[Vertex AI] Add documentation for Imagen symbols

FirebaseVertexAI/Sources/Types/Public/Imagen/ImagenAspectRatio.swift

@@ -14,16 +14,45 @@
 
 import Foundation
 
+/// An aspect ratio for images generated by Imagen.
+///
+/// To specify an aspect ratio for generated images, set ``ImagenGenerationConfig/aspectRatio`` in
+/// your ``ImagenGenerationConfig``. See the [Cloud
+/// documentation](https://cloud.google.com/vertex-ai/generative-ai/docs/image/generate-images#aspect-ratio)
+/// for more details and examples of the supported aspect ratios.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public struct ImagenAspectRatio {
+  /// Square (1:1) aspect ratio.
+  ///
+  /// Common uses for this aspect ratio include social media posts.
   public static let square1x1 = ImagenAspectRatio(kind: .square1x1)
 
+  /// Portrait widescreen (9:16) aspect ratio.
+  ///
+  /// This is the ``landscape16x9`` aspect ratio rotated 90 degrees. This a relatively new aspect
+  /// ratio that has been popularized by short form video apps (for example, YouTube shorts). Use
+  /// this for tall objects with strong vertical orientations such as buildings, trees, waterfalls,
+  /// or other similar objects.
   public static let portrait9x16 = ImagenAspectRatio(kind: .portrait9x16)
 
+  /// Widescreen (16:9) aspect ratio.
+  ///
+  /// This ratio has replaced ``landscape4x3`` as the most common aspect ratio for TVs, monitors,
+  /// and mobile phone screens (landscape). Use this aspect ratio when you want to capture more of
+  /// the background (for example, scenic landscapes).
   public static let landscape16x9 = ImagenAspectRatio(kind: .landscape16x9)
 
+  /// Portrait full screen (3:4) aspect ratio.
+  ///
+  /// This is the ``landscape4x3`` aspect ratio rotated 90 degrees. This lets to capture more of
+  /// the scene vertically compared to the ``square1x1`` aspect ratio.
   public static let portrait3x4 = ImagenAspectRatio(kind: .portrait3x4)
 
+  /// Fullscreen (4:3) aspect ratio.
+  ///
+  /// This aspect ratio is commonly used in media or film. It is also the dimensions of most old
+  /// (non-widescreen) TVs and medium format cameras. It captures more of the scene horizontally
+  /// (compared to ``square1x1``), making it a preferred aspect ratio for photography.
   public static let landscape4x3 = ImagenAspectRatio(kind: .landscape4x3)
 
   let rawValue: String

FirebaseVertexAI/Sources/Types/Public/Imagen/ImagenGCSImage.swift

@@ -14,9 +14,18 @@
 
 import Foundation
 
+/// An image generated by Imagen, stored in Cloud Storage (GCS) for Firebase.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public struct ImagenGCSImage {
+  /// The IANA standard MIME type of the image file; either `"image/png"` or `"image/jpeg"`.
+  ///
+  /// > Note: To request a different format, set ``ImagenGenerationConfig/imageFormat`` in
+  ///   your ``ImagenGenerationConfig``.
   public let mimeType: String
+
+  /// The URI of the file in Cloud Storage (GCS) for Firebase.
+  ///
+  /// This is a `"gs://"`-prefixed URI , for example, `"gs://bucket-name/path/sample_0.jpg"`.
   public let gcsURI: String
 
