Make the library fully cross-platform: remove GDI+ (System.Drawing.Common), CI on Linux

.github/workflows/ci.yml

@@ -9,9 +9,7 @@ on:
 
 jobs:
   build:
-    # Windows: the suite exercises System.Drawing, which only works there. On Linux
-    # DTS_FailingTests.DeleteWorksheetWithReferencedImage hangs the test host.
-    runs-on: windows-latest
+    runs-on: ubuntu-latest
     env:
       CODACY_PROJECT_TOKEN: ${{ secrets.CODACY_PROJECT_TOKEN }}
     steps:
@@ -31,22 +29,13 @@ jobs:
     - name: Build
       run: dotnet build --configuration Release --no-restore
 
-    # Unit tests only (no live services). Excluded by name:
-    # - DateFunctionsWorkWithDifferentCultureDateFormats_*: throws an unhandled
-    #   InvalidCastException on a worker thread, which crashes the test host and
-    #   aborts the whole run (pre-existing).
-    # - Eleven tests that fail on unmodified main: RunDrawingTests, Issuer246,
-    #   RunWorksheetTests, SetBackground, RCRelativeToABToR1C1_2, SimpleRelativeR1C1,
-    #   FullTwoColumn, FullColumn, FullTwoRow, FullRow, OperatorsActingOnNumericStrings.
-    # - Issue333: asserts the ISO text "2019-03-07" for the built-in mm-dd-yy format, which
-    #   is rendered in the current culture; the en-US runner gives "3/7/2019".
+    # Unit tests only (no live services).
     - name: Test with coverage
       run: >
         dotnet test PanoramicData.EPPlus.Test/PanoramicData.EPPlus.Test.csproj
         --configuration Release --no-build
         --collect "Code Coverage;Format=Cobertura" --results-directory ./coverage
         --blame-hang-timeout 5m
-        --filter "FullyQualifiedName!~DateFunctionsWorkWithDifferentCultureDateFormats&Name!=RunDrawingTests&Name!=Issuer246&Name!=RunWorksheetTests&Name!=SetBackground&Name!=RCRelativeToABToR1C1_2&Name!=SimpleRelativeR1C1&Name!=FullTwoColumn&Name!=FullColumn&Name!=FullTwoRow&Name!=FullRow&Name!=OperatorsActingOnNumericStrings&Name!=Issue333"
 
     - name: Upload coverage to Codacy
       if: ${{ env.CODACY_PROJECT_TOKEN != '' }}

Directory.Packages.props

@@ -7,7 +7,8 @@
     <!-- PanoramicData.EPPlus -->
     <PackageVersion Include="Microsoft.Extensions.Configuration.Json" Version="10.0.12" />
     <PackageVersion Include="Nerdbank.GitVersioning" Version="3.10.94" />
-    <PackageVersion Include="System.Drawing.Common" Version="10.0.12" />
+    <PackageVersion Include="SkiaSharp" Version="4.153.1" />
+    <PackageVersion Include="SkiaSharp.NativeAssets.Linux" Version="4.153.1" />
     <PackageVersion Include="System.Security.Cryptography.Pkcs" Version="9.0.0" />
     <!-- PanoramicData.EPPlus.Test -->
     <PackageVersion Include="FakeItEasy" Version="8.3.0" />

PanoramicData.EPPlus.Test/AddPictureFromBytesTests.cs

@@ -7,9 +7,8 @@
 namespace PanoramicData.EPPlus.Test;
 
 /// <summary>
-/// MagicSuite MS-25871: the byte-based AddPicture overload, which must work without System.Drawing
-/// so pictures can be added on platforms where GDI+ is unavailable (System.Drawing.Common 7 and
-/// later is Windows-only). Nothing in this class may reference System.Drawing.
+/// MagicSuite MS-25871: the byte-based AddPicture overloads, which work without any graphics library
+/// on every platform. Nothing in this class may reference System.Drawing image types.
 /// </summary>
 [TestClass]
 public class AddPictureFromBytesTests
@@ -33,21 +32,13 @@ public void AddPictureFromBytes_RoundTripsThroughASavedPackage()
 			saved = package.GetAsByteArray();
 		}
 
