Fixed usage of skew() with single argument #101

Author: FlorianRappl

CHANGELOG.md

@@ -5,6 +5,7 @@ Released on Tuesday, May 31 2022.
 - Dropped .NET Framework 4.6
 - Updated to use AngleSharp 0.17
 - Fixed casing issue with color, timing, and gradient functions (#109)
+- Fixed parsing of `skew` (#101)
 - Fixed shorthand properties using `inherit` being omitted (#100)
 - Added support for `conic-gradient` (#101)
 

src/AngleSharp.Css.Tests/Declarations/CssTransformProperty.cs

@@ -461,6 +461,18 @@ public void CssTransformSkewYLegal()
             Assert.AreEqual("skewY(1.07rad)", property.Value);
         }
 
+        [Test]
+        public void CssTransformSkewLegal_Issue101()
+        {
+            var snippet = "transform:  skew(20deg) ";
+            var property = ParseDeclaration(snippet);
+            Assert.AreEqual("transform", property.Name);
+            Assert.IsFalse(property.IsImportant);
+            Assert.IsFalse(property.IsInherited);
+            Assert.IsTrue(property.HasValue);
+            Assert.AreEqual("skew(20deg)", property.Value);
+        }
+
         [Test]
         public void CssTransformMultipleLegal()
         {

src/AngleSharp.Css/Parser/Micro/TransformParser.cs

@@ -62,17 +62,26 @@ public static ICssTransformFunctionValue ParseTransform(this StringSource source
         /// </summary>
         private static CssSkewValue ParseSkew2d(StringSource source)
         {
-            var x = source.ParseAngleOrCalc();
+            ICssValue x = source.ParseAngleOrCalc();
+            ICssValue y = Angle.Zero;
             var c = source.SkipGetSkip();
-            var y = source.ParseAngleOrCalc();
-            var f = source.SkipGetSkip();
 
-            if (x != null && y != null && c == Symbols.Comma && f == Symbols.RoundBracketClose)
+            if (x == null)
             {
-                return new CssSkewValue(x, y);
+                return null;
             }
 
-            return null;
+            if (c == Symbols.Comma) {
+                y = source.ParseAngleOrCalc();
+                c = source.SkipGetSkip();
+            }
+
+            if (c != Symbols.RoundBracketClose)
+            {
+                return null;
+            }
+
+            return new CssSkewValue(x, y);
         }
 
         /// <summary>

src/AngleSharp.Css/Values/Functions/CssSkewValue.cs

@@ -76,7 +76,7 @@ public String CssText
                     {
                         args = _beta.CssText;
                     }
-                    else if (_beta != null)
+                    else if (_beta != null && _beta.CssText != "0rad")
                     {
                         args = String.Concat(args, ", ", _beta.CssText);
                     }