   init(mimeType: String, gcsURI: String) {

FirebaseVertexAI/Sources/Types/Public/Imagen/ImagenGenerationConfig.swift

@@ -12,14 +12,60 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+/// Configuration options for generating images with Imagen.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public struct ImagenGenerationConfig {
+  /// Specifies elements to exclude from the generated image.
+  ///
+  /// Defaults to `nil`, which disables negative prompting. Use a comma-separated list to describe
+  /// unwanted elements or characteristics. See the [Cloud
+  /// documentation](https://cloud.google.com/vertex-ai/generative-ai/docs/image/generate-images#negative-prompt)
+  /// for more details.
+  ///
+  /// > Important: Support for negative prompts depends on the Imagen model.
   public var negativePrompt: String?
+
+  /// The number of image samples to generate; defaults to 1 if not specified.
+  ///
+  /// > Important: The number of sample images that may be generated in each request depends on the
+  ///   model (typically up to 4); see the
+  ///   [`sampleCount`](https://cloud.google.com/vertex-ai/generative-ai/docs/model-reference/imagen-api#parameter_list)
+  ///   documentation for more details.
   public var numberOfImages: Int?
+
+  /// The aspect ratio of generated images.
+  ///
+  /// Defaults to to square, 1:1. Supported aspect ratios depend on the model; see
+  /// ``ImagenAspectRatio`` for more details.
   public var aspectRatio: ImagenAspectRatio?
+
+  /// The image format of generated images.
+  ///
+  /// Defaults to PNG. See ``ImagenImageFormat`` for more details.
   public var imageFormat: ImagenImageFormat?
+
+  /// Whether to add an invisible watermark to generated images.
+  ///
+  /// If `true`, an invisible SynthID watermark is embedded in generated images to indicate that
+  /// they are AI generated; `false` disables watermarking.
+  ///
+  /// > Important: The default value depends on the model; see the
+  ///   [`addWatermark`](https://cloud.google.com/vertex-ai/generative-ai/docs/model-reference/imagen-api#parameter_list)
+  ///   documentation for model-specific details.
   public var addWatermark: Bool?
 
+  /// Initializes configuration options for generating images with Imagen.
+  ///
+  /// - Parameters:
+  ///   - negativePrompt: Specifies elements to exclude from the generated image; disabled if not
+  ///     specified. See ``negativePrompt``.
+  ///   - numberOfImages: The number of image samples to generate; defaults to 1 if not specified.
+  ///     See ``numberOfImages``.
+  ///   - aspectRatio: The aspect ratio of generated images; defaults to to square, 1:1. See
+  ///     ``aspectRatio``.
+  ///   - imageFormat: The image format of generated images; defaults to PNG. See ``imageFormat``.
+  ///   - addWatermark: Whether to add an invisible watermark to generated images; the default value
+  ///     depends on the model. See ``addWatermark``.
   public init(negativePrompt: String? = nil, numberOfImages: Int? = nil,
               aspectRatio: ImagenAspectRatio? = nil, imageFormat: ImagenImageFormat? = nil,
               addWatermark: Bool? = nil) {

FirebaseVertexAI/Sources/Types/Public/Imagen/ImagenGenerationResponse.swift

@@ -14,9 +14,29 @@
 
 import Foundation
 
+/// A response from a request to generate images with Imagen.
+///
+/// The type placeholder `T` is an image type of either ``ImagenInlineImage`` or ``ImagenGCSImage``.
+///
+/// This type is returned from:
+///   - ``ImagenModel/generateImages(prompt:)`` where `T` is ``ImagenInlineImage``
+///   - ``ImagenModel/generateImages(prompt:gcsURI:)`` where `T` is ``ImagenGCSImage``
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public struct ImagenGenerationResponse<T> {
+  /// The images generated by Imagen; see ``ImagenInlineImage`` and ``ImagenGCSImage``.
+  ///
+  /// > Important: The number of images generated may be fewer than the number requested if one or
+  ///   more were filtered out; see ``filteredReason``.
   public let images: [T]
+
+  /// The reason, if any, that generated images were filtered out.
+  ///
+  /// This property will only be populated if fewer images were generated than were requested,
+  /// otherwise it will be `nil`. Images may be filtered out due to the ``ImagenSafetyFilterLevel``,
+  /// the ``ImagenPersonFilterLevel``, or filtering included in the model. The filter levels may be
+  /// adjusted in your ``ImagenSafetySettings``. See the [Responsible AI and usage guidelines for
+  /// Imagen](https://cloud.google.com/vertex-ai/generative-ai/docs/image/responsible-ai-imagen)
+  /// for more details.
   public let filteredReason: String?
 }
 

