Display: clean up whiteboard arrow rendering

The arrow class shouldn't be in charge of adding to the drawing buffer. Also it meant that in a case of multiple arrows padding through one hex, multiple buffer entries would be added. Now it will use one per hex.

src/arrow.cpp

@@ -30,8 +30,7 @@ static lg::log_domain log_arrows("arrows");
 #define DBG_ARR LOG_STREAM(debug, log_arrows)
 
 arrow::arrow(bool hidden)
-	: layer_(drawing_layer::arrows)
-	, color_("red")
+	: color_("red")
 	, style_(STYLE_STANDARD)
 	, path_()
 	, previous_path_()
@@ -136,12 +135,12 @@ bool arrow::path_contains(const map_location& hex) const
 	return contains;
 }
 
-void arrow::draw_hex(const map_location& hex)
+image::locator arrow::get_image_for_loc(const map_location& hex) const
 {
-	if(path_contains(hex)) {
-		display::get_singleton()->drawing_buffer_add(layer_, hex, [tex = image::get_texture(symbols_map_[hex])](const rect& dest) {
-			draw::blit(tex, dest);
-		});
+	if(auto iter = symbols_map_.find(hex); iter != symbols_map_.end()) {
+		return iter->second;
+	} else {
+		return {}; // TODO: optional<locator>? Practically I don't think this path gets hit
 	}
 }
 

src/arrow.hpp

@@ -74,7 +74,7 @@ public:
 
 	bool path_contains(const map_location& hex) const;
 
-	virtual void draw_hex(const map_location& hex);
+	image::locator get_image_for_loc(const map_location& hex) const;
 
 	/** Checks that the path is not of length 0 or 1 */
 	static bool valid_path(const arrow_path_t& path);
@@ -91,8 +91,6 @@ protected:
 	 */
 	virtual void update_symbols();
 
-	drawing_layer layer_;
-
 	std::string color_;
 	/** represents the subdirectory that holds images for this arrow style */
 	std::string style_;

src/display.cpp

@@ -2702,11 +2702,17 @@ void display::draw_hex(const map_location& loc)
 	}
 
 	// Paint arrows
-	arrows_map_t::const_iterator arrows_in_hex = arrows_map_.find(loc);
-	if(arrows_in_hex != arrows_map_.end()) {
-		for (arrow* const a : arrows_in_hex->second) {
-			a->draw_hex(loc);
+	if(auto arrows_in_hex = arrows_map_.find(loc); arrows_in_hex != arrows_map_.end()) {
+		std::vector<texture> to_draw;
+		for(const arrow* a : arrows_in_hex->second) {
+			to_draw.push_back(image::get_texture(a->get_image_for_loc(loc)));
 		}
+
+		drawing_buffer_add(drawing_layer::arrows, loc, [to_draw = std::move(to_draw)](const rect& dest) {
+			for(const texture& t : to_draw) {
+				draw::blit(t, dest);
+			}
+		});
 	}
 
 	// Apply shroud, fog and linger overlay

src/display.hpp

@@ -961,10 +961,8 @@ private:
 	/** Currently set debug flags. */
 	std::bitset<__NUM_DEBUG_FLAGS> debug_flags_;
 
-	typedef std::list<arrow*> arrows_list_t;
-	typedef std::map<map_location, arrows_list_t > arrows_map_t;
 	/** Maps the list of arrows for each location */
-	arrows_map_t arrows_map_;
+	std::map<map_location, std::list<arrow*>> arrows_map_;
 
 	tod_color color_adjust_;