Add layout methods that write to memory instead of a file (#68)

Rubjerg.Graphviz.Test/TestDotLayout.cs

@@ -1,6 +1,4 @@
-using System;
 using System.Drawing;
-using System.Globalization;
 using System.IO;
 using System.Linq;
 using NUnit.Framework;
@@ -299,4 +297,49 @@ public void TestLabelEscaping(bool escape)
             }
         }
     }
+
+    [Test()]
+    public void TestOutputFormatsConsistency()
+    {
+        RootGraph root = CreateUniqueTestGraph();
+        Node node1 = root.GetOrAddNode("1");
+        _ = root.GetOrAddEdge(node1, node1);
+
+        var testFile = GetTestFilePath("out.txt");
+
+        {
+            root.ToXDotFile(testFile);
+            var fileContent = File.ReadAllText(testFile).Replace("\r\n", "\n");;
+            var stringContent = root.CreateLayout().ToDotString();
+            Assert.AreEqual(fileContent, stringContent);
+        }
+
+        {
+            root.ToSvgFile(testFile);
+            var fileContent = File.ReadAllText(testFile).Replace("\r\n", "\n");;
+            var stringContent = root.ToSvgString();
+            Assert.AreEqual(fileContent, stringContent);
+        }
+
+        {
+            root.ToPngFile(testFile);
+            var fileContent = File.ReadAllBytes(testFile);
+            var stringContent = root.ToPngBytes();
+            Assert.AreEqual(fileContent, stringContent);
+        }
+
+        {
+            root.ToPdfFile(testFile);
+            var fileContent = File.ReadAllBytes(testFile);
+            var stringContent = root.ToPdfBytes();
+            Assert.AreEqual(fileContent, stringContent);
+        }
+
+        {
+            root.ToPsFile(testFile);
+            var fileContent = File.ReadAllBytes(testFile);
+            var stringContent = root.ToPsBytes();
+            Assert.AreEqual(fileContent, stringContent);
+        }
+    }
 }

Rubjerg.Graphviz/Graph.cs

@@ -180,6 +180,7 @@ public override string ToString()
     /// Attributes with the empty string as default are not correctly exported.
     /// https://gitlab.com/graphviz/graphviz/-/issues/1887
     /// </summary>
+    /// <returns>string with unix line endings</returns>
     public string ToDotString()
     {
         return Rjagmemwrite(_ptr);
@@ -600,10 +601,24 @@ private void ToFile(string filepath, string format, string engine)
         _ = GraphvizCommand.Exec(this, format: format, filepath, engine: engine);
     }
 
+    private byte[] ToBytes(string format, string engine)
+    {
+        var (stdout, _) = GraphvizCommand.Exec(this, format: format, engine: engine);
+        return stdout;
+    }
+
+    public void ToXDotFile(string filepath, string engine = LayoutEngines.Dot) => ToFile(filepath, "xdot", engine);
     public void ToSvgFile(string filepath, string engine = LayoutEngines.Dot) => ToFile(filepath, "svg", engine);
     public void ToPngFile(string filepath, string engine = LayoutEngines.Dot) => ToFile(filepath, "png", engine);
     public void ToPdfFile(string filepath, string engine = LayoutEngines.Dot) => ToFile(filepath, "pdf", engine);
     public void ToPsFile(string filepath, string engine = LayoutEngines.Dot) => ToFile(filepath, "ps", engine);
+
+    /// <returns>string with unix line endings</returns>
+    public string ToSvgString(string engine = LayoutEngines.Dot) => GraphvizCommand.ConvertBytesToString(ToBytes("svg", engine));
+    public byte[] ToPngBytes(string engine = LayoutEngines.Dot) => ToBytes("png", engine);
+    public byte[] ToPdfBytes(string engine = LayoutEngines.Dot) => ToBytes("pdf", engine);
+    public byte[] ToPsBytes(string engine = LayoutEngines.Dot) => ToBytes("ps", engine);
+
     #endregion
 
 

Rubjerg.Graphviz/GraphvizCommand.cs

@@ -13,17 +13,29 @@ public class GraphvizCommand
     public static RootGraph CreateLayout(Graph input, string engine = LayoutEngines.Dot, CoordinateSystem coordinateSystem = CoordinateSystem.BottomLeft)
     {
         var (stdout, stderr) = Exec(input, engine: engine);
-        var resultGraph = RootGraph.FromDotString(stdout, coordinateSystem);
+        var stdoutStr = ConvertBytesToString(stdout);
+        var resultGraph = RootGraph.FromDotString(stdoutStr, coordinateSystem);
         resultGraph.Warnings = stderr;
         return resultGraph;
     }
 
+    public static string ConvertBytesToString(byte[] data)
+    {
+        using (MemoryStream ms = new MemoryStream(data))
+        using (StreamReader reader = new StreamReader(ms, true))
+        {
+            // Just to be safe, make sure the input has unix line endings. Graphviz does not properly support
+            // windows line endings passed to stdin when it comes to attribute line continuations.
+            return reader.ReadToEnd().Replace("\r\n", "\n");
+        }
+    }
+
     /// <summary>
     /// Start dot.exe to compute a layout.
     /// </summary>
     /// <exception cref="ApplicationException">When the Graphviz process did not return successfully</exception>
     /// <returns>stderr may contain warnings</returns>
-    public static (string stdout, string stderr) Exec(Graph input, string format = "xdot", string outputPath = null, string engine = LayoutEngines.Dot)
+    public static (byte[] stdout, string stderr) Exec(Graph input, string format = "xdot", string outputPath = null, string engine = LayoutEngines.Dot)
     {
         string exeName = "dot.exe";
         string arguments = $"-T{format} -K{engine}";
@@ -56,19 +68,21 @@ public static (string stdout, string stderr) Exec(Graph input, string format = "
 
         // Write to stdin
         using (StreamWriter sw = process.StandardInput)
-            sw.WriteLine(inputToStdin);
+            sw.Write(inputToStdin);
 
-        // Read from stdout
-        string stdout;
-        using (StreamReader sr = process.StandardOutput)
-            stdout = sr.ReadToEnd()
-                .Replace("\r\n", "\n"); // File operations do this automatically, but stream operations do not
+        // Read from stdout, can be binary output such as pdf
+        byte[] stdout;
+        using (MemoryStream memoryStream = new MemoryStream())
+        {
+            process.StandardOutput.BaseStream.CopyTo(memoryStream);
+            stdout = memoryStream.ToArray();
+        }
 
         // Read from stderr
         string stderr;
         using (StreamReader sr = process.StandardError)
-            stderr = sr.ReadToEnd()
-                .Replace("\r\n", "\n"); // File operations do this automatically, but stream operations do not
+            // Let's use unix line endings for consistency with stdout
+            stderr = sr.ReadToEnd().Replace("\r\n", "\n");
 
         process.WaitForExit();