Mermaid Chart MCP

Instructions

Implementation Reference

• src/renderer.ts:60-190 (handler)

  Core handler function that implements the Mermaid chart rendering logic using Puppeteer browser automation, Sharp for image processing, and optional MinIO upload.
  async renderChart(options: RenderOptions): Promise<RenderResult> { const { mermaidCode, outputPath, format = 'png', width = 1200, height = 800, backgroundColor = 'white', theme = 'default', uploadToMinio = false, minioExpiryDays = 7, } = options; try { // 确保输出目录存在 const outputDir = dirname(outputPath); await fs.ensureDir(outputDir); // 初始化浏览器 const browser = await this.initBrowser(); const page = await browser.newPage(); // 设置高分辨率视口和设备像素比 await page.setViewport({ width, height, deviceScaleFactor: 2, // 设置设备像素比为2，提高PNG渲染质量 }); // 增加页面错误监听 page.on('console', msg => { if (msg.type() === 'error') { console.error('页面控制台错误:', msg.text()); } }); page.on('pageerror', error => { console.error('页面运行时错误:', error); }); // 创建 HTML 内容 const htmlContent = this.createHtmlContent(mermaidCode, theme, backgroundColor); // 加载 HTML 内容 console.log('加载HTML内容...'); await page.setContent(htmlContent, { waitUntil: 'domcontentloaded', timeout: 30000 }); // 等待 Mermaid 渲染完成，增加更长的超时时间 console.log('等待Mermaid渲染...'); try { await page.waitForSelector('#mermaid-diagram', { timeout: 30000 }); // 检查是否渲染成功 const isRendered = await page.waitForFunction( () => { const element = document.querySelector('#mermaid-diagram'); const hasRendered = element && element.getAttribute('data-rendered') === 'true'; const hasSvg = element && element.querySelector('svg'); console.log('渲染状态检查:', { hasRendered, hasSvg }); return hasRendered || hasSvg; // 任一条件满足即可 }, { timeout: 60000, polling: 1000 } ); console.log('Mermaid渲染完成'); } catch (timeoutError) { // 如果超时，尝试获取页面状态信息 const pageContent = await page.content(); console.error('渲染超时，页面内容:', pageContent.substring(0, 500)); const diagramElement = await page.$('#mermaid-diagram'); if (diagramElement) { const innerHTML = await page.evaluate(el => el.innerHTML, diagramElement); console.error('图表元素内容:', innerHTML); } throw new Error(`Mermaid渲染超时: ${timeoutError instanceof Error ? timeoutError.message : String(timeoutError)}`); } // 根据格式渲染 if (format === 'svg') { await this.renderSVG(page, outputPath); } else if (format === 'pdf') { await this.renderPDF(page, outputPath, width, height); } else { await this.renderPNG(page, outputPath, width, height); } await page.close(); // 基础渲染结果 const result: RenderResult = { outputPath, format, width, height, }; // 如果需要上传到MinIO if (uploadToMinio) { try { console.log('🔄 开始MinIO上传...'); const minioConfig = createDefaultMinIOConfig(); const minioUploader = new MinIOUploader(minioConfig); await minioUploader.initialize(); const uploadResult = await minioUploader.uploadFile(outputPath, { expiryDays: minioExpiryDays }); result.uploadResult = uploadResult; if (uploadResult.success && uploadResult.url) { result.minioUrl = uploadResult.url; console.log('✅ MinIO上传成功'); } else { console.error('❌ MinIO上传失败:', uploadResult.error); } } catch (minioError) { console.error('❌ MinIO上传过程中发生错误:', minioError); result.uploadResult = { success: false, error: `MinIO上传失败: ${minioError instanceof Error ? minioError.message : String(minioError)}` }; } } return result; } catch (error) { throw new Error(`渲染失败: ${error instanceof Error ? error.message : String(error)}`); } }
• src/index.ts:43-95 (schema)

