| 1 | //! Our PNG writer is only correct if a decoder we did not write accepts it. |
| 2 | //! This drives python3's zlib as an independent inflater, unfilters the rows by |
| 3 | //! the spec, and requires an exact pixel match. Skips if python3 is unavailable. |
| 4 | |
| 5 | use nox_gfx::canvas::{Canvas, Paint, Stroke}; |
| 6 | use nox_gfx::color::{hex, rgba}; |
| 7 | use nox_gfx::geom::{pt, Rect, IDENTITY}; |
| 8 | use nox_gfx::path::Path; |
| 9 | use std::process::Command; |
| 10 | |
| 11 | const DECODER: &str = r#" |
| 12 | import sys, zlib, struct |
| 13 | png = open(sys.argv[1],'rb').read() |
| 14 | assert png[:8] == b'\x89PNG\r\n\x1a\n', 'bad signature' |
| 15 | i, idat, ihdr = 8, b'', None |
| 16 | while i < len(png): |
| 17 | n = struct.unpack_from('>I', png, i)[0] |
| 18 | tag = png[i+4:i+8] |
| 19 | body = png[i+8:i+8+n] |
| 20 | want = struct.unpack_from('>I', png, i+8+n)[0] |
| 21 | got = zlib.crc32(tag + body) & 0xffffffff |
| 22 | assert got == want, 'crc mismatch on %s' % tag |
| 23 | if tag == b'IHDR': ihdr = body |
| 24 | if tag == b'IDAT': idat += body |
| 25 | i += 12 + n |
| 26 | w, h, depth, ctype = struct.unpack('>IIBB', ihdr[:10]) |
| 27 | assert (depth, ctype) == (8, 6), 'expected 8-bit RGBA' |
| 28 | raw = zlib.decompress(idat) |
| 29 | bpp, stride = 4, w*4 |
| 30 | out = bytearray() |
| 31 | prev = bytearray(stride) |
| 32 | p = 0 |
| 33 | for y in range(h): |
| 34 | f = raw[p]; p += 1 |
| 35 | line = bytearray(raw[p:p+stride]); p += stride |
| 36 | for x in range(stride): |
| 37 | a = line[x-bpp] if x >= bpp else 0 |
| 38 | b = prev[x] |
| 39 | c = prev[x-bpp] if x >= bpp else 0 |
| 40 | if f == 1: line[x] = (line[x] + a) & 0xff |
| 41 | elif f == 2: line[x] = (line[x] + b) & 0xff |
| 42 | elif f == 3: line[x] = (line[x] + (a+b)//2) & 0xff |
| 43 | elif f == 4: |
| 44 | pp = a + b - c |
| 45 | pa, pb, pc = abs(pp-a), abs(pp-b), abs(pp-c) |
| 46 | pr = a if (pa <= pb and pa <= pc) else (b if pb <= pc else c) |
| 47 | line[x] = (line[x] + pr) & 0xff |
| 48 | elif f != 0: |
| 49 | raise SystemExit('bad filter %d' % f) |
| 50 | out += line |
| 51 | prev = line |
| 52 | assert p == len(raw), 'trailing data' |
| 53 | open(sys.argv[2],'wb').write(bytes(out)) |
| 54 | print('%d %d' % (w, h)) |
| 55 | "#; |
| 56 | |
| 57 | fn scene() -> Canvas { |
| 58 | let mut c = Canvas::new(233, 149); |
| 59 | c.clear(hex(0x101018)); |
| 60 | let mut p = Path::new(); |
| 61 | p.rrect(Rect::new(10.5, 8.25, 220.0, 120.75), 14.0); |
| 62 | c.fill(&p, &IDENTITY, &Paint::vgrad(Rect::new(0.0, 0.0, 1.0, 149.0), hex(0x7c5cff), hex(0x35d0ff))); |
| 63 | c.stroke(&p, &IDENTITY, &Paint::Solid(rgba(255, 255, 255, 90)), &Stroke::new(1.5)); |
| 64 | p.clear(); |
| 65 | p.circle(pt(70.0, 60.0), 33.0); |
| 66 | c.shadow(&p, &IDENTITY, 9.0, rgba(0, 0, 0, 200), pt(2.0, 5.0)); |
| 67 | c.fill(&p, &IDENTITY, &Paint::glow(pt(70.0, 60.0), 33.0, hex(0xffd166), rgba(255, 122, 89, 120))); |
| 68 | for i in 0..24 { |
| 69 | let x = 8.0 + i as f32 * 9.3; |
