Fixed RowIndexer on sub-images and added tests for that case

HPPH.Test/Image/ImageTest.cs

@@ -117,6 +117,25 @@ public class ImageTest
         }
     }
 
+    [TestMethod]
+    public void ImageRowIndexerSubImage()
+    {
+        (int width, int height) = SIZES[0];
+
+        IImage image = TestDataHelper.CreateTestImage<ColorARGB>(width, height);
+        image = image[163, 280, 720, 13];
+
+        Assert.AreEqual(image.Height, image.Rows.Count);
+
+        for (int y = 0; y < image.Height; y++)
+        {
+            IImageRow row = image.Rows[y];
+            Assert.AreEqual(image.Width, row.Length);
+            for (int x = 0; x < row.Length; x++)
+                Assert.AreEqual(TestDataHelper.GetColorFromLocation<ColorARGB>(163 + x, 280 + y), row[x]);
+        }
+    }
+
     [TestMethod]
     public void ImageRowEnumerator()
     {
@@ -154,6 +173,25 @@ public class ImageTest
         }
     }
 
+    [TestMethod]
+    public void ImageColumnIndexerSubImage()
+    {
+        (int width, int height) = SIZES[0];
+
+        IImage image = TestDataHelper.CreateTestImage<ColorARGB>(width, height);
+        image = image[163, 280, 720, 13];
+
+        Assert.AreEqual(image.Width, image.Columns.Count);
+
+        for (int x = 0; x < image.Width; x++)
+        {
+            IImageColumn column = image.Columns[x];
+            Assert.AreEqual(image.Height, column.Length);
+            for (int y = 0; y < column.Length; y++)
+                Assert.AreEqual(TestDataHelper.GetColorFromLocation<ColorARGB>(163 + x, 280 + y), column[y]);
+        }
+    }
+
     [TestMethod]
     public void ImageColumnEnumerator()
     {

HPPH.Test/Image/RefImageTest.cs

@@ -118,6 +118,25 @@ public class RefImageTest
         }
     }
 
+    [TestMethod]
+    public void ImageRowIndexerSubImage()
+    {
+        (int width, int height) = SIZES[0];
+
+        RefImage<ColorARGB> image = TestDataHelper.CreateTestImage<ColorARGB>(width, height).AsRefImage();
+        image = image[163, 280, 720, 13];
+
+        Assert.AreEqual(image.Height, image.Rows.Count);
+
+        for (int y = 0; y < image.Height; y++)
+        {
+            ImageRow<ColorARGB> row = image.Rows[y];
+            Assert.AreEqual(image.Width, row.Length);
+            for (int x = 0; x < row.Length; x++)
+                Assert.AreEqual(TestDataHelper.GetColorFromLocation<ColorARGB>(163 + x, 280 + y), row[x]);
+        }
+    }
+
     [TestMethod]
     public void ImageRowEnumerator()
     {
@@ -155,6 +174,25 @@ public class RefImageTest
         }
     }
 
+    [TestMethod]
+    public void ImageColumnIndexerSubImage()
+    {
+        (int width, int height) = SIZES[0];
+
+        RefImage<ColorARGB> image = TestDataHelper.CreateTestImage<ColorARGB>(width, height).AsRefImage();
+        image = image[163, 280, 720, 13];
+
+        Assert.AreEqual(image.Width, image.Columns.Count);
+
+        for (int x = 0; x < image.Width; x++)
+        {
+            ImageColumn<ColorARGB> column = image.Columns[x];
+            Assert.AreEqual(image.Height, column.Length);
+            for (int y = 0; y < column.Length; y++)
+                Assert.AreEqual(TestDataHelper.GetColorFromLocation<ColorARGB>(163 + x, 280 + y), column[y]);
+        }
+    }
+
     [TestMethod]
     public void ImageColumnEnumerator()
     {

HPPH/Images/ImageRows.cs

@@ -15,6 +15,7 @@ public readonly ref struct ImageRows<T>
     private readonly int _width;
     private readonly int _height;
     private readonly int _stride;
+    private readonly int _bpp;
 
     public int Count => _height;
 
@@ -29,7 +30,7 @@ public readonly ref struct ImageRows<T>
         {
             if ((row < 0) || (row >= _height)) throw new IndexOutOfRangeException();
 
-            return new ImageRow<T>(_data, ((row + _y) * _stride) + _x, _width);
+            return new ImageRow<T>(_data, ((row + _y) * _stride) + (_x * _bpp), _width);
         }
     }
 
@@ -46,6 +47,8 @@ public readonly ref struct ImageRows<T>
         this._width = width;
         this._height = height;
         this._stride = stride;
+
+        _bpp = T.ColorFormat.BytesPerPixel;
     }
 
     #endregion
@@ -110,6 +113,7 @@ internal class IColorImageRows<T> : IImageRows
     private readonly int _width;
     private readonly int _height;
     private readonly int _stride;
+    private readonly int _bpp;
 
     /// <inheritdoc />
     public int Count => _height;
@@ -126,7 +130,7 @@ internal class IColorImageRows<T> : IImageRows
         {
             if ((row < 0) || (row >= _height)) throw new IndexOutOfRangeException();
 
-            return new IColorImageRow<T>(_data, ((row + _y) * _stride) + _x, _width);
+            return new IColorImageRow<T>(_data, ((row + _y) * _stride) + (_x * _bpp), _width);
         }
     }
 
@@ -143,6 +147,8 @@ internal class IColorImageRows<T> : IImageRows
         this._width = width;
         this._height = height;
         this._stride = stride;
+
+        _bpp = T.ColorFormat.BytesPerPixel;
     }
 
     #endregion