Add feature to copy rectangular text selection as a bitmap image to clipboard.

This feature copies the rectangular text selection as a bitmap image to the clipboard, allowing users to paste it directly into any image editor or application that accepts images from the clipboard.
The copied bitmap can then be saved or edited in various image formats supported by those tools.

Author: mx7b7

src/CodeSnip/MainWindow.xaml

@@ -419,6 +419,12 @@
                                               Width="16" Height="16" Stretch="Uniform" />
                                     </MenuItem.Icon>
                                 </MenuItem>
+                                <MenuItem Header="Image" Click="CopyAsImage_Click">
+                                    <MenuItem.Icon>
+                                        <Path Data="{StaticResource ImageSave}" Fill="{DynamicResource MahApps.Brushes.AccentBase}"
+                                             Width="16" Height="16" Stretch="Uniform" />
+                                    </MenuItem.Icon>
+                                </MenuItem>
                             </MenuItem>
                             <Separator />
                             <MenuItem Header="Select All" InputGestureText="Ctrl+A" Click="SelectAll_Click">

src/CodeSnip/MainWindow.xaml.cs

@@ -3,6 +3,7 @@
 using CodeSnip.Services.Exporters;
 using CodeSnip.Views.HighlightingEditorView;
 using CodeSnip.Views.SnippetView;
+using ICSharpCode.AvalonEdit;
 using ICSharpCode.AvalonEdit.Document;
 using ICSharpCode.AvalonEdit.Folding;
 using ICSharpCode.AvalonEdit.Indentation;
@@ -15,6 +16,8 @@
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
 
 namespace CodeSnip
 {
@@ -436,7 +439,7 @@ private async void FormatAll_Click(object sender, RoutedEventArgs e)
                         }
                         else
                         {
-                            MessageBox.Show($"Formatting (rustfmt) failed:\n{ errorRust}");
+                            MessageBox.Show($"Formatting (rustfmt) failed:\n{errorRust}");
                         }
                         break;
 
@@ -635,6 +638,25 @@ private void CopyAsBase64String_Click(object sender, RoutedEventArgs e)
             }
         }
 
+        private void CopyAsImage_Click(object sender, RoutedEventArgs e)
+        {
+            if (textEditor.TextArea.Selection is not ICSharpCode.AvalonEdit.Editing.RectangleSelection selection || selection.IsEmpty)
+            {
+                MessageBox.Show("This action requires a rectangular selection (Alt + Mouse Drag or Alt + Shift + Arrow Keys).", "No Rectangular Selection", MessageBoxButton.OK, MessageBoxImage.Information);
+                return;
+            }
+            try
+            {
+                var bitmap = RenderSelectionToBitmap(selection);
+                Clipboard.SetImage(bitmap);
+            }
+            catch (Exception ex)
+            {
+                MessageBox.Show($"Failed to copy selection as image: {ex.Message}", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
+                Clipboard.SetText(ex.Message);
+            }
+        }
+
         private void ExportToHtml_Click(object sender, RoutedEventArgs e)
         {
             if (mainViewModel != null && mainViewModel.SelectedSnippet != null)
@@ -726,6 +748,87 @@ private void SetupFolding(Snippet snippet)
             textEditor.Options.AllowScrollBelowDocument = foldingStrategy != null;
         }
 
