From dea6736e82b98662a71d4738b813d99305eb9ce6 Mon Sep 17 00:00:00 2001
From: Tig <tig@users.noreply.github.com>
Date: Thu, 16 Oct 2025 17:55:43 -0600
Subject: [PATCH] Fixes #4284 (#4285)

Color alpha channel bug and add StandardColor tests

Updated the `Color` constructor for `StandardColor` to use `StandardColors.GetArgb` instead of casting to an integer, ensuring the alpha channel (`A`) is correctly set to `0xFF` (opaque). This resolves issues with name resolution and ARGB formatting.

Added a new test class, `ColorStandardColorTests`, to verify the behavior of `Color` when initialized with a `StandardColor`. Tests include:
- Verifying `ToString` returns the correct standard color name.
- Ensuring `ToString("G")` outputs the correct opaque ARGB value.

These changes address a bug where the alpha channel was incorrectly set to `0x00` (transparent).
---
 Terminal.Gui/Drawing/Color/Color.cs           |  2 +-
 .../Drawing/Color/ColorStandardColorTests.cs  | 27 +++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 Tests/UnitTestsParallelizable/Drawing/Color/ColorStandardColorTests.cs

diff --git a/Terminal.Gui/Drawing/Color/Color.cs b/Terminal.Gui/Drawing/Color/Color.cs
index f220de1ab..995249c13 100644
--- a/Terminal.Gui/Drawing/Color/Color.cs
+++ b/Terminal.Gui/Drawing/Color/Color.cs
@@ -113,7 +113,7 @@ public readonly partial record struct Color : ISpanParsable<Color>, IUtf8SpanPar
 
     /// <summary>Initializes a new instance of the <see cref="Color"/> color from a value in the <see cref="StandardColor"/> enum.</summary>
     /// <param name="colorName">The 16-color value.</param>
-    public Color (in StandardColor colorName) : this ((int)colorName) { }
+    public Color (in StandardColor colorName) : this (StandardColors.GetArgb (colorName)) { }
 
     /// <summary>
     ///     Initializes a new instance of the <see cref="Color"/> color from string. See
diff --git a/Tests/UnitTestsParallelizable/Drawing/Color/ColorStandardColorTests.cs b/Tests/UnitTestsParallelizable/Drawing/Color/ColorStandardColorTests.cs
new file mode 100644
index 000000000..eaf107010
--- /dev/null
+++ b/Tests/UnitTestsParallelizable/Drawing/Color/ColorStandardColorTests.cs
@@ -0,0 +1,27 @@
+using Xunit;
+
+namespace Terminal.Gui.DrawingTests;
+
+public class ColorStandardColorTests
+{
+    [Fact]
+    public void ToString_Returns_Standard_Name_For_StandardColor_CadetBlue()
+    {
+        // Without the fix, this uses Color(in StandardColor) -> this((int)colorName),
+        // which sets A=0x00 and prevents name resolution (expects A=0xFF).
+        var c = new Terminal.Gui.Drawing.Color(Terminal.Gui.Drawing.StandardColor.CadetBlue);
+
+        // Expected: named color
+        Assert.Equal("CadetBlue", c.ToString());
+    }
+
+    [Fact]
+    public void ToString_G_Prints_Opaque_ARGB_For_StandardColor_CadetBlue()
+    {
+        // Without the fix, A=0x00, so "G" prints "#005F9EA0" instead of "#FF5F9EA0".
+        var c = new Terminal.Gui.Drawing.Color(Terminal.Gui.Drawing.StandardColor.CadetBlue);
+
+        // Expected: #AARRGGBB with A=FF (opaque)
+        Assert.Equal("#FF5F9EA0", c.ToString("G", null));
+    }
+}
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