FirebaseVertexAI/Sources/Types/Public/Imagen/ImagenImageFormat.swift

@@ -14,15 +14,36 @@
 
 import Foundation
 
+/// An image format for images generated by Imagen.
+///
+/// To specify an image format for generated images, set ``ImagenGenerationConfig/imageFormat`` in
+/// your ``ImagenGenerationConfig``. See the [Cloud
+/// documentation](https://cloud.google.com/vertex-ai/generative-ai/docs/model-reference/imagen-api#output-options)
+/// for more details.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public struct ImagenImageFormat {
   let mimeType: String
   let compressionQuality: Int?
 
+  /// PNG image format.
+  ///
+  /// Portable Network Graphic (PNG) is a lossless image format, meaning no image data is lost
+  /// during compression. Images in PNG format are *typically* larger than JPEG images, though this
+  /// depends on the image content and JPEG compression quality.
   public static func png() -> ImagenImageFormat {
     return ImagenImageFormat(mimeType: "image/png", compressionQuality: nil)
   }
 
+  /// JPEG image format.
+  ///
+  /// Joint Photographic Experts Group (JPEG) is a lossy compression format, meaning some image data
+  /// is discarded during compression. Images in JPEG format are *typically* larger than PNG images,
+  /// though this depends on the image content and JPEG compression quality.
+  ///
+  /// - Parameters:
+  ///   - compressionQuality: The JPEG quality setting from 0 to 100, where `0` is highest level of
+  ///     compression (lowest image quality, smallest file size) and `100` is the lowest level of
+  ///     compression (highest image quality, largest file size); defaults to `75`.
   public static func jpeg(compressionQuality: Int? = nil) -> ImagenImageFormat {
     return ImagenImageFormat(mimeType: "image/jpeg", compressionQuality: compressionQuality)
   }

FirebaseVertexAI/Sources/Types/Public/Imagen/ImagenInlineImage.swift

@@ -14,9 +14,16 @@
 
 import Foundation
 
+/// An image generated by Imagen, represented as inline data.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public struct ImagenInlineImage {
+  /// The IANA standard MIME type of the image file; either `"image/png"` or `"image/jpeg"`.
+  ///
+  /// > Note: To request a different format, set ``ImagenGenerationConfig/imageFormat`` in
+  ///   your ``ImagenGenerationConfig``.
   public let mimeType: String
+
+  /// The image data in PNG or JPEG format.
   public let data: Data
 
   init(mimeType: String, bytesBase64Encoded: String) {

FirebaseVertexAI/Sources/Types/Public/Imagen/ImagenModel.swift

@@ -16,6 +16,15 @@ import FirebaseAppCheckInterop
 import FirebaseAuthInterop
 import Foundation
 
+/// Represents a remote Imagen model with the ability to generate images using text prompts.
+///
+/// See the [Cloud
+/// documentation](https://cloud.google.com/vertex-ai/generative-ai/docs/image/generate-images) for
+/// more details about the image generation capabilities offered by the Imagen model.
+///
+/// > Warning: For Vertex AI in Firebase, image generation using Imagen 3 models is in Public
+/// Preview, which means that the feature is not subject to any SLA or deprecation policy and
+/// could change in backwards-incompatible ways.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public final class ImagenModel {
   /// The resource name of the model in the backend; has the format "models/model-name".
@@ -53,6 +62,20 @@ public final class ImagenModel {
     self.requestOptions = requestOptions
   }
 