| 70 | c.fill_rect(Rect::new(x, 128.0, x + 6.0, 128.0 + (i % 7) as f32 * 2.5 + 3.0), hex(0x3ddc97)); |
| 71 | } |
| 72 | c |
| 73 | } |
| 74 | |
| 75 | #[test] |
| 76 | fn png_decodes_byte_identically_in_an_independent_decoder() { |
| 77 | if Command::new("python3").arg("--version").output().is_err() { |
| 78 | eprintln!("python3 not available, skipping"); |
| 79 | return; |
| 80 | } |
| 81 | let dir = std::env::temp_dir().join("nox-png-test"); |
| 82 | std::fs::create_dir_all(&dir).unwrap(); |
| 83 | let png_path = dir.join("scene.png"); |
| 84 | let out_path = dir.join("scene.raw"); |
| 85 | let script = dir.join("decode.py"); |
| 86 | std::fs::write(&script, DECODER).unwrap(); |
| 87 | |
| 88 | let c = scene(); |
| 89 | let png = c.to_png(); |
| 90 | std::fs::write(&png_path, &png).unwrap(); |
| 91 | let expected = c.to_rgba(); |
| 92 | |
| 93 | let raw_bytes = c.w * c.h * 4; |
| 94 | assert!( |
| 95 | png.len() * 3 < raw_bytes, |
| 96 | "png should be at least 3x smaller than raw ({} vs {raw_bytes})", |
| 97 | png.len() |
| 98 | ); |
| 99 | |
| 100 | let out = Command::new("python3") |
| 101 | .arg(&script) |
| 102 | .arg(&png_path) |
| 103 | .arg(&out_path) |
| 104 | .output() |
| 105 | .expect("run decoder"); |
| 106 | assert!( |
| 107 | out.status.success(), |
| 108 | "decoder rejected our png:\n{}", |
| 109 | String::from_utf8_lossy(&out.stderr) |
| 110 | ); |
| 111 | assert_eq!( |
| 112 | String::from_utf8_lossy(&out.stdout).trim(), |
| 113 | format!("{} {}", c.w, c.h) |
| 114 | ); |
| 115 | |
| 116 | let decoded = std::fs::read(&out_path).unwrap(); |
| 117 | assert_eq!(decoded.len(), expected.len(), "decoded size mismatch"); |
| 118 | for (i, (a, b)) in decoded.iter().zip(expected.iter()).enumerate() { |
| 119 | assert_eq!(a, b, "pixel byte {i} differs: decoded {a} vs encoded {b}"); |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | #[test] |
| 124 | fn png_survives_awkward_sizes() { |
| 125 | if Command::new("python3").arg("--version").output().is_err() { |
| 126 | return; |
| 127 | } |
| 128 | let dir = std::env::temp_dir().join("nox-png-test"); |
| 129 | std::fs::create_dir_all(&dir).unwrap(); |
| 130 | let script = dir.join("decode.py"); |
| 131 | std::fs::write(&script, DECODER).unwrap(); |
| 132 | |
| 133 | for (w, h) in [(1usize, 1usize), (1, 40), (40, 1), (3, 7), (255, 2), (2, 255)] { |
| 134 | let mut c = Canvas::new(w, h); |
| 135 | c.clear(rgba(9, 200, 30, 255)); |
| 136 | c.fill_rect(Rect::new(0.0, 0.0, w as f32 / 2.0, h as f32 / 2.0), rgba(255, 0, 0, 255)); |
| 137 | let png = c.to_png(); |
| 138 | let p = dir.join(format!("s{w}x{h}.png")); |
| 139 | let o = dir.join(format!("s{w}x{h}.raw")); |
| 140 | std::fs::write(&p, &png).unwrap(); |
| 141 | let out = Command::new("python3").arg(&script).arg(&p).arg(&o).output().unwrap(); |
| 142 | assert!( |
| 143 | out.status.success(), |
| 144 | "{w}x{h} rejected:\n{}", |
| 145 | String::from_utf8_lossy(&out.stderr) |
| 146 | ); |
| 147 | assert_eq!(std::fs::read(&o).unwrap(), c.to_rgba(), "{w}x{h} pixels differ"); |
| 148 | } |
| 149 | } |