Cropping a layer based on it's content

[ok-nick]

I'm assuming this isn't currently supported and I was looking at a few dependencies that do, but they include a lot of other stuff outside of psd's scope.
I was planning on doing this externally, but would it cause further optimizations if done internally? Any pointers on how it could be done? My goal is to export a layer as a png, excluding any white space.
I'm currently using the layer.rgba() method

[ok-nick]

Also quick question, how would you suggest exporting the return from layer.rgba() as a png?

[chinedufn]

Here's a quick example of creating an image::DynamicImage.

use image::{DynamicImage, GenericImage, Rgba};
use psd::Psd;

pub fn img_from_psd(psd: &Psd) -> DynamicImage {
    let pixels = psd.rgba();
    let pixel_count = pixels.len() / 4;

    let mut img = DynamicImage::new_rgba8(psd.width(), psd.height());

    for idx in 0..pixel_count {
        let x = idx as u32 % psd.width();
        let y = idx as u32 / psd.width();

        let mut pixel = [0; 4];
        let pixel_slice = &pixels[4 * idx..4 * idx + 4];
        pixel.copy_from_slice(pixel_slice);

        img.put_pixel(x, y, Rgba(pixel))
    }

    img
}

The image crate has methods for cropping as well as other image manipulation functions.

If you only need a PNG with no image manipulation you can also take a look at https://docs.rs/png/0.16.8/png/#using-the-encoder

---

I think you're right that something like cropping belongs outside of the psd crate.

Let me know if you need any more help with this issue, otherwise best of luck.

[chinedufn]

My goal is to export a layer as a png, excluding any white space.

Oh, and for the excluding any white space portion.

You can handle this with the image crate.

One brute force way:
- Iterate over columns from left to right and find the smallest x coordinate that isn't white.
- Iterate over rows line from top to bottom and find the largest x coordinate that isn't white.
- Same idea for right and bottom

You'll end up with the left, top, right and bottom crop coordinates. Then just call https://docs.rs/image/0.23.13/image/imageops/fn.crop.html

[chinedufn]

Here's a much simpler way to get an Image from a psd.

let img: image::ImageBuffer<image::Rgba<u8>, Vec<u8>> =
                image::ImageBuffer::from_vec(psd.width(), psd.height(), psd.pixels()).unwrap();
img.save("/tmp/foo.png").unwrap();