From e8a6cfb6722c00ed2ccb989777891b84482ba31f Mon Sep 17 00:00:00 2001
From: "Valeriano A.R" <valen.alfonso@gmail.com>
Date: Mon, 5 Nov 2018 00:13:45 +0100
Subject: [PATCH] Webcam: Buffer some frames to avoid garbage accumulation.

---
 VAR.Toolbox/Code/DirectShow/ISampleGrabber.cs |  2 +-
 .../Code/DirectShow/ISampleGrabberCB.cs       |  2 +-
 VAR.Toolbox/Code/Webcam.cs                    | 27 +++++++++++++------
 3 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/VAR.Toolbox/Code/DirectShow/ISampleGrabber.cs b/VAR.Toolbox/Code/DirectShow/ISampleGrabber.cs
index e60bb0a..2069d68 100644
--- a/VAR.Toolbox/Code/DirectShow/ISampleGrabber.cs
+++ b/VAR.Toolbox/Code/DirectShow/ISampleGrabber.cs
@@ -8,7 +8,7 @@ namespace VAR.Toolbox.Code.DirectShow
     /// individual media samples as they move through the filter graph.
     /// </summary>
     /// 
-	[ComImport,
+    [ComImport,
     Guid("6B652FFF-11FE-4FCE-92AD-0266B5D7C78F"),
     InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
     internal interface ISampleGrabber
diff --git a/VAR.Toolbox/Code/DirectShow/ISampleGrabberCB.cs b/VAR.Toolbox/Code/DirectShow/ISampleGrabberCB.cs
index f1ffa65..536faab 100644
--- a/VAR.Toolbox/Code/DirectShow/ISampleGrabberCB.cs
+++ b/VAR.Toolbox/Code/DirectShow/ISampleGrabberCB.cs
@@ -7,7 +7,7 @@ namespace VAR.Toolbox.Code.DirectShow
     /// The interface provides callback methods for the <see cref="ISampleGrabber.SetCallback"/> method.
     /// </summary>
     /// 
-	[ComImport,
+    [ComImport,
     Guid("0579154A-2B53-4994-B0D0-E773148EFF85"),
     InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
     internal interface ISampleGrabberCB
diff --git a/VAR.Toolbox/Code/Webcam.cs b/VAR.Toolbox/Code/Webcam.cs
index 6268b51..c8bb66f 100644
--- a/VAR.Toolbox/Code/Webcam.cs
+++ b/VAR.Toolbox/Code/Webcam.cs
@@ -252,12 +252,6 @@ namespace VAR.Toolbox.Code
 
         public event NewFrameEventHandler NewFrame;
 
-        private void OnNewFrame(Bitmap frame)
-        {
-            if (NewFrame != null)
-                NewFrame(this, frame);
-        }
-
         #endregion NewFrameEvent
 
         #region Grabber
@@ -266,9 +260,26 @@ namespace VAR.Toolbox.Code
         {
             private Webcam _parent;
 
+            private Bitmap[] _frames = null;
+            private int _numFrames = 10;
+            private int _currentFrameIndex = -1;
+
             public Grabber(Webcam parent)
             {
                 _parent = parent;
+                _frames = new Bitmap[_numFrames];
+            }
+
+            private Bitmap GetNextFrame()
+            {
+                _currentFrameIndex = (_currentFrameIndex + 1) % _numFrames;
+                Bitmap currentBitmap = _frames[_currentFrameIndex];
+                if (currentBitmap == null || currentBitmap?.Width != _parent.width || currentBitmap?.Height != _parent.height)
+                {
+                    currentBitmap = new Bitmap(_parent.width, _parent.height, PixelFormat.Format24bppRgb);
+                    _frames[_currentFrameIndex] = currentBitmap;
+                }
+                return currentBitmap;
             }
 
             public int SampleCB(double sampleTime, IntPtr sample)
@@ -281,7 +292,7 @@ namespace VAR.Toolbox.Code
                 if (_parent.NewFrame != null)
                 {
                     // create new image
-                    Bitmap _image = new Bitmap(_parent.width, _parent.height, PixelFormat.Format24bppRgb);
+                    Bitmap _image = GetNextFrame();
                     Rectangle _imageRect = new Rectangle(0, 0, _parent.width, _parent.height);
 
                     // lock bitmap data
@@ -311,7 +322,7 @@ namespace VAR.Toolbox.Code
                     _image.UnlockBits(imageData);
 
                     // notify parent
-                    _parent.OnNewFrame(_image);
+                    _parent.NewFrame?.Invoke(this, _image);
                 }
 
                 return 0;