Fix image viewer copy without transparency support

QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml.cs

@@ -19,6 +19,7 @@ using QuickLook.Common.Annotations;
 using QuickLook.Common.ExtensionMethods;
 using QuickLook.Common.Helpers;
 using QuickLook.Common.Plugin;
+using QuickLook.Plugin.ImageViewer.NativeMethods;
 using System;
 using System.ComponentModel;
 using System.Diagnostics;
@@ -293,13 +294,13 @@ public partial class ImagePanel : UserControl, INotifyPropertyChanged, IDisposab
         {
             if (_source is not null)
             {
-                Clipboard.SetImage(_source);
+                ClipboardEx.SetClipboardImage(_source);
                 return;
             }
 
             if (viewPanelImage.Source is BitmapSource bitmapSource)
             {
-                Clipboard.SetImage(bitmapSource);
+                ClipboardEx.SetClipboardImage(bitmapSource);
                 return;
             }
         }

QuickLook.Plugin/QuickLook.Plugin.ImageViewer/MetaProvider.cs

@@ -106,7 +106,7 @@ public class MetaProvider
     }
 }
 
-internal static class NativeMethods
+file static class NativeMethods
 {
     private static readonly bool Is64 = Environment.Is64BitProcess;
 

QuickLook.Plugin/QuickLook.Plugin.ImageViewer/NativeMethods/ClipboardEx.cs

@@ -0,0 +1,65 @@
+using System.Drawing;
+using System.Drawing.Imaging;
+using System.IO;
+using System.Runtime.InteropServices;
+using System.Threading;
+using System.Windows;
+using System.Windows.Media.Imaging;
+using Clipboard = System.Windows.Forms.Clipboard;
+
+namespace QuickLook.Plugin.ImageViewer.NativeMethods;
+
+internal static class ClipboardEx
+{
+    public static void SetClipboardImage(this BitmapSource img)
+    {
+        if (img == null)
+        {
+            return;
+        }
+
+        var thread = new Thread((img) =>
+        {
+            if (img == null)
+            {
+                return;
+            }
+
+            var image = (BitmapSource)img;
+
+            try
+            {
+                Clipboard.Clear();
+            }
+            catch (ExternalException) { }
+
+            try
+            {
+                using var pngMemStream = new MemoryStream();
+                using var bitmpa = image.ToBitmap();
+                var data = new DataObject();
+
+                bitmpa.Save(pngMemStream, ImageFormat.Png);
+                data.SetData("PNG", pngMemStream, false);
+
+                Clipboard.SetDataObject(data, true);
+            }
+            catch { }
+        });
+        thread.SetApartmentState(ApartmentState.STA);
+        thread.Start(img);
+    }
+
+    private static Bitmap ToBitmap(this BitmapSource source)
+    {
+        using (var outStream = new MemoryStream())
+        {
+            BitmapEncoder enc = new PngBitmapEncoder();
+            enc.Frames.Add(BitmapFrame.Create(source));
+            enc.Save(outStream);
+            var bitmap = new Bitmap(outStream);
+
+            return new Bitmap(bitmap);
+        }
+    }
+}

QuickLook.Plugin/QuickLook.Plugin.ImageViewer/QuickLook.Plugin.ImageViewer.csproj

@@ -8,6 +8,7 @@
         <FileAlignment>512</FileAlignment>
         <SignAssembly>false</SignAssembly>
         <UseWPF>true</UseWPF>
+        <UseWindowsForms>true</UseWindowsForms>
         <LangVersion>latest</LangVersion>
         <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
         <AllowUnsafeBlocks>true</AllowUnsafeBlocks>