Fix frame enumeration and clean up

src/ImageSharp/Formats/Bmp/BmpEncoderCore.cs

@@ -461,6 +461,7 @@ internal sealed class BmpEncoderCore : IImageEncoderInternals
     private void Write8BitColor<TPixel>(Stream stream, ImageFrame<TPixel> image, Span<byte> colorPalette)
         where TPixel : unmanaged, IPixel<TPixel>
     {
+        // TODO: Should we use the pixel sampling strategy here?
         using IQuantizer<TPixel> frameQuantizer = this.quantizer.CreatePixelSpecificQuantizer<TPixel>(this.configuration);
         using IndexedImageFrame<TPixel> quantized = frameQuantizer.BuildPaletteAndQuantizeFrame(image, image.Bounds());
 

src/ImageSharp/ImageFrameCollection.cs

@@ -180,7 +180,7 @@ public abstract class ImageFrameCollection : IDisposable, IEnumerable<ImageFrame
     }
 
     /// <inheritdoc />
-    public IEnumerator<ImageFrame> GetEnumerator()
+    IEnumerator<ImageFrame> IEnumerable<ImageFrame>.GetEnumerator()
     {
         this.EnsureNotDisposed();
 
@@ -188,7 +188,7 @@ public abstract class ImageFrameCollection : IDisposable, IEnumerable<ImageFrame
     }
 
     /// <inheritdoc/>
-    IEnumerator IEnumerable.GetEnumerator() => this.GetEnumerator();
+    IEnumerator IEnumerable.GetEnumerator() => ((IEnumerable<ImageFrame>)this).GetEnumerator();
 
     /// <summary>
     /// Throws <see cref="ObjectDisposedException"/> if the image frame is disposed.
@@ -208,7 +208,7 @@ public abstract class ImageFrameCollection : IDisposable, IEnumerable<ImageFrame
     protected abstract void Dispose(bool disposing);
 
     /// <summary>
-    /// Implements <see cref="GetEnumerator"/>.
+    /// Implements <see cref="IEnumerable{ImageFrame}.GetEnumerator"/>.
     /// </summary>
     /// <returns>The enumerator.</returns>
     protected abstract IEnumerator<ImageFrame> NonGenericGetEnumerator();

src/ImageSharp/ImageFrameCollection{TPixel}.cs

@@ -168,7 +168,7 @@ public sealed class ImageFrameCollection<TPixel> : ImageFrameCollection, IEnumer
     {
         this.EnsureNotDisposed();
 
-        var frame = ImageFrame.LoadPixelData(
+        ImageFrame<TPixel> frame = ImageFrame.LoadPixelData(
             this.parent.GetConfiguration(),
             source,
             this.RootFrame.Width,
@@ -298,7 +298,7 @@ public sealed class ImageFrameCollection<TPixel> : ImageFrameCollection, IEnumer
     {
         this.EnsureNotDisposed();
 
-        var frame = new ImageFrame<TPixel>(
+        ImageFrame<TPixel> frame = new(
             this.parent.GetConfiguration(),
             this.RootFrame.Width,
             this.RootFrame.Height);
@@ -364,7 +364,7 @@ public sealed class ImageFrameCollection<TPixel> : ImageFrameCollection, IEnumer
     /// </returns>
     public ImageFrame<TPixel> CreateFrame(TPixel backgroundColor)
     {
-        var frame = new ImageFrame<TPixel>(
+        ImageFrame<TPixel> frame = new(
             this.parent.GetConfiguration(),
             this.RootFrame.Width,
             this.RootFrame.Height,
@@ -374,7 +374,7 @@ public sealed class ImageFrameCollection<TPixel> : ImageFrameCollection, IEnumer
     }
 
     /// <inheritdoc/>
-    IEnumerator<ImageFrame<TPixel>> IEnumerable<ImageFrame<TPixel>>.GetEnumerator() => this.frames.GetEnumerator();
+    public IEnumerator<ImageFrame<TPixel>> GetEnumerator() => this.frames.GetEnumerator();
 
