Changed the default window capture for Windows 11 to use User32.PrintWindow (called GDI internally), which should solve #326. The background for this can be read in #373

src/Greenshot.Base/Core/Enums/PrintWindowFlags.cs

@@ -0,0 +1,38 @@
+/*
+ * Greenshot - a free and open source screenshot tool
+ * Copyright (C) 2007-2021 Thomas Braun, Jens Klingen, Robin Krom
+ *
+ * For more information see: https://getgreenshot.org/
+ * The Greenshot project is hosted on GitHub https://github.com/greenshot/greenshot
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+using System;
+
+namespace Greenshot.Base.Core.Enums
+{
+    [Flags]
+    public enum PrintWindowFlags : uint
+    {
+        /// <summary>Render the entire window.</summary>
+        PW_ENTIREWINDOW = 0,
+
+        /// <summary>Only the client area of the window is copied to hdcBlt. By default, the entire window is copied.</summary>
+        PW_CLIENTONLY = 1,
+
+        /// <summary>Undocumented</summary>
+        PW_RENDERFULLCONTENT = 0x00000002,
+    }
+}

src/Greenshot.Base/Core/WindowDetails.cs

@@ -1392,32 +1392,36 @@ namespace Greenshot.Base.Core
 
         /// <summary>
         /// Return an Image representing the Window!
-        /// As GDI+ draws it, it will be without Aero borders!
+        /// For Windows 7, as GDI+ draws it, it will be without Aero borders!
+        /// For Windows 10+, there is an option PW_RENDERFULLCONTENT, which makes sure the capture is "as is".
         /// </summary>
         public Image PrintWindow()
         {
             Rectangle windowRect = WindowRectangle;
             // Start the capture
-            Exception exceptionOccured = null;
+            Exception exceptionOccurred = null;
             Image returnImage;
             using (Region region = GetRegion())
             {
+                var backgroundColor = Color.Black;
                 PixelFormat pixelFormat = PixelFormat.Format24bppRgb;
                 // Only use 32 bpp ARGB when the window has a region
                 if (region != null)
                 {
                     pixelFormat = PixelFormat.Format32bppArgb;
+                    backgroundColor = Color.Transparent;
                 }
                 
-                returnImage = new Bitmap(windowRect.Width, windowRect.Height, pixelFormat);
+                returnImage = ImageHelper.CreateEmpty(windowRect.Width, windowRect.Height, pixelFormat, backgroundColor, 96,96);
                 using Graphics graphics = Graphics.FromImage(returnImage);
                 using (SafeDeviceContextHandle graphicsDc = graphics.GetSafeDeviceContext())
                 {
-                    bool printSucceeded = User32.PrintWindow(Handle, graphicsDc.DangerousGetHandle(), 0x0);
+                    var pwFlags = WindowsVersion.IsWindows10OrLater ? PrintWindowFlags.PW_RENDERFULLCONTENT : PrintWindowFlags.PW_ENTIREWINDOW;
+                    bool printSucceeded = User32.PrintWindow(Handle, graphicsDc.DangerousGetHandle(), pwFlags);
                     if (!printSucceeded)
                     {
-                        // something went wrong, most likely a "0x80004005" (Acess Denied) when using UAC
+                        // something went wrong, most likely a "0x80004005" (Access Denied) when using UAC
-                        exceptionOccured = User32.CreateWin32Exception("PrintWindow");
+                        exceptionOccurred = User32.CreateWin32Exception("PrintWindow");
                     }
                 }
 
@@ -1432,9 +1436,9 @@ namespace Greenshot.Base.Core
             }
 
             // Return null if error
-            if (exceptionOccured != null)
+            if (exceptionOccurred != null)
             {
-                Log.ErrorFormat("Error calling print window: {0}", exceptionOccured.Message);
+                Log.ErrorFormat("Error calling print window: {0}", exceptionOccurred.Message);
                 returnImage.Dispose();
                 return null;
             }

src/Greenshot.Base/UnmanagedHelpers/User32.cs

@@ -121,7 +121,7 @@ namespace Greenshot.Base.UnmanagedHelpers
 
         [DllImport("user32", SetLastError = true)]
         [return: MarshalAs(UnmanagedType.Bool)]
-        public static extern bool PrintWindow(IntPtr hWnd, IntPtr hDc, uint nFlags);
+        public static extern bool PrintWindow(IntPtr hWnd, IntPtr hDc, PrintWindowFlags pwFlags);
 
         [DllImport("user32", CharSet = CharSet.Unicode, SetLastError = true)]
         public static extern IntPtr SendMessage(IntPtr hWnd, uint wMsg, IntPtr wParam, IntPtr lParam);

src/Greenshot/Helpers/CaptureHelper.cs

@@ -969,6 +969,13 @@ namespace Greenshot.Helpers
                     // Take default screen
                     windowCaptureMode = WindowCaptureMode.Screen;
 
+                    // In https://github.com/greenshot/greenshot/issues/373 it was shown that PrintWindow (GDI) works great with Windows 11
+                    if (WindowsVersion.IsWindows11OrLater)
+                    {
+                        windowCaptureMode = WindowCaptureMode.GDI;
+                    }
+                    else
+                    {
                         // Change to GDI, if allowed
                         if (!windowToCapture.IsMetroApp && WindowCapture.IsGdiAllowed(process))
                         {
@@ -992,6 +999,7 @@ namespace Greenshot.Helpers
                             }
                         }
                     }
+                }
                 else if (windowCaptureMode == WindowCaptureMode.Aero || windowCaptureMode == WindowCaptureMode.AeroTransparent)
                 {
                     if (!dwmEnabled || (!windowToCapture.IsMetroApp && !WindowCapture.IsDwmAllowed(process)))
@@ -1034,7 +1042,7 @@ namespace Greenshot.Helpers
                                 }
 
                                 tmpCapture = windowToCapture.CaptureGdiWindow(captureForWindow);
-                                if (tmpCapture != null)
+                                if (tmpCapture != null && !WindowsVersion.IsWindows11OrLater)
                                 {
                                     // check if GDI capture any good, by comparing it with the screen content
                                     int blackCountGdi = ImageHelper.CountColor(tmpCapture.Image, Color.Black, false);