C#でGeminiを使うサンプルコード

準備

1. APIキーを作る
2. Microsoft.SemanticKernel.Connectors.Google をNugetする．
   プレリリースかもしれないのを注意しよう

注意事項

APIキーは直書きしないほうがいいよ
settingやchatServiceにアクセスするときは警告が出るかもしれないので，

#pragma warning disable SKEXP0070
#pragma warning restore SKEXP0070

で囲ってね

コード

クラス定義例

using Microsoft.SemanticKernel;
using Microsoft.SemanticKernel.ChatCompletion;
using Microsoft.SemanticKernel.Connectors.Google;
using System.Diagnostics;
public static class Gemini1p5f8b
{
    static string geminiModel = "gemini-1.5-flash-8b"; // コスパ良いよこれ
    static string gemini_api_key = "事前につくってね";
#pragma warning disable SKEXP0070
    public static GoogleAIGeminiChatCompletionService chatService = new GoogleAIGeminiChatCompletionService(modelId: geminiModel, apiKey: gemini_api_key);
    public static GeminiPromptExecutionSettings settings = new()
    {
        MaxTokens = 50,
        Temperature = 0.7
    };
#pragma warning restore SKEXP0070
    public static async Task<ChatMessageContent> Genext(this ChatHistory hist) => await chatService.GetChatMessageContentAsync(hist, settings);
}

例の使用例

public static async Task Test()
{
    var chatHistory = new ChatHistory();
    chatHistory.AddUserMessage(new ChatMessageContentItemCollection
    {
         new TextContent("この画像を基に，お話を創作してください．"),
         new ImageContent(File.ReadAllBytes(@"C:\Users\omae\Desktop\test.png"),"image/png")
    });
    var reply = await chatHistory.Genext();
    chatHistory.Add(reply);

    foreach(var hist in chatHistory)
    {
        Debug.Print($"{hist.Role}: {hist.Content}");
    }
}

リトライ処理追加版(おまけ)

    public static async Task<ChatMessageContent> GenextWithRetry(this ChatHistory hist, TimeSpan timeout)
    {
        const int retryMax = 4;
        int tryCount = 0;
        while (tryCount++ < retryMax)
        {
            using (var cts = new CancellationTokenSource(timeout))
            {
                try
                {
                    ChatMessageContent generated = await Genext(hist).WaitAsync(cts.Token);
                    ResultCheck(generated);
                    return generated;
                }
                catch (OperationCanceledException)
                {
                    Debug.Print("Timeout occurred, retrying...");
                }
                catch (Exception ex)
                {
                    Debug.Print($"Error occurred: {ex.Message}, retrying...");
                }
            }
#pragma warning disable SKEXP0070
            settings.Temperature = Random.Shared.NextSingle() * 0.5f + 0.6f;
#pragma warning restore SKEXP0070
        }
        throw new Exception("自主的リトライ上限に達しました");
        void ResultCheck(ChatMessageContent result)
        {
            if (result.Content == "") throw new Exception("何も生成してません");
        }
    }

参考にさせて頂いた記事