Migrate the LAYER_BACKGROUND code to its class

This commit migrates the code to draw the LAYER_BACKGROUND sprites to the
layer_background class. The feature that allowed to hide the terrain was not
migrated; see #449.

Closes #449.
See #430.

client/control.cpp

@@ -2365,19 +2365,6 @@ void request_toggle_city_trade_routes()
   update_map_canvas_visible();
 }
 
-/**
-   Toggle display of terrain
- */
-void request_toggle_terrain()
-{
-  if (!can_client_change_view()) {
-    return;
-  }
-
-  gui_options.draw_terrain ^= 1;
-  update_map_canvas_visible();
-}
-
 /**
    Toggle display of coastline
  */
@@ -3692,11 +3679,6 @@ void key_city_productions_toggle() { request_toggle_city_productions(); }
  */
 void key_city_trade_routes_toggle() { request_toggle_city_trade_routes(); }
 
-/**
-   Handle user 'toggle terrain display' input
- */
-void key_terrain_toggle() { request_toggle_terrain(); }
-
 /**
    Handle user 'toggle coastline display' input
  */

client/control.h

@@ -139,7 +139,6 @@ void request_toggle_city_growth();
 void request_toggle_city_productions();
 void request_toggle_city_buycost();
 void request_toggle_city_trade_routes();
-void request_toggle_terrain();
 void request_toggle_coastline();
 void request_toggle_roads_rails();
 void request_toggle_irrigation();
@@ -194,7 +193,6 @@ void key_city_growth_toggle();
 void key_city_productions_toggle();
 void key_city_buycost_toggle();
 void key_city_trade_routes_toggle();
-void key_terrain_toggle();
 void key_coastline_toggle();
 void key_roads_rails_toggle();
 void key_irrigation_toggle();

client/layer.h

@@ -16,6 +16,7 @@
 class QPixmap;
 
 struct city;
+struct player;
 struct tileset;
 struct unit;
 struct unit_type;
@@ -137,6 +138,22 @@ class layer {
                     const tile_corner *pcorner, const unit *punit,
                     const city *pcity, const unit_type *putype) const;
 
+  /**
+   * Initializes data specific to one player. This allows to cache tiles
+   * depending on the actual players in a game.
+   *
+   * \see free_player
+   */
+  virtual void initialize_player(const player *player) { Q_UNUSED(player); }
+
+  /**
+   * Frees data initialized by initialize_player. Note that this takes the
+   * player ID and not a pointer to the player.
+   *
+   * \see initialize_player
+   */
+  virtual void free_player(int player_id) { Q_UNUSED(player_id); }
+
   mapview_layer type() const { return m_layer; }
 
 protected:

client/layer_background.cpp

@@ -13,16 +13,81 @@
 
 #include "layer_background.h"
 
+#include "client_main.h"
+#include "colors_common.h"
+#include "control.h" // unit_is_in_focus
+#include "game.h"
+#include "sprite_g.h"
 #include "tilespec.h"
 
