Add chars mode.

README.txt

@@ -1,5 +1,8 @@
 cnoise - colored noise, sets random pixels in selected colors
-    paramater is not used yet
+    parameter is not used yet
+
+chars - display characters randomly
+    parameter is not used yet
 
 bimood - color cycling mood lamp with two complementary colors
     parameter is the seconds for one cycle through the colors

src/bin/chars/main.rs

@@ -0,0 +1,88 @@
+use std::env::args;
+use std::fs::File;
+use std::io::stdout;
+use std::io::Read;
+use std::io::Write;
+use std::iter::repeat_with;
+use std::thread::sleep;
+use std::time::Duration;
+
+use rand::thread_rng;
+use rand::Rng;
+
+use pixelfoo::color::Color;
+
+type Frame = Vec<Vec<Color>>;
+
+fn send<T: Write>(w: &mut T, f: &Frame) -> std::io::Result<()> {
+    for l in f {
+        for c in l {
+            w.write_all(&c.rgb())?;
+        }
+    }
+    w.flush()
+}
+
+fn pick_color<R>(c0: Color, c1: Color, rng: &mut R) -> Color
+where
+    R: Rng,
+{
+    if rng.gen::<f64>() < 0.5 {
+        c0.interpolate(c1, rng.gen::<f64>().powf(2.0))
+    } else {
+        Color::black()
+    }
+}
+
+fn main() -> std::io::Result<()> {
+    let args = args().collect::<Vec<_>>();
+    eprintln!("executing {}", args[0]);
+
+    let x_size = args[1].parse::<usize>().unwrap();
+    let y_size = args[2].parse::<usize>().unwrap();
+    eprintln!("screen size {}x{}", x_size, y_size);
+
+    let mut f = File::open("apps/pet-2.bin")?;
+    let mut buffer = Vec::new();
+    f.read_to_end(&mut buffer)?;
+
+    let t_frame = 0.040; // s
+    let delay = Duration::new(0, (1_000_000_000.0 * t_frame) as u32);
+
+    let c0 = Color::new(0, 138, 170);
+    let c1 = Color::new(0, 160, 95);
+
+    let mut rng = thread_rng();
+
+    let mut frame = repeat_with(|| {
+        repeat_with(|| pick_color(c0, c1, &mut rng))
+            .take(x_size)
+            .collect::<Vec<_>>()
+    })
+    .take(y_size)
+    .collect::<Vec<_>>();
+    loop {
+        let x = rng.gen_range(0, x_size / 8);
+        let y = rng.gen_range(0, y_size / 8);
+        let color = pick_color(c0, c1, &mut rng);
+        let start_index = rng.gen_range(0, buffer.len() / 8) * 8;
+        for i in start_index..(start_index + 8) {
+            let b = buffer[i];
+            for j in 0..8 {
+                frame[y][x] = {
+                    if b & (1 << j) != 0 {
+                        color
+                    } else {
+                        Color::black()
+                    }
+                };
+            }
+        }
+
+        let mut buf = Vec::with_capacity(x_size * y_size * 3);
+        send(&mut buf, &frame)?;
+        stdout().write_all(&buf)?;
+        stdout().flush()?;
+        sleep(delay);
+    }
+}