electron 截图，两种方式：desktopCapturer.getSources 与 navigator.mediaDevices.getUserMedia

 1 // In the renderer process.

import { desktopCapturer } from 'electron';
import { screen } from '@electron/remote';

export async function captureScreen() {
  const url_base64 = await getCaptureBySourceThumbnail();
  // const url_base64 = await getCaptureByStream(await getStream());
  return url_base64;
}

// 获取屏幕尺寸
function getSize() {
  // scaleFactor 缩放因子
  const { size, scaleFactor } = screen.getPrimaryDisplay();
  return {
    width: size.width * scaleFactor,
    height: size.height * scaleFactor
  };
}

// 通过 source thumbnail 获取截图
async function getCaptureBySourceThumbnail() {
  if (process.platform !== 'win32') return;
  const sources = await desktopCapturer.getSources({
    types: ['window', 'screen'],
    thumbnailSize: getSize()
  });
  if (!sources || !sources.length) throw new Error('sources 为空');
  return sources[0].thumbnail.toDataURL();
}

// 获取 web RTC 视频流
async function getStream() {
  const { width, height } = getSize();

  return await navigator.mediaDevices.getUserMedia({
    audio: false,
    video: {
      mandatory: {
        chromeMediaSource: 'desktop',
        // chromeMediaSourceId: source.id,
        minWidth: width, // 直接设置 width、height 会报错
        maxWidth: width,
        minHeight: height,
        maxHeight: height
      }
    }
  });
}

// 关闭视频流
function closeStream(stream) {
  const tracks = stream.getTracks() || [];
  for (const track of tracks) {
    track.stop();
  }
}

// 通过 web RTC 视频流获取截图（存在鼠标）
function getCaptureByStream(stream) {
  const { width, height } = getSize();

  return new Promise(resolve => {
    const _video = document.createElement('video');
    _video.srcObject = stream;
    _video.onloadedmetadata = () => {
      _video.play();

      const _canvas = document.createElement('canvas');
      _canvas.width = width;
      _canvas.height = height;
      const _context = _canvas.getContext('2d');
      _context.drawImage(_video, 0, 0, _canvas.width, _canvas.height);
      const url_base64 = _canvas.toDataURL('image/png');
      _video.pause();
      closeStream(stream);

      return resolve(url_base64);
    };
  });
}