118 lines
4.7 KiB
C#
118 lines
4.7 KiB
C#
using DramaLing.Api.Models.DTOs;
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using DramaLing.Api.Models.Entities;
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namespace DramaLing.Api.Services.AI.Gemini;
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/// <summary>
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/// 圖片描述生成服務實作
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/// </summary>
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public class ImageDescriptionGenerator : IImageDescriptionGenerator
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{
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private readonly IGeminiClient _geminiClient;
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private readonly ILogger<ImageDescriptionGenerator> _logger;
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public ImageDescriptionGenerator(
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IGeminiClient geminiClient,
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ILogger<ImageDescriptionGenerator> logger)
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{
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_geminiClient = geminiClient ?? throw new ArgumentNullException(nameof(geminiClient));
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_logger = logger ?? throw new ArgumentNullException(nameof(logger));
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}
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public async Task<string> GenerateImageDescriptionAsync(Flashcard flashcard, GenerationOptionsDto options)
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{
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try
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{
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_logger.LogInformation("Starting image description generation for flashcard {FlashcardId}", flashcard.Id);
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var prompt = BuildImageDescriptionPrompt(flashcard, options);
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var response = await _geminiClient.CallGeminiAPIAsync(prompt);
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if (string.IsNullOrWhiteSpace(response))
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{
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throw new InvalidOperationException("Gemini API returned empty response");
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}
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var description = ExtractImageDescription(response);
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var optimizedPrompt = OptimizeForReplicate(description, options);
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_logger.LogInformation("Image description generated successfully for flashcard {FlashcardId}", flashcard.Id);
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return optimizedPrompt;
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}
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catch (Exception ex)
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{
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_logger.LogError(ex, "Image description generation failed for flashcard {FlashcardId}", flashcard.Id);
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throw;
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}
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}
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private string BuildImageDescriptionPrompt(Flashcard flashcard, GenerationOptionsDto options)
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{
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return $@"# 總覽
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你是一位專業插畫設計師兼職英文老師，專門為英語學習教材製作插畫圖卡，用來幫助學生理解英文例句的意思。
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# 例句資訊
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例句：{flashcard.Example}
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# SOP
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1. 根據上述英文例句，請撰寫一段圖像描述提示詞，用於提供圖片生成AI作為生成圖片的提示詞
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2. 請將下方「風格指南」的所有要求加入提示詞中
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3. 並於圖片提示詞最後加上：「Absolutely no visible text, characters, letters, numbers, symbols, handwriting, labels, or any form of writing anywhere in the image — including on signs, books, clothing, screens, or backgrounds.」
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# 圖片提示詞規範
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## 情境清楚
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1. 角色描述具體清楚
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2. 動作明確具象
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3. 場景明確具體
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4. 物品明確具體
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5. 語意需與原句一致
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6. 避免過於抽象或象徵性符號
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## 風格指南
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- 風格類型：扁平插畫（Flat Illustration）
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- 線條特徵：無描邊線條（outline-less）
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- 色調：暖色調、柔和、低飽和
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- 人物樣式：簡化卡通人物，表情自然，不誇張
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- 背景構成：圖形簡化，使用色塊區分層次
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- 整體氛圍：溫馨、平靜、適合教育情境
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- 技術風格：無紋理、無漸層、無光影寫實感
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請根據以上規範，為這個英文例句生成圖片描述提示詞，並確保完全符合風格指南要求。";
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}
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private string ExtractImageDescription(string geminiResponse)
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{
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// 從 Gemini 回應中提取圖片描述
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var description = geminiResponse.Trim();
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// 移除可能的 markdown 標記
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if (description.StartsWith("```"))
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{
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var lines = description.Split('\n');
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description = string.Join('\n', lines.Skip(1).SkipLast(1));
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}
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return description.Trim();
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}
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private string OptimizeForReplicate(string description, GenerationOptionsDto options)
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{
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var optimizedPrompt = description;
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// 確保包含扁平插畫風格要求
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if (!optimizedPrompt.Contains("flat illustration"))
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{
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optimizedPrompt += ". Style guide: flat illustration style, outline-less shapes, warm and soft color tones, low saturation, cartoon-style characters with natural expressions, simplified background with color blocks, cozy and educational atmosphere, no texture, no gradients, no photorealism, no fantasy elements.";
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}
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// 強制加入禁止文字的規則
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if (!optimizedPrompt.Contains("Absolutely no visible text"))
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{
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optimizedPrompt += " Absolutely no visible text, characters, letters, numbers, symbols, handwriting, labels, or any form of writing anywhere in the image — including on signs, books, clothing, screens, or backgrounds.";
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}
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return optimizedPrompt;
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}
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} |