Parallelize capture saving to disk for ImageCapture

ScreenToGif/Capture/BaseCapture.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Concurrent;
+using System.Collections.Generic;
 using System.Threading.Tasks;
 using System.Windows;
 using ScreenToGif.Model;
@@ -65,6 +66,11 @@ public abstract class BaseCapture : ICapture
 
     protected BlockingCollection<FrameInfo> BlockingCollection { get; private set; } = new();
 
+    /// <summary>
+    /// If true, multiple frames can be saved in parallel
+    /// </summary>
+    protected virtual bool SupportsParallelSaving => false;
+
     #endregion
 
     ~BaseCapture()
@@ -94,22 +100,29 @@ public virtual void Start(int delay, int left, int top, int width, int height, d
         BlockingCollection ??= new BlockingCollection<FrameInfo>();
 
         //Spin up a Task to consume the BlockingCollection.
-        _task = Task.Factory.StartNew(() =>
+        int NumConsumers = GetConsumerCount();
+        List<Task> consumers = new(NumConsumers);
+        for (int i = 0; i < NumConsumers; ++i)
         {
-            try
-            {
-                while (true)
-                    Save(BlockingCollection.Take());
-            }
-            catch (InvalidOperationException)
+            consumers.Add(Task.Factory.StartNew(() =>
             {
-                //It means that Take() was called on a completed collection.
-            }
-            catch (Exception e)
-            {
-                Application.Current.Dispatcher.Invoke(() => OnError?.Invoke(e));
-            }
-        });
+                try
+                {
+                    while (true)
+                        Save(BlockingCollection.Take());
+                }
+                catch (InvalidOperationException)
+                {
+                    //It means that Take() was called on a completed collection.
+                }
+                catch (Exception e)
+                {
+                    Application.Current.Dispatcher.Invoke(() => OnError?.Invoke(e));
+                }
+            }, TaskCreationOptions.LongRunning));
+        }
+
+        _task = Task.WhenAll(consumers);
 
         WasStarted = true;
         IsAcceptingFrames = true;
@@ -121,6 +134,25 @@ public virtual void ResetConfiguration()
     public virtual void Save(FrameInfo info)
     { }
 
+    /// <summary>
+    /// Return the amount of consumers that should be used simultaneously,
+    /// based on system resources.
+    /// </summary>
+    /// <returns>Number of consumer tasks to spawn</returns>
+    protected virtual int GetConsumerCount()
+    {
+        if (!SupportsParallelSaving)
+        {
+            return 1;
+        }
+
+        const int minCpuCount = 1;
+        const int maxCpuUtilizationPercentage = 25;
+
+        int processorCount = Environment.ProcessorCount;
+        return Math.Max(processorCount * maxCpuUtilizationPercentage / 100, minCpuCount);
+    }
+
     public virtual int Capture(FrameInfo frame)
     {
         return 0;

ScreenToGif/Capture/DirectImageCapture.cs

@@ -103,6 +103,10 @@ internal class DirectImageCapture : BaseCapture
     /// </summary>
     protected internal bool MajorCrashHappened = false;
 
+    protected override bool SupportsParallelSaving => true;
+
+    private readonly object _projectLock = new object();
+
     #endregion
 
     public override void Start(int delay, int left, int top, int width, int height, double dpi, ProjectInfo project)
@@ -374,6 +378,7 @@ public override int Capture(FrameInfo frame)
             bitmap.UnlockBits(mapDest);
 
             //Set frame details.
+            frame.Index = FrameCount;
             FrameCount++;
             frame.Path = $"{Project.FullPath}{FrameCount}.png";
             frame.Delay = FrameRate.GetMilliseconds();
@@ -562,6 +567,7 @@ public override int CaptureWithCursor(FrameInfo frame)
             bitmap.UnlockBits(mapDest);
 
             //Set frame details.
+            frame.Index = FrameCount;
             FrameCount++;
             frame.Path = $"{Project.FullPath}{FrameCount}.png";
             frame.Delay = FrameRate.GetMilliseconds();
@@ -709,6 +715,7 @@ public override int ManualCapture(FrameInfo frame, bool showCursor = false)
             bitmap.UnlockBits(mapDest);
 
             //Set frame details.
+            frame.Index = FrameCount;
             FrameCount++;
             frame.Path = $"{Project.FullPath}{FrameCount}.png";
             frame.Delay = FrameRate.GetMilliseconds();
@@ -995,7 +1002,10 @@ public override void Save(FrameInfo frame)
         frame.Image?.Dispose();
         frame.Image = null;
 
-        Project.Frames.Add(frame);
+        lock (_projectLock)
+        {
+            Project.Frames.Add(frame);
+        }
     }
 
     public override async Task Stop()
@@ -1006,6 +1016,9 @@ public override async Task Stop()
         DisposeInternal();
 
         await base.Stop();
+
+        // If frames were saved in parallel, they may have been stored out of order, so we sort them here
+        Project.Frames.Sort((a, b) => a.Index.CompareTo(b.Index));
     }
 
     internal void DisposeInternal()

ScreenToGif/Capture/ImageCapture.cs

@@ -7,6 +7,7 @@
 using ScreenToGif.Native.Structs;
 using ScreenToGif.Util;
 using ScreenToGif.Util.Settings;
+using SharpDX.Direct3D11;
 using Image = System.Drawing.Image;
 
 namespace ScreenToGif.Capture;
@@ -21,12 +22,16 @@ internal class ImageCapture : BaseCapture
     protected IntPtr CompatibleBitmap;
     private IntPtr _oldBitmap;
 
+    private readonly object _projectLock = new object();
+
     protected int CursorStep { get; set; }
 
     private CopyPixelOperations PixelOperations { get; set; }
 
     #endregion
 
+    protected override bool SupportsParallelSaving => true;
+
     public override void Start(int delay, int left, int top, int width, int height, double scale, ProjectInfo project)
     {
         base.Start(delay, left, top, width, height, scale, project);
@@ -63,6 +68,7 @@ public override int Capture(FrameInfo frame)
                 return FrameCount;
 
             //Set frame details.
+            frame.Index = FrameCount;
             FrameCount++;
             frame.Path = $"{Project.FullPath}{FrameCount}.png";
             frame.Delay = FrameRate.GetMilliseconds();
@@ -146,6 +152,7 @@ public override int CaptureWithCursor(FrameInfo frame)
             #endregion
 
             //Set frame details.
+            frame.Index = FrameCount;
             FrameCount++;
             frame.Path = $"{Project.FullPath}{FrameCount}.png";
             frame.Delay = FrameRate.GetMilliseconds();
@@ -174,7 +181,10 @@ public override void Save(FrameInfo frame)
         frame.Image.Dispose();
         frame.Image = null;
 
-        Project.Frames.Add(frame);
+        lock(_projectLock)
+        {
+            Project.Frames.Add(frame);
+        }
     }
 
     public override async Task Stop()
@@ -195,5 +205,8 @@ public override async Task Stop()
         {
             LogWriter.Log(e, "Impossible to stop and clean resources used by the recording.");
         }
+
+        // If frames were saved in parallel, they may have been stored out of order, so we sort them here
+        Project.Frames.Sort((a, b) => a.Index.CompareTo(b.Index));
     }
 }