获取electron窗口截图，转成base64

getScreenshotData.ts

import { desktopCapturer } from 'electron';

let video: HTMLVideoElement;

/**
 * 获取窗口截图，转成base64
 * @param document 
 */
export default function getScreenshotData(document: Document) {

    return new Promise(async (resolve, reject) => {
        const captureSources = await desktopCapturer.getSources({ types: ['window']});
        const targetCaptureSource = captureSources.filter(item => item.name === document.title)[0];
        if (targetCaptureSource) {
            try {
                const mediaStream = await navigator.mediaDevices.getUserMedia({
                    audio: false,
                    video: {
                        mandatory: {
                            chromeMediaSource: 'desktop',
                            chromeMediaSourceId: targetCaptureSource.id,
                            maxWidth: document.body.clientWidth,
                            maxHeight: document.body.clientHeight,
                            minWidth: document.body.clientWidth,
                            minHeight: document.body.clientHeight
                        }
                    }
                } as MediaStreamConstraints);
                {
                    if(!video) {
                        video = document.createElement('video');
                    }
                    video.srcObject = mediaStream;
                    video.onloadedmetadata = () => {
                        video.play();
                        let canvas = document.createElement('canvas');
                        canvas.width = document.body.clientWidth;
                        canvas.height = document.body.clientHeight;
                        const ctx = canvas.getContext('2d');
                        ctx.drawImage(video, 0, 0, canvas.width, canvas.height);
                        video.pause();
                        resolve(canvas.toDataURL('image/jpeg'));
                    }
                }
            } catch(e) {
                reject(e);
            }
        }
    });
}