From 6181b2bce343204f7594f5c559d9b7ee09525abe Mon Sep 17 00:00:00 2001
From: Dan Amlund <dan@danamlund.dk>
Date: Sat, 3 Feb 2018 16:29:30 +0100
Subject: [PATCH] Add tweak that replaces dwarf mode FPS counter with one that
 does not count when paused

---
 dfhack.init-example                        |   3 +
 plugins/tweak/tweak.cpp                    |   7 ++
 plugins/tweak/tweaks/pausing-fps-counter.h | 137 +++++++++++++++++++++
 3 files changed, 147 insertions(+)
 create mode 100644 plugins/tweak/tweaks/pausing-fps-counter.h

diff --git a/dfhack.init-example b/dfhack.init-example
index 82210a2a6..fb846a47f 100644
--- a/dfhack.init-example
+++ b/dfhack.init-example
@@ -202,6 +202,9 @@ tweak hotkey-clear
 # Allows lowercase letters in embark profile names, and allows exiting the name prompt without saving
 tweak embark-profile-name
 
+# dwarf mode FPS counter that does not jump to FPS_CAP when paused
+tweak pausing-fps-counter
+
 # Misc. UI tweaks
 tweak block-labors              # Prevents labors that can't be used from being toggled
 tweak burrow-name-cancel
diff --git a/plugins/tweak/tweak.cpp b/plugins/tweak/tweak.cpp
index 252f4c738..6b5b1f687 100644
--- a/plugins/tweak/tweak.cpp
+++ b/plugins/tweak/tweak.cpp
@@ -98,6 +98,7 @@
 #include "tweaks/kitchen-prefs-empty.h"
 #include "tweaks/max-wheelbarrow.h"
 #include "tweaks/military-assign.h"
+#include "tweaks/pausing-fps-counter.h"
 #include "tweaks/nestbox-color.h"
 #include "tweaks/shift-8-scroll.h"
 #include "tweaks/stable-cursor.h"
@@ -232,6 +233,9 @@ DFhackCExport command_result plugin_init (color_ostream &out, std::vector <Plugi
         "    Preserve list order and cursor position when assigning to squad,\n"
         "    i.e. stop the rightmost list of the Positions page of the military\n"
         "    screen from constantly jumping to the top.\n"
+        "  tweak pausing-fps-counter [disable]\n"
+        "    Replace fortress mode FPS counter with one that stops counting \n"
+        "    when paused.\n"
         "  tweak shift-8-scroll [disable]\n"
         "    Gives Shift+8 (or *) priority when scrolling menus, instead of \n"
         "    scrolling the map\n"
@@ -303,6 +307,9 @@ DFhackCExport command_result plugin_init (color_ostream &out, std::vector <Plugi
 
     TWEAK_HOOK("nestbox-color", nestbox_color_hook, drawBuilding);
 
+    TWEAK_HOOK("pausing-fps-counter", dwarfmode_pausing_fps_counter_hook, render);
+    TWEAK_HOOK("pausing-fps-counter", title_pausing_fps_counter_hook, render);
+
     TWEAK_HOOK("shift-8-scroll", shift_8_scroll_hook, feed);
 