     /// <inheritdoc/>
     IEnumerator IEnumerable.GetEnumerator() => ((IEnumerable)this.frames).GetEnumerator();
@@ -408,7 +408,7 @@ public sealed class ImageFrameCollection<TPixel> : ImageFrameCollection, IEnumer
 
     private ImageFrame<TPixel> CopyNonCompatibleFrame(ImageFrame source)
     {
-        var result = new ImageFrame<TPixel>(
+        ImageFrame<TPixel> result = new(
             this.parent.GetConfiguration(),
             source.Size(),
             source.Metadata.DeepClone());

src/ImageSharp/Image{TPixel}.cs

@@ -80,9 +80,7 @@ public sealed class Image<TPixel> : Image
     /// <param name="metadata">The images metadata.</param>
     internal Image(Configuration configuration, int width, int height, ImageMetadata metadata)
         : base(configuration, PixelTypeInfo.Create<TPixel>(), metadata, width, height)
-    {
+        => this.frames = new ImageFrameCollection<TPixel>(this, width, height, default(TPixel));
-        this.frames = new ImageFrameCollection<TPixel>(this, width, height, default(TPixel));
-    }
 
     /// <summary>
     /// Initializes a new instance of the <see cref="Image{TPixel}"/> class
@@ -115,9 +113,7 @@ public sealed class Image<TPixel> : Image
         int height,
         ImageMetadata metadata)
         : base(configuration, PixelTypeInfo.Create<TPixel>(), metadata, width, height)
-    {
+        => this.frames = new ImageFrameCollection<TPixel>(this, width, height, memoryGroup);
-        this.frames = new ImageFrameCollection<TPixel>(this, width, height, memoryGroup);
-    }
 
     /// <summary>
     /// Initializes a new instance of the <see cref="Image{TPixel}"/> class
@@ -135,9 +131,7 @@ public sealed class Image<TPixel> : Image
         TPixel backgroundColor,
         ImageMetadata metadata)
         : base(configuration, PixelTypeInfo.Create<TPixel>(), metadata, width, height)
-    {
+        => this.frames = new ImageFrameCollection<TPixel>(this, width, height, backgroundColor);
-        this.frames = new ImageFrameCollection<TPixel>(this, width, height, backgroundColor);
-    }
 
     /// <summary>
     /// Initializes a new instance of the <see cref="Image{TPixel}" /> class
@@ -148,9 +142,7 @@ public sealed class Image<TPixel> : Image
     /// <param name="frames">The frames that will be owned by this image instance.</param>
     internal Image(Configuration configuration, ImageMetadata metadata, IEnumerable<ImageFrame<TPixel>> frames)
         : base(configuration, PixelTypeInfo.Create<TPixel>(), metadata, ValidateFramesAndGetSize(frames))
-    {
+        => this.frames = new ImageFrameCollection<TPixel>(this, frames);
-        this.frames = new ImageFrameCollection<TPixel>(this, frames);
-    }
 
     /// <inheritdoc />
     protected override ImageFrameCollection NonGenericFrameCollection => this.Frames;
@@ -181,7 +173,7 @@ public sealed class Image<TPixel> : Image
     /// <exception cref="ArgumentOutOfRangeException">Thrown when the provided (x,y) coordinates are outside the image boundary.</exception>
     public TPixel this[int x, int y]
     {
-        [MethodImpl(InliningOptions.ShortMethod)]
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
         get
         {
             this.EnsureNotDisposed();
@@ -190,7 +182,7 @@ public sealed class Image<TPixel> : Image
             return this.PixelSourceUnsafe.PixelBuffer.GetElementUnsafe(x, y);
         }
 
-        [MethodImpl(InliningOptions.ShortMethod)]
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
         set
         {
             this.EnsureNotDisposed();
@@ -212,7 +204,7 @@ public sealed class Image<TPixel> : Image
 
         try
         {
-            var accessor = new PixelAccessor<TPixel>(buffer);
+            PixelAccessor<TPixel> accessor = new(buffer);
             processPixels(accessor);
         }
         finally
@@ -243,8 +235,8 @@ public sealed class Image<TPixel> : Image
 
