rust: improve pixel-cell example

rust/examples/pixel-cell.rs

@@ -1,11 +1,16 @@
-//! sixel example
+//! pixel example
 //!
-//! used to determine the number of pixels per cell, which is relative to font size
-
-use libnotcurses_sys::*;
+//! Shows how to get the size of a cell in pixels
+//!
+//! It works on the following terminals:
+//! - kitty
+//! - xterm (invoked with `xterm -ti vt340`)
+//! - alacritty (WIP https://github.com/ayosec/alacritty/tree/graphics)
 
 use rand::{distributions::Uniform, Rng};
 
+use libnotcurses_sys::*;
+
 fn main() -> NcResult<()> {
     let mut nc = FullMode::new()?;
 
@@ -13,31 +18,40 @@ fn main() -> NcResult<()> {
         return Err(NcError::new_msg("Current terminal doesn't support pixels."));
     }
 
-    // the dimensions of the terminal
-    // let (trows, tcols) = nc.term_dim_yx();
-
-    // choose the size of the cell in pixels
-    let pixels_w = 10;
-    let pixels_h = 19;
+    // get the dimensions of the terminal in rows,cols & x,y pixels
+    let mut ws: libc::winsize = unsafe { std::mem::zeroed() };
+    unsafe { libc::ioctl(0, libc::TIOCGWINSZ, &mut ws) };
+    let term_rows = ws.ws_row;
+    let term_cols = ws.ws_col;
+    let term_y = ws.ws_ypixel;
+    let term_x = ws.ws_xpixel;
+    // calculate the size of the cell in pixels
+    let cell_y = (term_y / term_rows) as u32;
+    let cell_x = (term_x / term_cols) as u32;
+    // println!(
+    //     "rows,cols={},{}; term y,x={},{}; cell y,x={},{}",
+    //     term_rows, term_cols, term_y, term_x, cell_y, cell_x
+    // );
 
     // print visual delimiters around our pixelized cell
-    println!("0▗│▖\n│─ ─...\n2▝│▘");
-    println!("pixels per cell: {}x{}", pixels_w, pixels_h);
+    println!("0▗│▖\n│─ ─\n2▝│▘");
+    println!("a cell is {}x{} pixels", cell_y, cell_x);
 
     // fill the buffer with random color pixels
     let mut rng = rand::thread_rng();
     let range = Uniform::from(50..=180);
-    let mut buffer = Vec::<u8>::with_capacity((pixels_w*pixels_h*4) as usize);
+    let mut buffer = Vec::<u8>::with_capacity((cell_y * cell_x * 4) as usize);
     #[allow(unused_parens)]
-    for _byte in (0..={pixels_w*pixels_h}) {
+    for _byte in (0..={ cell_x * cell_y }) {
         buffer.push(rng.sample(&range));
         buffer.push(rng.sample(&range));
         buffer.push(rng.sample(&range));
         buffer.push(255);
     }
 
-    let pixels = NcVisual::from_rgba(buffer.as_slice(), pixels_h, pixels_w*4, pixels_w)?;
-    let voptions = NcVisualOptions::without_plane(1, 2, 0, 0, pixels_h, pixels_w, NCBLIT_PIXEL, 0);
+    // show the newly created ncvisual delimited with the box drawing characters
+    let pixels = NcVisual::from_rgba(buffer.as_slice(), cell_y, cell_x * 4, cell_x)?;
+    let voptions = NcVisualOptions::without_plane(1, 2, 0, 0, cell_y, cell_x, NCBLIT_PIXEL, 0);
     pixels.render(&mut nc, &voptions)?;
 
     rsleep![&mut nc, 10];