Trait jpeg_encoder::ImageBuffer

source ·

pub trait ImageBuffer {
    // Required methods
    fn get_jpeg_color_type(&self) -> JpegColorType;
    fn width(&self) -> u16;
    fn height(&self) -> u16;
    fn fill_buffers(&self, y: u16, buffers: &mut [Vec<u8>; 4]);
}

Expand description

Buffer used as input value for image encoding

Image encoding with Encoder::encode_image needs an ImageBuffer as input for the image data. For convenience the Encoder::encode function contains implementations for common byte based pixel formats. Users that needs other pixel formats or don’t have the data available as byte slices can create their own buffer implementations.

Example: ImageBuffer implementation for RgbImage from the `image` crate

use image::RgbImage;
use jpeg_encoder::{ImageBuffer, JpegColorType, rgb_to_ycbcr};

pub struct RgbImageBuffer {
    image: RgbImage,
}

impl ImageBuffer for RgbImageBuffer {
    fn get_jpeg_color_type(&self) -> JpegColorType {
        // Rgb images are encoded as YCbCr in JFIF files
        JpegColorType::Ycbcr
    }

    fn width(&self) -> u16 {
        self.image.width() as u16
    }

    fn height(&self) -> u16 {
        self.image.height() as u16
    }

    fn fill_buffers(&self, y: u16, buffers: &mut [Vec<u8>; 4]){
        for x in 0..self.width() {
            let pixel = self.image.get_pixel(x as u32 ,y as u32);

            let (y,cb,cr) = rgb_to_ycbcr(pixel[0], pixel[1], pixel[2]);

            // For YCbCr the 4th buffer is not used
            buffers[0].push(y);
            buffers[1].push(cb);
            buffers[2].push(cr);
        }
    }
}