Implement units cycling

client/control.cpp

@@ -37,12 +37,10 @@
 
 // client
 #include "audio/audio.h"
-#include "chatline.h"
 #include "client_main.h"
 #include "climap.h"
 #include "climisc.h"
 #include "control.h"
-#include "editor.h"
 #include "goto.h"
 #include "governor.h"
 #include "options.h"
@@ -359,14 +357,34 @@ static void ask_server_for_actions(struct unit *punit)
 }
 
 /**
-   Return TRUE iff this unit is in focus.
+   Return TRUE if this unit is in focus.
  */
 bool unit_is_in_focus(const struct unit *punit)
 {
   const auto &focus = get_units_in_focus();
   return std::find(focus.begin(), focus.end(), punit) != focus.end();
 }
 
+/**
+   Returns TRUE if this unit is on stand by.
+
+   A unit is on stand by, if it is idle or sentried and not busy
+   building anything.
+*/
+bool unit_is_on_stand_by(const struct unit *punit)
+{
+  if (ACTIVITY_IDLE != punit->activity
+      && ACTIVITY_SENTRY != punit->activity) {
+    return false;
+  }
+
+  if (!can_unit_do_activity(punit, ACTIVITY_IDLE)) {
+    return false;
+  }
+
+  return true;
+}
+
 /**
    Return TRUE iff a unit on this tile is in focus.
  */

client/control.h

@@ -141,6 +141,7 @@ void wakeup_sentried_units(struct tile *ptile);
 void clear_unit_orders(struct unit *punit);
 
 bool unit_is_in_focus(const struct unit *punit);
+bool unit_is_on_stand_by(const struct unit *punit);
 struct unit *get_focus_unit_on_tile(const struct tile *ptile);
 struct unit *head_of_units_in_focus();
 std::vector<unit *> &get_units_in_focus();

client/hudwidget.cpp

@@ -1,5 +1,5 @@
 /*
- Copyright (c) 1996-2023 Freeciv21 and Freeciv contributors. This file is
+ Copyright (c) 1996-2024 Freeciv21 and Freeciv contributors. This file is
  part of Freeciv21. Freeciv21 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 3 of the
@@ -44,6 +44,12 @@
 #include "widgets/decorations.h"
 
 static QString popup_terrain_info(struct tile *ptile);
+static bool cycle_units_predicate(const struct unit *current_unit,
+                                  const struct unit *candidate);
+static std::tuple<int, int>
+cycle_units_get_count_and_index(const struct unit *current_unit);
+static void cycle_units_select_index(const struct unit *current_unit,
+                                     int index);
 
 /**
    Returns true if player has any unit of unit_type
@@ -528,6 +534,9 @@ hud_units::hud_units(QWidget *parent)
   setLayout(main_layout);
   mw = new move_widget(this);
   setFocusPolicy(Qt::ClickFocus);
+
+  connect(&unit_label, &click_label::wheel_scrolled, this,
+          &hud_units::cycle_units);
 }
 
 /**
@@ -770,6 +779,18 @@ void hud_units::update_actions()
   show();
 }
 
+/**
+   Cycle idle or sentried units for the unittype of the currently
+   selected unit.
+
+   The sign of direction determines in which direction the units will
+   be cycled.
+ */
+void hud_units::cycle_units(const int direction)
+{
+  ::cycle_units(direction);
+}
+
 /**
    Custom label with extra mouse events
  */
@@ -789,6 +810,24 @@ void click_label::mousePressEvent(QMouseEvent *e)
   }
 }
 