-		if (!OperatingSystem.IsWindowsVersionAtLeast(6, 1))
-		{
-			// Reading a picture back goes through ExcelPicture's loading constructor, which uses
-			// System.Drawing and deliberately throws where that is unsupported. Adding and saving
-			// (asserted above) work everywhere; assert the documented limit rather than skip.
-			using var unsupported = new ExcelPackage(new MemoryStream(saved));
-			Assert.ThrowsException<PlatformNotSupportedException>(() => unsupported.Workbook.Worksheets[0].Drawings);
-			return;
-		}
 
 		using var reopened = new ExcelPackage(new MemoryStream(saved));
 		var drawing = reopened.Workbook.Worksheets[0].Drawings["CatBytes"];
 		Assert.IsInstanceOfType(drawing, typeof(ExcelPicture));
 
 		var reopenedPicture = (ExcelPicture)drawing;
+		CollectionAssert.AreEqual(OnePixelPng, reopenedPicture.ImageBytes, "the picture reads back through the public API");
 		using var partStream = reopenedPicture.Part.GetStream();
 		using var ms = new MemoryStream();
 		partStream.CopyTo(ms);
@@ -87,4 +78,84 @@ public void AddPictureFromBytes_DuplicateBytes_ShareOnePackagePart()
 
 		Assert.AreEqual(first.UriPic.OriginalString, second.UriPic.OriginalString, "identical bytes deduplicate to one image part");
 	}
+
+	[TestMethod]
+	public void AddPictureFromBytes_ReadsSizeFromTheHeader()
+	{
+		using var package = new ExcelPackage();
+		var worksheet = package.Workbook.Worksheets.Add("Pictures");
+
+		var picture = worksheet.Drawings.AddPicture("Auto", OnePixelPng);
+
+		Assert.AreEqual("image/png", picture.ContentType);
+		Assert.AreEqual(1, picture.GetPixelWidth());
+		Assert.AreEqual(1, picture.GetPixelHeight());
+	}
+
+	[TestMethod]
+	public void AddPictureFromStream_StoresTheBytesVerbatim()
+	{
+		using var package = new ExcelPackage();
+		var worksheet = package.Workbook.Worksheets.Add("Pictures");
+
+		var picture = worksheet.Drawings.AddPicture("Streamed", new MemoryStream(OnePixelPng));
+
+		CollectionAssert.AreEqual(OnePixelPng, picture.ImageBytes);
+	}
+
+	[TestMethod]
+	public void AddPictureFromFile_ReadsBytesAndSize()
+	{
+		var file = new FileInfo(Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N") + ".png"));
+		File.WriteAllBytes(file.FullName, OnePixelPng);
+		try
+		{
+			using var package = new ExcelPackage();
+			var worksheet = package.Workbook.Worksheets.Add("Pictures");
+
+			var picture = worksheet.Drawings.AddPicture("File", file);
+
+			CollectionAssert.AreEqual(OnePixelPng, picture.ImageBytes);
+			Assert.AreEqual(1, picture.GetPixelWidth());
+		}
+		finally
+		{
+			file.Delete();
+		}
+	}
+
+	[TestMethod]
+	public void ImageHeaderReader_ReadsPngJpegGifAndBmp()
+	{
+		var png = OfficeOpenXml.Compatibility.ImageHeaderReader.Read(OnePixelPng);
+		Assert.AreEqual((1, 1), (png.Width, png.Height));
+
+		var jpeg = OfficeOpenXml.Compatibility.ImageHeaderReader.Read(EPPlusTest.Properties.Resources.Test1);
+		Assert.AreEqual("image/jpeg", jpeg.ContentType);
+		Assert.IsTrue(jpeg.Width > 1 && jpeg.Height > 1);
+
+		// GIF89a, 3x2
+		byte[] gif = [0x47, 0x49, 0x46, 0x38, 0x39, 0x61, 3, 0, 2, 0, 0, 0, 0];
+		var g = OfficeOpenXml.Compatibility.ImageHeaderReader.Read(gif);
+		Assert.AreEqual((3, 2), (g.Width, g.Height));
+
+		// BITMAPINFOHEADER, 5x4, 2835 pixels per metre (72 DPI)
+		var bmp = new byte[54];
+		bmp[0] = 0x42;
+		bmp[1] = 0x4D;
+		bmp[14] = 40;
+		bmp[18] = 5;
+		bmp[22] = 4;
+		bmp[38] = 0x13;
+		bmp[39] = 0x0B;
+		var b = OfficeOpenXml.Compatibility.ImageHeaderReader.Read(bmp);
+		Assert.AreEqual((5, 4), (b.Width, b.Height));
+		Assert.AreEqual(72F, b.HorizontalResolution, 0.1F);
+	}
+
+	[TestMethod]
+	public void ImageHeaderReader_RejectsTruncatedData()
+	{
+		Assert.ThrowsException<InvalidDataException>(() => OfficeOpenXml.Compatibility.ImageHeaderReader.Read([0x89, 0x50, 0x4E, 0x47]));
+	}
 }