         try
         {
-            var accessor1 = new PixelAccessor<TPixel>(buffer1);
+            PixelAccessor<TPixel> accessor1 = new(buffer1);
-            var accessor2 = new PixelAccessor<TPixel2>(buffer2);
+            PixelAccessor<TPixel2> accessor2 = new(buffer2);
             processPixels(accessor1, accessor2);
         }
         finally
@@ -283,9 +275,9 @@ public sealed class Image<TPixel> : Image
 
         try
         {
-            var accessor1 = new PixelAccessor<TPixel>(buffer1);
+            PixelAccessor<TPixel> accessor1 = new(buffer1);
-            var accessor2 = new PixelAccessor<TPixel2>(buffer2);
+            PixelAccessor<TPixel2> accessor2 = new(buffer2);
-            var accessor3 = new PixelAccessor<TPixel3>(buffer3);
+            PixelAccessor<TPixel3> accessor3 = new(buffer3);
             processPixels(accessor1, accessor2, accessor3);
         }
         finally
@@ -348,7 +340,7 @@ public sealed class Image<TPixel> : Image
     {
         this.EnsureNotDisposed();
 
-        var clonedFrames = new ImageFrame<TPixel>[this.frames.Count];
+        ImageFrame<TPixel>[] clonedFrames = new ImageFrame<TPixel>[this.frames.Count];
         for (int i = 0; i < clonedFrames.Length; i++)
         {
             clonedFrames[i] = this.frames[i].Clone(configuration);
@@ -367,7 +359,7 @@ public sealed class Image<TPixel> : Image
     {
         this.EnsureNotDisposed();
 
-        var clonedFrames = new ImageFrame<TPixel2>[this.frames.Count];
+        ImageFrame<TPixel2>[] clonedFrames = new ImageFrame<TPixel2>[this.frames.Count];
         for (int i = 0; i < clonedFrames.Length; i++)
         {
             clonedFrames[i] = this.frames[i].CloneAs<TPixel2>(configuration);
@@ -444,7 +436,7 @@ public sealed class Image<TPixel> : Image
         return rootSize;
     }
 
-    [MethodImpl(InliningOptions.ShortMethod)]
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private void VerifyCoords(int x, int y)
     {
         if ((uint)x >= (uint)this.Width)
@@ -458,9 +450,6 @@ public sealed class Image<TPixel> : Image
         }
     }
 
-    [MethodImpl(InliningOptions.ColdPath)]
     private static void ThrowArgumentOutOfRangeException(string paramName)
-    {
+        => throw new ArgumentOutOfRangeException(paramName);
-        throw new ArgumentOutOfRangeException(paramName);
-    }
 }

src/ImageSharp/Processing/Processors/Quantization/DefaultPixelSamplingStrategy.cs

@@ -79,7 +79,7 @@ public class DefaultPixelSamplingStrategy : IPixelSamplingStrategy
 
             r = Math.Max(this.MinimumScanRatio, r); // always visit the minimum defined portion of the image.
 
-            var ratio = new Rational(r);
+            Rational ratio = new(r);
 
             int denom = (int)ratio.Denominator;
             int num = (int)ratio.Numerator;

src/ImageSharp/Processing/Processors/Quantization/QuantizerUtilities.cs

@@ -50,7 +50,7 @@ public static class QuantizerUtilities
         Guard.NotNull(quantizer, nameof(quantizer));
         Guard.NotNull(source, nameof(source));
 
-        var interest = Rectangle.Intersect(source.Bounds(), bounds);
+        Rectangle interest = Rectangle.Intersect(source.Bounds(), bounds);
         Buffer2DRegion<TPixel> region = source.PixelBuffer.GetRegion(interest);
 
         // Collect the palette. Required before the second pass runs.
@@ -77,9 +77,9 @@ public static class QuantizerUtilities
         where TPixel : unmanaged, IPixel<TPixel>
     {
         Guard.NotNull(source, nameof(source));
-        var interest = Rectangle.Intersect(source.Bounds(), bounds);
+        Rectangle interest = Rectangle.Intersect(source.Bounds(), bounds);
 
-        var destination = new IndexedImageFrame<TPixel>(
+        IndexedImageFrame<TPixel> destination = new(
             quantizer.Configuration,
             interest.Width,
             interest.Height,