WPF - CompositionTargetRenderHandler add null check

Author: amaitland

CefSharp.Wpf/Rendering/Experimental/CompositionTargetRenderHandler.cs

@@ -8,7 +8,6 @@
 using System.Windows.Controls;
 using System.Windows.Media;
 using System.Windows.Media.Imaging;
-using System.Windows.Threading;
 using Rect = CefSharp.Structs.Rect;
 
 namespace CefSharp.Wpf.Rendering.Experimental
@@ -25,6 +24,12 @@ public class CompositionTargetRenderHandler : IRenderHandler
         private readonly object lockObj = new object();
         private ChromiumWebBrowser browser;
 
+        /// <summary>
+        /// Default constructor
+        /// </summary>
+        /// <param name="browser">ChromiumWebBrowser instance</param>
+        /// <param name="dpiX">DPI X</param>
+        /// <param name="dpiY">DPI Y</param>
         public CompositionTargetRenderHandler(ChromiumWebBrowser browser, double dpiX, double dpiY)
         {
             this.browser = browser;
@@ -103,7 +108,7 @@ private void OnRendering(object sender, EventArgs args)
 
         private void UpdateImage(PaintElement element)
         {
-            if (element.IsDirty && element.Image != null)
+            if (element != null && element.IsDirty && element.Image != null)
             {
                 var bitmap = element.Image.Source as WriteableBitmap;
                 if (bitmap == null || bitmap.PixelWidth != element.Width || bitmap.PixelHeight != element.Height)