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

//! Does a screen declare its own OPAQUE BLACK backdrop? Disc-wide.
//!
//! `sylpheed-port` observed that the splash builds declare `palogo_eff0.prm` as a
//! full-screen primitive at t=0 with `fade_argb 0xff000000` -- alpha 255 over RGB
//! 000000 -- and turned it into a candidate predicate: a declared opaque-black
//! backdrop separates STANDALONE screens from COMPOSITED ones. On their sixteen
//! exported screens it splits 12 / 4, with all four exceptions independently known
//! to be composited (the two `press_start` plates, and two loading builds that
//! carry the `pgloading_*` set without its backdrop).
//!
//! That matters because the corpus previously told them "no content rule exists,
//! take the entry index" -- correct for the question asked (recognise the splash),
//! but this is a content rule for a different and useful question. They asked for
//! it to be tested against an archive they do not have. This is that test.
//!
//! CONTROL: it must reproduce the 12/4 split on GP_TITLE's sixteen composable
//! bundles before its disc-wide numbers mean anything.
//!
//!     cargo run -p sylpheed-formats --example black_backdrop_predicate
use sylpheed_formats::{pak::PakArchive, ui_layout};
use std::io::Write;
use std::path::PathBuf;

/// A screen declares its own backdrop if some `.prm` primitive holds
/// `fade == 0xff000000` at t = 0: full alpha over black.
fn has_black_backdrop(b: &ui_layout::UiBuild) -> Option<String> {
    for el in &b.elements {
        if !el.name.ends_with(".prm") { continue }
        if let Some(k) = el.keyframes.iter().find(|k| k.time == Some(0)) {
            if k.fade == 0xff00_0000 { return Some(el.name.clone()) }
        }
    }
    None
}

fn main() {
    let root = PathBuf::from(std::env::var("SYLPHEED_DISC").expect("SYLPHEED_DISC"));

    println!("== CONTROL: GP_TITLE's 16 composable bundles (port reports 12 with, 4 without)");
    let ar = PakArchive::open(root.join("dat/GP_TITLE.pak")).expect("GP_TITLE.pak");
    let (mut y, mut n) = (0, 0);
    for e in 0..16usize {
        let Ok(by) = ar.read(&ar.entries()[e]) else { continue };
        let Some(b) = ui_layout::parse_build(&by) else { continue };
        match has_black_backdrop(&b) {
            Some(nm) => { y += 1; println!("   entry {e:>2}  YES  {nm}") }
            None => { n += 1; println!("   entry {e:>2}  no") }
        }
    }
    println!("   -> {y} with, {n} without\n");

    println!("== DISC-WIDE, over every screen build");
    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 tot, mut with) = (0usize, 0usize);
    for pak in &paks {
        let Ok(ar) = PakArchive::open(pak) else { continue };
        let name = pak.file_name().unwrap().to_string_lossy().to_string();
        let (mut t, mut w) = (0usize, 0usize);
        for e in ar.entries() {
            let Ok(by) = ar.read(e) else { continue };
            if !ui_layout::is_build(&by) { continue }
            let Some(b) = ui_layout::parse_build(&by) else { continue };
            t += 1;
            if has_black_backdrop(&b).is_some() { w += 1 }
        }
        if t > 0 {
            println!("{name:30} {w:4} / {t:<4} declare a black backdrop");
            std::io::stdout().flush().ok();
        }
        tot += t; with += w;
    }
    println!("\n{with} of {tot} screen builds disc-wide declare an opaque-black backdrop \
              ({:.1} %)", 100.0 * with as f64 / tot as f64);
    println!("--- END ---");
}