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feat: 添加 API 接口支持服务端生成图表图片

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- 新增 Node.js + Express 后端服务 (server.js)
- POST /api/chart: JSON 请求体生成图表 PNG
- GET /api/chart: URL 参数生成图表 PNG
- 支持所有前端配置参数(图表类型/主题/标签/堆叠/分割等)
- 使用 @napi-rs/canvas + echarts 服务端渲染
- 自定义分辨率和像素倍率
- 添加 /api/health 和 /api/docs 接口
- 更新 README 文档，添加 API 使用说明
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hz4th_coder
2026-07-16 11:33:39 +08:00
parent ad3e74e391
commit d4ce91efd1
5 changed files with 1773 additions and 51 deletions
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server.js
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const express = require('express');
const cors = require('cors');
const { createCanvas } = require('@napi-rs/canvas');
const echarts = require('echarts');
const path = require('path');
const app = express();
const PORT = process.env.PORT || 16023;
// 中间件
app.use(cors());
app.use(express.json({ limit: '10mb' }));
app.use(express.urlencoded({ extended: true, limit: '10mb' }));
// 静态文件（前端页面）
app.use(express.static(path.join(__dirname)));
// ===== 预设颜色方案 =====
const colorPalettes = {
default: ['#5470c6', '#91cc75', '#fac858', '#ee6666', '#73c0de', '#3ba272', '#fc8452', '#9a60b4', '#ea7ccc'],
dark: ['#4fc3f7', '#81c784', '#fff176', '#ff8a65', '#ba68c8', '#4dd0e1', '#ffab91', '#aed581', '#f48fb1'],
macarons: ['#2ec7c9', '#b6a2de', '#5ab1ef', '#ffb980', '#d87a80', '#8d98b3', '#e5cf0d', '#97b552', '#95706d'],
gradient: ['#7f7fd5', '#86a8e7', '#91eae4', '#ff6b6b', '#feca57', '#48dbfb', '#ff9ff3', '#54a0ff', '#5f27cd'],
retro: ['#d4a5a5', '#95b9c7', '#f6e8c3', '#dfceb4', '#a4c3b5', '#c9b1ff', '#f5c7b8', '#b8d4e3', '#e8c8a0']
};
// ===== 数据解析（与前端一致） =====
function parseData(rawText) {
const lines = rawText.trim().split('\n').filter(l => l.trim());
if (lines.length < 2) {
throw new Error('数据至少需要包含表头和一行数据');
}
// 自动检测分隔符
let delimiter = ',';
if (lines[0].includes('\t')) {
delimiter = '\t';
} else if (lines[0].split('|').length > lines[0].split(',').length) {
delimiter = '|';
}
const rows = lines.map(line => {
return line.split(delimiter).map(cell => cell.trim());
});
const headers = rows[0];
const categories = [];
const seriesData = {};
for (let i = 1; i < headers.length; i++) {
seriesData[headers[i]] = [];
}
for (let i = 1; i < rows.length; i++) {
categories.push(rows[i][0]);
for (let j = 1; j < rows[i].length && j < headers.length; j++) {
const val = parseFloat(rows[i][j]);
seriesData[headers[j]].push(isNaN(val) ? 0 : val);
}
}
return {
categories,
seriesNames: headers.slice(1),
seriesData
};
}
// ===== 颜色工具 =====
function adjustColor(hex, amount) {
hex = hex.replace('#', '');
const num = parseInt(hex, 16);
let r = Math.min(255, ((num >> 16) & 0xff) + amount);
let g = Math.min(255, ((num >> 8) & 0xff) + amount);
let b = Math.min(255, (num & 0xff) + amount);
return `rgb(${r},${g},${b})`;
}
// ===== 构建 ECharts option =====
function buildChartOption(params) {
const {
data,
chartType = 'bar',
title = '',
theme = 'default',
showLegend = true,
showGrid = true,
showLabel = false,
stackMode = false,
smoothLine = true,
enableSplit = false,
splitIndex = 3,
leftLabel = '左侧',
rightLabel = '右侧',
splitStyle = 'solid',
seriesColors: customColors = null
} = params;