PanoramicData.EPPlus.Test/CompoundDoc.cs

@@ -1,5 +1,4 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
-using System.Runtime.Versioning;
 using OfficeOpenXml;
 using OfficeOpenXml.Style;
 using OfficeOpenXml.Utils.CompundDocument;
@@ -164,7 +163,6 @@ public void Issue131()
 
 		package.Save();
 	}
-	[SupportedOSPlatform("windows")]
 	[TestMethod, Ignore]
 	public void Sample7EncrLargeTest()
 	{

PanoramicData.EPPlus.Test/ConditionalFormatting/ConditionalFormatting.cs

@@ -42,7 +42,7 @@ public static void MyClassInitialize(TestContext testContext)
 			Directory.CreateDirectory(string.Format("Test"));
 		}
 
-		_excelPackage = new ExcelPackage(new FileInfo(@"Test\ConditionalFormatting.xlsx"));
+		_excelPackage = new ExcelPackage(new FileInfo(Path.Combine("Test", "ConditionalFormatting.xlsx")));
 	}
 
 	// Use ClassCleanup to run code after all tests in a class have run

PanoramicData.EPPlus.Test/DTS_FailingTests.cs

@@ -1,5 +1,4 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
-using System.Runtime.Versioning;
 using OfficeOpenXml;
 using System.IO;
 
@@ -9,7 +8,6 @@ namespace PanoramicData.EPPlus.Test;
 public class DTS_FailingTests
 {
 
-	[SupportedOSPlatform("windows")]
 	[TestMethod]
 	public void DeleteWorksheetWithReferencedImage()
 	{
@@ -32,7 +30,6 @@ public void DeleteWorksheetWithReferencedImage()
 		}
 	}
 
-	[SupportedOSPlatform("windows")]
 	[TestMethod]
 	public void CopyAndDeleteWorksheetWithImage()
 	{

PanoramicData.EPPlus.Test/DrawingTest.cs

@@ -1,5 +1,4 @@
 using EPPlusTest.Properties;
-using System.Runtime.Versioning;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using OfficeOpenXml;
 using OfficeOpenXml.Drawing;
@@ -16,7 +15,6 @@ namespace PanoramicData.EPPlus.Test;
 [TestClass]
 public class DrawingTest : TestBase
 {
-	[SupportedOSPlatform("windows")]
 	[TestMethod]
 	public void RunDrawingTests()
 	{
@@ -61,7 +59,6 @@ public void ReadDrawing()
 		Assert.AreEqual(cht.Title.Text, "Test");
 	}
 
-	[SupportedOSPlatform("windows")]
 	public void Picture()
 	{
 		var ws = _pck.Workbook.Worksheets.Add("Picture");
@@ -112,7 +109,6 @@ public void Picture()
 	}
 	//[TestMethod]
 	//[Ignore]
-	[SupportedOSPlatform("windows")]
 	public void DrawingSizingAndPositioning()
 	{
 		var ws = _pck.Workbook.Worksheets.Add("DrawingPosSize");
@@ -255,7 +251,6 @@ public void PieChart3D()
 	}
 	//[TestMethod]
 	//[Ignore]
-	[SupportedOSPlatform("windows")]
 	public void Scatter()
 	{
 		var ws = _pck.Workbook.Worksheets.Add("Scatter");
@@ -281,7 +276,9 @@ public void Scatter()
 		ser.DataLabel.Fill.Color = Color.BlueViolet;
 		ser.DataLabel.Font.Color = Color.White;
 		ser.DataLabel.Font.Italic = true;
-		ser.DataLabel.Font.SetFromFont(new Font("bookman old style", 8));
+		ser.DataLabel.Font.LatinFont = "bookman old style";
+		ser.DataLabel.Font.ComplexFont = "bookman old style";
+		ser.DataLabel.Font.Size = 8;
 		Assert.IsTrue(chrt.ChartType == eChartType.XYScatterSmoothNoMarkers, "Invalid Charttype");
 		chrt.Series[0].Header = "Test serie";
 		chrt = ws.Drawings.AddChart("ScatterChart2", eChartType.XYScatterSmooth) as ExcelScatterChart;
@@ -575,7 +572,6 @@ public void LineMarker()
 	}
 	//[TestMethod]
 	//[Ignore]
-	[SupportedOSPlatform("windows")]
 	public void Drawings()
 	{
 		var ws = _pck.Workbook.Worksheets.Add("Shapes");
@@ -601,7 +597,10 @@ public void Drawings()
 		rt = (ws.Drawings["shape2"] as ExcelShape).RichText.Add("\r\nAdded formated richtext");
 		rt.Bold = true;
 		rt.Color = Color.DarkGoldenrod;
-		rt.SetFromFont(new Font("Times new roman", 18, FontStyle.Underline));
+		rt.LatinFont = "Times new roman";
+		rt.ComplexFont = "Times new roman";
+		rt.Size = 18;
+		rt.UnderLine = eUnderLineType.Single;
 		rt.UnderLineColor = Color.Green;
 
