以编程方式捕获网页屏幕截图对于生成预览、创建基于图像的报告等非常有用。在本指南中，我们将构建一个 next.js api 路由，该路由采用 url 并生成 png 屏幕截图。我们的设置使用 puppeteer 和 chrome-aws-lambda 来利用无头 chrome 浏览器，使其多功能且可用于生产。
我们将首先设置一个新的 next.js 项目，并逐步浏览代码以了解 api 如何捕获屏幕截图。
先决条件
- 设置 next.js 应用
- 使用 puppeteer 配置 api 路由
- 为捕获接口创建react组件
- puppeteer 的本地与部署配置说明
开始新的 next.js 项目
- 创建一个新的 next.js 应用程序：
npx create-next-app@latest capture-image-app cd capture-image-app
- 安装必要的依赖项：
npm install puppeteer puppeteer-core chrome-aws-lambda busboy
第2步：创建生成屏幕截图的api路由
现在，我们将设置一个 api 端点来根据提供的 url 捕获并返回屏幕截图。
在pages/api文件夹中，创建一个名为generate-png.ts的新文件并添加以下代码：
import { nextapirequest, nextapiresponse } from "next";
import busboy, { busboy } from "busboy"; // use busboy for multipart parsing
import chromium from "chrome-aws-lambda";
import puppeteercore from "puppeteer-core"; // import puppeteer-core directly
import puppeteer from "puppeteer"; // import puppeteer directly
// conditional import for puppeteer based on the environment
const puppeteermodule = process.env.node_env === "production" ? puppeteercore : puppeteer;
export const config = {
api: {
bodyparser: false, // disable default body parsing to handle raw binary data (blob)
},
};
const delay = (ms: number): promise => new promise((resolve) => settimeout(resolve, ms));
export default async function handler(
req: nextapirequest,
res: nextapiresponse
): promise {
try {
if (req.method === "post") {
const bb: busboy = busboy({ headers: req.headers });
let width: number = 1920; // default width
let height: number = 0; // default height
let delaytime: number = 6000;
const buffers: buffer[] = [];
bb.on("file", (_name: string, file: nodejs.readablestream) => {
file.on("data", (data: buffer) => buffers.push(data));
});
bb.on("field", (name: string, value: string) => {
if (name === "width") width = parseint(value, 10) || 1920;
if (name === "height") height = parseint(value, 10) || 0;
if (name === "delay") delaytime = parseint(value, 10) || 6000;
});
bb.on("finish", async () => {
const blobbuffer: buffer = buffer.concat(buffers);
const htmlcontent: string = blobbuffer.tostring("utf-8");
const browser = await puppeteermodule.launch({
args: ["--start-maximized"],
executablepath: process.env.node_env === "production"
? await chromium.executablepath || "/usr/bin/chromium-browser"
: undefined, // no custom executable path needed for local
headless: true,
});
const page = await browser.newpage();
// load the html content directly
await page.setcontent(htmlcontent, { waituntil: "networkidle0" });
//@ts-expect-error todo
const bodyheight = await page.evaluate(() => {
return document.body.scrollheight; // get the full scrollable height of the body
});
await page.setviewport({
width: number(width),
height: height || bodyheight, // use the provided height or fallback to the full body height
devicescalefactor: 2,
});
await delay(delaytime);
const screenshotbuffer = await page.screenshot({
fullpage: !height,
type: "png",
omitbackground: false,
});
await browser.close();
res.setheader("content-type", "image/png");
res.setheader(
"content-disposition",
"attachment; filename=screenshot.png"
);
res.status(200).end(screenshotbuffer);
});
req.pipe(bb); // pipe the request stream to busboy
} else {
res.setheader("allow", ["post"]);
res.status(405).end(`method ${req.method} not allowed`);
}
} catch (error) {
console.error("error", error);
res.status(500).end("internal server error");
}
}
*说明：为本地环境和生产环境选择 puppeteer
*
在此代码中，我们为 puppeteer 设置了动态导入：
本地开发：如果 node_env 不是生产环境，它会使用 puppeteer，它设置起来更简单，并且不需要 chrome-aws-lambda。
生产：对于无服务器部署，环境将检测 node_env 作为生产并加载 puppeteer-core 以及 chrome-aws-lambda，这使得它可以在 aws lambda 和其他类似环境中工作。在此设置中，chrome-aws-lambda 提供正确的 chromium 路径，确保与无服务器提供商的兼容性。
第 3 步：为 ui 创建一个简单的 react 组件
在这里，我们将创建一个简单的表单，让用户输入网页捕获的值。此表单将触发生成功能以捕获并下载 pdf 格式的屏幕截图。
import { useState } from "react";
export default function ScreenCaptureComponent() {
const [isProcessing, setProcessing] = useState(false);
const [width, setWidth] = useState("1920");
const [height, setHeight] = useState("1000");
const [delay, setDelay] = useState("6000");
// Function to clone HTML and prepare for capture
function takeScreenshot() {
const clonedElement = document.body.cloneNode(true) as HTMLElement;
const blob = new Blob([clonedElement.outerHTML], { type: "text/html" });
return blob;
}
// Function to capture screenshot by sending cloned HTML to API
async function generateCapture() {
setProcessing(true);
const htmlBlob = takeScreenshot();
if (!htmlBlob) {
setProcessing(false);
return;
}
try {
const formData = new FormData();
formData.append("file", htmlBlob);
formData.append("width", width);
formData.append("height", height);
formData.append("delay", delay);
const response = await fetch("/api/generate-png", {
method: "POST",
body: formData,
});
if (!response.ok) throw new Error("Capture failed");
const blob = await response.blob();
const downloadUrl = URL.createObjectURL(blob);
const link = document.createElement("a");
link.href = downloadUrl;
link.download = "capture.png";
link.click();
URL.revokeObjectURL(downloadUrl);
} catch (error) {
console.error("Failed to capture screenshot", error);
} finally {
setProcessing(false);
}
}
return (
Webpage Screenshot Capture
{/* Example HTML Element to Capture */}
Content to Capture
This is an example of the HTML content that will be captured.
);
}
结论
本教程涵盖在 next.js 中设置网页捕获工具、使用 puppeteer 处理屏幕截图以及创建交互式前端组件。请记住在本地使用 puppeteer 并在生产中切换到 puppeteer-core，以减少捆绑包大小并优化无服务器环境。快乐编码！