const parsedData = parseData(data);
const palette = colorPalettes[theme] || colorPalettes.default;
const seriesColorsArr = customColors || parsedData.seriesNames.map((_, i) => palette[i % palette.length]);
// 背景色和文字色
const bgColor = theme === 'dark' ? '#1a1a2e' : '#ffffff';
const textColor = theme === 'dark' ? '#e0e0e0' : '#333333';
const axisLineColor = theme === 'dark' ? '#444' : '#ddd';
// 构建系列
const series = parsedData.seriesNames.map((name, idx) => {
const dataArr = parsedData.seriesData[name];
const color = seriesColorsArr[idx] || palette[idx % palette.length];
let type = chartType === 'bar-line'
? (idx % 2 === 0 ? 'bar' : 'line')
: chartType;
const seriesItem = {
name: name,
type: type,
data: [...dataArr],
itemStyle: { color: color },
emphasis: {
focus: 'series',
itemStyle: {
shadowBlur: 10,
shadowColor: 'rgba(0,0,0,0.3)'
}
}
};
if (stackMode) {
seriesItem.stack = 'total';
}
if (type === 'line') {
seriesItem.smooth = smoothLine;
seriesItem.lineStyle = { width: 3 };
seriesItem.symbolSize = 8;
seriesItem.areaStyle = theme === 'gradient' ? { opacity: 0.15 } : undefined;
}
if (type === 'bar') {
seriesItem.barMaxWidth = 40;
seriesItem.itemStyle.borderRadius = stackMode ? [0, 0, 0, 0] : [4, 4, 0, 0];
}
if (showLabel) {
seriesItem.label = {
show: true,
position: 'top',
fontSize: 11,
color: textColor,
formatter: (p) => {
if (p.value >= 10000) return (p.value / 10000).toFixed(1) + 'w';
if (p.value >= 1000) return (p.value / 1000).toFixed(1) + 'k';
return p.value;
}
};
}
return seriesItem;
});
// 区域分割
if (enableSplit && splitIndex < parsedData.categories.length && series.length > 0) {
const splitLineColor = theme === 'dark' ? '#ff6b6b' : '#e74c3c';
series[0].markArea = {
silent: true,
data: [
[
{
name: leftLabel,
xAxis: parsedData.categories[0],
itemStyle: {
color: theme === 'dark' ? 'rgba(79,195,247,0.06)' : 'rgba(79,70,229,0.05)',
borderWidth: 0
},
label: {
show: true,
position: 'insideTop',
fontSize: 13,
fontWeight: 'bold',
color: theme === 'dark' ? '#4fc3f7' : '#4f46e5',
offset: [0, 10]
}
},
{ xAxis: parsedData.categories[splitIndex - 1] }
],
[
{
name: rightLabel,
xAxis: parsedData.categories[splitIndex],
itemStyle: {
color: theme === 'dark' ? 'rgba(255,107,107,0.06)' : 'rgba(239,68,68,0.05)',
borderWidth: 0
},
label: {
show: true,
position: 'insideTop',
fontSize: 13,
fontWeight: 'bold',
color: theme === 'dark' ? '#ff6b6b' : '#ef4444',
offset: [0, 10]
}
},
{ xAxis: parsedData.categories[parsedData.categories.length - 1] }
]
]
};
}
// 完整 option
const option = {
backgroundColor: bgColor,
title: title ? {
text: title,
left: 'center',
top: 15,
textStyle: {
color: textColor,
fontSize: 18,
fontWeight: 600
}
} : undefined,
tooltip: { show: false },
legend: showLegend ? {
show: true,
top: title ? 50 : 15,
textStyle: { color: textColor, fontSize: 12 },
itemGap: 20,
icon: 'roundRect'
} : { show: false },
grid: {
left: '3%',
right: '4%',
bottom: '3%',
top: showLegend ? (title ? 90 : 60) : (title ? 60 : 30),
containLabel: true
},
xAxis: {
type: 'category',
data: parsedData.categories,
axisLine: { lineStyle: { color: axisLineColor } },
axisLabel: {
color: textColor,
fontSize: 12,
interval: 0,
rotate: parsedData.categories.length > 10 ? 30 : 0
},
axisTick: { show: false }
},
yAxis: {
type: 'value',
axisLine: { show: false },
