Experimenting with Linux support.

Domain/Misc/ConnectionIconBlock.cs

@@ -1,4 +1,6 @@
 using System.Drawing;
+using System.Runtime.InteropServices;
+using System.IO;
 using PdfSharp.Drawing;
 
 namespace Trizbort.Domain.Misc {
@@ -84,7 +86,15 @@ public void DrawBlock(XGraphics graphics) {
 //
 
 
-      graphics.DrawImage(Image, pos.ToPointF() + offsets);
+      if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows)) {
+        graphics.DrawImage(Image, pos.ToPointF() + offsets);
+      }
+      else {
+        MemoryStream strm = new MemoryStream();
+        Image.Save(strm, System.Drawing.Imaging.ImageFormat.Png);
+        XImage ximg = XImage.FromStream(strm);
+        graphics.DrawImage(ximg, pos.ToPointF() + offsets);
+      }
     }
   }
 }

Domain/Misc/TextBlock.cs

@@ -27,6 +27,7 @@ THE SOFTWARE.
 using System.Drawing;
 using System.Linq;
 using PdfSharp.Drawing;
+using System.Runtime.InteropServices;
 
 namespace Trizbort.Domain.Misc {
   internal class TextBlock {
@@ -45,9 +46,37 @@ internal class TextBlock {
     private Vector m_size;
     private XSize m_sizeChecker;
     private string m_text = string.Empty;
+    // This provides a perhaps more useful/educational exception.
+    // It appears that PDFSharp still has Windows dependencies?
+    // private XFont initialXFont = new XFont("Arial", 12F);
 
     public static int RebuildCount => s_rebuildCount;
 
+    private XSize BrokenMeasureString(XGraphics graphics, String str, Font font) {
+       if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows)) {
+         return graphics.MeasureString(str, font);
+       }
+       else {
+	 Console.WriteLine(String.Format("Measured string '{0}' as ({1}, {2})",
+           str, str.Length * 9F, font.Height));
+         return new XSize(str.Length * 9F, font.Height);
+       }
+    }
+
+    private void BrokenDrawString(XGraphics graphics, String str, Font font, Brush brush,
+           double x, double y, XStringFormat fmt) {
+       if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows)) {
+         graphics.DrawString(str, font, brush, x, y, fmt);
+       }
+       else {
+         Console.WriteLine("Not drawing string: " + str);
+         // graphics.DrawString(str, font, brush, x, y, fmt); // Crash!
+         // XFont xfont = font;  // Crash!
+         // XFont xfont = new XFont("Arial", 9F); // Crash!
+         // XBrush xbrush = brush; // Does NOT crash.
+       }
+    }
+
     public string Text {
       get => m_text;
       set {
@@ -76,7 +105,7 @@ public string Text {
     public Rect Draw(XGraphics graphics, Font font, Brush brush, Vector pos, Vector size, XStringFormat format) {
       // do a quick test to see if text is going to get drawn at the same size as last time;
       // if so, assume we don't need to recompute our layout for that reason.
-      var sizeChecker = graphics.MeasureString("M q", font);
+      var sizeChecker = BrokenMeasureString(graphics, "M q", font);
             if (sizeChecker != m_sizeChecker ||
                 pos != m_pos ||
                 m_size != size ||
@@ -117,7 +146,7 @@ public Rect Draw(XGraphics graphics, Font font, Brush brush, Vector pos, Vector
         graphics.SmoothingMode = XSmoothingMode.HighQuality;
 
 
-        graphics.DrawString(line, font, brush, origin.X, origin.Y, m_actualFormat);
+        BrokenDrawString(graphics, line, font, brush, origin.X, origin.Y, m_actualFormat);
         origin += m_delta;
         size.Y -= m_lineHeight;
       }
@@ -146,17 +175,17 @@ private void RebuildCachedLayout(XGraphics graphics, Font font, ref Vector pos,
       m_size = size;
 
       var text = m_text;
-      if (text.IndexOf('\n') == -1 && size.X > 0 && size.Y > 0 && graphics.MeasureString(text, font).Width > size.X) {
+      if (text.IndexOf('\n') == -1 && size.X > 0 && size.Y > 0 && BrokenMeasureString(graphics, text, font).Width > size.X) {
         // wrap single-line text to fit in rectangle
 
         // measure a space, countering the APIs unwillingness to measure spaces
-        var spaceLength = (float) (graphics.MeasureString("M M", font).Width - graphics.MeasureString("M", font).Width * 2);
-        var hyphenLength = (float) graphics.MeasureString("-", font).Width;
+        var spaceLength = (float) (BrokenMeasureString(graphics, "M M", font).Width - BrokenMeasureString(graphics, "M", font).Width * 2);
+        var hyphenLength = (float) BrokenMeasureString(graphics, "-", font).Width;
 
         var wordsStep1 = new List<Word>();
         foreach (var word in text.Split(new[] {" "}, StringSplitOptions.RemoveEmptyEntries)) {
           if (wordsStep1.Count != 0) wordsStep1.Add(new Word(" ", spaceLength));
-          wordsStep1.Add(new Word(word, (float) graphics.MeasureString(word, font).Width));
+          wordsStep1.Add(new Word(word, (float) BrokenMeasureString(graphics, word, font).Width));
         }
 
         bool isSplitDash = Setup.Settings.WrapTextAtDashes;
@@ -170,14 +199,14 @@ private void RebuildCachedLayout(XGraphics graphics, Font font, ref Vector pos,
               else if (tWordList.Count != 0 && isSplitDash)
                 tWordList.Add(new Word("-", hyphenLength));
 
