54 lines
1.9 KiB
Rust
54 lines
1.9 KiB
Rust
/// Tests "editing"/re-encoding of an image:
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/// decoding, editing, re-encoding
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use std::fs::File;
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use std::io::{BufReader, BufWriter};
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use std::path::Path;
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use png::DecodingError::LimitsExceeded;
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pub type BoxResult<T> = Result<T, Box<dyn std::error::Error + Send + Sync>>;
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fn main() -> BoxResult<()> {
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// # Decode
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// Read test image from pngsuite
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let path_in = Path::new(r"./tests/pngsuite/basi0g01.png");
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// The decoder is a build for reader and can be used to set various decoding options
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// via `Transformations`. The default output transformation is `Transformations::IDENTITY`.
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let decoder = png::Decoder::new(BufReader::new(File::open(path_in)?));
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let mut reader = decoder.read_info()?;
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// Allocate the output buffer.
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let png_info = reader.info();
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let mut buf = vec![0; reader.output_buffer_size().ok_or(LimitsExceeded)?];
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println!("{png_info:?}");
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// # Encode
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let path_out = Path::new(r"./target/test_modified.png");
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let file = File::create(path_out)?;
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let ref mut w = BufWriter::new(file);
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// Get defaults for interlaced parameter.
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let mut info_out = png_info.clone();
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let info_default = png::Info::default();
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// Edit previous info
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info_out.interlaced = info_default.interlaced;
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let mut encoder = png::Encoder::with_info(w, info_out)?;
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encoder.set_depth(png_info.bit_depth);
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// Edit some attribute
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encoder.add_text_chunk(
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"Testing tEXt".to_string(),
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"This is a tEXt chunk that will appear before the IDAT chunks.".to_string(),
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)?;
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// Save picture with changed info
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let mut writer = encoder.write_header()?;
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let mut counter = 0u8;
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while let Ok(info) = reader.next_frame(&mut buf) {
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let bytes = &buf[..info.buffer_size()];
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writer.write_image_data(&bytes)?;
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counter += 1;
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println!("Written frame: {}", counter);
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}
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Ok(())
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}
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