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use crate::common::{Color, Version};
use super::OutVec;
use super::ImageBuilder;
pub struct GifBuilder {
version: Version,
width: u16,
height: u16,
global_color_table: Option<Vec<Color>>,
background_color_index: u8,
imagebuilders: Vec<ImageBuilder>
}
impl GifBuilder {
pub fn new(version: Version, width: u16, height: u16) -> Self {
Self {
version,
width,
height,
global_color_table: None,
background_color_index: 0,
imagebuilders: vec![]
}
}
pub fn global_color_table(mut self, vec: Vec<Color>) -> Self {
if vec.len() == 0 || vec.len() > 256 {
//TODO: Throw error instead of panic
panic!("GCT has to be less than or 256 colors in size, and at least one");
}
self.global_color_table = Some(vec);
self
}
pub fn background_color_index(mut self, ind: u8) -> Self {
if self.global_color_table.is_none() {
//TODO: Throw error or let it go by, who knows
panic!("Setting background color index with noGCT!");
}
self.background_color_index = ind;
self
}
pub fn image(mut self, ib: ImageBuilder) -> Self {
self.imagebuilders.push(ib);
self
}
pub fn write_to_vec(&self) -> Vec<u8> {
let mut out = OutVec::new();
self
.write_header(&mut out)
.write_logical_screen_descriptor(&mut out)
.write_global_color_table(&mut out)
.write_images(&mut out)
.write_trailer(&mut out);
out.vec()
}
fn write_header(&self, out: &mut OutVec) -> &Self {
out.push_slice(b"GIF");
//TODO: Automatically detect version
match self.version {
Version::Gif87a => out.push_slice(b"87a"),
Version::Gif89a => out.push_slice(b"89a")
};
self
}
fn write_logical_screen_descriptor(&self, out: &mut OutVec) -> &Self {
out.push_u16(self.width).push_u16(self.height);
let mut packed: u8 = 0;
if let Some(gct) = &self.global_color_table {
packed |= 0b1000_0000; // Set the GCT flag
// GCT size is calulated by raising two to this number plus one,
// so we have to work backwards.
let size = (gct.len() as f32).log2().ceil() - 1f32;
packed |= size as u8;
}
//TODO: Color Resolution and Sort Flag fields in packed.
out.push_u8(packed);
out.push_u8(self.background_color_index)
.push_u8(0x00); //TOOD: Allow setting pixel aspect ratio
self
}
fn write_global_color_table(&self, out: &mut OutVec) -> &Self {
if let Some(gct) = &self.global_color_table {
out.push_colors(&gct);
}
self
}
fn write_images(&self, out: &mut OutVec) -> &Self {
//TODO: Deduplicate color table size code
let mcs = if let Some(gct) = &self.global_color_table {
((gct.len() as f32).log2().ceil() - 1f32) as u8
} else {
0
};
for ib in &self.imagebuilders {
let image = ib.write_to_vec(mcs);
out.push_slice(&image);
}
self
}
fn write_trailer(&self, out: &mut OutVec) {
/*
"This block is a single-field block indicating the end of the GIF Data Stream.
It contains the fixed value 0x3B."
*/
out.push_u8(0x3B);
}
}
#[cfg(test)]
pub mod gifbuilder_test {
use super::*;
#[test]
pub fn writer_header() {
let mut out = OutVec::new();
GifBuilder::new(Version::Gif87a, 0, 0).write_header(&mut out);
assert_eq!(out.vec(), b"GIF87a");
}
#[test]
pub fn write_logical_screen_descriptor() {
let mut out = OutVec::new();
GifBuilder::new(Version::Gif87a, 4, 4).write_logical_screen_descriptor(&mut out);
assert_eq!(out.vec(), vec![0x04, 0x00, 0x04, 0x00, 0x00, 0x00, 0x00]);
let mut out = OutVec::new();
let gct = vec![
Color::new(0, 0, 0), Color::new(0, 0, 0), Color::new(0, 0, 0),
Color::new(0, 0, 0), Color::new(0, 0, 0)
];
GifBuilder::new(Version::Gif87a, 4, 4).global_color_table(gct).write_logical_screen_descriptor(&mut out);
assert_eq!(out.vec(), vec![0x04, 0x00, 0x04, 0x00, 0b1000_0010, 0x00, 0x00]);
}
#[test]
pub fn write_global_color_table() {
let mut out = OutVec::new();
let gct = vec![
Color::new(1, 2, 3), Color::new(253, 254, 255)
];
GifBuilder::new(Version::Gif87a, 4, 4).global_color_table(gct).write_global_color_table(&mut out);
assert_eq!(out.vec(), vec![1, 2, 3, 253, 254, 255]);
}
#[test]
fn write_images() {
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![
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
];
let mut out = OutVec::new();
GifBuilder::new(Version::Gif87a, 4, 4)
.global_color_table(gct)
.image(ImageBuilder::new(4, 4)
.color_table(colortable)
.indicies(indicies.clone())
).image(ImageBuilder::new(4, 4)
.indicies(indicies)
).write_images(&mut out);
assert_eq!(out.vec(), expected_out);
}
#[test]
fn write_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 mut out = OutVec::new();
let actual_out = GifBuilder::new(Version::Gif87a, 4, 4)
.global_color_table(gct)
.image(ImageBuilder::new(4, 4)
.color_table(colortable)
.indicies(indicies.clone())
).image(ImageBuilder::new(4, 4)
.indicies(indicies)
).write_to_vec();
assert_eq!(actual_out, expected_out);
}
}
|
