
 
     LOG_DEBUG("Unmanaging window: %lu", client->window);
 
+    if (dwn->alt_tab_client == client) {
+        workspace_end_alt_tab();
+    }
+
     client_sync_log("client_unmanage: remove from MRU");
     workspace_mru_remove(client->workspace, client);
 
@@ -274,7 +278,7 @@ void client_unmanage(Client *client)
     if (ws != NULL && ws->focused == NULL) {
         Client *next = workspace_mru_get_previous(dwn->current_workspace, NULL);
         if (next != NULL) {
-            client_focus(next);
+            client_focus(next, true);
         } else {
             XSetInputFocus(dwn->display, dwn->root, RevertToPointerRoot, CurrentTime);
             atoms_set_active_window(None);
@@ -316,7 +320,7 @@ Client *client_find_by_frame(Window frame)
 }
 
 
-void client_focus(Client *client)
+void client_focus(Client *client, bool update_mru)
 {
     client_sync_log("client_focus: START");
 
@@ -354,7 +358,9 @@ void client_focus(Client *client)
 
     if (ws != NULL) {
         ws->focused = client;
-        workspace_mru_push(client->workspace, client);
+        if (update_mru) {
+            workspace_mru_push(client->workspace, client);
+        }
     }
 
     client_sync_log("client_focus: raising");
@@ -442,7 +448,7 @@ void client_minimize(Client *client)
     if (ws != NULL && ws->focused == client) {
         Client *next = workspace_mru_get_previous(client->workspace, client);
         if (next != NULL) {
-            client_focus(next);
+            client_focus(next, true);
         } else {
             ws->focused = NULL;
             XSetInputFocus(dwn->display, dwn->root, RevertToPointerRoot, CurrentTime);
@@ -459,7 +465,7 @@ void client_restore(Client *client)
 
     client->flags &= ~CLIENT_MINIMIZED;
     client_show(client);
-    client_focus(client);
+    client_focus(client, true);
 }
 
 
@@ -848,7 +854,7 @@ void client_set_maximize(Client *client, bool maximized)
         client_configure(client);
         decorations_render(client, true);
         client_raise(client);
-        client_focus(client);
+        client_focus(client, true);
     } else {
         client->flags &= ~CLIENT_MAXIMIZED;
 

src/keys.c

@@ -457,6 +457,10 @@ void keys_handle_release(XKeyEvent *ev)
         super_pressed = false;
         super_used_in_combo = false;
     }
+
+    if (keysym == XK_Alt_L || keysym == XK_Alt_R) {
+        workspace_end_alt_tab();
+    }
 }
 
 
@@ -629,12 +633,12 @@ void key_toggle_minimize(void)
 
 void key_focus_next(void)
 {
-    workspace_focus_next();
+    workspace_alt_tab_next();
 }
 
 void key_focus_prev(void)
 {
-    workspace_focus_prev();
+    workspace_alt_tab_prev();
 }
 
 void key_workspace_next(void)

src/main.c

@@ -377,7 +377,7 @@ static void handle_enter_notify(XCrossingEvent *ev)
     if (c != NULL && c->workspace == (unsigned int)dwn->current_workspace) {
         int delay = dwn->config->focus_follow_delay_ms;
         if (delay <= 0) {
-            client_focus(c);
+            client_focus(c, true);
         } else {
             dwn->pending_focus_client = c;
             dwn->pending_focus_time = get_time_ms() + delay;
@@ -453,11 +453,11 @@ static void handle_button_press(XButtonEvent *ev)
 
     if (is_client_window) {
         XAllowEvents(dwn->display, ReplayPointer, ev->time);
-        client_focus(c);
+        client_focus(c, true);
         return;
     }
 
