Vendor dependencies for 0.3.0 release

vendor/png/examples/change-png-info.rs

@@ -0,0 +1,53 @@
+/// Tests "editing"/re-encoding of an image:
+/// decoding, editing, re-encoding
+use std::fs::File;
+use std::io::{BufReader, BufWriter};
+use std::path::Path;
+
+use png::DecodingError::LimitsExceeded;
+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(BufReader::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().ok_or(LimitsExceeded)?];
+    println!("{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()];
+        writer.write_image_data(&bytes)?;
+        counter += 1;
+        println!("Written frame: {}", counter);
+    }
+    Ok(())
+}