记录--手把手教你，用electron实现截图软件寻技术

这里给大家分享我在网上总结出来的一些知识，希望对大家有所帮助

背景

因为我们日常开发项目的时候，需要和同事对接api和文档还有UI图，所以有时候要同时打开多个窗口，并在多个窗口中切换，来选择自己要的信息，如果api和文档不多的情况还好，但是有时候就是要做大量的页面，为了提升效率我决定自己做一个截图工具，并把自己要的信息截图钉在窗口上。

在做之前先看看最终展示效果吧：

先是截图

截图后的图片展示

工具

nodejs
pnpm
electron
vite
react

实现

原理逻辑

其实也并不难理解，首先是主窗体发起截图请求，然后会打开另一个负责截图透明且全屏的窗体，唤起后透明窗体会让electron截取整个屏幕发给逻辑页面，页面会把图片绘制满屏实现定格效果，然后再用canvas做绘制区域的生成，根据生成出的区域对刚才满屏图片进行裁切导出，最后传递给主窗体去显示还可以存到剪贴板种。

具体的api可以看看官方文档： www.electronjs.org/zh/docs/lat…

路由配置

本次开发使用了electron-vite-react，具体构建和配置就是用它的默认配置就好了，值得注意的是，本次需要要做三个窗体，一个主窗体，一个截屏窗体，一个是图片展示窗体，于是索性就引入react-router-dom了。

先来安装一下：

git clone https://github.com/electron-vite/electron-vite-react

pnpm add react-router-dom

pnpm add antd

但是要注意的是，我们需要把路由设置成hash模式，不然本地打包时会无法找到。

    import type { FC } from "react";
    import { Routes, Route } from "react-router-dom";
    import { Provider } from "react-redux";
    import { store } from "@/stores";
    import "./index.scss";

    import Home from "@/pages/home";
    import ShotScreen from "@/pages/shotScreen";
    import ViewImage from "@/pages/viewImage";

    const App: FC = () => (
    	<Provider store={store}>
    		<div className="app">
    			<Routes>
    				<Route path="/" element={<Home />}></Route>
    				<Route path="/shotScreen" element={<ShotScreen />}></Route>
    				<Route path="/viewImage" element={<ViewImage />}></Route>
    			</Routes>
    		</div>
    	</Provider>
    );

    export default App;

主窗体

我们先准备好主页面Home，里面很简单，就是放入一个按钮然后点击按钮开打截屏页

        import React, {
        	useEffect,
        	useState,
        	useImperativeHandle,
        	forwardRef,
        } from "react";
        import { ScissorOutlined } from "@ant-design/icons";
        import { Button, Card } from "antd";
        import { ipcRenderer } from "electron";

        const ShotScreenCard = forwardRef((props: any, ref: any) => {
        	useImperativeHandle(ref, () => ({
        		handleCutScreen,
        	}));
        	const [isCutScreen, setIsCutScreen] = useState(true);

        	function handleCutScreen() {
        		ipcRenderer.send("ss:open-win");
        	}

        	return (
        		<Card
        			title="截屏"
        			hoverable
        			bordered={false}
        			extra={<a href="#">更多</a>}
        			style={{ maxWidth: 300 }}
        			onClick={handleCutScreen}
        		>
        			<div className="cardContent">
        				<ScissorOutlined />
        			</div>
        		</Card>
        	);
        });

        export default ShotScreenCard;

截图页

在这里我也尝试过自己用Konva自己手写一个截图页，但是功能实在太多了，最后还是放弃了，如果大家有兴趣可以自己尝试，在这里我介绍两个不多的插件：

react-screenshots： github.com/nashaofu/sc…
js-web-screen-shot github.com/likaia/js-s…

这样截图页很简单，我们使用react-screenshots来帮我们实现截图功能，代码如下：

    import React, { useCallback, useEffect, useState } from "react";
    import Screenshots, { Bounds } from "react-screenshots";
    import { ipcRenderer } from "electron";
    import "react-screenshots/lib/style.css";
    import "./index.scss";

    export default function ShotScreen() {
    	const [screenShotImg, setScreenShotImg] = useState("");

    	useEffect(() => {
    		getShotScreenImg();
    	}, []);

    	async function getShotScreenImg() {
    		const img = await ipcRenderer.invoke("ss:get-shot-screen-img");
    		setScreenShotImg(img);
    		return img;
    	}

    	const onSave = useCallback((blob: Blob, bounds: Bounds) => {
    		const downloadUrl = URL.createObjectURL(blob);
    		ipcRenderer.send("ss:download-img", downloadUrl);
    	}, []);

    	const onCancel = useCallback(() => {
    		ipcRenderer.send("ss:close-win");
    	}, []);

    	const onOk = useCallback((blob: Blob, bounds: Bounds) => {
    		const downloadUrl = URL.createObjectURL(blob);
    		ipcRenderer.send("ss:save-img", downloadUrl);
    	}, []);

    	return (
    		<Screenshots
    			url={screenShotImg}
    			width={window.innerWidth}
    			height={window.innerHeight}
    			onSave={onSave}
    			onCancel={onCancel}
    			onOk={onOk}
    		/>
    	);
    }

electron 通讯

web页面和electron 之间需要通讯，来获取屏幕的图片，具体可以看文档：www.electronjs.org/zh/docs/lat…, 代码入下：

        // 截图
        ipcMain.handle("ss:get-shot-screen-img", async () => {
        		const { width, height } = getScreenSize();
        		const sources = [
        			...(await desktopCapturer.getSources({
        				types: ["screen"],
        				thumbnailSize: {
        					width,
        					height,
        				},
        			})),
        		];
        		const source = sources.filter((e: any) => e.id == "screen:0:0")[0];
        		const img = source.thumbnail.toDataURL();
        		return img;
        	});