-              tWordList.Add(new Word(tWord, (float) graphics.MeasureString(tWord, font).Width));
+              tWordList.Add(new Word(tWord, (float) BrokenMeasureString(graphics, tWord, font).Width));
             }
 
             words.AddRange(tWordList);
           } else {
             if (words.Count != 0)
               words.Add(new Word(" ", spaceLength));
-            words.Add(new Word(splits[0], (float) graphics.MeasureString(splits[0], font).Width));
+            words.Add(new Word(splits[0], (float) BrokenMeasureString(graphics, splits[0], font).Width));
           }
 
         var lineLength = 0.0f;

Domain/StatusBar/Status.cs

@@ -3,6 +3,7 @@
 using System.Drawing;
 using System.Linq;
 using System.Windows.Forms;
+using System.Runtime.InteropServices;
 
 namespace Trizbort.Domain.StatusBar {
   public enum StatusItems {
@@ -92,12 +93,22 @@ private void updateInfoMessage(IStatusWidget helpItem) {
     }
 
     private void setDefaultItems() {
-      Items = new List<StatusItem> {
-        new StatusItem {Id = StatusItems.tsb_Info, Show = true},
-        new StatusItem {Id = StatusItems.tsb_CapsLock, Show = true, Widget = new CapsLockStatusWidget()},
-        new StatusItem {Id = StatusItems.tsb_NumLock, Show = true, Widget = new NumLockStatusWidget()}, 
-        new StatusItem {Id = StatusItems.tsb_Zoom, Show = true, Widget = new ZoomStatusWidget()}
-      };
+      if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows)) {
+        Items = new List<StatusItem> {
+          new StatusItem {Id = StatusItems.tsb_Info, Show = true},
+          new StatusItem {Id = StatusItems.tsb_CapsLock, Show = true, Widget = new CapsLockStatusWidget()},
+          new StatusItem {Id = StatusItems.tsb_NumLock, Show = true, Widget = new NumLockStatusWidget()},
+          new StatusItem {Id = StatusItems.tsb_Zoom, Show = true, Widget = new ZoomStatusWidget()}
+        };
+      }
+      // Is KeyLocked() is not supported in Mono on Linux and MacOS yet.
+      // https://github.com/mono/mono/blob/main/mcs/class/System.Windows.Forms/System.Windows.Forms/Control.cs#L3487
+      else {
+        Items = new List<StatusItem> {
+          new StatusItem {Id = StatusItems.tsb_Info, Show = true},
+          new StatusItem {Id = StatusItems.tsb_Zoom, Show = true, Widget = new ZoomStatusWidget()}
+        };
+      }
     }
   }
 }

UI/Controls/Canvas.cs

@@ -1778,13 +1778,8 @@ private void drawElements(XGraphics graphics, Palette palette, bool finalRender)
         context.Hover = !context.Selected && element == HoverElement && !finalRender;
         if (context.Hover && dragMode == DragModes.MovePort) context.Hover = false;
 
-        try {
-          var elementBounds = element.UnionBoundsWith(Rect.Empty, true).ToRectangleF();
-          if (finalRender || clipToScreen.IntersectsWith(elementBounds)) element.Draw(graphics, palette, context);
-        }
-        catch (Exception) {
-          // avoid GDI+ exceptions (vast shapes, etc.) taking down the canvas
-        }
+        var elementBounds = element.UnionBoundsWith(Rect.Empty, true).ToRectangleF();
+        if (finalRender || clipToScreen.IntersectsWith(elementBounds)) element.Draw(graphics, palette, context);
       }
     }
 

UI/Controls/TrizbortTextBox.cs

@@ -13,7 +13,9 @@ public string Watermark {
 
     private void updateCue() {
       if (this.IsHandleCreated && mCue != null) {
-        SendMessage(this.Handle, EM_SETCUEBANNER, (IntPtr) 1, mCue);
+        if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows)) {
+          SendMessage(this.Handle, EM_SETCUEBANNER, (IntPtr) 1, mCue);
+        }
       }
     }
 

UI/MainForm.cs

@@ -406,7 +406,12 @@ private void FileExportHugoMenuItem_Click(object sender, EventArgs e) {
 
     private void FileExportImageMenuItem_Click(object sender, EventArgs e) {
       using (var dialog = new SaveFileDialog()) {
-        dialog.Filter = "PNG Images|*.png|JPEG Images|*.jpg|BMP Images|*.bmp|Enhanced Metafiles (EMF)|*.emf|All Files|*.*||";
+        if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows)) {
+          dialog.Filter = "PNG Images|*.png|JPEG Images|*.jpg|BMP Images|*.bmp|Enhanced Metafiles (EMF)|*.emf|All Files|*.*||";
+        }
+        else {
+	  dialog.Filter = "PNG Images|*.png|JPEG Images|*.jpg|BMP Images|*.bmp|All Files|*.*||";
+        }
         dialog.Title = "Export Image";
         dialog.DefaultExt = getExtensionForDefaultImageType();
         dialog.InitialDirectory = PathHelper.SafeGetDirectoryName(ApplicationSettingsController.AppSettings.LastExportImageFileName);
@@ -750,7 +755,9 @@ private bool saveImage(string fileName) {
         format = ImageFormat.Jpeg;
       else if (StringComparer.InvariantCultureIgnoreCase.Compare(ext, ".bmp") == 0)
         format = ImageFormat.Bmp;
-      else if (StringComparer.InvariantCultureIgnoreCase.Compare(ext, ".emf") == 0) format = ImageFormat.Emf;
+      else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux)
+               && StringComparer.InvariantCultureIgnoreCase.Compare(ext, ".emf") == 0)
+	format = ImageFormat.Emf;
 
       var size = Canvas.ComputeCanvasBounds(true).Size * (ApplicationSettingsController.AppSettings.SaveAt100 ? 1.0f : Canvas.ZoomFactor);
       size.X = Numeric.Clamp(size.X, 16, 8192);