-    client_focus(c);
+    client_focus(c, true);
 
     if (c->frame != None && ev->window == c->frame) {
         ButtonType btn = decorations_hit_test_button(c, ev->x, ev->y);
@@ -573,7 +573,7 @@ static void handle_client_message(XClientMessageEvent *ev)
             if (c->workspace != (unsigned int)dwn->current_workspace) {
                 workspace_switch(c->workspace);
             }
-            client_focus(c);
+            client_focus(c, true);
         }
     } else if (ev->message_type == ewmh.NET_CLOSE_WINDOW) {
         if (c != NULL) {
@@ -897,7 +897,7 @@ void dwn_run(void)
                 Workspace *ws = workspace_get_current();
                 if (ws != NULL && ws->focused != dwn->pending_focus_client) {
                     if (dwn->pending_focus_client->workspace == (unsigned int)dwn->current_workspace) {
-                        client_focus(dwn->pending_focus_client);
+                        client_focus(dwn->pending_focus_client, true);
                     }
                 }
                 dwn->pending_focus_client = NULL;

src/panel.c

@@ -372,10 +372,14 @@ void panel_render_taskbar(Panel *panel, int x, int *width)
     if (available_width < 0) available_width = 0;
     int item_count = 0;
 
-    for (Client *c = dwn->client_list; c != NULL; c = c->next) {
-        if (c->workspace == (unsigned int)dwn->current_workspace) {
-            item_count++;
-        }
+    Workspace *ws = workspace_get_current();
+    if (ws == NULL) {
+        *width = 0;
+        return;
+    }
+
+    for (Client *c = ws->mru_head; c != NULL; c = c->mru_next) {
+        item_count++;
     }
 
     if (item_count == 0) {
@@ -388,14 +392,12 @@ void panel_render_taskbar(Panel *panel, int x, int *width)
         item_width = TASKBAR_ITEM_WIDTH;
     }
 
-    Workspace *ws = workspace_get_current();
-
-    for (Client *c = dwn->client_list; c != NULL; c = c->next) {
+    for (Client *c = ws->mru_head; c != NULL; c = c->mru_next) {
         if (c->workspace != (unsigned int)dwn->current_workspace) {
             continue;
         }
 
-        bool focused = (ws != NULL && ws->focused == c);
+        bool focused = (ws->focused == c);
         bool minimized = client_is_minimized(c);
 
         unsigned long bg;
@@ -554,7 +556,7 @@ void panel_handle_click(Panel *panel, int x, int y, int button)
                     if (ws != NULL && ws->focused == c) {
                         client_minimize(c);
                     } else {
-                        client_focus(c);
+                        client_focus(c, true);
                     }
                 }
             } else if (button == 3) {
@@ -593,7 +595,11 @@ Client *panel_hit_test_taskbar(Panel *panel, int x, int y)
     }
 
     Workspace *ws = workspace_get_current();
-    const char *layout_symbol = layout_get_symbol(ws != NULL ? ws->layout : LAYOUT_TILING);
+    if (ws == NULL) {
+        return NULL;
+    }
+
+    const char *layout_symbol = layout_get_symbol(ws->layout);
     int layout_width = panel_text_width(layout_symbol, strlen(layout_symbol));
     int taskbar_start = PANEL_PADDING + MAX_WORKSPACES * WORKSPACE_WIDTH + WIDGET_SPACING + layout_width + WIDGET_SPACING;
     if (x < taskbar_start) {
@@ -607,10 +613,8 @@ Client *panel_hit_test_taskbar(Panel *panel, int x, int y)
     if (available_width < 0) available_width = 0;
     int item_count = 0;
 
-    for (Client *c = dwn->client_list; c != NULL; c = c->next) {
-        if (c->workspace == (unsigned int)dwn->current_workspace) {
-            item_count++;
-        }
+    for (Client *c = ws->mru_head; c != NULL; c = c->mru_next) {
+        item_count++;
     }
 
     if (item_count == 0) {
@@ -625,13 +629,11 @@ Client *panel_hit_test_taskbar(Panel *panel, int x, int y)
     int index = (x - taskbar_start) / item_width;
     int i = 0;
 
