feat: add Image Serialization Plugin

Author: mackoj

Sources/SnapshotTesting/Plugins/ImageSerializer.swift

@@ -0,0 +1,99 @@
+#if canImport(SwiftUI)
+import Foundation
+import ImageSerializationPlugin
+
+#if canImport(UIKit)
+import UIKit
+#elseif canImport(AppKit)
+import AppKit
+#endif
+
+/// A class responsible for encoding and decoding images using various image serialization plugins.
+///
+/// The `ImageSerializer` class leverages plugins that conform to the `ImageSerialization` protocol to encode and decode images in different formats.
+/// It automatically retrieves all available image serialization plugins from the `PluginRegistry` and uses them based on the specified `ImageSerializationFormat`.
+/// If no plugin is found for the requested format, it defaults to using PNG encoding/decoding.
+public class ImageSerializer {
+  
+  /// A collection of plugins that conform to the `ImageSerialization` protocol.
+  let plugins: [ImageSerialization]
+  
+  public init() {
+    self.plugins = PluginRegistry.allPlugins()
+  }
+
+  // TODO: async throws will be added later
+  /// Encodes a given image into the specified image format using the appropriate plugin.
+  ///
+  /// This method attempts to encode the provided `SnapImage` into the desired format using the first plugin that supports the specified `ImageSerializationFormat`.
+  /// If no plugin is found for the format, it defaults to encoding the image as PNG.
+  ///
+  /// - Parameters:
+  ///   - image: The `SnapImage` to encode.
+  ///   - imageFormat: The format in which to encode the image.
+  /// - Returns: The encoded image data, or `nil` if encoding fails.
+  public func encodeImage(_ image: SnapImage, imageFormat: ImageSerializationFormat) /*async throws*/ -> Data? {
+    for plugin in self.plugins  {
+      if type(of: plugin).imageFormat == imageFormat {
+        return plugin.encodeImage(image)
+      }
+    }
+    // Default to PNG
+    return encodePNG(image)
+  }
+  
+  // TODO: async throws will be added later
+  /// Decodes image data into a `SnapImage` using the appropriate plugin based on the specified image format.
+  ///
+  /// This method attempts to decode the provided data into a `SnapImage` using the first plugin that supports the specified `ImageSerializationFormat`.
+  /// If no plugin is found for the format, it defaults to decoding the data as PNG.
+  ///
+  /// - Parameters:
+  ///   - data: The image data to decode.
+  ///   - imageFormat: The format in which the image data is encoded.
+  /// - Returns: The decoded `SnapImage`, or `nil` if decoding fails.
+  public func decodeImage(_ data: Data, imageFormat: ImageSerializationFormat) /*async throws*/ -> SnapImage? {
+    for plugin in self.plugins {
+      if type(of: plugin).imageFormat == imageFormat {
+        return plugin.decodeImage(data)
+      }
+    }
+    // Default to PNG
+    return decodePNG(data)
+  }
+  
+  // MARK: - Actual default Image Serializer
+  
+  /// Encodes a `SnapImage` as PNG data.
+  ///
+  /// This method provides a default implementation for encoding images as PNG. It is used as a fallback if no suitable plugin is found for the requested format.
+  ///
+  /// - Parameter image: The `SnapImage` to encode.
+  /// - Returns: The encoded PNG data, or `nil` if encoding fails.
+  private func encodePNG(_ image: SnapImage) -> Data? {
+#if canImport(UIKit)
+    return image.pngData()
+#elseif canImport(AppKit)
+    guard let cgImage = image.cgImage(forProposedRect: nil, context: nil, hints: nil) else {
+      return nil
+    }
+    let bitmapRep = NSBitmapImageRep(cgImage: cgImage)
+    return bitmapRep.representation(using: .png, properties: [:])
+#endif
+  }
+  
+  /// Decodes PNG data into a `SnapImage`.
+  ///
+  /// This method provides a default implementation for decoding PNG data into a `SnapImage`. It is used as a fallback if no suitable plugin is found for the requested format.
+  ///
+  /// - Parameter data: The PNG data to decode.
+  /// - Returns: The decoded `SnapImage`, or `nil` if decoding fails.
+  private func decodePNG(_ data: Data) -> SnapImage? {
+#if canImport(UIKit)
+    return UIImage(data: data)
+#elseif canImport(AppKit)
+    return NSImage(data: data)
+#endif
+  }
+}
+#endif