fix issue 158 Shading is computed wrong.

* added unit tests
jinek · Nov 30, 2024 · b5abbac · b5abbac
1 parent bfae13f
commit b5abbac
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Showing 2 changed files with 40 additions and 2 deletions.
diff --git a/src/Consolonia.Core/Drawing/PixelBufferImplementation/Pixel.cs b/src/Consolonia.Core/Drawing/PixelBufferImplementation/Pixel.cs
@@ -125,9 +125,13 @@ public Pixel Blend(Pixel pixelAbove)
                     newBackground = Background;
                     break;
                 case PixelBackgroundMode.Shaded:
+#if DEBUG
+                    if (pixelAbove.Foreground.Symbol.Text != " ")
+                        throw new ArgumentOutOfRangeException(nameof(pixelAbove), "Someone is attempting to shade a pixel with a non-blank symbol and the behavior of that is not defined");
+#endif
                     (newForeground, newBackground) = Shade();
-                    newForeground = newForeground.Blend(pixelAbove.Foreground);
-                    break;
+                    return new Pixel(newForeground, newBackground);
+
                 default: throw new ArgumentOutOfRangeException(nameof(pixelAbove));
             }
 

diff --git a/src/Tests/Consolonia.Core.Tests/PixelTests.cs b/src/Tests/Consolonia.Core.Tests/PixelTests.cs
@@ -142,6 +142,40 @@ public void BlendColoredBackground()
             Assert.That(newPixel.Background.Color, Is.EqualTo(Colors.Blue));
         }
 
+        [Test]
+        public void BlendShadedBackground()
+        {
+            var pixel = new Pixel(new PixelForeground(new SimpleSymbol("x"), Colors.Gray), new PixelBackground(Colors.White));
+            var pixel2 = new Pixel(new PixelBackground(PixelBackgroundMode.Shaded));
+            Pixel newPixel = pixel.Blend(pixel2);
+            Assert.True(newPixel.Foreground.Symbol.Text == "x");
+            // foreground should be lighter than original
+            Assert.True(newPixel.Foreground.Color.R < pixel.Foreground.Color.R &&
+                        newPixel.Foreground.Color.G < pixel.Foreground.Color.G &&
+                        newPixel.Foreground.Color.B < pixel.Foreground.Color.B);
+            // background should be darker than original
+            Assert.True(newPixel.Background.Color.R < pixel.Background.Color.R &&
+                        newPixel.Background.Color.G < pixel.Background.Color.G &&
+                        newPixel.Background.Color.B < pixel.Background.Color.B);
+        }
+
+        [Test]
+        public void BlendShadedBackground2()
+        {
+            var pixel = new Pixel(new PixelForeground(new SimpleSymbol("x"), Colors.Gray), new PixelBackground(Colors.Black));
+            var pixel2 = new Pixel(new PixelBackground(PixelBackgroundMode.Shaded));
+            Pixel newPixel = pixel.Blend(pixel2);
+            Assert.True(newPixel.Foreground.Symbol.Text == "x");
+            // foreground should be darker than original
+            Assert.True(newPixel.Foreground.Color.R < pixel.Foreground.Color.R &&
+                        newPixel.Foreground.Color.G < pixel.Foreground.Color.G &&
+                        newPixel.Foreground.Color.B < pixel.Foreground.Color.B);
+            // background should be darker than original
+            Assert.True(newPixel.Background.Color.R > pixel.Background.Color.R &&
+                        newPixel.Background.Color.G > pixel.Background.Color.G &&
+                        newPixel.Background.Color.B > pixel.Background.Color.B);
+        }
+
         [Test]
         public void HashCode()
         {