Add new applet: Screen Recorder (screen-recorder@kprakesh)

[kpr-dev590]

Description

This PR introduces Screen Recorder, a new applet that allows users to easily capture their primary monitor directly from the Cinnamon panel.

Applet UUID: screen-recorder@kprakesh

Features

• Format Selection: Supports recording in both .webm (VP8/Vorbis) and .mp4 (H.264/AAC) formats.
• Audio Toggle: Optional system audio capture using PulseAudio (pactl get-default-sink).
• Custom Save Location: Users can define their preferred output directory in the settings.
• Visual Feedback: The panel icon updates to a red "REC" indicator while recording is active.

Technical Details & Compliance

• Execution: Utilizes ffmpeg -f x11grab for screen capture.
• Security: Fully compliant with Spices best practices. All shell executions use argument vectors (Util.spawn(["bash", "-c", ...]) and Util.spawn(["killall", ...])) rather than spawnCommandLineAsync to prevent shell injection vulnerabilities.
• License: GPL-3.0 declared in both source headers and info.json.

Dependencies

• ffmpeg

[fredcw]

According to Gemini:

This is a solid, functional Cinnamon applet. It’s clean, follows the standard boilerplate for Cinnamon desklets/applets, and handles the UI feedback (the red "REC" label) very well.

However, from a "production-ready" standpoint, there are a few risks—specifically regarding how it manages the ffmpeg process.

The Good Stuff
Settings Integration: You’ve correctly implemented AppletSettings, which makes the applet user-friendly.

Visual Feedback: Changing the icon color and label while recording is a great UX touch so users don't forget it's running.

Timestamping: Using GLib.DateTime for unique filenames prevents accidental overwrites.

Areas for Improvement

1. The killall Problem (Critical)
   Currently, you use killall -SIGINT ffmpeg. This is risky. If the user is running another instance of ffmpeg (e.g., converting a video or using another recording tool), your applet will kill that process too.

Solution: You should capture the PID (Process ID) of the specific ffmpeg instance you started and kill only that.

2. Process Monitoring
   If ffmpeg crashes (e.g., out of disk space or an invalid argument), your applet will still show "REC" and the stop button, even though nothing is happening.

Solution: Use GLib.child_watch_add to detect when the process terminates and reset the UI automatically.

3. Shell Command Safety
   You are passing a large string to bash -c. If a user puts a space or a special character in their saveDirectory (like "My Videos"), the command might break or behave unexpectedly.

Solution: Use GLib.shell_quote for paths or pass arguments as an array.

Suggested Code Refactor
Here is how I would tweak the start and stop functions to be more robust:

startRecording() {
    let monitor = Main.layoutManager.primaryMonitor;
    let screen_resolution = `${monitor.width}x${monitor.height}`;
    let now = GLib.DateTime.new_now_local();
    let timestamp = now.format("%Y-%m-%d_%H-%M-%S");
    
    let save_dir = this.saveDirectory.replace("~", GLib.get_home_dir());
    let output_file = `${save_dir}/ScreenRecord_${timestamp}.${this.outputFormat}`;

    // Properly escape the path for the shell
    let escaped_output = GLib.shell_quote(output_file);

    let audio_flag = this.recordAudio ? "-f pulse -i $(pactl get-default-sink).monitor" : "";
    let codec_flags = (this.outputFormat === "webm") 
        ? "-c:v libvpx -crf 10 -b:v 1M -c:a libvorbis" 
        : "-c:v libx264 -preset ultrafast -c:a aac";

    let ffmpeg_cmd = `ffmpeg -video_size ${screen_resolution} -framerate 30 -f x11grab -i :0.0 ${audio_flag} ${codec_flags} ${escaped_output}`;

    // Use GLib to spawn so we can track the PID
    let [success, argv] = GLib.shell_parse_argv(`bash -c '${ffmpeg_cmd}'`);
    if (success) {
        let [result, pid] = GLib.spawn_async(null, argv, null, GLib.SpawnFlags.SEARCH_PATH | GLib.SpawnFlags.DO_NOT_REAP_CHILD, null);
        this.current_pid = pid;

        // Watch for accidental crashes/closures
        GLib.child_watch_add(GLib.PRIORITY_DEFAULT, this.current_pid, (pid, status) => {
            if (this.isRecording) this.stopRecording(true); // Reset UI if ffmpeg dies
            GLib.spawn_close_pid(pid);
        });
    }

    // ... (UI Update Code) ...
    this.isRecording = true;
}

stopRecording(was_crash = false) {
    if (this.current_pid && !was_crash) {
        Util.spawn(["kill", "-SIGINT", this.current_pid.toString()]);
    }
    this.current_pid = null;
    
    // ... (UI Reset Code) ...
    this.isRecording = false;
}

Final Verdict
It’s a great utility! If this is for personal use, your current code is fine. If you plan to publish this on the Cinnamon Spices (the official applet store), you should definitely switch to PID-based tracking to avoid interfering with other system processes.