            ipcMain.on("ss:open-win", () => {
            	closeShotScreenWin();
            	hideMainWin();
            	openShotScreenWin();
            });

            ipcMain.on("ss:close-win", () => {
            	closeShotScreenWin();
            });

            ipcMain.on("ss:save-img", async (e, downloadUrl) => {
            	downloadURLShotScreenWin(downloadUrl);
            	await openViewImageWin(true);
            });

            ipcMain.on("ss:download-img", async (e, downloadUrl) => {
            	downloadURLShotScreenWin(downloadUrl, true);
            });

            ipcMain.handle("ss:get-desktop-capturer-source", async () => {
            	return [
            		...(await desktopCapturer.getSources({ types: ["screen"] })),
            		...(await selfWindws()),
            	];
            });

截图窗口的设置

截图窗口就像一个100%透明的玻璃浮在我们的电脑屏幕上，这时候我们就要设置他的 width：100%,height:100%,不可移动，并且透明，具体配置如下：

import {
	app,
	BrowserWindow,
	shell,
	dialog,
	DownloadItem,
	WebContents,
	clipboard,
	nativeImage,
} from "electron";
import path from "node:path";
import { getScreenSize, preload, url, indexHtml, PUBLIC } from "./utils";
import { getFilePath, setHistoryImg } from "./store";

let shotScreenWin: BrowserWindow | null = null;
let savePath: string = "";

function createShotScreenWin(): BrowserWindow {
	const { width, height } = getScreenSize();
	shotScreenWin = new BrowserWindow({
		title: "pear-rec 截屏",
		icon: path.join(PUBLIC, "logo@2x.ico"),
		width, // 宽度(px), 默认值为 800
		height, // 高度(px), 默认值为 600
		autoHideMenuBar: true, // 自动隐藏菜单栏
		useContentSize: true, // width 和 height 将设置为 web 页面的尺寸
		movable: false, // 是否可移动
		frame: false, // 无边框窗口
		resizable: false, // 窗口大小是否可调整
		hasShadow: false, // 窗口是否有阴影
		transparent: true, // 使窗口透明
		fullscreenable: true, // 窗口是否可以进入全屏状态
		fullscreen: true, // 窗口是否全屏
		simpleFullscreen: true, // 在 macOS 上使用 pre-Lion 全屏
		alwaysOnTop: false, // 窗口是否永远在别的窗口的上面
		webPreferences: {
			preload,
			nodeIntegration: true,
			contextIsolation: false,
		},
	});

	// shotScreenWin.webContents.openDevTools();

	if (url) {
		shotScreenWin.loadURL(url + "#/shotScreen");
	} else {
		shotScreenWin.loadFile(indexHtml, {
			hash: "shotScreen",
		});
	}
	shotScreenWin.maximize();
	shotScreenWin.setFullScreen(true);

	shotScreenWin?.webContents.session.on(
		"will-download",
		(e: any, item: DownloadItem, webContents: WebContents) => {
			const fileName = item.getFilename();
			const filePath = getFilePath() as string;
			const ssFilePath = path.join(savePath || `${filePath}/ss`, `${fileName}`);
			item.setSavePath(ssFilePath);
			item.once("done", (event: any, state: any) => {
				if (state === "completed") {
					copyImg(ssFilePath);
					setHistoryImg(ssFilePath);
					setTimeout(() => {
						closeShotScreenWin();
						// shell.showItemInFolder(ssFilePath);
					}, 1000);
				}
			});
		},
	);

	return shotScreenWin;
}

// 打开关闭录屏窗口
function closeShotScreenWin() {
	shotScreenWin?.isDestroyed() || shotScreenWin?.close();
	shotScreenWin = null;
}

function openShotScreenWin() {
	if (!shotScreenWin || shotScreenWin?.isDestroyed()) {
		shotScreenWin = createShotScreenWin();
	}
	shotScreenWin?.show();
}

function showShotScreenWin() {
	shotScreenWin?.show();
}

function hideShotScreenWin() {
	shotScreenWin?.hide();
}

function minimizeShotScreenWin() {
	shotScreenWin?.minimize();
}

function maximizeShotScreenWin() {
	shotScreenWin?.maximize();
}

function unmaximizeShotScreenWin() {
	shotScreenWin?.unmaximize();
}

async function downloadURLShotScreenWin(
	downloadUrl: string,
	isShowDialog?: boolean,
) {
	savePath = "";
	isShowDialog && (savePath = await showOpenDialogShotScreenWin());
	shotScreenWin?.webContents.downloadURL(downloadUrl);
}

async function showOpenDialogShotScreenWin() {
	let res = await dialog.showOpenDialog({
		properties: ["openDirectory"],
	});

	const savePath = res.filePaths[0] || "";

	return savePath;
}

function copyImg(filePath: string) {
	const image = nativeImage.createFromPath(filePath);
	clipboard.writeImage(image);
}

export {
	createShotScreenWin,
	closeShotScreenWin,
	openShotScreenWin,
	showShotScreenWin,
	hideShotScreenWin,
	minimizeShotScreenWin,
	maximizeShotScreenWin,
	unmaximizeShotScreenWin,
	downloadURLShotScreenWin,
};