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bflatasticandClaude Opus 5.5
6a446b4fa3
file.info takes and reports the title, author, author title, description, keywords, rating, copyright status, notice and URL in one undo step, plus the read-only created (file.new) and modified (every save to a file) dates; junk values are refused. Document.metadata (DocMetadata) round-trips natively. PDF export writes author, subject and keywords to the info dictionary and XMP, PNG export writes tEXt/iTXt chunks, SVG export writes <desc> and, with the metadata option, every field as Dublin Core. The File Info dialog (fileInfo, ui.fileInfoDialog) edits it with keyword chips and star ratings. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
48 lines
2.1 KiB
Rust
48 lines
2.1 KiB
Rust
//! PNG text chunks (`tEXt`, uncompressed `iTXt`) read back; the PNG writer adds them
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//! ([`vectorcraft_render::encode::png::with_text`]).
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/// The `tEXt` and uncompressed `iTXt` entries of a PNG before its image data: (keyword, text).
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pub fn text(png: &[u8]) -> Vec<(String, String)> {
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if !png.starts_with(b"\x89PNG\r\n\x1a\n") {
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return vec![];
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}
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super::ppi::png_chunks(png)
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.take_while(|(ty, _)| *ty != b"IDAT")
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.filter_map(|(ty, data)| {
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let nul = data.iter().position(|b| *b == 0)?;
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let keyword: String = data.get(..nul)?.iter().map(|b| char::from(*b)).collect();
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let rest = data.get(nul + 1..)?;
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let text = match ty {
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b"tEXt" => rest.iter().map(|b| char::from(*b)).collect(),
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// Compression flag 0, method, then the language tag and translated keyword.
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b"iTXt" if rest.first() == Some(&0) => {
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let mut parts = rest.get(2..)?.splitn(3, |b| *b == 0);
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let (_, _, text) = (parts.next()?, parts.next()?, parts.next()?);
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String::from_utf8_lossy(text).into_owned()
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}
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_ => return None,
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};
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Some((keyword, text))
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})
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.collect()
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}
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#[cfg(test)]
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mod tests {
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use vectorcraft_render::encode::png::with_text;
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use super::*;
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#[test]
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fn text_chunks_round_trip_and_stay_valid() {
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let png = vectorcraft_render::Rendered { width: 2, height: 1, pixels: vec![255; 8] }.to_png().unwrap();
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let out = with_text(png.clone(), &[("Title", "Café".into()), ("Author", "Łukasz".into()), ("bad\u{1}", "x".into())]);
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assert_eq!(text(&out), [("Title".to_string(), "Café".to_string()), ("Author".into(), "Łukasz".into())]);
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// Still a PNG every decoder reads (the CRCs check out).
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let img = image::load_from_memory(&out).unwrap();
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assert_eq!((img.width(), img.height()), (2, 1));
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assert_eq!(with_text(b"not a png".to_vec(), &[("Title", "x".into())]), b"not a png");
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assert_eq!(with_text(png.clone(), &[]), png);
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}
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}
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