Sylpheed/crates/sylpheed-formats/examples/rest_fallback_audit.rs

//! Does "1 697 fallback fires return a visible pose" survive being said out loud?
//!
//! `rest-fallback-census.txt` reports that of 2 305 elements where the dwell
//! fallback decides, 1 697 rest at `alpha > 0`. It was written as if that number
//! were the defect. **It is only a defect where the element is a transient.** An
//! element that genuinely ends visible and stays visible SHOULD rest visible, and
//! the fallback happening to be the path that got there is not an error.
//!
//! The port agent hit the mirror image of this: it counted a screen's own exit
//! ramp as the end of an element's visibility, so `ptmsg` — the main menu's
//! permanent footer — came out as "a 2-unit flash". The story collapsed when
//! said aloud. This asks the same question of my number.
//!
//! Split the 1 697 by what the element's LAST keyframe does:
//!   * last alpha > 0  -> the element ends visible; resting visible is right
//!   * last alpha == 0 -> it fades out; a visible rest is a transient's peak
//!
//!     cargo run -p sylpheed-formats --example rest_fallback_audit
use sylpheed_formats::{pak::PakArchive, ui_layout};
use std::path::PathBuf;

fn main() {
    let root = PathBuf::from(std::env::var("SYLPHEED_DISC").expect("SYLPHEED_DISC"));
    let mut paks: Vec<PathBuf> = std::fs::read_dir(root.join("dat")).expect("dat/")
        .filter_map(|e| e.ok().map(|e| e.path()))
        .filter(|p| p.extension().is_some_and(|x| x == "pak")).collect();
    paks.sort();
    let (mut fires, mut vis, mut ends_visible, mut ends_zero, mut at_peak) = (0, 0, 0, 0, 0);
    // ⚠️ The port agent's exit-ramp finding applies to THIS split too: if a
    // screen's exit ramp drives every element to a=0, then "last keyframe a=0"
    // says nothing about the element being a transient. Measure it on ALL
    // elements before using it on the 1 697.
    let (mut all_el, mut all_end_zero) = (0usize, 0usize);
    for pak in &paks {
        let Ok(ar) = PakArchive::open(pak) else { continue };
        for e in ar.entries() {
            let Ok(by) = ar.read(e) else { continue };
            let Some(b) = ui_layout::parse_build(&by) else { continue };
            for el in &b.elements {
                if el.keyframes.len() < 2 { continue }
                all_el += 1;
                if (el.keyframes.last().unwrap().fade >> 24) & 0xff == 0 { all_end_zero += 1 }
                if el.keyframes.windows(2).any(|w| w[0].x == w[1].x && w[0].y == w[1].y
                    && w[0].scale_x == w[1].scale_x && w[0].scale_y == w[1].scale_y
                    && w[0].fade == w[1].fade) { continue }
                fires += 1;
                let Some(r) = el.rest() else { continue };
                let a = (r.fade >> 24) & 0xff;
                if a == 0 { continue }
                vis += 1;
                let last = (el.keyframes.last().unwrap().fade >> 24) & 0xff;
                if last > 0 { ends_visible += 1 } else { ends_zero += 1 }
                let peak = el.keyframes.iter().map(|k| (k.fade >> 24) & 0xff).max().unwrap_or(0);
                if a == peak { at_peak += 1 }
            }
        }
    }
    println!("fallback fires                         {fires}");
    println!("  of those, rest alpha > 0             {vis}");
    println!("    element's LAST keyframe alpha > 0  {ends_visible}   <- ends visible; resting visible is CORRECT");
    println!("    element's LAST keyframe alpha = 0  {ends_zero}   <- fades out; a visible rest is a transient's peak");
    println!("  rest alpha == the element's MAX      {at_peak}");
    println!("\nCONTROL on the split itself — is 'ends at a=0' near-universal?");
    println!("  all elements with >= 2 keyframes     {all_el}");
    println!("  of those, last keyframe alpha = 0    {all_end_zero}  ({:.1} %)",
             100.0 * all_end_zero as f64 / all_el as f64);
    println!("\n--- END (if this line is missing, the run did not finish) ---");
}