axisTick: { show: false },
axisLabel: { color: textColor, fontSize: 11 },
splitLine: {
show: showGrid,
lineStyle: {
color: theme === 'dark' ? '#333' : '#f0f0f0',
type: 'dashed'
}
}
},
series: series,
animation: false // 服务端渲染关闭动画
};
return option;
}
// ===== API: 生成图表图片 =====
app.post('/api/chart', (req, res) => {
try {
const params = req.body;
if (!params.data) {
return res.status(400).json({ error: '缺少 data 参数（CSV 格式数据）' });
}
const width = parseInt(params.width) || 800;
const height = parseInt(params.height) || 500;
const format = params.format || 'png';
const pixelRatio = parseInt(params.pixelRatio) || 2;
// 构建图表配置
const option = buildChartOption(params);
// 创建 canvas 并渲染
const canvas = createCanvas(width * pixelRatio, height * pixelRatio);
const chart = echarts.init(canvas, null, {
renderer: 'canvas',
width: width,
height: height,
devicePixelRatio: pixelRatio
});
chart.setOption(option);
// 输出图片
if (format === 'svg') {
// SVG 需要用 SVG 渲染器重新渲染
// node-canvas 不支持 SVG，返回 PNG 并提示
const buffer = canvas.toBuffer('image/png');
res.set({
'Content-Type': 'image/png',
'Content-Length': buffer.length,
'X-Chart-Format': 'png',
'X-Chart-Note': 'SVG format not supported in server-side rendering, returned PNG instead'
});
res.send(buffer);
} else {
const buffer = canvas.toBuffer('image/png');
res.set({
'Content-Type': 'image/png',
'Content-Length': buffer.length,
'X-Chart-Width': width,
'X-Chart-Height': height,
'X-Chart-Pixel-Ratio': pixelRatio
});
res.send(buffer);
}
chart.dispose();
} catch (err) {
console.error('Chart generation error:', err);
res.status(500).json({ error: '图表生成失败: ' + err.message });
}
});
// ===== API: 生成图表（GET 方式，方便 URL 直接调用） =====
app.get('/api/chart', (req, res) => {
try {
const params = {
data: req.query.data,
chartType: req.query.chartType || req.query.type || 'bar',
title: req.query.title || '',
theme: req.query.theme || 'default',
showLegend: req.query.showLegend !== 'false',
showGrid: req.query.showGrid !== 'false',
showLabel: req.query.showLabel === 'true',
stackMode: req.query.stackMode === 'true',
smoothLine: req.query.smoothLine !== 'false',
enableSplit: req.query.enableSplit === 'true',
splitIndex: parseInt(req.query.splitIndex) || 3,
leftLabel: req.query.leftLabel || '左侧',
rightLabel: req.query.rightLabel || '右侧',
splitStyle: req.query.splitStyle || 'solid',
width: parseInt(req.query.width) || 800,
height: parseInt(req.query.height) || 500,
format: req.query.format || 'png',
pixelRatio: parseInt(req.query.pixelRatio) || 2
};
if (!params.data) {
return res.status(400).json({ error: '缺少 data 参数' });
}
// 解码 data（支持 URL 编码的换行符）
params.data = params.data.replace(/\\n/g, '\n');
const option = buildChartOption(params);
const width = params.width;
const height = params.height;
const pixelRatio = params.pixelRatio;
const canvas = createCanvas(width * pixelRatio, height * pixelRatio);
const chart = echarts.init(canvas, null, {
renderer: 'canvas',
width: width,
height: height,
devicePixelRatio: pixelRatio
});
chart.setOption(option);
const buffer = canvas.toBuffer('image/png');
res.set({
'Content-Type': 'image/png',
'Content-Length': buffer.length,
'X-Chart-Width': width,
'X-Chart-Height': height
});
res.send(buffer);
chart.dispose();
} catch (err) {
console.error('Chart generation error:', err);
