Add Crop Option

README.md

@@ -47,13 +47,17 @@ Run `cast2gif --help` to get the usage instructions:
     Renders Asciinema .cast files as gif, svg, or animated png.
 
     USAGE:
-        cast2gif [FLAGS] <cast_file> <out_file>
+        cast2gif [FLAGS] [OPTIONS] <cast_file> <out_file>
 
     FLAGS:
         -f, --force      Overwrite existing output file
         -h, --help       Prints help information
         -V, --version    Prints version information
 
+    OPTIONS:
+        -c, --crop <crop>    crop the recording while rendering. Specify crop in terminal cells as
+                            `top=[int],left=[int],width=[int],height=[int]`.
+
     ARGS:
         <cast_file>    The asciinema .cast file to render
         <out_file>     The file to render to

src/cli.rs

@@ -37,13 +37,22 @@ pub fn run() {
     .expect("Panic while handling panic");
 }
 
+#[derive(Debug)]
 enum OutputFormat {
     Gif,
     // TODO: Other image formats
     // Png,
     // Svg,
 }
 
+#[derive(Debug, Clone, Copy)]
+pub struct CropSettings {
+    pub top: u16,
+    pub left: u16,
+    pub width: u16,
+    pub height: u16,
+}
+
 fn execute_cli() -> anyhow::Result<()> {
     use clap::{crate_authors, crate_version, App, AppSettings, Arg};
 
@@ -60,6 +69,13 @@ fn execute_cli() -> anyhow::Result<()> {
         .arg(Arg::with_name("out_file")
             .help("The file to render to")
             .required(true))
+        .arg(Arg::with_name("crop")
+            .long("crop")
+            .short("c")
+            .help("crop the recording while rendering. \
+                   Specify crop in terminal cells as \
+                   `top=[int],left=[int],width=[int],height=[int]`.")
+            .takes_value(true))
         // TODO: Implement other file formats
         // .arg(Arg::with_name("format")
         //     .long("format")
@@ -137,6 +153,45 @@ fn execute_cli() -> anyhow::Result<()> {
     //     Some("png") => OutputFormat::Png,
     //     Some(other) => panic!("Invalid option to --format: {}", other),
     // };
+    let crop = {
+        let mut top = None;
+        let mut left = None;
+        let mut width = None;
+        let mut height = None;
+
+        if let Some(crop_str) = args.value_of("crop") {
+            for pair in crop_str.split(",") {
+                let split: Vec<_> = pair.split("=").collect();
+                let key = split.get(0);
+                let value = split.get(1);
+
+                if let Some(value) = value {
+                    let value: u16 = value.parse().context("Could not parse crop value as int")?;
+
+                    if let Some(&key) = key {
+                        match key {
+                            "top" => top = Some(value),
+                            "left" => left = Some(value),
+                            "width" => width = Some(value),
+                            "height" => height = Some(value),
+                            _ => continue,
+                        }
+                    }
+                }
+            }
+        };
+
+        if top.is_none() || left.is_none() || width.is_none() || height.is_none() {
+            None
+        } else {
+            Some(CropSettings {
+                top: top.unwrap(),
+                left: left.unwrap(),
+                width: width.unwrap(),
+                height: height.unwrap(),
+            })
+        }
+    };
 
     // Create the progress bars
     let multi = MultiProgress::new();
@@ -158,6 +213,7 @@ fn execute_cli() -> anyhow::Result<()> {
                     cast_file,
                     &out_file,
                     progress_handler,
+                    crop
                 )
                 .expect("TODO");
             });

src/frame_renderer/fontkit.rs

@@ -18,7 +18,7 @@ use std::iter::FromIterator;
 use std::sync::Arc;
 
 use super::parse_color;
-use crate::types::*;
+use crate::{cli::CropSettings, types::*};
 
 lazy_static! {
     static ref FONT_DATA: Arc<Vec<u8>> = Arc::new(Vec::from_iter(
@@ -34,7 +34,7 @@ thread_local! {
     static FONT: Font = Font::from_bytes(FONT_DATA.clone(), 0).expect("Could not load font");
 }
 
-pub(crate) fn render_frame_to_png(frame: TerminalFrame) -> RgbaFrame {
+pub(crate) fn render_frame_to_png(frame: TerminalFrame, crop: Option<CropSettings>) -> RgbaFrame {
     flame!(guard "Render Frame To PNG");
 
     flame!(start "Init Values");
@@ -43,6 +43,11 @@ pub(crate) fn render_frame_to_png(frame: TerminalFrame) -> RgbaFrame {
     // TODO: Configurable background color
     const DEFAULT_BG_COLOR: RGBA8 = RGBA::new(0, 0, 0, 255);
 