+  /// **[Public Preview]** Generates images using the Imagen model and returns them as inline data.
+  ///
+  /// The individual ``ImagenInlineImage/data`` is provided for each of the generated
+  /// ``ImagenGenerationResponse/images``.
+  ///
+  /// > Note: By default, 1 image sample is generated; see ``ImagenGenerationConfig/numberOfImages``
+  /// to configure the number of images that are generated.
+  ///
+  /// > Warning: For Vertex AI in Firebase, image generation using Imagen 3 models is in Public
+  /// Preview, which means that the feature is not subject to any SLA or deprecation policy and
+  /// could change in backwards-incompatible ways.
+  ///
+  /// - Parameters:
+  ///   - prompt: A text prompt describing the image(s) to generate.
   public func generateImages(prompt: String) async throws
     -> ImagenGenerationResponse<ImagenInlineImage> {
     return try await generateImages(
@@ -65,12 +88,34 @@ public final class ImagenModel {
     )
   }
 
-  public func generateImages(prompt: String, gcsUri: String) async throws
+  /// **[Public Preview]** Generates images using the Imagen model and stores them in Cloud Storage
+  /// (GCS) for Firebase.
+  ///
+  /// The generated images are stored in a subdirectory of the requested `gcsURI`, named as a random
+  /// numeric hash. For example, for the `gcsURI` `"gs://bucket-name/path/"`, the generated images
+  /// are stored in `"gs://bucket-name/path/1234567890123/"` with the names `sample_0.png`,
+  /// `sample_1.png`, `sample_2.png`, ..., `sample_N.png`. In this example, `1234567890123` is the
+  /// hash value and `N` is the number of images that were generated, up to the number requested in
+  /// ``ImagenGenerationConfig/numberOfImages``. The individual ``ImagenGCSImage/gcsURI`` is
+  /// provided for each of the generated ``ImagenGenerationResponse/images``.
+  ///
+  /// > Note: By default, 1 image sample is generated; see ``ImagenGenerationConfig/numberOfImages``
+  /// to configure the number of images that are generated.
+  ///
+  /// > Warning: For Vertex AI in Firebase, image generation using Imagen 3 models is in Public
+  /// Preview, which means that the feature is not subject to any SLA or deprecation policy and
+  /// could change in backwards-incompatible ways.
+  ///
+  /// - Parameters:
+  ///   - prompt: A text prompt describing the image(s) to generate.
+  ///   - gcsURI: The Cloud Storage (GCS) for Firebase URI where the generated images are stored.
+  ///     This is a `"gs://"`-prefixed URI , for example, `"gs://bucket-name/path/"`.
+  public func generateImages(prompt: String, gcsURI: String) async throws
     -> ImagenGenerationResponse<ImagenGCSImage> {
     return try await generateImages(
       prompt: prompt,
       parameters: ImagenModel.imageGenerationParameters(
-        storageURI: gcsUri,
+        storageURI: gcsURI,
         generationConfig: generationConfig,
         safetySettings: safetySettings
       )

FirebaseVertexAI/Sources/Types/Public/Imagen/ImagenPersonFilterLevel.swift

@@ -12,6 +12,11 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+/// A filter level controlling whether generation of images containing people or faces is allowed.
+///
+/// See the
+/// [`personGeneration`](https://cloud.google.com/vertex-ai/generative-ai/docs/model-reference/imagen-api#parameter_list)
+/// documentation for more details.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public struct ImagenPersonFilterLevel: ProtoEnum {
   enum Kind: String {
@@ -20,8 +25,23 @@ public struct ImagenPersonFilterLevel: ProtoEnum {
     case allowAll = "allow_all"
   }
 
