Add option to output frames as PNGs

sandorex · sandorex · commit d55294bf1ed5 · 2026-04-10T16:53:40.000+02:00
diff --git a/src/lib.rs b/src/lib.rs
@@ -6,11 +6,13 @@ mod theme;
 mod vt;
 
 use std::fmt::{Debug, Display};
+use std::fs::File;
 use std::io::{BufRead, Write};
 use std::{iter, thread, time::Instant};
 
-use anyhow::{anyhow, Result};
+use anyhow::{anyhow, Context, Result};
 use clap::ArgEnum;
+use gifski::progress::{NoProgress, ProgressBar, ProgressReporter};
 use log::info;
 
 use crate::asciicast::Asciicast;
@@ -40,6 +42,8 @@ pub struct Config {
     pub speed: f64,
     pub theme: Option<Theme>,
     pub show_progress_bar: bool,
+    pub output_frames: bool,
+    pub output_filename: String,
 }
 
 impl Default for Config {
@@ -59,6 +63,8 @@ impl Default for Config {
             speed: DEFAULT_SPEED,
             theme: Default::default(),
             show_progress_bar: true,
+            output_frames: false,
+            output_filename: "".to_string(),
         }
     }
 }
@@ -129,7 +135,7 @@ impl Display for Theme {
     }
 }
 
-pub fn run<I: BufRead, O: Write + Send>(input: I, output: O, config: Config) -> Result<()> {
+pub fn run<I: BufRead>(input: I, config: Config) -> Result<()> {
     let Asciicast { header, events, .. } = asciicast::open(input)?;
 
     if header.term_cols == 0 || header.term_rows == 0 {
@@ -188,50 +194,84 @@ pub fn run<I: BufRead, O: Write + Send>(input: I, output: O, config: Config) ->
 
     let (width, height) = renderer.pixel_size();
 
-    info!("gif dimensions: {}x{}", width, height);
+    info!("output dimensions: {}x{}", width, height);
 
-    let repeat = if config.no_loop {
-        gifski::Repeat::Finite(0)
-    } else {
-        gifski::Repeat::Infinite
-    };
+    let start_time = Instant::now();
 
-    let settings = gifski::Settings {
-        width: Some(width as u32),
-        height: Some(height as u32),
-        fast: true,
-        repeat,
-        ..Default::default()
-    };
+    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 (collector, writer) = gifski::new(settings)?;
-    let start_time = Instant::now();
+        // create the directory in advance
+        std::fs::create_dir(&config.output_filename)?;
 
-    thread::scope(|s| {
-        let writer_handle = s.spawn(move || {
-            if config.show_progress_bar {
-                let mut pr = gifski::progress::ProgressBar::new(count);
-                let result = writer.write(output, &mut pr);
-                pr.finish();
-                println!();
-                result
-            } else {
-                let mut pr = gifski::progress::NoProgress {};
-                writer.write(output, &mut pr)
-            }
-        });
+        let mut pr: Box<dyn ProgressReporter> = if config.show_progress_bar {
+            Box::new(ProgressBar::new(count))
+        } else {
+            Box::new(NoProgress {})
+        };
 
         for (i, frame) in frames.enumerate() {
-            let (time, lines, cursor) = frame?;
-            let image = renderer.render(lines, cursor);
-            let time = if i == 0 { 0.0 } else { time };
-            collector.add_frame_rgba(i, image, time + config.last_frame_duration)?;
+            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)
+                .with_context(|| anyhow!("Could not encode frame {i}"))?;
+
+            if !pr.increase() {
+                return Err(anyhow!("Progress bar interrupted"));
+            }
         }
+    } else {
+        let repeat = if config.no_loop {
+            gifski::Repeat::Finite(0)
+        } else {
+            gifski::Repeat::Infinite
+        };
+
+        let settings = gifski::Settings {
+            width: Some(width as u32),
+            height: Some(height as u32),
+            fast: true,
+            repeat,
+            ..Default::default()
+        };
+
+        let (collector, writer) = gifski::new(settings)?;
+        let output = File::create(&config.output_filename)?;
+
+        thread::scope(|s| {
+            let writer_handle = s.spawn(move || {
+                if config.show_progress_bar {
+                    let mut pr = gifski::progress::ProgressBar::new(count);
+                    let result = writer.write(output, &mut pr);
+                    pr.finish();
+                    println!();
+                    result
+                } else {
+                    let mut pr = gifski::progress::NoProgress {};
+                    writer.write(output, &mut pr)
+                }
+            });
+
+            for (i, frame) in frames.enumerate() {
+                let (time, lines, cursor) = frame?;
+                let image = renderer.render(lines, cursor);
+                let time = if i == 0 { 0.0 } else { time };
+                collector.add_frame_rgba(i, image, time + config.last_frame_duration)?;
+            }
 
