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alvinometricalvinometric
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Working on writing tags
1 parent b49d74b commit b811988

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3 files changed

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3 files changed

+252
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‎src/jpeg.rs

Lines changed: 193 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -41,4 +41,197 @@ impl JPEGReader {
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4242
Ok(HashMap::new())
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}
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pub fn write_iptc(
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buffer: &Vec<u8>,
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data: &HashMap<IPTCTag, String>,
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) -> Result<Vec<u8>, Box<dyn Error>> {
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let mut new_buffer = Vec::new();
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// Copy the initial JPEG marker (SOI)
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if buffer.len() < 2 || buffer[0] != 0xFF || buffer[1] != 0xD8 {
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return Err("Not a valid JPEG file".into());
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}
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new_buffer.extend_from_slice(&buffer[0..2]);
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let mut offset = 2;
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// Convert IPTC data to binary format first
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let iptc_data = Self::convert_iptc_to_binary(data)?;
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let mut found_app13 = false;
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let mut inserted_app13 = false;
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// Copy segments until we find SOS
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while offset + 1 < buffer.len() {
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// Every JPEG segment must start with 0xFF
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if buffer[offset] != 0xFF {
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offset += 1;
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continue;
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}
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let marker = buffer[offset + 1];
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// Skip empty markers
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if marker == 0xFF {
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offset += 1;
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continue;
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}
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// For markers without length field
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if marker == 0x00 || marker == 0x01 || (marker >= 0xD0 && marker <= 0xD7) {
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new_buffer.extend_from_slice(&buffer[offset..offset + 2]);
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offset += 2;
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continue;
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}
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// End of image marker
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if marker == 0xD9 {
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new_buffer.extend_from_slice(&buffer[offset..offset + 2]);
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break;
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}
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// Start of scan marker - copy the rest of the file
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if marker == 0xDA {
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// If we haven't inserted APP13 yet, do it now
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if !found_app13 && !inserted_app13 {
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// Write APP13 marker
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new_buffer.extend_from_slice(&[0xFF, 0xED]);
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// Write length (including length bytes)
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let total_length = (iptc_data.len() + 2) as u16;
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new_buffer.push((total_length >> 8) as u8);
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new_buffer.push(total_length as u8);
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// Write IPTC data
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new_buffer.extend_from_slice(&iptc_data);
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}
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// Copy SOS marker and all remaining data
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new_buffer.extend_from_slice(&buffer[offset..]);
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break;
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}
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// Check if we can read the length
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if offset + 3 >= buffer.len() {
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new_buffer.extend_from_slice(&buffer[offset..]);
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break;
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}
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let length = buffer.read_u16be(offset + 2) as usize;
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// Validate segment length
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if length < 2 || offset + 2 + length > buffer.len() {
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new_buffer.extend_from_slice(&buffer[offset..]);
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break;
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}
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// If this is APP13, replace it with our new data
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if marker == 0xED {
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found_app13 = true;
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// Write APP13 marker
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new_buffer.extend_from_slice(&[0xFF, 0xED]);
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// Write length (including length bytes)
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let total_length = (iptc_data.len() + 2) as u16;
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new_buffer.push((total_length >> 8) as u8);
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new_buffer.push(total_length as u8);
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// Write IPTC data
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new_buffer.extend_from_slice(&iptc_data);
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offset += 2 + length;
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} else {
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// If we haven't found APP13 and this is after APP0/APP1 but before other segments,
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// insert our APP13 data here
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if !found_app13 && !inserted_app13 && marker > 0xE1 {
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// Write APP13 marker
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new_buffer.extend_from_slice(&[0xFF, 0xED]);
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// Write length (including length bytes)
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let total_length = (iptc_data.len() + 2) as u16;
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new_buffer.push((total_length >> 8) as u8);
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new_buffer.push(total_length as u8);
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// Write IPTC data
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new_buffer.extend_from_slice(&iptc_data);
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inserted_app13 = true;
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}
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// Copy the marker and its data
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new_buffer.extend_from_slice(&buffer[offset..offset + 2 + length]);
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offset += 2 + length;
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}
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}
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Ok(new_buffer)
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}
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fn convert_iptc_to_binary(data: &HashMap<IPTCTag, String>) -> Result<Vec<u8>, Box<dyn Error>> {
162+
let mut binary = Vec::new();
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// Add Photoshop header
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binary.extend_from_slice(b"Photoshop 3.0\0");
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binary.push(0x00); // Pad to even length
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// Add 8BIM marker and IPTC block
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let mut iptc_block = Vec::new();
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// Add IPTC data
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for (tag, value) in data {
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if let Some((record, dataset)) = Self::get_record_dataset(tag) {
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// Field delimiter
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iptc_block.push(0x1C);
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// Record number and dataset number
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iptc_block.push(record);
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iptc_block.push(dataset);
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// Value length (big endian)
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let value_bytes = value.as_bytes();
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let value_len = value_bytes.len() as u16;
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iptc_block.push((value_len >> 8) as u8);
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iptc_block.push(value_len as u8);
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// Value
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iptc_block.extend_from_slice(value_bytes);
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}
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}
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// Add 8BIM marker
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binary.extend_from_slice(b"8BIM");
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// Resource ID for IPTC (0x0404)
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binary.extend_from_slice(&[0x04, 0x04]);
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// Empty name (padded to even length)
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binary.push(0x00);
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binary.push(0x00);
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// Block size (big endian)
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let block_size = iptc_block.len() as u32;
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binary.extend_from_slice(&[
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(block_size >> 24) as u8,
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(block_size >> 16) as u8,
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(block_size >> 8) as u8,
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block_size as u8,
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]);
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// Add the IPTC block
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binary.extend_from_slice(&iptc_block);
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// Pad to even length if needed
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if binary.len() % 2 != 0 {
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binary.push(0x00);
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}
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Ok(binary)
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}
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fn get_record_dataset(tag: &IPTCTag) -> Option<(u8, u8)> {
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match tag {
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IPTCTag::City => Some((2, 90)),
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IPTCTag::Keywords => Some((2, 25)),
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IPTCTag::ByLine => Some((2, 80)),
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IPTCTag::Caption => Some((2, 120)),
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IPTCTag::CopyrightNotice => Some((2, 116)),
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IPTCTag::Credit => Some((2, 110)),
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IPTCTag::Headline => Some((2, 105)),
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IPTCTag::ObjectName => Some((2, 5)),
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IPTCTag::Source => Some((2, 115)),
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IPTCTag::Urgency => Some((2, 10)),
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_ => None,
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}
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}
44237
}

