armcord/src/preload/capturer.ts

//Fixed context isolation version https://github.com/getferdi/ferdi/blob/develop/src/webview/screenshare.ts
//original https://github.com/electron/electron/issues/16513#issuecomment-602070250
import {ipcRenderer} from "electron";
import {addStyle, addScript} from "../utils";
import fs from "fs";
import path from "path";
const desktopCapturer = {
    getSources: (opts: any) => ipcRenderer.invoke("DESKTOP_CAPTURER_GET_SOURCES", opts)
};
const CANCEL_ID = "desktop-capturer-selection__cancel";

interface IPCSources {
    id: string;
    name: string;
    thumbnail: HTMLCanvasElement;
}

export async function getDisplayMediaSelector() {
    const sources: IPCSources[] = await desktopCapturer.getSources({
        types: ["screen", "window"]
    });
    return `<div class="desktop-capturer-selection__scroller">
  <ul class="desktop-capturer-selection__list">
    ${sources
        .map(
            ({id, name, thumbnail}) => `
      <li class="desktop-capturer-selection__item">
        <button class="desktop-capturer-selection__btn" data-id="${id}" title="${name}">
          <img class="desktop-capturer-selection__thumbnail" src="${thumbnail.toDataURL()}" />
          <span class="desktop-capturer-selection__name">${name}</span>
        </button>
      </li>
    `
        )
        .join("")}
    <li class="desktop-capturer-selection__item">
      <button class="desktop-capturer-selection__btn" data-id="${CANCEL_ID}" title="Cancel">
        <span class="desktop-capturer-selection__name desktop-capturer-selection__name--cancel">Cancel</span>
      </button>
    </li>
  </ul>
</div>`;
}

const screenShareJS = `
window.navigator.mediaDevices.getDisplayMedia = () => new Promise(async (resolve, reject) => {
  try {
    const selectionElem = document.createElement('div');
    selectionElem.classList = ['desktop-capturer-selection'];
    selectionElem.innerHTML = await window.armcord.getDisplayMediaSelector();
    document.body.appendChild(selectionElem);
    document
      .querySelectorAll('.desktop-capturer-selection__btn')
      .forEach((button) => {
        button.addEventListener('click', async () => {
          try {
            const id = button.getAttribute('data-id');
            if (id === '${CANCEL_ID}') {
              reject(new Error('Cancelled by user'));
            } else {
              const stream = await window.navigator.mediaDevices.getUserMedia({
                audio: false,
                video: {
                  mandatory: {
                    chromeMediaSource: 'desktop',
                    chromeMediaSourceId: id,
                  },
                },
              });
              resolve(stream);
            }
          } catch (err) {
            reject(err);
          } finally {
            selectionElem.remove();
          }
        });
      });
  } catch (err) {
    reject(err);
  }
});
`;

document.addEventListener("DOMContentLoaded", function () {
    addScript(screenShareJS);
    const screenshareCss = path.join(__dirname, "../", "/content/css/screenshare.css");
    addStyle(fs.readFileSync(screenshareCss, "utf8"));
    console.log("Capturer injected.");
});