+/**
+   Wheel event for click_label
+ */
+void click_label::wheelEvent(QWheelEvent *e)
+{
+  static int accumulatedDelta = 0;
+  accumulatedDelta += e->angleDelta().y();
+
+  if (abs(accumulatedDelta) < 120) {
+    return;
+  }
+
+  int steps = accumulatedDelta / 120;
+  accumulatedDelta = accumulatedDelta - steps * 120;
+
+  emit wheel_scrolled(steps);
+}
+
 /**
    Centers on current unit
  */
@@ -1731,3 +1770,124 @@ void hud_battle_log::showEvent(QShowEvent *event)
   m_timer.restart();
   setVisible(true);
 }
+
+/**
+   This predicate is called by cycle_units and friends to filter
+   relevant units from the iterated units.
+
+   current_unit is the currently selected unit.
+   candidate is the candidate checked for relevance.
+ */
+static bool cycle_units_predicate(const struct unit *current_unit,
+                                  const struct unit *candidate)
+{
+  fc_assert_ret_val(current_unit != nullptr && candidate != nullptr, false);
+
+  if (candidate->utype != current_unit->utype) {
+    return false;
+  }
+
+  return unit_is_on_stand_by(candidate);
+}
+
+/**
+  Gets the count of relevant units and determines the index of the
+  current unit among these units.
+
+  If current_unit is not among the relevant units, then index 0 is
+  assumed by default.
+
+  current_unit is the currently selected unit.
+ */
+static std::tuple<int, int>
+cycle_units_get_count_and_index(const struct unit *current_unit)
+{
+  fc_assert_ret_val(current_unit != nullptr, std::make_tuple(0, 0));
+
+  int unit_count = 0;
+  int current_unit_index = 0;
+
+  unit_list_iterate(client_player()->units, punit)
+  {
+    if (!cycle_units_predicate(current_unit, punit)) {
+      continue;
+    }
+
+    if (current_unit->id == punit->id) {
+      current_unit_index = unit_count;
+    }
+
+    unit_count++;
+  }
+  unit_list_iterate_end;
+
+  return {unit_count, current_unit_index};
+}
+
+/**
+   Selects the next unit when units are cycled.
+
+   current_unit is the currently selected unit.
+   index is the index of the unit to be selected next among the
+   relevant units.
+ */
+static void cycle_units_select_index(const struct unit *current_unit,
+                                     int index)
+{
+  fc_assert_ret(current_unit != nullptr);
+
+  // Select the next unit.
+  int unit_count = 0;
+  unit_list_iterate(client_player()->units, punit)
+  {
+    if (!cycle_units_predicate(current_unit, punit)) {
+      continue;
+    }
+
+    if (unit_count == index) {
+      unit_focus_set_and_select(punit);
+    }
+
+    unit_count++;
+  }
+  unit_list_iterate_end;
+}
+
+/**
+   Cycle idle or sentried units for the unittype of the currently
+   selected unit.
+
+   The sign of direction determines in which direction the units will
+   be cycled.
+ */
+void cycle_units(const int direction)
+{
+  if (get_num_units_in_focus() != 1) {
+    return;
+  }
+
+  struct unit *current_unit = head_of_units_in_focus();
+
+  auto [unit_count, current_unit_index] =
+      cycle_units_get_count_and_index(current_unit);
+
+  if (unit_count == 0) {
+    return;
+  }
+
+  // Determine the index of the unit to be selected next.
+  int cycle_unit_index = current_unit_index;
+  if (direction > 0) {
+    cycle_unit_index++;
+  } else if (direction < 0) {
+    cycle_unit_index--;
+  }
+
+  if (cycle_unit_index < 0) {
+    cycle_unit_index = unit_count - 1;
+  } else if (cycle_unit_index >= unit_count) {
+    cycle_unit_index = 0;
+  }
+
+  cycle_units_select_index(current_unit, cycle_unit_index);
+}

client/hudwidget.h

@@ -1,5 +1,5 @@
 /**************************************************************************
- Copyright (c) 1996-2020 Freeciv21 and Freeciv contributors. This file is
+ Copyright (c) 1996-2024 Freeciv21 and Freeciv contributors. This file is
  part of Freeciv21. Freeciv21 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 3 of the
@@ -43,6 +43,7 @@ struct tile;
 struct unit;
 struct unit_list;
 
+void cycle_units(const int direction);
 void show_new_turn_info();
 bool has_player_unit_type(Unit_type_id utype);
 
@@ -144,11 +145,13 @@ class click_label : public QLabel {
   click_label();
 signals:
   void left_clicked();
+  void wheel_scrolled(const int delta);
 private slots:
   void mouse_clicked();
 
 protected:
   void mousePressEvent(QMouseEvent *e) override;
+  void wheelEvent(QWheelEvent *e) override;
 };
 
 /****************************************************************************
@@ -221,6 +224,9 @@ class hud_units : public QFrame {
   move_widget *mw;
   unit_list *ul_units;
   tile *current_tile;
+
+private slots:
+  void cycle_units(const int delta);
 };
 
 /****************************************************************************

client/views/view_units.cpp

@@ -550,11 +550,8 @@ void units_view::find_nearest()
   if ((punit = find_nearest_unit(utype, ptile))) {
     queen()->mapview_wdg->center_on_tile(punit->tile);
 
-    if (ACTIVITY_IDLE == punit->activity
-        || ACTIVITY_SENTRY == punit->activity) {
-      if (can_unit_do_activity(punit, ACTIVITY_IDLE)) {
-        unit_focus_set_and_select(punit);
-      }
+    if (unit_is_on_stand_by(punit)) {
+      unit_focus_set_and_select(punit);
     }
   }
 

docs/Manuals/Game/unit-controls.rst

@@ -42,3 +42,6 @@ appear in quotes after the Unit ID value.
 If the unit selected is not in your field of vision on the map, then you can click on the icon for the unit on
 the left side and the game map will center on the unit for you. As with other widgets in Freeciv21, you can
 click+drag the widget to move it by using the plus symbol in the upper left corner.
+
+If you scroll your mouse wheel over the unit icon on the left side of the widget, the game will cycle through
+idle or sentried units of the same unit type.