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use annotation::Annotation;
use error::Result;
use image::{self, DynamicImage, FilterType, GenericImage, ImageFormat, imageops, RgbaImage};
use rusttype::Font;
use std::io;

use AA_FACTOR;

pub struct Canvas {
    base: DynamicImage,
    overlay: DynamicImage,
    width: u32,
    height: u32,
}

impl Canvas {
    pub fn read_from_buffer(buf: &[u8]) -> Result<Canvas> {
        let base = image::load_from_memory(buf)?;
        let (width, height) = base.dimensions();
        Ok(Canvas {
            base,
            overlay: DynamicImage::ImageRgba8(RgbaImage::new(width * AA_FACTOR, height * AA_FACTOR)),
            width,
            height,
        })
    }

    pub fn add_annotation<'a>(&mut self, annotation: &Annotation, font: &Font<'a>, scale_multiplier: f32) {
        let scale_factor = (self.height as f32 / 10.0) * scale_multiplier;
        annotation.render_text(&mut self.overlay, font, scale_factor, self.width, self.height);
    }

    pub fn render(&mut self) {
        let downsampled_text = imageops::resize(&self.overlay, self.width, self.height, FilterType::CatmullRom);
        imageops::overlay(&mut self.base, &mut DynamicImage::ImageRgba8(downsampled_text), 0, 0);
    }

    pub fn save_jpg<W: io::Write>(&self, stream: &mut W) -> io::Result<()> {
        self.base.save(stream, ImageFormat::JPEG)
            .map_err(|e| io::Error::new(io::ErrorKind::Other, e))
    }

    pub fn save_png<W: io::Write>(&self, stream: &mut W) -> io::Result<()> {
        self.base.save(stream, ImageFormat::PNG)
            .map_err(|e| io::Error::new(io::ErrorKind::Other, e))
    }
}