+        private RenderTargetBitmap RenderSelectionToBitmap(ICSharpCode.AvalonEdit.Editing.RectangleSelection selection)
+        {
+            // 1. Get the selected text
+            string selectedText = selection.GetText();
+
+            // 2. Create a new, off-screen TextEditor
+            var virtualEditor = new TextEditor
+            {
+                // 3. Apply the same properties as the main editor
+                FontFamily = textEditor.FontFamily,
+                FontSize = textEditor.FontSize,
+                Background = textEditor.Background,
+                Foreground = textEditor.Foreground,
+                SyntaxHighlighting = textEditor.SyntaxHighlighting,
+                Text = selectedText,
+                Options = textEditor.Options
+            };
+
+            // 4. Force the layout to be calculated
+            var viewbox = new Viewbox { Child = virtualEditor };
+            viewbox.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
+            viewbox.Arrange(new Rect(viewbox.DesiredSize));
+
+            // 5. Get the actual dimensions of the content
+            double contentWidth = virtualEditor.TextArea.TextView.ActualWidth;
+            double contentHeight = virtualEditor.TextArea.TextView.ActualHeight;
+
+            if (contentWidth <= 0 || contentHeight <= 0)
+            {
+                throw new InvalidOperationException("The selected content has no visible area to capture.");
+            }
+
+            // Define padding and footer for the watermark ---
+            double padding = 4;
+            double footerHeight = 20;
+            double totalWidth = contentWidth + (2 * padding);
+            double totalHeight = contentHeight + (2 * padding) + footerHeight;
+
+            // Create a DrawingVisual to compose the final image
+            var drawingVisual = new DrawingVisual();
+            using (var dc = drawingVisual.RenderOpen())
+            {
+                // Layer 1: Draw the outer background/border
+                // For a dark theme, a slightly lighter background works well.
+                // For a light theme, a slightly darker one.
+                var editorBg = (textEditor.Background as SolidColorBrush)?.Color ?? Colors.White;
+                var borderColor = Color.Add(editorBg, Color.FromRgb(10, 10, 10));
+                dc.DrawRectangle(new SolidColorBrush(borderColor), null, new Rect(0, 0, totalWidth, totalHeight));
+
+                // Layer 2: Draw the code itself by rendering the virtual editor
+                var codeBrush = new VisualBrush(virtualEditor);
+                dc.DrawRectangle(codeBrush, null, new Rect(padding, padding, contentWidth, contentHeight));
+
+                // Layer 3: Draw the watermark
+                var watermarkText = new FormattedText(
+                    "Generated by CodeSnip",
+                    System.Globalization.CultureInfo.CurrentCulture,
+                    FlowDirection.LeftToRight,
+                    new Typeface(new FontFamily("Segoe UI"), FontStyles.Normal, FontWeights.Normal, FontStretches.Normal),
+                    12,
+                    new SolidColorBrush(Color.FromArgb(128, 170, 170, 170)), // Semi-transparent gray
+                    VisualTreeHelper.GetDpi(this).PixelsPerDip);
+
+                // Position it in the bottom right corner
+                var watermarkPosition = new Point(totalWidth - padding - watermarkText.Width, totalHeight - padding - watermarkText.Height);
+                dc.DrawText(watermarkText, watermarkPosition);
+            }
+
+            // 6. Render the composed DrawingVisual to a bitmap
+            var dpi = VisualTreeHelper.GetDpi(this);
+            var rtb = new RenderTargetBitmap(
+                (int)Math.Ceiling(totalWidth * dpi.DpiScaleX),
+                (int)Math.Ceiling(totalHeight * dpi.DpiScaleY),
+                dpi.PixelsPerInchX,
+                dpi.PixelsPerInchY,
+                PixelFormats.Pbgra32);
+
+            rtb.Render(drawingVisual);
+            return rtb;
+        }
+
         private static string MapLangCodeToMarkdown(string code)
         {
             return code.ToLower() switch

src/CodeSnip/Resources/Icons.xaml

@@ -117,10 +117,12 @@
 	<PathGeometry x:Key="InfoCircle">M13,9H11V7H13M13,17H11V11H13M12,2A10,10 0 0,0 2,12A10,10 0 0,0 12,22A10,10 0 0,0 22,12A10,10 0 0,0 12,2Z</PathGeometry>
 
     <PathGeometry x:Key="FormatIndentDecrease">M 11,17 H 21 V 15 H 11 Z M 3,12 7,16 V 8 Z m 0,9 H 21 V 19 H 3 Z M 3,3 V 5 H 21 V 3 Z m 8,6 H 21 V 7 H 11 Z m 0,4 H 21 V 11 H 11 Z</PathGeometry>
-    
+
+    <PathGeometry x:Key="ImageSave">M22.71,6.29a1,1,0,0,0-1.42,0L20,7.59V2a1,1,0,0,0-2,0V7.59l-1.29-1.3a1,1,0,0,0-1.42,1.42l3,3a1,1,0,0,0,.33.21.94.94,0,0,0,.76,0,1,1,0,0,0,.33-.21l3-3A1,1,0,0,0,22.71,6.29ZM19,13a1,1,0,0,0-1,1v.38L16.52,12.9a2.79,2.79,0,0,0-3.93,0l-.7.7L9.41,11.12a2.85,2.85,0,0,0-3.93,0L4,12.6V7A1,1,0,0,1,5,6h8a1,1,0,0,0,0-2H5A3,3,0,0,0,2,7V19a3,3,0,0,0,3,3H17a3,3,0,0,0,3-3V14A1,1,0,0,0,19,13ZM5,20a1,1,0,0,1-1-1V15.43l2.9-2.9a.79.79,0,0,1,1.09,0l3.17,3.17,0,0L15.46,20Zm13-1a.89.89,0,0,1-.18.53L13.31,15l.7-.7a.77.77,0,0,1,1.1,0L18,17.21Z</PathGeometry>
+
 
 
-	<Geometry x:Key="ContentCopy">M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z</Geometry>
+    <Geometry x:Key="ContentCopy">M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z</Geometry>
     <Geometry x:Key="CodeBrackets">M15,4V6H18V18H15V20H20V4M4,4V20H9V18H6V6H9V4H4Z</Geometry>
 
 </ResourceDictionary>