 
@@ -761,7 +760,6 @@ public void MultiChartSeries()
 	}
 	//[TestMethod]
 	//[Ignore]
-	[SupportedOSPlatform("windows")]
 	public void DeleteDrawing()
 	{
 		var ws = _pck.Workbook.Worksheets.Add("DeleteDrawing1");
@@ -901,7 +899,7 @@ public void TestHeaderaddress()
 	[TestMethod]
 	public void AllDrawingsInsideMarkupCompatibility()
 	{
-		var workbooksDir = Path.Combine(AppContext.BaseDirectory, @"..\..\workbooks");
+		var workbooksDir = Path.Combine(AppContext.BaseDirectory, Path.Combine("..", "..", "workbooks"));
 
 		// This is codeplex issue 15028: Making an unrelated change to an Excel file that contains drawings that ALL exist
 		// inside MarkupCompatibility/Choice nodes causes the drawings.xml file to be incorrectly garbage collected
@@ -959,7 +957,6 @@ public void AllDrawingsInsideMarkupCompatibility()
 		// Cleanup:
 		File.Delete(savedPath);
 	}
-	[SupportedOSPlatform("windows")]
 	public void DrawingRowheightDynamic()
 	{
 		var ws = _pck.Workbook.Worksheets.Add("PicResize");

PanoramicData.EPPlus.Test/Encrypt.cs

@@ -11,24 +11,24 @@ public class Encrypt : TestBase
 	[Ignore]
 	public void ReadWriteEncrypt()
 	{
-		using (ExcelPackage pck = new(new FileInfo(@"Test\Drawing.xlsx"), true))
+		using (ExcelPackage pck = new(new FileInfo(Path.Combine("Test", "Drawing.xlsx")), true))
 		{
 			pck.Encryption.Password = "EPPlus";
 			pck.Encryption.Algorithm = EncryptionAlgorithm.AES192;
 			pck.Workbook.Protection.SetPassword("test");
 			pck.Workbook.Protection.LockStructure = true;
 			pck.Workbook.Protection.LockWindows = true;
 
-			pck.SaveAs(new FileInfo(@"Test\DrawingEncr.xlsx"));
+			pck.SaveAs(new FileInfo(Path.Combine("Test", "DrawingEncr.xlsx")));
 		}
 
-		using (ExcelPackage pck = new(new FileInfo(_worksheetPath + @"\DrawingEncr.xlsx"), true, "EPPlus"))
+		using (ExcelPackage pck = new(new FileInfo(_worksheetPath + "DrawingEncr.xlsx"), true, "EPPlus"))
 		{
 			pck.Encryption.IsEncrypted = false;
-			pck.SaveAs(new FileInfo(_worksheetPath + @"\DrawingNotEncr.xlsx"));
+			pck.SaveAs(new FileInfo(_worksheetPath + "DrawingNotEncr.xlsx"));
 		}
 
-		FileStream fs = new(_worksheetPath + @"\DrawingEncr.xlsx", FileMode.Open, FileAccess.ReadWrite);
+		FileStream fs = new(_worksheetPath + "DrawingEncr.xlsx", FileMode.Open, FileAccess.ReadWrite);
 		using (ExcelPackage pck = new(fs, "EPPlus"))
 		{
 			pck.Encryption.IsEncrypted = false;