Panic attempt to divide by zero

[tristan-morris]

This library is absolutely amazing!!

I'm processing some large images (so I'm pushing it!) and manage to get a panic during resize.

• 65536 to 65536/2 = Panic
• 65537 to 65536/2 = Fine

use fast_image_resize::{PixelType, Resizer, images::Image};

fn main() {
    let w_h = 65536;

    let buffer = vec![0u8; w_h * w_h * 4];
    let src_image = Image::from_vec_u8(w_h as u32, w_h as u32, buffer, PixelType::U8x4).unwrap();

    let new_w_h = 32768;

    println!(
        "Resizing image from {}x{} to {}x{}",
        w_h, w_h, new_w_h, new_w_h
    );

    let mut dst_image = Image::new(new_w_h as u32, new_w_h as u32, PixelType::U8x4);

    Resizer::new()
        .resize(&src_image, &mut dst_image, None)
        .unwrap();

    println!("Resizing completed successfully.");
}

user@box:~/resizer/resizer$ cargo run --release --
>Resizing image from 65536x65536 to 32768x32768
>thread 'main' panicked at /home/user/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/fast_image_resize-5.2.1/src/threading.rs:68:22:
>attempt to divide by zero
>note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

user@box:~/resizer/resizer$ cargo run --release --
> Resizing image from 65537x65537 to 32768x32768
>Resizing completed successfully

This method seems to be the issue, I haven't had a chance to fix it yet.

/// It is not optimal to split images on too small parts.
/// We have to calculate minimal height of one part.
/// For small images, it is equal to `constant / area`.
/// For tall images, it is equal to `height / 256`.
fn calculate_max_h_parts_number(width: u32, height: u32) -> u32 {
    if width == 0 || height == 0 {
        return 1;
    }
    let area = height * height.max(width);
    let min_height = ((1 << 14) / area).max(height / 256).max(1);
    height / min_height.max(1)
}

[Cykooz]

Ohh. It looks like taking this code from another library was a bad idea. But I didn't have any ideas how to implement such heuristic without a lot of benchmarks and tests.

I will fix it soon.

[Cykooz]

I released version 5.2.2

[tristan-morris]

Amazing! Thank you for the super fast fix!!