Resize images to 768x768px in GenerativeAIMultimodalSample (#75)

Examples/GenerativeAISample/GenerativeAIMultimodalSample/ViewModels/PhotoReasoningViewModel.swift

@@ -20,6 +20,10 @@ import SwiftUI
 
 @MainActor
 class PhotoReasoningViewModel: ObservableObject {
+  // Maximum value for the larger of the two image dimensions (height and width) in pixels. This is
+  // being used to reduce the image size in bytes.
+  private static let largestImageDimension = 768.0
+
   private var logger = Logger(subsystem: Bundle.main.bundleIdentifier!, category: "generative-ai")
 
   @Published
@@ -61,7 +65,22 @@ class PhotoReasoningViewModel: ObservableObject {
       var images = [PartsRepresentable]()
       for item in selectedItems {
         if let data = try? await item.loadTransferable(type: Data.self) {
-          images.append(ModelContent.Part.png(data))
+          guard let image = UIImage(data: data) else {
+            logger.error("Failed to parse data as an image, skipping.")
+            continue
+          }
+          if image.size.fits(largestDimension: PhotoReasoningViewModel.largestImageDimension) {
+            images.append(image)
+          } else {
+            guard let resizedImage = image
+              .preparingThumbnail(of: image.size
+                .aspectFit(largestDimension: PhotoReasoningViewModel.largestImageDimension)) else {
+              logger.error("Failed to resize image: \(image)")
+              continue
+            }
+
+            images.append(resizedImage)
+          }
         }
       }
 
@@ -81,3 +100,20 @@ class PhotoReasoningViewModel: ObservableObject {
     }
   }
 }
+
+private extension CGSize {
+  func fits(largestDimension length: CGFloat) -> Bool {
+    return width <= length && height <= length
+  }
+
+  func aspectFit(largestDimension length: CGFloat) -> CGSize {
+    let aspectRatio = width / height
+    if width > height {
+      let width = min(self.width, length)
+      return CGSize(width: width, height: round(width / aspectRatio))
+    } else {
+      let height = min(self.height, length)
+      return CGSize(width: round(height * aspectRatio), height: height)
+    }
+  }
+}