Automatically export frames based on path

Author: sandorex

src/lib.rs

@@ -7,7 +7,7 @@ mod vt;
 
 use std::fmt::{Debug, Display};
 use std::fs::File;
-use std::io::{BufRead, Write};
+use std::io::BufRead;
 use std::{iter, thread, time::Instant};
 
 use anyhow::{anyhow, Context, Result};
@@ -199,13 +199,17 @@ pub fn run<I: BufRead>(input: I, config: Config) -> Result<()> {
     let start_time = Instant::now();
 
     if config.output_frames {
-        // check for existance of the output directory to provide a clear error message
-        if std::fs::exists(&config.output_filename)? {
-            return Err(anyhow!("Frame output path {:?} already exists", config.output_filename));
+        let dir_path = std::path::PathBuf::from(&config.output_filename);
+
+        // create directory if it does not already exist
+        if !dir_path.try_exists()? {
+            std::fs::create_dir(&dir_path)?;
         }
 
-        // create the directory in advance
-        std::fs::create_dir(&config.output_filename)?;
+        // make sure output directory is empty
+        if !dir_path.read_dir()?.next().is_none() {
+            return Err(anyhow!("Output directory is not empty"));
+        }
 
         let mut pr: Box<dyn ProgressReporter> = if config.show_progress_bar {
             Box::new(ProgressBar::new(count))
@@ -216,12 +220,8 @@ pub fn run<I: BufRead>(input: I, config: Config) -> Result<()> {
         for (i, frame) in frames.enumerate() {
             let (_, lines, cursor) = frame?;
 
-            let frame_file_path = std::path::PathBuf::new()
-                .join(&config.output_filename)
-                .join(format!("{}.png", i));
-
             let svg = renderer.render_pixmap(lines, cursor);
-            svg.save_png(frame_file_path)
+            svg.save_png(dir_path.join(format!("{}.png", i)))
                 .with_context(|| anyhow!("Could not encode frame {i}"))?;
 
             if !pr.increase() {

src/main.rs

@@ -48,14 +48,14 @@ impl clap::builder::TypedValueParser for ThemeValueParser {
 #[clap(author, version, about, long_about = None)]
 struct Cli {
     /// asciicast path/filename or URL
-    input_filename_or_url: String,
+    #[clap(value_name = "INPUT_FILENAME_OR_URL")]
+    input: String,
 
-    /// GIF path/filename (output directory if outputting frames)
-    output_filename: String,
-
-    /// Output each frame as PNG image
-    #[clap(long)]
-    output_frames: bool,
+    /// GIF path/filename
+    ///
+    /// If path ends with a slash or is a directory frames are saved instead
+    #[clap(value_name = "OUTPUT_FILENAME_OR_DIR")]
+    output: String,
 
     /// Select frame rendering backend
     #[clap(long, arg_enum, default_value_t = agg::Renderer::default())]
@@ -176,6 +176,10 @@ fn main() -> Result<()> {
         .format_timestamp(None)
         .init();
 
+    // output frames if path ends with a path separator or is a directory
+    let output_frames = cli.output.ends_with(std::path::MAIN_SEPARATOR_STR)
+        || std::fs::metadata(&cli.output).is_ok_and(|x| x.is_dir());
+
     let config = agg::Config {
         cols: cli.cols,
         font_dirs: cli.font_dir,
@@ -191,17 +195,17 @@ fn main() -> Result<()> {
         speed: cli.speed,
         theme: cli.theme.map(|theme| theme.0),
         show_progress_bar: !cli.quiet,
-        output_frames: cli.output_frames,
-        output_filename: cli.output_filename.clone(),
+        output_frames: output_frames,
+        output_filename: cli.output.clone(),
     };
 
-    let input = BufReader::new(reader(&cli.input_filename_or_url)?);
+    let input = BufReader::new(reader(&cli.input)?);
     match agg::run(input, config) {
         Ok(ok) => Ok(ok),
         Err(err) => {
             // do not try to delete a directory
-            if !cli.output_frames {
-                std::fs::remove_file(&cli.output_filename)?;
+            if !output_frames {
+                std::fs::remove_file(&cli.output)?;
             }
 
             Err(err)