     TWEAK_HOOK("stable-cursor", stable_cursor_hook, feed);
diff --git a/plugins/tweak/tweaks/pausing-fps-counter.h b/plugins/tweak/tweaks/pausing-fps-counter.h
new file mode 100644
index 000000000..ee76aab15
--- /dev/null
+++ b/plugins/tweak/tweaks/pausing-fps-counter.h
@@ -0,0 +1,137 @@
+#include "df/global_objects.h"
+#include "modules/Gui.h"
+#include "modules/Screen.h"
+#include "df/enabler.h"
+#include "df/viewscreen_dwarfmodest.h"
+#include "df/viewscreen_titlest.h"
+
+struct dwarfmode_pausing_fps_counter_hook : df::viewscreen_dwarfmodest {
+    typedef df::viewscreen_dwarfmodest interpose_base;
+
+    static const uint32_t history_length = 3;
+
+    // whether init.txt have [FPS:YES]
+    static bool init_have_fps_yes()
+    {
+        static bool first = true;
+        static bool init_have_fps_yes;
+
+        if (first && df::global::gps)
+        {
+            // if first time called, then display_frames is set iff init.txt have [FPS:YES]
+            first = false;
+            init_have_fps_yes = (df::global::gps->display_frames == 1);
+        }
+        return init_have_fps_yes;
+    }
+
+    DEFINE_VMETHOD_INTERPOSE(void, render, ())
+    {
+        INTERPOSE_NEXT(render)();
+
+        if (!df::global::pause_state || !df::global::enabler || !df::global::world
+            || !df::global::gps || !df::global::pause_state)
+            return;
+
+        // if init.txt does not have [FPS:YES] then dont show this FPS counter
+        if (!dwarfmode_pausing_fps_counter_hook::init_have_fps_yes())
+            return;
+
+        static bool prev_paused = true;
+        static uint32_t prev_clock = 0;
+        static int32_t prev_frames = 0;
+        static uint32_t elapsed_clock = 0;
+        static uint32_t elapsed_frames = 0;
+        static double history[history_length];
+
+        if (prev_clock == 0)
+        {
+            // init
+            for (int i = 0; i < history_length; i++)
+                history[i] = 0.0;
+        }
+
+        // disable default FPS counter because it is rendered on top of this FPS counter.
+        if (df::global::gps->display_frames == 1)
+            df::global::gps->display_frames = 0;
+
+        if (*df::global::pause_state)
+            prev_paused = true;
+        else
+        {
+            uint32_t clock = df::global::enabler->clock;
+            int32_t frames = df::global::world->frame_counter;
+
+            if (!prev_paused && prev_clock != 0
+                && clock >= prev_clock && frames >= prev_frames)
+            {
+                // if we were previously paused, then dont add clock/frames,
+                // but wait for the next time render is called.
+                elapsed_clock += clock - prev_clock;
+                elapsed_frames += frames - prev_frames;
+            }
+
+            prev_paused = false;
+            prev_clock = clock;
+            prev_frames = frames;
+
+            // add FPS to history every second or after at least one frame.
+            if (elapsed_clock >= 1000 && elapsed_frames >= 1)
+            {
+                double fps = elapsed_frames / (elapsed_clock / 1000.0);
+                for (int i = history_length - 1; i >= 1; i--)
+                    history[i] = history[i - 1];
+                history[0] = fps;
+
+                elapsed_clock = 0;
+                elapsed_frames = 0;
+            }
+        }
+
+        // average fps over a few seconds to stabilize the counter.
+        double fps_sum = 0.0;
+        int fps_count = 0;
+        for (int i = 0; i < history_length; i++)
+        {
+            if (history[i] > 0.0)
+            {
+                fps_sum += history[i];
+                fps_count++;
+            }
+        }
+
+        double fps = fps_count == 0 ? 1.0 : fps_sum / fps_count;
+        double gfps = df::global::enabler->calculated_gfps;
+
+        std::stringstream fps_counter;
+        fps_counter << "FPS:"
+                    << setw(4) << fixed << setprecision(fps >= 1.0 ? 0 : 2) << fps
+                    << " (" << gfps << ")";
+
+        // show this FPS counter same as the default counter.
+        int x = 10;
+        int y = 0;
+        OutputString(COLOR_WHITE, x, y, fps_counter.str(),
+                     false, 0, COLOR_CYAN, false);
+    }
+};
+
+struct title_pausing_fps_counter_hook : df::viewscreen_titlest {
+    typedef df::viewscreen_titlest interpose_base;
+
+    DEFINE_VMETHOD_INTERPOSE(void, render, ())
+    {
+        INTERPOSE_NEXT(render)();
+
+        // if init.txt have FPS:YES then enable default FPS counter when exiting dwarf mode.
+        // So it is enabled if starting adventure mode without exiting dwarf fortress.
+        if (dwarfmode_pausing_fps_counter_hook::init_have_fps_yes()
+            && df::global::gps && df::global::gps->display_frames == 0)
+            df::global::gps->display_frames = 1;
+    }
+};
+
+
+IMPLEMENT_VMETHOD_INTERPOSE(dwarfmode_pausing_fps_counter_hook, render);
+
+IMPLEMENT_VMETHOD_INTERPOSE(title_pausing_fps_counter_hook, render);