  Input schema/JSON Schema definition for the render_mermaid_chart tool parameters.
  inputSchema: { type: 'object', properties: { mermaidCode: { type: 'string', description: 'Mermaid 图表代码', }, outputPath: { type: 'string', description: '输出文件路径（包含文件名和扩展名）', }, format: { type: 'string', enum: ['png', 'svg', 'pdf'], description: '输出格式（png, svg, pdf），默认为 png', default: 'png', }, width: { type: 'number', description: '图片宽度（像素），默认为 1200', default: 1200, }, height: { type: 'number', description: '图片高度（像素），默认为 800', default: 800, }, backgroundColor: { type: 'string', description: '背景颜色，默认为 white', default: 'white', }, theme: { type: 'string', enum: ['default', 'dark', 'forest', 'neutral'], description: 'Mermaid 主题，默认为 default', default: 'default', }, uploadToMinio: { type: 'boolean', description: '是否上传到MinIO存储并返回在线链接，默认为 false', default: false, }, minioExpiryDays: { type: 'number', description: 'MinIO文件有效期（天数），默认7天，最大30天，超过30天按30天计算', default: 7, minimum: 1, maximum: 30, }, }, required: ['mermaidCode', 'outputPath'], },
• src/index.ts:37-99 (registration)

  Registration of the tool in the ListToolsRequestSchema handler, including name, description, and schema.
  this.server.setRequestHandler(ListToolsRequestSchema, async () => { return { tools: [ { name: 'render_mermaid_chart', description: '将 Mermaid 代码渲染为高质量图片文件', inputSchema: { type: 'object', properties: { mermaidCode: { type: 'string', description: 'Mermaid 图表代码', }, outputPath: { type: 'string', description: '输出文件路径（包含文件名和扩展名）', }, format: { type: 'string', enum: ['png', 'svg', 'pdf'], description: '输出格式（png, svg, pdf），默认为 png', default: 'png', }, width: { type: 'number', description: '图片宽度（像素），默认为 1200', default: 1200, }, height: { type: 'number', description: '图片高度（像素），默认为 800', default: 800, }, backgroundColor: { type: 'string', description: '背景颜色，默认为 white', default: 'white', }, theme: { type: 'string', enum: ['default', 'dark', 'forest', 'neutral'], description: 'Mermaid 主题，默认为 default', default: 'default', }, uploadToMinio: { type: 'boolean', description: '是否上传到MinIO存储并返回在线链接，默认为 false', default: false, }, minioExpiryDays: { type: 'number', description: 'MinIO文件有效期（天数），默认7天，最大30天，超过30天按30天计算', default: 7, minimum: 1, maximum: 30, }, }, required: ['mermaidCode', 'outputPath'], }, }, ], }; });
• src/index.ts:102-171 (registration)

  Registration of the CallToolRequestSchema handler that dispatches to the render_mermaid_chart implementation.
  this.server.setRequestHandler(CallToolRequestSchema, async (request) => { const { name, arguments: args } = request.params; if (name === 'render_mermaid_chart') { try { const { mermaidCode, outputPath, format = 'png', width = 1200, height = 800, backgroundColor = 'white', theme = 'default', uploadToMinio = false, minioExpiryDays = 7, } = args as { mermaidCode: string; outputPath: string; format?: 'png' | 'svg' | 'pdf'; width?: number; height?: number; backgroundColor?: string; theme?: 'default' | 'dark' | 'forest' | 'neutral'; uploadToMinio?: boolean; minioExpiryDays?: number; }; // 验证必需参数 if (!mermaidCode || !outputPath) { throw new Error('mermaidCode 和 outputPath 是必需参数'); } // 渲染图表 const result = await this.renderer.renderChart({ mermaidCode, outputPath, format, width, height, backgroundColor, theme, uploadToMinio, minioExpiryDays, }); return { content: [ { type: 'text', text: this.formatRenderResult(result), }, ], }; } catch (error) { const errorMessage = error instanceof Error ? error.message : '未知错误'; return { content: [ { type: 'text', text: `渲染失败: ${errorMessage}`, }, ], isError: true, }; } } throw new Error(`未知工具: ${name}`); }); }
• src/renderer.ts:7-17 (helper)

  TypeScript interface defining the input options for the renderChart handler, matching the schema.
  export interface RenderOptions { mermaidCode: string; outputPath: string; format?: 'png' | 'svg' | 'pdf'; width?: number; height?: number; backgroundColor?: string; theme?: 'default' | 'dark' | 'forest' | 'neutral'; uploadToMinio?: boolean; // 是否上传到MinIO minioExpiryDays?: number; // MinIO文件有效期（天数），默认7天，最大30天 }