Added export option for printers, but it needs some tuning.

NetworkDiagram/ExportOptionsWindow.axaml

@@ -4,11 +4,10 @@
         Title="{DynamicResource ExportOptionsTitle}" Width="400" Height="180"
         WindowStartupLocation="CenterOwner" CanResize="False"
         Background="{DynamicResource BgWhite}">
-    <StackPanel Margin="20" Spacing="20">
-        <TextBlock Text="{DynamicResource ExportWhiteBgMsg}" TextWrapping="Wrap" HorizontalAlignment="Center" TextAlignment="Center"/>
-        <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" Spacing="20">
-            <Button Content="Yes (White)" Click="White_Click" Width="100" Classes="ModernButtonStyle"/>
-            <Button Content="No (Transparent)" Click="Transparent_Click" Width="140" Classes="SecondaryButtonStyle"/>
-        </StackPanel>
+    <StackPanel Margin="20" Spacing="10">
+        <TextBlock Text="{DynamicResource ExportWhiteBgMsg}" TextWrapping="Wrap" HorizontalAlignment="Center" TextAlignment="Center" Margin="0,0,0,10"/>
+        <Button Content="{DynamicResource ExportWhiteBtn}" Click="White_Click" HorizontalAlignment="Stretch" Classes="ModernButtonStyle"/>
+        <Button Content="{DynamicResource ExportTransparentBtn}" Click="Transparent_Click" HorizontalAlignment="Stretch" Classes="SecondaryButtonStyle"/>
+        <Button Content="{DynamicResource ExportBWBtn}" Click="BlackAndWhite_Click" HorizontalAlignment="Stretch" Classes="SecondaryButtonStyle"/>
     </StackPanel>
 </Window>

NetworkDiagram/ExportOptionsWindow.axaml.cs

@@ -3,6 +3,14 @@ using Avalonia.Interactivity;
 
 namespace NetworkDiagram
 {
+    public enum ExportOption
+    {
+        Cancel,
+        Transparent,
+        White,
+        BlackAndWhite
+    }
+
     public partial class ExportOptionsWindow : Window
     {
         public ExportOptionsWindow()
@@ -12,12 +20,17 @@ namespace NetworkDiagram
 
         private void White_Click(object? sender, RoutedEventArgs e)
         {
-            Close(true);
+            Close(ExportOption.White);
         }
 
         private void Transparent_Click(object? sender, RoutedEventArgs e)
         {
-            Close(false);
+            Close(ExportOption.Transparent);
+        }
+
+        private void BlackAndWhite_Click(object? sender, RoutedEventArgs e)
+        {
+            Close(ExportOption.BlackAndWhite);
         }
     }
 }

NetworkDiagram/Localization/Strings.cs.axaml

@@ -19,7 +19,10 @@
     <x:String x:Key="SaveDialogBtn">Uložit</x:String>
     
     <!-- Messages -->
-    <x:String x:Key="ExportWhiteBgMsg">Chcete bílé pozadí? (Ne = průhlednost)</x:String>
+    <x:String x:Key="ExportWhiteBgMsg">Vyberte styl pozadí a barev:</x:String>
+    <x:String x:Key="ExportWhiteBtn">Bílé pozadí</x:String>
+    <x:String x:Key="ExportTransparentBtn">Průhledné pozadí</x:String>
+    <x:String x:Key="ExportBWBtn">Pro tisk (šedotisk)</x:String>
     <x:String x:Key="ExportOptionsTitle">Možnosti exportu</x:String>
     <x:String x:Key="ExportSuccess">Export byl úspěšný!</x:String>
     <x:String x:Key="EmptyDiagramMsg">Diagram je prázdný.</x:String>

NetworkDiagram/Localization/Strings.en.axaml

@@ -19,7 +19,10 @@
     <x:String x:Key="SaveDialogBtn">Save</x:String>
     
     <!-- Messages -->
-    <x:String x:Key="ExportWhiteBgMsg">Do you want a white background? (No will result in transparency)</x:String>
+    <x:String x:Key="ExportWhiteBgMsg">Select export background and color style:</x:String>
+    <x:String x:Key="ExportWhiteBtn">White Background</x:String>
+    <x:String x:Key="ExportTransparentBtn">Transparent Background</x:String>
+    <x:String x:Key="ExportBWBtn">Printer Friendly (Grayscale)</x:String>
     <x:String x:Key="ExportOptionsTitle">Export Options</x:String>
     <x:String x:Key="ExportSuccess">Export successful!</x:String>
     <x:String x:Key="EmptyDiagramMsg">Diagram is empty.</x:String>

