Gemini API 画像編集サンプル

GeminiEdit.cs

using System.Text;
using System.Text.Json;

public class GoogleAI
{
    private readonly string _apiKey;

    public GoogleAI(string apiKey)
    {
        _apiKey = apiKey;
    }

    public async Task<string> GenerateContentObject(string contentText, string base64Image, string mimeType, string modelName)
    {
        var url = $"https://generativelanguage.googleapis.com/v1beta/models/{modelName}:generateContent?key={_apiKey}";

        var requestJson = new
        {
            contents = new object[]
            {
                new
                {
                    parts = new object[]
                    {
                        new { text = contentText },
                        new
                        {
                            inlineData = new
                            {
                                mimeType = mimeType,
                                data = base64Image
                            }
                        }
                    }
                }
            }
        };

        var jsonString = JsonSerializer.Serialize(requestJson);
        var stringContent = new StringContent(jsonString, Encoding.UTF8, "application/json");

        using var httpClient = new HttpClient();
        var response = await httpClient.PostAsync(url, stringContent);
        response.EnsureSuccessStatusCode();

        return await response.Content.ReadAsStringAsync();
    }

    private const string ApiKey = "YOUR-API-KEY";
    private const string ModelName = "gemini-2.0-flash-exp";

    static async Task Main(string[] args)
    {
        if (string.IsNullOrEmpty(ApiKey))
        {
            Console.WriteLine("APIキーが設定されていません。");
            return;
        }

        Console.Write("画像ファイルのパスを入力してください:");
        var imgPath = Console.ReadLine();
        var mimeType = MimeTypes.GetMimeType(Path.GetExtension(imgPath));

        Console.Write("編集内容を入力してください:");
        var prompt = Console.ReadLine();

        try
        {
            var base64Image = Convert.ToBase64String(File.ReadAllBytes(imgPath));

            var genAi = new GoogleAI(ApiKey);
            var responseString = await genAi.GenerateContentObject(prompt, base64Image, mimeType, ModelName);
            Console.WriteLine("\n応答: " + responseString);

            // 画像データを処理
            using JsonDocument doc = JsonDocument.Parse(responseString);
            if (doc.RootElement.TryGetProperty("candidates", out JsonElement candidates) && candidates.GetArrayLength() > 0)
            {
                foreach (JsonElement candidate in candidates.EnumerateArray())
                {
                    if (candidate.TryGetProperty("content", out JsonElement content))
                    {
                        foreach (JsonElement part in content.GetProperty("parts").EnumerateArray())
                        {
                            if (part.TryGetProperty("inlineData", out JsonElement imagePart))
                            {
                                string extractedBase64Image = imagePart.GetProperty("data").GetString();
                                SaveImage(extractedBase64Image, "output.png");
                                Console.WriteLine("画像が 'output.png' に保存されました。");
                            }
                        }
                    }
                }
            }
        }
        catch (HttpRequestException ex)
        {
            Console.WriteLine($"HTTPリクエストでの例外が発生しました: {ex.Message}");
            if (ex.InnerException != null)
            {
                Console.WriteLine($"Inner Exception: {ex.InnerException.Message}");
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"例外が発生しました: {ex.Message}");
        }
    }

    private static void SaveImage(string base64Image, string outputPath)
    {
        var imageBytes = Convert.FromBase64String(base64Image);
        File.WriteAllBytes(outputPath, imageBytes);
    }
}

public static class MimeTypes
{
    private static readonly Dictionary<string, string> _mimeTypes = new Dictionary<string, string>
    {
        { ".jpg", "image/jpeg" },
        { ".jpeg", "image/jpeg" },
        { ".png", "image/png" },
        { ".gif", "image/gif" },
        // Add more MIME types as needed
    };

    public static string GetMimeType(string extension)
    {
        if (_mimeTypes.TryGetValue(extension.ToLower(), out var mimeType))
        {
            return mimeType;
        }
        throw new ArgumentException($"Unknown MIME type for extension: {extension}");
    }
}