-        drop(collector);
-        writer_handle.join().unwrap()?;
-        Result::<()>::Ok(())
-    })?;
+            drop(collector);
+            writer_handle.join().unwrap()?;
+            Result::<()>::Ok(())
+        })?;
+    }
 
     info!(
         "rendering finished in {}s",
diff --git a/src/main.rs b/src/main.rs
@@ -50,9 +50,13 @@ struct Cli {
     /// asciicast path/filename or URL
     input_filename_or_url: String,
 
-    /// GIF path/filename
+    /// GIF path/filename (output directory if outputting frames)
     output_filename: String,
 
+    /// Output each frame as PNG image
+    #[clap(long)]
+    output_frames: bool,
+
     /// Select frame rendering backend
     #[clap(long, arg_enum, default_value_t = agg::Renderer::default())]
     renderer: agg::Renderer,
@@ -187,15 +191,19 @@ 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(),
     };
 
     let input = BufReader::new(reader(&cli.input_filename_or_url)?);
-    let mut output = File::create(&cli.output_filename)?;
-
-    match agg::run(input, &mut output, config) {
+    match agg::run(input, config) {
         Ok(ok) => Ok(ok),
         Err(err) => {
-            std::fs::remove_file(cli.output_filename)?;
+            // do not try to delete a directory
+            if !cli.output_frames {
+                std::fs::remove_file(&cli.output_filename)?;
+            }
+
             Err(err)
         }
     }
diff --git a/src/renderer.rs b/src/renderer.rs
@@ -3,10 +3,12 @@ mod resvg;
 
 use imgref::ImgVec;
 use rgb::{RGB8, RGBA8};
+use tiny_skia::Pixmap;
 
 use crate::theme::Theme;
 
 pub trait Renderer {
+    fn render_pixmap(&mut self, lines: Vec<avt::Line>, cursor: Option<(usize, usize)>) -> Pixmap;
     fn render(&mut self, lines: Vec<avt::Line>, cursor: Option<(usize, usize)>) -> ImgVec<RGBA8>;
     fn pixel_size(&self) -> (usize, usize);
 }
diff --git a/src/renderer/fontdue.rs b/src/renderer/fontdue.rs
@@ -3,6 +3,7 @@ use crate::theme::Theme;
 use imgref::ImgVec;
 use log::debug;
 use rgb::RGBA8;
+use tiny_skia::{PremultipliedColorU8, Pixmap};
 use std::collections::HashMap;
 
 type CharVariant = (char, bool, bool);
@@ -167,6 +168,19 @@ fn mix_colors(fg: RGBA8, bg: RGBA8, ratio: u8) -> RGBA8 {
 }
 
 impl Renderer for FontdueRenderer {
+    fn render_pixmap(&mut self, lines: Vec<avt::Line>, cursor: Option<(usize, usize)>) -> tiny_skia::Pixmap {
+        let buf = self.render(lines, cursor);
+        let mut pixmap = Pixmap::new(buf.width() as u32, buf.height() as u32).unwrap();
+
+        // TODO could this be done more efficiently as it is currently copying all the data
+        let pixels = pixmap.pixels_mut();
+        for (i, color) in buf.pixels().enumerate() {
+            pixels[i] = PremultipliedColorU8::from_rgba(color.r, color.g, color.b, color.a).unwrap();
+        }
+
+        pixmap
+    }
+
     fn render(&mut self, lines: Vec<avt::Line>, cursor: Option<(usize, usize)>) -> ImgVec<RGBA8> {
         let mut buf: Vec<RGBA8> =
             vec![self.theme.background.alpha(255); self.pixel_width * self.pixel_height];
diff --git a/src/renderer/resvg.rs b/src/renderer/resvg.rs
@@ -241,7 +241,7 @@ impl<'a> ResvgRenderer<'a> {
 }
 
 impl<'a> Renderer for ResvgRenderer<'a> {
-    fn render(&mut self, lines: Vec<avt::Line>, cursor: Option<(usize, usize)>) -> ImgVec<RGBA8> {
+    fn render_pixmap(&mut self, lines: Vec<avt::Line>, cursor: Option<(usize, usize)>) -> tiny_skia::Pixmap {
         let mut svg = self.header.clone();
         self.push_lines(&mut svg, lines, cursor);
         svg.push_str(Self::footer());
@@ -251,7 +251,12 @@ impl<'a> Renderer for ResvgRenderer<'a> {
             tiny_skia::Pixmap::new(self.pixel_width as u32, self.pixel_height as u32).unwrap();
 
         resvg::render(&tree, self.transform, &mut pixmap.as_mut());
-        let buf = pixmap.take().as_rgba().to_vec();
+
+        pixmap
+    }
+
+    fn render(&mut self, lines: Vec<avt::Line>, cursor: Option<(usize, usize)>) -> ImgVec<RGBA8> {
+        let buf = self.render_pixmap(lines, cursor).take().as_rgba().to_vec();
 
         ImgVec::new(buf, self.pixel_width, self.pixel_height)
     }
