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use super::{ColorTable, Image, LogicalScreenDescriptor, Version};
pub struct Gif {
pub header: Version,
pub logical_screen_descriptor: LogicalScreenDescriptor,
pub global_color_table: Option<ColorTable>,
pub images: Vec<Image>
// Trailer at the end of this struct is 0x3B //
}
impl Gif {
pub fn to_vec(&self) -> Vec<u8> {
let mut out = vec![];
out.extend_from_slice((&self.header).into());
let mut boxed: Box<[u8]> = (&self.logical_screen_descriptor).into();
out.extend_from_slice(&*boxed);
// While we output the color table, grab it's length to use when
// outputting the image, or 0 if we don't have a GCT
let mcs = if let Some(gct) = &self.global_color_table {
boxed = gct.into();
out.extend_from_slice(&*boxed);
gct.packed_len()
} else {
0
};
for image in self.images.iter() {
boxed = image.as_boxed_slice(mcs);
out.extend_from_slice(&*boxed);
}
// Write Trailer
out.push(0x3B);
out
}
}
#[cfg(test)]
pub mod gif {
use crate::Color;
use crate::writer::{GifBuilder, ImageBuilder};
use super::*;
#[test]
fn to_vec() {
let gct = vec![
Color::new(1, 2, 3), Color::new(253, 254, 255)
];
let colortable = vec![
Color::new(0, 0, 0), Color::new(128, 0, 255)
];
let indicies = vec![0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0];
let expected_out = vec![
0x47, 0x49, 0x46, 0x38, 0x37, 0x61, // Version - GIF87a
0x04, 0x00, 0x04, 0x00, 0b1000_0000, 0x00, 0x00, // Logical Screen Descriptor
1, 2, 3, 253, 254, 255, // Global Color Table
0x2C, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x04, 0x00, 0b1000_0000, // Image Descriptor 1
0, 0, 0, 128, 0, 255, // Color Table
0x02, 0x05, 0x84, 0x1D, 0x81, 0x7A, 0x50, 0x00, // Image Data 1
0x2C, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x04, 0x00, 0b0000_0000, // Image Descriptor 2
0x02, 0x05, 0x84, 0x1D, 0x81, 0x7A, 0x50, 0x00, // Image Data 2
0x3B // Trailer
];
let actual_out = GifBuilder::new(Version::Gif87a, 4, 4)
.global_color_table(gct.into())
.image(ImageBuilder::new(4, 4)
.color_table(colortable.into())
.indicies(indicies.clone())
).image(ImageBuilder::new(4, 4)
.indicies(indicies)
).build().to_vec();
assert_eq!(actual_out, expected_out);
}
}
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