+    let crop_rows = crop.map(|x| x.height).unwrap_or(rows);
+    let crop_cols = crop.map(|x| x.width).unwrap_or(cols);
+    let crop_top = crop.map(|x| x.top).unwrap_or(0);
+    let crop_left = crop.map(|x| x.left).unwrap_or(0);
+
     // Glyph rendering config
     lazy_static! {
         // static ref TRANS: Transform2F = Transform2F::default();
@@ -73,8 +78,8 @@ pub(crate) fn render_frame_to_png(frame: TerminalFrame) -> RgbaFrame {
     let font_transform =
         Transform2F::from_translation(Vector2F::new(0., -font_height_offset as f32));
 
-    let height = (rows as i32 * font_height) as usize;
-    let width = (cols as i32 * font_width) as usize;
+    let height = (crop_rows as i32 * font_height) as usize;
+    let width = (crop_cols as i32 * font_width) as usize;
 
     // Image to render to
     let pixel_count = width * height;
@@ -89,11 +94,11 @@ pub(crate) fn render_frame_to_png(frame: TerminalFrame) -> RgbaFrame {
     flame!(end "Init Values");
 
     flame!(start "Render Cells");
-    for row in 0..rows {
-        for col in 0..cols {
+    for (row_i, row) in (crop_top..(crop_top + crop_rows)).enumerate() {
+        for (col_i, col) in (crop_left..(crop_left + crop_cols)).enumerate() {
             let cell = frame.screen.cell(row, col).expect("Error indexing cell");
-            let ypos = row as i32 * font_height;
-            let xpos = col as i32 * font_width;
+            let ypos = row_i as i32 * font_height;
+            let xpos = col_i as i32 * font_width;
             let mut subimg = image.sub_image_mut(
                 xpos as usize,
                 ypos as usize,

src/lib.rs

@@ -1,3 +1,4 @@
+use cli::CropSettings;
 use lazy_static::lazy_static;
 use thiserror::Error;
 
@@ -76,6 +77,7 @@ fn png_raster_thread<Fi>(
     frames: Fi,
     progress_sender: flume::Sender<ProgressCmd>,
     frame_sender: flume::Sender<RgbaFrame>,
+    crop: Option<CropSettings>,
 ) where
     Fi: IntoIterator<Item = Result<TerminalFrame, AsciinemaError>>,
 {
@@ -93,7 +95,7 @@ fn png_raster_thread<Fi>(
         let fs = frame_sender.clone();
         let ps = progress_sender.clone();
         rayon::spawn(move || {
-            let frame = frame_renderer::render_frame_to_png(frame);
+            let frame = frame_renderer::render_frame_to_png(frame, crop);
             fs.send(frame).expect("TODO");
             ps.send(ProgressCmd::IncrementRasterProgress).expect("TODO");
         });
@@ -125,6 +127,7 @@ pub fn convert_to_gif_with_progress<R, W, C>(
     reader: R,
     writer: W,
     update_progress: C,
+    crop: Option<CropSettings>,
 ) -> Result<(), Error>
 where
     R: Read + Send + 'static,
@@ -146,7 +149,7 @@ where
 
     // Spawn the png rasterizer thread
     let ps = progress_sender.clone();
-    rayon::spawn(move || png_raster_thread(term_frames, ps, raster_sender));
+    rayon::spawn(move || png_raster_thread(term_frames, ps, raster_sender, crop));
 
     // Create gifski gif encoder
     let (collector, gif_writer) = gifski::new(gifski::Settings {
@@ -197,10 +200,10 @@ impl gifski::progress::ProgressReporter for GifWriterProgressHandler {
     fn done(&mut self, _msg: &str) {}
 }
 
-pub fn convert_to_gif<R, W>(reader: R, writer: W) -> Result<(), Error>
+pub fn convert_to_gif<R, W>(reader: R, writer: W, crop: Option<CropSettings>) -> Result<(), Error>
 where
     R: Read + Send + 'static,
     W: Write + Send,
 {
-    convert_to_gif_with_progress(reader, writer, NullProgressHandler)
+    convert_to_gif_with_progress(reader, writer, NullProgressHandler, crop)
 }