 namespace freeciv {
 
+layer_background::layer_background(struct tileset *ts)
+    : freeciv::layer(ts, LAYER_BACKGROUND)
+{
+}
+
 std::vector<drawn_sprite> layer_background::fill_sprite_array(
     const tile *ptile, const tile_edge *pedge, const tile_corner *pcorner,
     const unit *punit, const city *pcity, const unit_type *putype) const
 {
-  return ::fill_sprite_array(tileset(), LAYER_BACKGROUND, ptile, pedge,
-                             pcorner, punit, pcity, putype);
+  // Set up background color.
+  player *owner = nullptr;
+  if (gui_options.solid_color_behind_units) {
+    /* Unit drawing is disabled when the view options are turned off,
+     * but only where we're drawing on the mapview. */
+    bool do_draw_unit =
+        (punit
+         && (gui_options.draw_units || !ptile
+             || (gui_options.draw_focus_unit && unit_is_in_focus(punit))));
+    if (do_draw_unit) {
+      owner = unit_owner(punit);
+    } else if (pcity && gui_options.draw_cities) {
+      owner = city_owner(pcity);
+    }
+  }
+  if (owner) {
+    return {drawn_sprite(tileset(),
+                         m_player_background[player_index(owner)].get())};
+  } else {
+    return {};
+  }
+}
+
+void layer_background::initialize_player(const player *player)
+{
+  // Get the color. In pregame, players have no color so we just use red.
+  const auto color = player_has_color(tileset(), player)
+                         ? *get_player_color(tileset(), player)
+                         : Qt::red;
+
+  auto sprite = create_player_sprite(color);
+
+  const auto id = player_index(player);
+  m_player_background.at(id) = std::unique_ptr<QPixmap>(
+      crop_sprite(sprite.get(), 0, 0, tileset_tile_width(tileset()),
+                  tileset_tile_height(tileset()), get_mask_sprite(tileset()),
+                  0, 0, tileset_scale(tileset()), false));
+}
+
+void layer_background::free_player(int player_id)
+{
+  m_player_background.at(player_id) = nullptr;
+}
+
+/**
+ * Create a sprite with the given color.
+ */
+std::unique_ptr<QPixmap>
+layer_background::create_player_sprite(const QColor &pcolor) const
+{
+  if (tileset_scale(tileset()) == 1.0f) {
+    return std::unique_ptr<QPixmap>(create_sprite(128, 64, &pcolor));
+  } else {
+    return std::unique_ptr<QPixmap>(
+        create_sprite(tileset_full_tile_width(tileset()),
+                      tileset_full_tile_height(tileset()), &pcolor));
+  }
 }
 
 } // namespace freeciv

client/layer_background.h

@@ -12,20 +12,31 @@
       \____/        ********************************************************/
 #pragma once
 
+#include "fc_types.h"
 #include "layer.h"
 
+#include <QPixmap>
+
 namespace freeciv {
 
 class layer_background : public layer {
 public:
-  layer_background(struct tileset *ts) : freeciv::layer(ts, LAYER_BACKGROUND)
-  {
-  }
+  explicit layer_background(struct tileset *ts);
 
   std::vector<drawn_sprite>
   fill_sprite_array(const tile *ptile, const tile_edge *pedge,
                     const tile_corner *pcorner, const unit *punit,
-                    const city *pcity, const unit_type *putype) const;
+                    const city *pcity,
+                    const unit_type *putype) const override;
+
+  void initialize_player(const player *player) override;
+  void free_player(int player_id) override;
+
+private:
+  std::unique_ptr<QPixmap> create_player_sprite(const QColor &pcolor) const;
+
+  std::array<std::unique_ptr<QPixmap>, MAX_NUM_PLAYER_SLOTS>
+      m_player_background;
 };
 
 } // namespace freeciv

client/options.cpp

@@ -152,7 +152,6 @@ struct client_options gui_options = {
     true,  //.draw_city_productions =
     false, //.draw_city_buycost =
     false, //.draw_city_trade_routes =
-    true,  //.draw_terrain =
     false, //.draw_coastline =
     true,  //.draw_roads_rails =
     true,  //.draw_irrigation =
@@ -1636,10 +1635,6 @@ static struct client_option client_options[] = {
                        "between cities which have trade routes."),
                     COC_GRAPHICS, GUI_STUB, false,
                     view_option_changed_callback),
-    GEN_BOOL_OPTION(draw_terrain, N_("Draw the terrain"),
-                    N_("Setting this option will draw the terrain."),
-                    COC_GRAPHICS, GUI_STUB, true,
-                    view_option_changed_callback),
     GEN_BOOL_OPTION(
         draw_coastline, N_("Draw the coast line"),
         N_("Setting this option will draw a line to separate the "

client/options.h

@@ -125,7 +125,6 @@ struct client_options {
   bool draw_city_productions;
   bool draw_city_buycost;
   bool draw_city_trade_routes;
-  bool draw_terrain;
   bool draw_coastline;
   bool draw_roads_rails;
   bool draw_irrigation;

client/packhand.cpp

@@ -4557,8 +4557,6 @@ void handle_ruleset_game(const struct packet_ruleset_game *packet)
   game.plr_bg_color =
       rgbcolor_new(packet->background_red, packet->background_green,
                    packet->background_blue);
-
-  tileset_background_init(tileset);
 }
 
 /**