feat: add support for image generation using gpt-image-1 (#971)

* feat: add gpt-image-1 support

* feat: add example to generate image using gpt-image-1 model

* style: missing period in comments

* feat: add missing fields to example

* docs: add GPT Image 1 to README

* revert: keep `examples/images/main.go` unchanged

* docs: remove unnecessary newline from example in README file

image.go

@@ -13,51 +13,101 @@ const (
 	CreateImageSize256x256   = "256x256"
 	CreateImageSize512x512   = "512x512"
 	CreateImageSize1024x1024 = "1024x1024"
+
 	// dall-e-3 supported only.
 	CreateImageSize1792x1024 = "1792x1024"
 	CreateImageSize1024x1792 = "1024x1792"
+
+	// gpt-image-1 supported only.
+	CreateImageSize1536x1024 = "1536x1024" // Landscape
+	CreateImageSize1024x1536 = "1024x1536" // Portrait
 )
 
 const (
-	CreateImageResponseFormatURL     = "url"
+	// dall-e-2 and dall-e-3 only.
 	CreateImageResponseFormatB64JSON = "b64_json"
+	CreateImageResponseFormatURL     = "url"
 )
 
 const (
-	CreateImageModelDallE2 = "dall-e-2"
-	CreateImageModelDallE3 = "dall-e-3"
+	CreateImageModelDallE2    = "dall-e-2"
+	CreateImageModelDallE3    = "dall-e-3"
+	CreateImageModelGptImage1 = "gpt-image-1"
 )
 
 const (
 	CreateImageQualityHD       = "hd"
 	CreateImageQualityStandard = "standard"
+
+	// gpt-image-1 only.
+	CreateImageQualityHigh   = "high"
+	CreateImageQualityMedium = "medium"
+	CreateImageQualityLow    = "low"
 )
 
 const (
+	// dall-e-3 only.
 	CreateImageStyleVivid   = "vivid"
 	CreateImageStyleNatural = "natural"
 )
 
+const (
+	// gpt-image-1 only.
+	CreateImageBackgroundTransparent = "transparent"
+	CreateImageBackgroundOpaque      = "opaque"
+)
+
+const (
+	// gpt-image-1 only.
+	CreateImageModerationLow = "low"
+)
+
+const (
+	// gpt-image-1 only.
+	CreateImageOutputFormatPNG  = "png"
+	CreateImageOutputFormatJPEG = "jpeg"
+	CreateImageOutputFormatWEBP = "webp"
+)
+
 // ImageRequest represents the request structure for the image API.
 type ImageRequest struct {
-	Prompt         string `json:"prompt,omitempty"`
-	Model          string `json:"model,omitempty"`
-	N              int    `json:"n,omitempty"`
-	Quality        string `json:"quality,omitempty"`
-	Size           string `json:"size,omitempty"`
-	Style          string `json:"style,omitempty"`
-	ResponseFormat string `json:"response_format,omitempty"`
-	User           string `json:"user,omitempty"`
+	Prompt            string `json:"prompt,omitempty"`
+	Model             string `json:"model,omitempty"`
+	N                 int    `json:"n,omitempty"`
+	Quality           string `json:"quality,omitempty"`
+	Size              string `json:"size,omitempty"`
+	Style             string `json:"style,omitempty"`
+	ResponseFormat    string `json:"response_format,omitempty"`
+	User              string `json:"user,omitempty"`
+	Background        string `json:"background,omitempty"`
+	Moderation        string `json:"moderation,omitempty"`
+	OutputCompression int    `json:"output_compression,omitempty"`
+	OutputFormat      string `json:"output_format,omitempty"`
 }
 
 // ImageResponse represents a response structure for image API.
 type ImageResponse struct {
 	Created int64                    `json:"created,omitempty"`
 	Data    []ImageResponseDataInner `json:"data,omitempty"`
+	Usage   ImageResponseUsage       `json:"usage,omitempty"`
 
 	httpHeader
 }
 
+// ImageResponseInputTokensDetails represents the token breakdown for input tokens.
+type ImageResponseInputTokensDetails struct {
+	TextTokens  int `json:"text_tokens,omitempty"`
+	ImageTokens int `json:"image_tokens,omitempty"`
+}
+
+// ImageResponseUsage represents the token usage information for image API.
+type ImageResponseUsage struct {
+	TotalTokens        int                             `json:"total_tokens,omitempty"`
+	InputTokens        int                             `json:"input_tokens,omitempty"`
+	OutputTokens       int                             `json:"output_tokens,omitempty"`
+	InputTokensDetails ImageResponseInputTokensDetails `json:"input_tokens_details,omitempty"`
+}
+
 // ImageResponseDataInner represents a response data structure for image API.
 type ImageResponseDataInner struct {
 	URL           string `json:"url,omitempty"`
@@ -91,6 +141,8 @@ type ImageEditRequest struct {
 	N              int      `json:"n,omitempty"`
 	Size           string   `json:"size,omitempty"`
 	ResponseFormat string   `json:"response_format,omitempty"`
+	Quality        string   `json:"quality,omitempty"`
+	User           string   `json:"user,omitempty"`
 }
 
 // CreateEditImage - API call to create an image. This is the main endpoint of the DALL-E API.
@@ -159,6 +211,7 @@ type ImageVariRequest struct {
 	N              int      `json:"n,omitempty"`
 	Size           string   `json:"size,omitempty"`
 	ResponseFormat string   `json:"response_format,omitempty"`
+	User           string   `json:"user,omitempty"`
 }
 
 // CreateVariImage - API call to create an image variation. This is the main endpoint of the DALL-E API.