png_to_jpeg/
png_to_jpeg.rs

1use libvips::{ops, VipsApp, VipsImage};
2use std::env;
3use std::path::Path;
4
5// Load a JPEG file, transform and convert it to PNG
6// Use the following cargo command to run this example
7// cargo run --example jpeg_to_png
8
9fn main() {
10    // this initializes the libvips library. it has to live as long as the application lives (or as long as you want to use the library within your app)
11    // you can't have multiple objects of this type and when it is dropped it will call the libvips functions to free all internal structures.
12    let app = VipsApp::new(
13        "Test Libvips",
14        false,
15    )
16    .expect("Cannot initialize libvips");
17
18    //set number of threads in libvips's threadpool
19    app.concurrency_set(2);
20    let cargo_toml_dir = env::current_dir()
21        .expect("Where is my Cargo.toml file?")
22        .display()
23        .to_string();
24    let image_path = Path::new("examples/test.png")
25        .display()
26        .to_string();
27
28    // loads an image from file
29    let image = VipsImage::new_from_file(&format!(
30        "{}/{}",
31        cargo_toml_dir, image_path
32    ))
33    .unwrap();
34
35    // will resize the image and return a new instance.
36    // libvips works most of the time with immutable objects, so it will return a new object
37    // the VipsImage struct implements Drop, which will free the memory
38    let resized = ops::resize(
39        &image,
40        0.5,
41    )
42    .unwrap();
43
44    //optional parameters
45    let options = ops::JpegsaveOptions {
46        q: 90,
47        background: vec![255.0],
48        interlace: true,
49        optimize_coding: true,
50        optimize_scans: true,
51        ..ops::JpegsaveOptions::default()
52    };
53
54    // alternatively you can use `jpegsave` that will use the default options
55    match ops::jpegsave_with_opts(
56        &resized,
57        &format!(
58            "{}/examples/{}",
59            cargo_toml_dir, "png_to_jpeg.jpg"
60        ),
61        &options,
62    ) {
63        Err(_) => println!(
64            "error: {}",
65            app.error_buffer()
66                .unwrap()
67        ),
68        Ok(_) => println!("png_to_jpeg.jpg was created within the examples directory!"),
69    }
70}
png_to_jpeg/png_to_jpeg.rs

png_to_jpeg/
png_to_jpeg.rs