NetworkDiagram/MainWindow.axaml.cs

@@ -18,6 +18,7 @@ using Avalonia.Media.Imaging;
 using Avalonia.Platform.Storage;
 using Avalonia.Threading;
 using Avalonia.VisualTree;
+using System.Runtime.InteropServices;
 using NetworkDiagram.Models;
 using Avalonia.Controls.Templates;
 
@@ -342,7 +343,9 @@ namespace NetworkDiagram
             nameText.Bind(TextBlock.TextProperty, new Avalonia.Data.Binding("Name"));
             stack.Children.Add(nameText);
 
+            var textDark = Application.Current!.FindResource("TextDark");
             var descText = new TextBlock { FontSize = 11, FontStyle = FontStyle.Italic, HorizontalAlignment = Avalonia.Layout.HorizontalAlignment.Center, TextWrapping = TextWrapping.Wrap, TextAlignment = TextAlignment.Center, Opacity = 0.8 };
+            if (textDark is IBrush td) descText.Foreground = td;
             descText.Bind(TextBlock.TextProperty, new Avalonia.Data.Binding("Description"));
             descText.Bind(TextBlock.IsVisibleProperty, new Avalonia.Data.Binding("Description") { Converter = Avalonia.Data.Converters.StringConverters.IsNotNullOrEmpty });
             stack.Children.Add(descText);
@@ -737,8 +740,8 @@ namespace NetworkDiagram
             if (_currentDiagram.Devices.Count == 0) return;
 
             var prompt = new ExportOptionsWindow();
-            var result = await prompt.ShowDialog<bool?>(this);
-            if (result == null) return;
+            var result = await prompt.ShowDialog<ExportOption>(this);
+            if (result == ExportOption.Cancel) return;
 
             var topLevel = GetTopLevel(this);
             if (topLevel == null) return;
@@ -764,7 +767,7 @@ namespace NetworkDiagram
                 var tempCanvas = new Canvas {
                     Width = width,
                     Height = height,
-                    Background = result.Value ? Brushes.White : Brushes.Transparent
+                    Background = (result == ExportOption.White || result == ExportOption.BlackAndWhite) ? Brushes.White : Brushes.Transparent
                 };
 
                 // Create a container to host temp canvas for rendering
@@ -773,13 +776,28 @@ namespace NetworkDiagram
 
                 var rtb = new RenderTargetBitmap(new PixelSize(width, height), new Vector(96, 96));
 
+                // Fetch resources once for efficiency and consistency
+                var primaryBlue = Application.Current!.FindResource("PrimaryBlue") as IBrush;
+                var accentBlue = Application.Current!.FindResource("AccentBlue") as IBrush;
+                var textDark = Application.Current!.FindResource("TextDark") as IBrush ?? Brushes.Black;
+                var gridBlue = Application.Current!.FindResource("GridBlue") as IBrush;
+
+                bool isGrayscale = result == ExportOption.BlackAndWhite;
+                if (isGrayscale)
+                {
+                    primaryBlue = Brushes.Black;
+                    accentBlue = Brushes.Black;
+                    textDark = Brushes.Black;
+                    gridBlue = Brushes.Black;
+                }
+
                 // 1. Draw connections
                 foreach (var conn in _currentDiagram.Connections)
                 {
                     if (_connectionLines.TryGetValue(conn, out var line))
                     {
                         var tempLine = new Line {
-                            Stroke = line.Stroke,
+                            Stroke = isGrayscale ? Brushes.Black : line.Stroke,
                             StrokeThickness = line.StrokeThickness,
                             StrokeDashArray = line.StrokeDashArray,
                             StartPoint = new Point(line.StartPoint.X - minX, line.StartPoint.Y - minY),
@@ -799,8 +817,8 @@ namespace NetworkDiagram
                             CornerRadius = new CornerRadius(8),
                             Padding = new Thickness(12),
                             Background = Brushes.White,
-                            BorderBrush = (IBrush)Application.Current!.FindResource("GridBlue")!,
-                            BorderThickness = new Thickness(1),
+                            BorderBrush = gridBlue ?? Brushes.Blue,
+                            BorderThickness = new Thickness(isGrayscale ? 2 : 1),
                             MinWidth = 100,
                             MinHeight = 80,
                             MaxWidth = 180
@@ -808,22 +826,21 @@ namespace NetworkDiagram
 
                         var stack = new StackPanel { Spacing = 4 };
                         
-                        var img = new Image { Width = 64, Height = 64 };
+                        var img = new Image { Width = 64, Height = 64, HorizontalAlignment = Avalonia.Layout.HorizontalAlignment.Center };
                         if (ImageConverter.Instance.Convert(device.IconPath, typeof(IImage), null, System.Globalization.CultureInfo.CurrentCulture) is IImage iimg)
                         {
                             img.Source = iimg;
                         }
 
