From 29dc478e2bd6440cb58f15fedc61e1aff145b450 Mon Sep 17 00:00:00 2001
From: Jaex <Jaex@users.noreply.github.com>
Date: Mon, 17 Jan 2022 09:13:58 +0300
Subject: [PATCH] fixed #4951: Added support to limit region capture/image
 editor fps

---
 ShareX.HelpersLib/FPSManager.cs               | 51 ++++++++++++++-----
 ShareX.HelpersLib/TimerResolutionManager.cs   | 12 ++++-
 .../Forms/RegionCaptureForm.cs                |  2 +-
 ShareX/Program.cs                             |  1 +
 4 files changed, 50 insertions(+), 16 deletions(-)

diff --git a/ShareX.HelpersLib/FPSManager.cs b/ShareX.HelpersLib/FPSManager.cs
index e9d68a7ca..63aa83793 100644
--- a/ShareX.HelpersLib/FPSManager.cs
+++ b/ShareX.HelpersLib/FPSManager.cs
@@ -25,45 +25,68 @@
 
 using System;
 using System.Diagnostics;
+using System.Threading;
 
 namespace ShareX.HelpersLib
 {
     public class FPSManager
     {
-        public event Action FPSChanged;
+        public event Action FPSUpdated;
 
         public int FPS { get; private set; }
+        public int FPSLimit { get; set; } = 100;
 
         private int frameCount;
-        private Stopwatch timer;
+        private Stopwatch fpsTimer, frameTimer;
 
         public FPSManager()
         {
-            timer = new Stopwatch();
+            fpsTimer = new Stopwatch();
+            frameTimer = new Stopwatch();
         }
 
-        protected void OnFPSChanged()
+        protected void OnFPSUpdated()
         {
-            FPSChanged?.Invoke();
+            FPSUpdated?.Invoke();
         }
 
         public void Update()
         {
-            if (!timer.IsRunning)
-            {
-                timer.Start();
-            }
-
             frameCount++;
 
-            if (timer.ElapsedMilliseconds >= 1000)
+            if (!fpsTimer.IsRunning)
             {
-                FPS = (int)(frameCount / timer.Elapsed.TotalSeconds);
+                fpsTimer.Start();
+            }
+            else if (fpsTimer.ElapsedMilliseconds >= 1000)
+            {
+                FPS = (int)(frameCount / fpsTimer.Elapsed.TotalSeconds);
 
-                OnFPSChanged();
+                OnFPSUpdated();
 
                 frameCount = 0;
-                timer.Restart();
+                fpsTimer.Restart();
+            }
+
+            if (FPSLimit > 0)
+            {
+                if (!frameTimer.IsRunning)
+                {
+                    frameTimer.Start();
+                }
+                else
+                {
+                    double currentFrameDuration = frameTimer.Elapsed.TotalMilliseconds;
+                    double targetFrameDuration = 1000d / FPSLimit;
+
+                    if (currentFrameDuration < targetFrameDuration)
+                    {
+                        int diff = (int)Math.Round(targetFrameDuration - currentFrameDuration);
+                        Thread.Sleep(diff);
+                    }
+
+                    frameTimer.Restart();
+                }
             }
         }
     }
diff --git a/ShareX.HelpersLib/TimerResolutionManager.cs b/ShareX.HelpersLib/TimerResolutionManager.cs
index c8337fc2e..4eae7b4c9 100644
--- a/ShareX.HelpersLib/TimerResolutionManager.cs
+++ b/ShareX.HelpersLib/TimerResolutionManager.cs
@@ -28,13 +28,23 @@
 
 namespace ShareX.HelpersLib
 {
-    public static class TimerResolutionManager
+    public class TimerResolutionManager : IDisposable
     {
         private static readonly object thisLock = new object();
 
         private static bool enabled;
         private static uint lastPeriod;
 
+        public TimerResolutionManager(uint period = 1)
+        {
+            Enable(period);
+        }
+
+        public void Dispose()
+        {
+            Disable();
+        }
+
         public static bool Enable(uint period = 1)
         {
             lock (thisLock)
diff --git a/ShareX.ScreenCaptureLib/Forms/RegionCaptureForm.cs b/ShareX.ScreenCaptureLib/Forms/RegionCaptureForm.cs
index 8a794b151..5dcefabba 100644
--- a/ShareX.ScreenCaptureLib/Forms/RegionCaptureForm.cs
+++ b/ShareX.ScreenCaptureLib/Forms/RegionCaptureForm.cs
@@ -109,7 +109,7 @@ public RegionCaptureForm(RegionCaptureMode mode, RegionCaptureOptions options, B
                 Duration = TimeSpan.FromMilliseconds(200)
             };
             fpsManager = new FPSManager();
-            fpsManager.FPSChanged += FpsManager_FPSChanged;
+            fpsManager.FPSUpdated += FpsManager_FPSChanged;
 
             if (IsEditorMode && Options.ShowEditorPanTip)
             {
diff --git a/ShareX/Program.cs b/ShareX/Program.cs
index eb34b5013..834759b19 100644
--- a/ShareX/Program.cs
+++ b/ShareX/Program.cs
@@ -296,6 +296,7 @@ private static void Main(string[] args)
             MultiInstance = CLI.IsCommandExist("multi", "m");
 
             using (ApplicationInstanceManager instanceManager = new ApplicationInstanceManager(!MultiInstance, args, SingleInstanceCallback))
+            using (TimerResolutionManager timerResolutionManager = new TimerResolutionManager())
             {
                 Run();
             }