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