src/block/indexedimage.rs


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use std::convert::TryFrom;

use super::{ColorTable, ImageDescriptor};
use crate::LZW;

pub struct IndexedImage {
    pub image_descriptor: ImageDescriptor,
    pub local_color_table: Option<ColorTable>,
    pub indicies: Vec<u8>,
}

impl IndexedImage {
    pub fn left(&self) -> u16 {
        self.image_descriptor.left
    }

    pub fn top(&self) -> u16 {
        self.image_descriptor.left
    }

    pub fn width(&self) -> u16 {
        self.image_descriptor.width
    }

    pub fn height(&self) -> u16 {
        self.image_descriptor.height
    }

    pub fn as_boxed_slice(&self, minimum_code_size: u8) -> Box<[u8]> {
        let mut out = vec![];

        let mut boxed: Box<[u8]> = (&self.image_descriptor).into();
        out.extend_from_slice(&*boxed);

        // Get the mcs while we write out the color table
        let mut mcs = if let Some(lct) = &self.local_color_table {
            boxed = lct.into();
            out.extend_from_slice(&*boxed);

            lct.packed_len()
        } else {
            minimum_code_size + 1
        };

        if mcs < 2 {
            mcs = 2; // Must be true: 0 <= mcs <= 8
        }

        // First write out the MCS
        out.push(mcs);

        let compressed = LZW::encode(mcs, &self.indicies);

        for chunk in compressed.chunks(255) {
            out.push(chunk.len() as u8);
            out.extend_from_slice(chunk);
        }
        // Data block length 0 to indicate an end
        out.push(0x00);

        out.into_boxed_slice()
    }
}

pub struct CompressedImage {
    pub image_descriptor: ImageDescriptor,
    pub local_color_table: Option<ColorTable>,
    pub lzw_minimum_code_size: u8,
    pub blocks: Vec<Vec<u8>>,
}