-                        var primaryBlue = Application.Current!.FindResource("PrimaryBlue");
                         var txt = new TextBlock {
                             Text = device.Name,
                             FontWeight = FontWeight.Bold,
-                            FontSize = 12,
+                            FontSize = isGrayscale ? 14 : 12,
                             HorizontalAlignment = Avalonia.Layout.HorizontalAlignment.Center,
                             TextWrapping = TextWrapping.Wrap,
-                            TextAlignment = TextAlignment.Center
+                            TextAlignment = TextAlignment.Center,
+                            Foreground = primaryBlue
                         };
-                        if (primaryBlue is IBrush brush) txt.Foreground = brush;
 
                         stack.Children.Add(img);
                         stack.Children.Add(txt);
@@ -832,27 +849,28 @@ namespace NetworkDiagram
                         {
                             var desc = new TextBlock {
                                 Text = device.Description,
-                                FontSize = 11,
+                                FontSize = isGrayscale ? 18 : 11,
+                                FontWeight = isGrayscale ? FontWeight.Bold : FontWeight.Normal,
                                 FontStyle = FontStyle.Italic,
                                 HorizontalAlignment = Avalonia.Layout.HorizontalAlignment.Center,
                                 TextWrapping = TextWrapping.Wrap,
                                 TextAlignment = TextAlignment.Center,
-                                Opacity = 0.8,
-                                Foreground = Brushes.Black
+                                Foreground = textDark,
+                                Opacity = isGrayscale ? 1.0 : 0.8
                             };
                             stack.Children.Add(desc);
                         }
 
-                        var accentBlue = Application.Current!.FindResource("AccentBlue");
                         foreach (var ip in device.IpAddresses)
                         {
                             var tb = new TextBlock {
                                 Text = ip,
-                                FontSize = 10,
+                                FontSize = isGrayscale ? 14 : 10,
+                                FontWeight = isGrayscale ? FontWeight.Bold : FontWeight.Normal,
                                 HorizontalAlignment = Avalonia.Layout.HorizontalAlignment.Center,
-                                TextWrapping = TextWrapping.Wrap
+                                TextWrapping = TextWrapping.Wrap,
+                                Foreground = accentBlue
                             };
-                            if (accentBlue is IBrush b) tb.Foreground = b;
                             stack.Children.Add(tb);
                         }
 
@@ -870,8 +888,65 @@ namespace NetworkDiagram
                 await Task.Delay(100);
                 rtb.Render(container);
 
-                using var stream = await file.OpenWriteAsync();
-                rtb.Save(stream);
+                if (result == ExportOption.BlackAndWhite)
+                {
+                    using var ms = new MemoryStream();
+                    rtb.Save(ms);
+                    ms.Position = 0;
+                    var wb = WriteableBitmap.Decode(ms);
+                    ApplyGrayscale(wb);
+                    using var stream = await file.OpenWriteAsync();
+                    wb.Save(stream);
+                }
+                else
+                {
+                    using var stream = await file.OpenWriteAsync();
+                    rtb.Save(stream);
+                }
+            }
+        }
+
+        private void ApplyGrayscale(WriteableBitmap bitmap)
+        {
+            using (var lockedBitmap = bitmap.Lock())
+            {
+                int totalBytes = lockedBitmap.RowBytes * lockedBitmap.Size.Height;
+                byte[] buffer = new byte[totalBytes];
+                Marshal.Copy(lockedBitmap.Address, buffer, 0, totalBytes);
+
+                for (int y = 0; y < lockedBitmap.Size.Height; y++)
+                {
+                    int rowOffset = y * lockedBitmap.RowBytes;
+                    for (int x = 0; x < lockedBitmap.Size.Width; x++)
+                    {
+                        int i = rowOffset + x * 4;
+                        if (i + 3 >= totalBytes) continue;
+
+                        byte b = buffer[i];
+                        byte g = buffer[i + 1];
+                        byte r = buffer[i + 2];
+                        byte a = buffer[i + 3];
+
+                        if (a < 128)
+                        {
+                            // Transparent -> White
+                            buffer[i] = 255;
+                            buffer[i + 1] = 255;
+                            buffer[i + 2] = 255;
+                        }
+                        else
+                        {
+                            // Standard luminance for grayscale
+                            byte val = (byte)(0.299 * r + 0.587 * g + 0.114 * b);
+                            buffer[i] = val;
+                            buffer[i + 1] = val;
+                            buffer[i + 2] = val;
+                        }
+                        buffer[i + 3] = 255; // Always opaque for printing
+                    }
+                }
+
+                Marshal.Copy(buffer, 0, lockedBitmap.Address, totalBytes);
             }
         }
         #endregion