‎src/lib.rs

Lines changed: 25 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -54,6 +54,31 @@ impl IPTC {
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returned_tag.unwrap().clone()
5555
}
5656

57+
pub fn set_tag(&mut self, tag: IPTCTag, value: &str) {
58+
self.data.insert(tag, value.to_string());
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}
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pub fn write_to_file(&self, image_path: &Path) -> Result<(), Box<dyn Error>> {
62+
let file = File::open(image_path)?;
63+
let bufreader = BufReader::new(file);
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let img_reader = ImageReader::new(bufreader).with_guessed_format()?;
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let format = img_reader.format().ok_or("Image format not supported")?;
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let file = File::open(image_path)?;
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let mut bufreader = BufReader::new(file);
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let mut buffer: Vec<u8> = Vec::new();
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bufreader.read_to_end(&mut buffer)?;
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let new_buffer = if format == ImageFormat::Jpeg {
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JPEGReader::write_iptc(&buffer, &self.data)?
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} else {
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return Err("Writing IPTC data is only supported for JPEG files".into());
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};
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std::fs::write(image_path, new_buffer)?;
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Ok(())
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}
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5782
pub fn read_from_path(image_path: &Path) -> Result<Self, Box<dyn Error>> {
5883
let file = File::open(image_path)?;
5984
let bufreader = BufReader::new(file);

‎tests/smiley.rs

Lines changed: 34 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,5 @@
11
use std::error::Error;
2+
use std::fs;
23
use std::path::Path;
34

45
use iptc::IPTC;
@@ -32,3 +33,36 @@ fn exiv2_iptc_example() -> Result<(), Box<dyn Error>> {
3233

3334
Ok(())
3435
}
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#[test]
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fn test_write_iptc() -> Result<(), Box<dyn Error>> {
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// Create a copy of the test file so we don't modify the original
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let original_path = Path::new("tests/smiley.jpg");
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let test_path = Path::new("tests/smiley_write_test.jpg");
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let debug_path = Path::new("tests/smiley_debug.jpg");
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fs::copy(original_path, test_path)?;
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// Read the original IPTC data
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let mut iptc = IPTC::read_from_path(&test_path)?;
47+
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// Modify some tags
49+
iptc.set_tag(IPTCTag::City, "Oslo");
50+
iptc.set_tag(IPTCTag::Keywords, "New keyword");
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// Write the changes
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iptc.write_to_file(&test_path)?;
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// Make a copy for debugging
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fs::copy(test_path, debug_path)?;
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// Read back and verify
59+
let new_iptc = IPTC::read_from_path(&test_path)?;
60+
assert_eq!(new_iptc.get(IPTCTag::City), "Oslo");
61+
assert_eq!(new_iptc.get(IPTCTag::Keywords), "New keyword");
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// Clean up
64+
fs::remove_file(test_path)?;
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fs::remove_file(debug_path)?;
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Ok(())
68+
}

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