tauri/examples/streaming/main.rs

// Copyright 2019-2022 Tauri Programme within The Commons Conservancy
// SPDX-License-Identifier: Apache-2.0
// SPDX-License-Identifier: MIT

#![cfg_attr(
  all(not(debug_assertions), target_os = "windows"),
  windows_subsystem = "windows"
)]

fn main() {
  use std::{
    cmp::min,
    io::{Read, Seek, SeekFrom},
    path::PathBuf,
    process::{Command, Stdio},
  };
  use tauri::http::{HttpRange, ResponseBuilder};

  let video_file = PathBuf::from("test_video.mp4");
  let video_url =
    "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/BigBuckBunny.mp4";

  if !video_file.exists() {
    // Downloading with curl this saves us from adding
    // a Rust HTTP client dependency.
    println!("Downloading {video_url}");
    let status = Command::new("curl")
      .arg("-L")
      .arg("-o")
      .arg(&video_file)
      .arg(video_url)
      .stdout(Stdio::inherit())
      .stderr(Stdio::inherit())
      .output()
      .unwrap();

    assert!(status.status.success());
    assert!(video_file.exists());
  }

  tauri::Builder::default()
    .invoke_handler(tauri::generate_handler![video_uri])
    .register_uri_scheme_protocol("stream", move |_app, request| {
      // prepare our response
      let mut response = ResponseBuilder::new();
      // get the file path
      let path = request.uri().strip_prefix("stream://localhost/").unwrap();
      let path = percent_encoding::percent_decode(path.as_bytes())
        .decode_utf8_lossy()
        .to_string();

      if path != "example/test_video.mp4" {
        // return error 404 if it's not out video
        return response.mimetype("text/plain").status(404).body(Vec::new());
      }

      // read our file
      let mut content = std::fs::File::open(&video_file)?;
      let mut buf = Vec::new();

      // default status code
      let mut status_code = 200;

      // if the webview sent a range header, we need to send a 206 in return
      // Actually only macOS and Windows are supported. Linux will ALWAYS return empty headers.
      if let Some(range) = request.headers().get("range") {
        // Get the file size
        let file_size = content.metadata().unwrap().len();

        // we parse the range header with tauri helper
        let range = HttpRange::parse(range.to_str().unwrap(), file_size).unwrap();
        // let support only 1 range for now
        let first_range = range.first();
        if let Some(range) = first_range {
          let mut real_length = range.length;

          // prevent max_length;
          // specially on webview2
          if range.length > file_size / 3 {
            // max size sent (400ko / request)
            // as it's local file system we can afford to read more often
            real_length = min(file_size - range.start, 1024 * 400);
          }

          // last byte we are reading, the length of the range include the last byte
          // who should be skipped on the header
          let last_byte = range.start + real_length - 1;
          // partial content
          status_code = 206;

          // Only macOS and Windows are supported, if you set headers in linux they are ignored
          response = response
            .header("Connection", "Keep-Alive")
            .header("Accept-Ranges", "bytes")
            .header("Content-Length", real_length)
            .header(
              "Content-Range",
              format!("bytes {}-{}/{}", range.start, last_byte, file_size),
            );

          // FIXME: Add ETag support (caching on the webview)

          // seek our file bytes
          content.seek(SeekFrom::Start(range.start))?;
          content.take(real_length).read_to_end(&mut buf)?;
        } else {
          content.read_to_end(&mut buf)?;
        }
      }

      response.mimetype("video/mp4").status(status_code).body(buf)
    })
    .run(tauri::generate_context!(
      "../../examples/streaming/tauri.conf.json"
    ))
    .expect("error while running tauri application");
}

// returns the scheme and the path of the video file
// we're using this just to allow using the custom `stream` protocol or tauri built-in `asset` protocol
#[tauri::command]
fn video_uri() -> (&'static str, std::path::PathBuf) {
  #[cfg(feature = "protocol-asset")]
  {
    let mut path = std::env::current_dir().unwrap();
    path.push("test_video.mp4");
    ("asset", path)
  }

  #[cfg(not(feature = "protocol-asset"))]
  ("stream", "example/test_video.mp4".into())
}