-    for (Client *c = dwn->client_list; c != NULL; c = c->next) {
-        if (c->workspace == (unsigned int)dwn->current_workspace) {
-            if (i == index) {
-                return c;
-            }
-            i++;
+    for (Client *c = ws->mru_head; c != NULL; c = c->mru_next) {
+        if (i == index) {
+            return c;
         }
+        i++;
     }
 
     return NULL;

src/workspace.c

@@ -95,11 +95,11 @@ void workspace_switch(int index)
     Workspace *ws = workspace_get(index);
     if (ws != NULL) {
         if (ws->focused != NULL) {
-            client_focus(ws->focused);
+            client_focus(ws->focused, true);
         } else {
             Client *first = workspace_get_first_client(index);
             if (first != NULL) {
-                client_focus(first);
+                client_focus(first, true);
             } else {
                 XSetInputFocus(dwn->display, dwn->root, RevertToPointerRoot, CurrentTime);
                 atoms_set_active_window(None);
@@ -409,7 +409,7 @@ void workspace_focus_next(void)
     }
 
     if (next != NULL && next != ws->focused) {
-        client_focus(next);
+        client_focus(next, true);
     }
 }
 
@@ -435,7 +435,7 @@ void workspace_focus_prev(void)
     }
 
     if (prev != NULL && prev != ws->focused) {
-        client_focus(prev);
+        client_focus(prev, true);
     }
 }
 
@@ -443,7 +443,7 @@ void workspace_focus_master(void)
 {
     Client *master = workspace_get_first_client(dwn->current_workspace);
     if (master != NULL) {
-        client_focus(master);
+        client_focus(master, true);
     }
 }
 
@@ -518,3 +518,87 @@ Client *workspace_mru_get_previous(int workspace, Client *current)
 
     return NULL;
 }
+
+void workspace_alt_tab_next(void)
+{
+    if (dwn == NULL) return;
+
+    Workspace *ws = workspace_get_current();
+    if (ws == NULL || ws->mru_head == NULL) return;
+
+    if (!dwn->is_alt_tabbing) {
+        dwn->is_alt_tabbing = true;
+        dwn->alt_tab_client = ws->focused;
+        XGrabKeyboard(dwn->display, dwn->root, True, 
+                      GrabModeAsync, GrabModeAsync, CurrentTime);
+    }
+
+    Client *current = dwn->alt_tab_client;
+    if (current == NULL) {
+        current = ws->mru_head;
+    }
+
+    if (current != NULL && current->mru_next != NULL) {
+        dwn->alt_tab_client = current->mru_next;
+    } else {
+        dwn->alt_tab_client = ws->mru_head;
+    }
+
+    if (dwn->alt_tab_client != NULL) {
+        client_focus(dwn->alt_tab_client, false);
+    }
+}
+
+void workspace_alt_tab_prev(void)
+{
+    if (dwn == NULL) return;
+
+    Workspace *ws = workspace_get_current();
+    if (ws == NULL || ws->mru_head == NULL) return;
+
+    if (!dwn->is_alt_tabbing) {
+        dwn->is_alt_tabbing = true;
+        dwn->alt_tab_client = ws->focused;
+        XGrabKeyboard(dwn->display, dwn->root, True, 
+                      GrabModeAsync, GrabModeAsync, CurrentTime);
+    }
+
+    Client *current = dwn->alt_tab_client;
+
+    
+    if (current != NULL && current->mru_prev != NULL) {
+        dwn->alt_tab_client = current->mru_prev;
+    } else {
+        dwn->alt_tab_client = ws->mru_tail;
+    }
+
+    if (dwn->alt_tab_client != NULL) {
+        client_focus(dwn->alt_tab_client, false);
+    }
+}
+
+void workspace_end_alt_tab(void)
+{
+    if (dwn == NULL || !dwn->is_alt_tabbing) return;
+
+    dwn->is_alt_tabbing = false;
+
+        if (dwn->alt_tab_client != NULL) {
+
+            workspace_mru_push(dwn->current_workspace, dwn->alt_tab_client);
+
+            /* Redraw panel to show new MRU order */
+
+            panel_render_all();
+
+        }
+
+        
+
+        dwn->alt_tab_client = NULL;
+
+        XUngrabKeyboard(dwn->display, CurrentTime);
+
+    }
+
+