Combine chart data into single image

Web/Controllers/LeafCharterController.cs

@@ -1,5 +1,7 @@
 using System;
+using System.Collections.Generic;
 using System.Drawing;
+using System.Drawing.Imaging;
 using System.IO;
 using System.Linq;
 using System.Web.Mvc;
@@ -25,7 +27,7 @@ namespace LeafWeb.Web.Controllers
 			return View(leafInputId);
 		}
 
-	    public ActionResult LeafCharts(int leafInputId, int number)
+	    public ActionResult LeafCharts(int leafInputId)
 	    {
 		    var leafOutputFile = 
 				DataService
@@ -36,30 +38,68 @@ namespace LeafWeb.Web.Controllers
 		    if (leafOutputFile == null)
 			    throw new ArgumentOutOfRangeException(); // TODO: break
 
-			return File(GetChartImage(leafOutputFile.Contents, number), "image/png", "mychart.png");
+		    var curveData = GetCurveData(leafOutputFile.Contents);
+
+			var charts = GetChartBitmaps(curveData).ToList();
+
+		    var combinedChart = CombineBitmaps(charts);
+
+		    foreach (var chart in charts) chart.Dispose(); // cleanup
+
+			using (var ms = new MemoryStream())
+		    {
+				combinedChart.Save(ms, ImageFormat.Png);
+			    ms.Seek(0, SeekOrigin.Begin);
+				return File(ms.ToArray(), "image/png", "mychart.png");
+			}
 		}
 
-		private byte[] GetChartImage(byte[] fileContents, int number, ChartImageFormat format = ChartImageFormat.Png)
+		private CurveData[] GetCurveData(byte[] fileContents)
 		{
 			LeafGasComparison[] leafGasComparisons;
 			using (var parser = new LeafGasComparisonParser(fileContents))
 				leafGasComparisons = parser.Parse();
 
-			var curveData = CurveDataConverter.Convert(leafGasComparisons).ToArray();
+			return CurveDataConverter.Convert(leafGasComparisons).ToArray();
+		}
 
+		private IEnumerable<Bitmap> GetChartBitmaps(CurveData[] curveData)
+		{
 			var charts = LeafWebCharter.ProduceCharts(curveData[0]);
-
-			//Image.FromFile()
-
-			using (var ms = new MemoryStream())
+			
+			foreach (var chart in charts)
 			{
-				charts.Skip(number).First().SaveImage(ms, format);
+				// http://stackoverflow.com/a/336396/99492
+				var ms = new MemoryStream(); // this gets attached to the bmp, dispose of it later
+				chart.SaveImage(ms, ChartImageFormat.Bmp);
 				ms.Seek(0, SeekOrigin.Begin);
-
-				return ms.ToArray();
+				yield return new Bitmap(ms);
 			}
 		}
 
+		private Bitmap CombineBitmaps(IList<Bitmap> bitmaps, int columnCount = 2)
+		{
+			var cellWidth = bitmaps[0].Width;
+			var cellHeight = bitmaps[0].Height;
+			var width = cellWidth * 2;
+			var height = cellHeight * bitmaps.Count / 2;
+
+			var combinedBitmap = new Bitmap(width, height);
+			using (var g = Graphics.FromImage(combinedBitmap))
+			{
+				var currentCol = 0;
+				var currentRow = 0;
+				foreach (var image in bitmaps)
+				{
+					g.DrawImage(image, currentCol * cellWidth, currentRow * cellHeight);
+
+					currentCol = (currentCol + 1)%columnCount;
+					currentRow += currentCol == 0 ? 1 : 0;
+				}
+			}
+			return combinedBitmap;
+		}
+
 		public ActionResult ChartSample()
 		{
 			var chart = new Chart