+  /// Disallow generation of images containing people or faces; images of people are filtered out.
   public static let blockAll = ImagenPersonFilterLevel(kind: .blockAll)
+
+  /// Allow generation of images containing adults only; images of children are filtered out.
+  ///
+  /// > Important: Generation of images containing people or faces may require your use case to be
+  /// reviewed and approved by Cloud support; see the [Responsible AI and usage
+  /// guidelines](https://cloud.google.com/vertex-ai/generative-ai/docs/image/responsible-ai-imagen#person-face-gen)
+  /// for more details.
   public static let allowAdult = ImagenPersonFilterLevel(kind: .allowAdult)
+
+  /// Allow generation of images containing people of all ages.
+  ///
+  /// > Important: Generation of images containing people or faces may require your use case to be
+  /// reviewed and approved; see the [Responsible AI and usage
+  /// guidelines](https://cloud.google.com/vertex-ai/generative-ai/docs/image/responsible-ai-imagen#person-face-gen)
+  /// for more details.
   public static let allowAll = ImagenPersonFilterLevel(kind: .allowAll)
 
   let rawValue: String

FirebaseVertexAI/Sources/Types/Public/Imagen/ImagenSafetyFilterLevel.swift

@@ -12,6 +12,16 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+/// A filter level controlling how aggressively to filter sensitive content.
+///
+/// Text prompts provided as inputs and images (generated or uploaded) through Imagen on Vertex AI
+/// are assessed against a list of safety filters, which include 'harmful categories' (for example,
+/// `violence`, `sexual`, `derogatory`, and `toxic`). This filter level controls how aggressively to
+/// filter out potentially harmful content from responses. See the
+/// [`safetySetting`](https://cloud.google.com/vertex-ai/generative-ai/docs/model-reference/imagen-api#parameter_list)
+/// documentation and the [Responsible AI and usage
+/// guidelines](https://cloud.google.com/vertex-ai/generative-ai/docs/image/responsible-ai-imagen#safety-filters)
+/// for more details.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public struct ImagenSafetyFilterLevel: ProtoEnum {
   enum Kind: String {
@@ -21,9 +31,21 @@ public struct ImagenSafetyFilterLevel: ProtoEnum {
     case blockNone = "block_none"
   }
 
+  /// The most aggressive filtering level; most strict blocking.
   public static let blockLowAndAbove = ImagenSafetyFilterLevel(kind: .blockLowAndAbove)
+
+  /// Blocks some problematic prompts and responses.
   public static let blockMediumAndAbove = ImagenSafetyFilterLevel(kind: .blockMediumAndAbove)
+
+  /// Reduces the number of requests blocked due to safety filters.
+  ///
+  /// > Important: This may increase objectionable content generated by Imagen.
   public static let blockOnlyHigh = ImagenSafetyFilterLevel(kind: .blockOnlyHigh)
+
+  /// The least aggressive filtering level; blocks very few problematic prompts and responses.
+  ///
+  /// > Important: Access to this feature is restricted and may require your use case to be reviewed
+  /// and approved by Cloud support.
   public static let blockNone = ImagenSafetyFilterLevel(kind: .blockNone)
 
   let rawValue: String

FirebaseVertexAI/Sources/Types/Public/Imagen/ImagenSafetySettings.swift

@@ -14,11 +14,23 @@
 
 import Foundation
 
+/// Settings for controlling the aggressiveness of filtering out sensitive content.
+///
+/// See the [Responsible AI and usage
+/// guidelines](https://cloud.google.com/vertex-ai/generative-ai/docs/image/responsible-ai-imagen#config-safety-filters)
+/// for more details.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public struct ImagenSafetySettings {
   let safetyFilterLevel: ImagenSafetyFilterLevel?
   let personFilterLevel: ImagenPersonFilterLevel?
 
+  /// Initializes safety settings for the Imagen model.
+  ///
+  /// - Parameters:
+  ///   - safetyFilterLevel: A filter level controlling how aggressively to filter out sensitive
+  ///   content from generated images.
+  ///   - personFilterLevel: A filter level controlling whether generation of images containing
+  ///   people or faces is allowed.
   public init(safetyFilterLevel: ImagenSafetyFilterLevel? = nil,
               personFilterLevel: ImagenPersonFilterLevel? = nil) {
     self.safetyFilterLevel = safetyFilterLevel