Support color: transparent

Author: swhitty

SwiftDraw/Parser.XML.Color.swift

@@ -55,7 +55,8 @@ extension XMLParser {
   }
 
   private func parseColorNone(data: String) -> DOM.Color? {
-    if data.trimmingCharacters(in: .whitespaces) == "none" {
+    let trimmed = data.trimmingCharacters(in: .whitespaces)
+    if trimmed == "none" || trimmed == "transparent" {
       return DOM.Color.none // .none resolves to Optional.none
     }
     return nil

SwiftDrawTests/Parser.XML.ColorTests.swift

@@ -40,6 +40,12 @@ final class ParserColorTests: XCTestCase {
     XCTAssertEqual(try XMLParser().parseColor("\t none \t"), .none)
   }
 
+  func testColorTransparent() {
+    XCTAssertEqual(try XMLParser().parseColor("transparent"), .none)
+    XCTAssertEqual(try XMLParser().parseColor(" transparent"), .none)
+    XCTAssertEqual(try XMLParser().parseColor("\t transparent \t"), .none)
+  }
+
   func testColorCurrent() {
     XCTAssertEqual(try XMLParser().parseColor("currentColor"), .currentColor)
     XCTAssertEqual(try XMLParser().parseColor(" currentColor"), .currentColor)