Also, you should handle the absence of ffmpeg in a more user friendly way since cinnamon can be installed on a lot of distros that may not install ffmpeg by default and people may not read the readme.md

[kpr-dev590]

According to Gemini:

This is a solid, functional Cinnamon applet. It’s clean, follows the standard boilerplate for Cinnamon desklets/applets, and handles the UI feedback (the red "REC" label) very well.
However, from a "production-ready" standpoint, there are a few risks—specifically regarding how it manages the ffmpeg process.
The Good Stuff
Settings Integration: You’ve correctly implemented AppletSettings, which makes the applet user-friendly.
Visual Feedback: Changing the icon color and label while recording is a great UX touch so users don't forget it's running.
Timestamping: Using GLib.DateTime for unique filenames prevents accidental overwrites.
Areas for Improvement

1. The killall Problem (Critical)
   Currently, you use killall -SIGINT ffmpeg. This is risky. If the user is running another instance of ffmpeg (e.g., converting a video or using another recording tool), your applet will kill that process too.

Solution: You should capture the PID (Process ID) of the specific ffmpeg instance you started and kill only that.

2. Process Monitoring
   If ffmpeg crashes (e.g., out of disk space or an invalid argument), your applet will still show "REC" and the stop button, even though nothing is happening.

Solution: Use GLib.child_watch_add to detect when the process terminates and reset the UI automatically.

3. Shell Command Safety
   You are passing a large string to bash -c. If a user puts a space or a special character in their saveDirectory (like "My Videos"), the command might break or behave unexpectedly.

Solution: Use GLib.shell_quote for paths or pass arguments as an array.
Suggested Code Refactor
Here is how I would tweak the start and stop functions to be more robust:

startRecording() {
    let monitor = Main.layoutManager.primaryMonitor;
    let screen_resolution = `${monitor.width}x${monitor.height}`;
    let now = GLib.DateTime.new_now_local();
    let timestamp = now.format("%Y-%m-%d_%H-%M-%S");
    
    let save_dir = this.saveDirectory.replace("~", GLib.get_home_dir());
    let output_file = `${save_dir}/ScreenRecord_${timestamp}.${this.outputFormat}`;

    // Properly escape the path for the shell
    let escaped_output = GLib.shell_quote(output_file);

    let audio_flag = this.recordAudio ? "-f pulse -i $(pactl get-default-sink).monitor" : "";
    let codec_flags = (this.outputFormat === "webm") 
        ? "-c:v libvpx -crf 10 -b:v 1M -c:a libvorbis" 
        : "-c:v libx264 -preset ultrafast -c:a aac";

    let ffmpeg_cmd = `ffmpeg -video_size ${screen_resolution} -framerate 30 -f x11grab -i :0.0 ${audio_flag} ${codec_flags} ${escaped_output}`;

    // Use GLib to spawn so we can track the PID
    let [success, argv] = GLib.shell_parse_argv(`bash -c '${ffmpeg_cmd}'`);
    if (success) {
        let [result, pid] = GLib.spawn_async(null, argv, null, GLib.SpawnFlags.SEARCH_PATH | GLib.SpawnFlags.DO_NOT_REAP_CHILD, null);
        this.current_pid = pid;

        // Watch for accidental crashes/closures
        GLib.child_watch_add(GLib.PRIORITY_DEFAULT, this.current_pid, (pid, status) => {
            if (this.isRecording) this.stopRecording(true); // Reset UI if ffmpeg dies
            GLib.spawn_close_pid(pid);
        });
    }

    // ... (UI Update Code) ...
    this.isRecording = true;
}

stopRecording(was_crash = false) {
    if (this.current_pid && !was_crash) {
        Util.spawn(["kill", "-SIGINT", this.current_pid.toString()]);
    }
    this.current_pid = null;
    
    // ... (UI Reset Code) ...
    this.isRecording = false;
}

Final Verdict
It’s a great utility! If this is for personal use, your current code is fine. If you plan to publish this on the Cinnamon Spices (the official applet store), you should definitely switch to PID-based tracking to avoid interfering with other system processes.

Also, you should handle the absence of ffmpeg in a more user friendly way since cinnamon can be installed on a lot of distros that may not install ffmpeg by default and people may not read the readme.md

Thank you for your feedback!

All requested changes regarding ffmpeg process handling, shell safety, and dependency checks have been implemented and pushed.

[fredcw]

Sorry, I forgot about this. Also, I've just noticed that there's already an applet which does screen recording using ffmpeg https://cinnamon-spices.linuxmint.com/applets/view/41

[kpr-dev590]

@fredcw I actually originally built this just for my own personal use to tinker with my setup, and figured I'd submit it just in case anyone else in the community found it helpful. I'm totally fine with closing this. Thanks for your time!