add linux audio screensharing (#130)

Co-authored-by: V <vendicated@riseup.net>
Co-authored-by: kaitlynkitty <87152313+kaitlynkittyy@users.noreply.github.com>
Co-authored-by: Curve <fynnbwdt@gmail.com>

src/renderer/patches/index.ts

@@ -8,3 +8,4 @@
 import "./spellCheck";
 import "./platformClass";
 import "./windowsTitleBar";
+import "./screenShareAudio";

src/renderer/patches/screenShareAudio.ts

@@ -0,0 +1,42 @@
+/*
+ * SPDX-License-Identifier: GPL-3.0
+ * Vesktop, a desktop app aiming to give you a snappier Discord Experience
+ * Copyright (c) 2023 Vendicated and Vencord contributors
+ */
+
+import { isLinux } from "renderer/utils";
+
+if (isLinux) {
+    const original = navigator.mediaDevices.getDisplayMedia;
+
+    async function getVirtmic() {
+        try {
+            const devices = await navigator.mediaDevices.enumerateDevices();
+            const audioDevice = devices.find(({ label }) => label === "vencord-screen-share");
+            return audioDevice?.deviceId;
+        } catch (error) {
+            return null;
+        }
+    }
+
+    navigator.mediaDevices.getDisplayMedia = async function (opts) {
+        const stream = await original.call(this, opts);
+        const id = await getVirtmic();
+
+        if (id) {
+            const audio = await navigator.mediaDevices.getUserMedia({
+                audio: {
+                    deviceId: {
+                        exact: id
+                    },
+                    autoGainControl: false,
+                    echoCancellation: false,
+                    noiseSuppression: false
+                }
+            });
+            audio.getAudioTracks().forEach(t => stream.addTrack(t));
+        }
+
+        return stream;
+    };
+}