res.status(500).json({ error: '图表生成失败: ' + err.message });
}
});
// ===== API: 健康检查 =====
app.get('/api/health', (req, res) => {
res.json({
status: 'ok',
service: 'data-chart-tool',
version: '1.1.0',
endpoints: {
'POST /api/chart': '生成图表图片（JSON body）',
'GET /api/chart': '生成图表图片（URL 参数）',
'GET /api/health': '健康检查'
}
});
});
// ===== API: 文档/使用说明 =====
app.get('/api/docs', (req, res) => {
res.json({
name: '数据可视化图表生成器 API',
version: '1.1.0',
endpoints: [
{
method: 'POST',
path: '/api/chart',
description: '通过 JSON 请求体生成图表图片',
'Content-Type': 'application/json',
params: {
data: { type: 'string', required: true, description: 'CSV 格式数据（第一行表头，第一列横坐标）' },
chartType: { type: 'string', default: 'bar', options: ['bar', 'line', 'bar-line'], description: '图表类型' },
title: { type: 'string', default: '', description: '图表标题' },
theme: { type: 'string', default: 'default', options: ['default', 'dark', 'macarons', 'gradient', 'retro'], description: '主题风格' },
showLegend: { type: 'boolean', default: true, description: '是否显示图例' },
showGrid: { type: 'boolean', default: true, description: '是否显示网格线' },
showLabel: { type: 'boolean', default: false, description: '是否显示数据标签' },
stackMode: { type: 'boolean', default: false, description: '是否堆叠模式' },
smoothLine: { type: 'boolean', default: true, description: '折线图是否平滑' },
enableSplit: { type: 'boolean', default: false, description: '是否启用区域分割' },
splitIndex: { type: 'number', default: 3, description: '分割位置索引' },
leftLabel: { type: 'string', default: '左侧', description: '左侧区域标签' },
rightLabel: { type: 'string', default: '右侧', description: '右侧区域标签' },
splitStyle: { type: 'string', default: 'solid', options: ['solid', 'dashed', 'dotted'], description: '分割线样式' },
width: { type: 'number', default: 800, description: '图片宽度(px)' },
height: { type: 'number', default: 500, description: '图片高度(px)' },
format: { type: 'string', default: 'png', options: ['png'], description: '输出格式' },
pixelRatio: { type: 'number', default: 2, description: '像素倍率（清晰度）' }
},
returns: 'image/png',
example: {
request: `curl -X POST http://localhost:16023/api/chart \\
-H "Content-Type: application/json" \\
-d '{
"data": "产品, Q1, Q2, Q3, Q4\\n手机, 1200, 1800, 2100, 2500\\n平板, 800, 950, 1100, 1300",
"chartType": "bar",
"title": "季度销售对比",
"theme": "default",
"width": 800,
"height": 500
}' -o chart.png`,
response: 'PNG 图片二进制流'
}
},
{
method: 'GET',
path: '/api/chart',
description: '通过 URL 参数生成图表图片（适合简单场景）',
params: {
data: { type: 'string', required: true, description: 'CSV 数据（换行用 \\n 分隔）' },
type: { type: 'string', default: 'bar', description: '图表类型' },
title: { type: 'string', description: '图表标题' },
theme: { type: 'string', default: 'default', description: '主题风格' },
width: { type: 'number', default: 800 },
height: { type: 'number', default: 500 }
},
returns: 'image/png',
example: {
request: `curl "http://localhost:16023/api/chart?data=产品,Q1,Q2\\n手机,100,200\\n平板,150,250&type=bar&title=测试" -o chart.png`
}
}
]
});
});
// ===== 启动服务 =====
app.listen(PORT, '0.0.0.0', () => {
console.log(`🚀 数据可视化图表生成器已启动`);
console.log(`📊 Web UI: http://0.0.0.0:${PORT}`);
console.log(`📡 API: http://0.0.0.0:${PORT}/api/chart`);
console.log(`📖 文档: http://0.0.0.0:${PORT}/api/docs`);
console.log(`❤️ 健康: http://0.0.0.0:${PORT}/api/health`);
});