Use display cache to boost performance

Also modifies the test to refresh the cache.

src/display.cpp

@@ -35,6 +35,15 @@ static const flag_id json_flag_THERMOMETER( "THERMOMETER" );
 
 static const itype_id fuel_type_muscle( "muscle" );
 
+// Cache for the overmap widget string
+static disp_overmap_cache disp_om_cache;
+
+disp_overmap_cache::disp_overmap_cache()
+{
+    _center = overmap::invalid_tripoint;
+    _mission = overmap::invalid_tripoint;
+}
+
 // Get remotely controlled vehicle, or vehicle character is inside of
 vehicle *display::vehicle_driven( const Character &u )
 {
@@ -1232,14 +1241,19 @@ std::string display::colorized_overmap_text( const avatar &u, const int width, c
     map &here = get_map();
 
     // Map is roughly centered around this point
-    const point_abs_omt center_xy = u.global_omt_location().xy();
+    const tripoint_abs_omt &center_xyz = u.global_omt_location();
+    const tripoint_abs_omt &mission_xyz = u.get_active_mission_target();
+    // Retrieve cached string instead of constantly rebuilding it
+    if( disp_om_cache.is_valid_for( center_xyz, mission_xyz ) ) {
+        return disp_om_cache.get_val();
+    }
 
     // Scan each row of overmap tiles
     for( int row = -( height / 2 ); row <= height - ( height / 2 ) - 1; row++ ) {
         // Scan across the width of the row
         for( int col = -( width / 2 ); col <= width - ( width / 2 ) - 1; col++ ) {
             // Get colorized symbol for this point
-            const tripoint_abs_omt omt( center_xy + point( col, row ), here.get_abs_sub().z );
+            const tripoint_abs_omt omt( center_xyz.xy() + point( col, row ), here.get_abs_sub().z );
             std::pair<std::string, nc_color> sym_color = display::overmap_tile_symbol_color( u, omt );
 
             // Highlight player character location in the center
@@ -1250,6 +1264,10 @@ std::string display::colorized_overmap_text( const avatar &u, const int width, c
         }
         overmap_text += "\n";
     }
+
+    // Rebuild the cache so we can reuse it if nothing changes
+    disp_om_cache.rebuild( center_xyz, mission_xyz, overmap_text );
+
     return overmap_text;
 }
 

src/display.h

@@ -9,6 +9,36 @@
 class avatar;
 class Character;
 
+struct disp_overmap_cache {
+    private:
+        tripoint_abs_omt _center;
+        tripoint_abs_omt _mission;
+        std::string _om_wgt_str;
+
+    public:
+        disp_overmap_cache();
+
+        // Returns true if the stored overmap string can be used with the given
+        // center (player) position and mission target.
+        bool is_valid_for( const tripoint_abs_omt &center, const tripoint_abs_omt &mission ) const {
+            return _center == center && _mission == mission;
+        }
+
+        // Rebuild the cache using the validation parameters "center" and "mission"
+        // and store the associated widget string.
+        void rebuild( const tripoint_abs_omt &center, const tripoint_abs_omt &mission,
+                      const std::string &om_wgt_str ) {
+            _center = center;
+            _mission = mission;
+            _om_wgt_str = om_wgt_str;
+        }
+
+        // Retreive the cached widget string
+        const std::string &get_val() const {
+            return _om_wgt_str;
+        }
+};
+
 // The display namespace contains UI string output and colorization functions
 // Some return plain strings or translations, some return a (string, color) pair,
 // and some return a string with colorization tags embedded.

tests/widget_test.cpp

@@ -4,8 +4,10 @@
 #include "player_helpers.h"
 #include "map.h"
 #include "map_helpers.h"
+#include "mission.h"
 #include "monster.h"
 #include "morale.h"
+#include "overmap.h"
 #include "overmapbuffer.h"
 #include "options_helpers.h"
 #include "weather.h"
@@ -952,11 +954,12 @@ TEST_CASE( "widgets showing weather conditions", "[widget][weather]" )
 // Fill a 3x3 overmap area around the avatar with a given overmap terrain
 static void fill_overmap_area( const avatar &ava, const oter_id &oter )
 {
-    const tripoint_abs_omt ava_pos( ms_to_omt_copy( get_map().getabs( ava.pos() ) ) );
+    const tripoint_abs_omt &ava_pos = ava.global_omt_location();
     for( int x = -1; x <= 1; ++x ) {
         for( int y = -1; y <= 1; ++y ) {
             const tripoint offset( x, y, 0 );
             overmap_buffer.ter_set( ava_pos + offset, oter );
+            overmap_buffer.set_seen( ava_pos + offset, true );
         }
     }
 }
@@ -965,8 +968,12 @@ TEST_CASE( "multi-line overmap text widget", "[widget][overmap]" )
 {
     widget overmap_w = widget_test_overmap_3x3_text.obj();
     avatar &ava = get_avatar();
+    mission msn;
+    // Use mission target to invalidate the om cache
+    msn.set_target( ava.global_omt_location() + tripoint( 5, 0, 0 ) );
     clear_avatar();
     clear_map();
+    ava.on_mission_assignment( msn );
 
     SECTION( "field" ) {
         const std::string brown_dot = "<color_c_brown>.</color>";
@@ -978,6 +985,7 @@ TEST_CASE( "multi-line overmap text widget", "[widget][overmap]" )
         };
 
         fill_overmap_area( ava, oter_id( "field" ) );
+        msn.set_target( msn.get_target() + tripoint( 1, 0, 0 ) );
         CHECK( overmap_w.layout( ava ) == join( field_3x3, "" ) );
     }
 
@@ -991,6 +999,7 @@ TEST_CASE( "multi-line overmap text widget", "[widget][overmap]" )
         };
 
         fill_overmap_area( ava, oter_id( "forest" ) );
+        msn.set_target( msn.get_target() + tripoint( 2, 0, 0 ) );
         CHECK( overmap_w.layout( ava ) == join( forest_3x3, "" ) );
     }
 
@@ -1004,6 +1013,7 @@ TEST_CASE( "multi-line overmap text widget", "[widget][overmap]" )
         };
 
         fill_overmap_area( ava, oter_id( "central_lab" ) );
+        msn.set_target( msn.get_target() + tripoint( 3, 0, 0 ) );
         CHECK( overmap_w.layout( ava ) == join( lab_3x3, "" ) );
     }