Add gif components

8 files changed, 320 insertions, 0 deletions

diff --git a/src/components/color.rs b/src/components/color.rs
new file mode 100644
index 0000000..dc134ef
--- /dev/null
+++ b/src/components/color.rs
@@ -0,0 +1,11 @@
+pub struct Color {
+	pub r: u8,
+	pub g: u8,
+	pub b: u8
+}
+
+impl Color {
+	pub fn new(r: u8, g: u8, b: u8) -> Self {
+		Self { r, g, b }
+	}
+}
\ No newline at end of file
diff --git a/src/components/colortable.rs b/src/components/colortable.rs
new file mode 100644
index 0000000..f756169
--- /dev/null
+++ b/src/components/colortable.rs
@@ -0,0 +1,67 @@
+use std::ops::Deref;
+pub use super::Color;
+
+pub struct ColorTable {
+	table: Vec<Color>
+}
+
+impl ColorTable {
+	pub fn new() -> Self {
+		Self {
+			table: vec![]
+		}
+	}
+
+	/// Returns the number of colors in the color table as used by the packed
+	/// fields in the Logical Screen Descriptor and Image Descriptor. You can
+	/// get the actual size with the [`len`](struct.ColorTable.html#method.len) method.
+	pub fn packed_len(&self) -> u8 {
+		((self.table.len() as f32).log2().ceil() - 1f32) as u8
+	}
+
+	/// Returns the number of items in the table
+	pub fn len(&self) -> usize {
+		self.table.len()
+	}
+
+	/// Pushes a color on to the end of the table
+	pub fn push(&mut self, color: Color) {
+		self.table.push(color);
+	}
+}
+
+impl Deref for ColorTable {
+	type Target = [Color];
+
+	fn deref(&self) -> &Self::Target {
+		&self.table
+	}
+}
+
+impl From<Vec<Color>> for ColorTable {
+	fn from(table: Vec<Color>) -> Self{
+		ColorTable {
+			table
+		}
+	}
+}
+
+impl From<&ColorTable> for Box<[u8]> {
+	fn from(table: &ColorTable) -> Self {
+		let mut vec = vec![];
+
+		for color in table.iter() {
+			vec.extend_from_slice(&[color.r, color.g, color.b]);
+		}
+
+		let packed_len = 2u8.pow(table.packed_len() as u32 + 1);
+		let padding = (packed_len as usize - table.len()) * 3;
+		if padding > 0 {
+			vec.extend_from_slice(&vec![0; padding]);
+		}
+
+		vec.into_boxed_slice()
+	}
+}
+
+//TODO: TryFrom Vec<u8> (must be multiple of 3 len) and From Vec<Color>
\ No newline at end of file
diff --git a/src/components/gif.rs b/src/components/gif.rs
new file mode 100644
index 0000000..2709fe8
--- /dev/null
+++ b/src/components/gif.rs
@@ -0,0 +1,82 @@
+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);
+	}
+}
\ No newline at end of file
diff --git a/src/components/image.rs b/src/components/image.rs
new file mode 100644
index 0000000..07f9555
--- /dev/null
+++ b/src/components/image.rs
@@ -0,0 +1,47 @@
+use crate::LZW;
+use super::{ColorTable, ImageDescriptor};
+
+pub struct Image {
+	pub image_descriptor: ImageDescriptor,
+	pub local_color_table: Option<ColorTable>,
+	pub indicies: Vec<u8>
+}
+
+impl Image {
+	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);
+
+		// Table based image data //
+
+		// 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
+		};
+
+		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()
+	}
+}
\ No newline at end of file
diff --git a/src/components/imagedescriptor.rs b/src/components/imagedescriptor.rs
new file mode 100644
index 0000000..c911baa
--- /dev/null
+++ b/src/components/imagedescriptor.rs
@@ -0,0 +1,45 @@
+pub struct ImageDescriptor {
+	// Image Seperator 0x2C is the first byte //
+	pub left: u16,
+	pub top: u16,
+	pub width: u16,
+	pub height: u16,
+	pub packed: u8
+}
+
+impl ImageDescriptor {
+	pub fn color_table_present(&mut self, is_present: bool) {
+		if is_present {
+			self.packed |= 0b1000_0000;
+		} else {
+			self.packed &= 0b0111_1111;
+		}
+	}
+
+	pub fn color_table_size(&mut self, size: u8) {
+		// GCT size is calulated by raising two to this number plus one,
+		// so we have to work backwards.
+		let size = (size as f32).log2().ceil() - 1f32;
+		self.packed |= size as u8;
+	}
+
+	//TODO: Setter for sort flag in packed field
+	//TODO: Setter for interlace flag in packed field
+}
+
+impl From<&ImageDescriptor> for Box<[u8]> {
+	fn from(desc: &ImageDescriptor) -> Self {
+		let mut vec = vec![];
+
+		vec.push(0x2C); // Image Seperator
+		vec.extend_from_slice(&desc.left.to_le_bytes());
+		vec.extend_from_slice(&desc.top.to_le_bytes());
+		vec.extend_from_slice(&desc.width.to_le_bytes());
+		vec.extend_from_slice(&desc.height.to_le_bytes());
+		vec.push(desc.packed);
+
+		vec.into_boxed_slice()
+	}
+}
+
+//TODO: Impl to allow changing the packed field easier
\ No newline at end of file
diff --git a/src/components/logicalscreendescriptor.rs b/src/components/logicalscreendescriptor.rs
new file mode 100644
index 0000000..b20c9d5
--- /dev/null
+++ b/src/components/logicalscreendescriptor.rs
@@ -0,0 +1,40 @@
+pub struct LogicalScreenDescriptor {
+	pub width: u16,
+	pub height: u16,
+	pub packed: u8,
+	pub background_color_index: u8,
+	pub pixel_aspect_ratio: u8
+}
+
+impl LogicalScreenDescriptor {
+	pub fn color_table_present(&mut self, is_present: bool) {
+		if is_present {
+			self.packed |= 0b1000_0000;
+		} else {
+			self.packed &= 0b0111_1111;
+		}
+	}
+
+	pub fn color_table_size(&mut self, size: u8) {
+		// GCT size is calulated by raising two to this number plus one,
+		// so we have to work backwards.
+		let size = (size as f32).log2().ceil() - 1f32;
+		self.packed |= size as u8;
+	}
+
+	//TODO: Setter for sort flag in packed field
+	//TODO: Setter for color resolution in packed field
+}
+
+impl From<&LogicalScreenDescriptor> for Box<[u8]> {
+	fn from(lsd: &LogicalScreenDescriptor) -> Self {
+		let mut vec = vec![];
+		vec.extend_from_slice(&lsd.width.to_le_bytes());
+		vec.extend_from_slice(&lsd.height.to_le_bytes());
+		vec.push(lsd.packed);
+		vec.push(lsd.background_color_index);
+		vec.push(lsd.pixel_aspect_ratio);
+
+		vec.into_boxed_slice()
+	}
+}
\ No newline at end of file
diff --git a/src/components/mod.rs b/src/components/mod.rs
new file mode 100644
index 0000000..1650d36
--- /dev/null
+++ b/src/components/mod.rs
@@ -0,0 +1,15 @@
+mod color;
+mod colortable;
+mod gif;
+mod image;
+mod imagedescriptor;
+mod logicalscreendescriptor;
+mod version;
+
+pub use color::Color;
+pub use colortable::ColorTable;
+pub use gif::Gif;
+pub use image::Image;
+pub use imagedescriptor::ImageDescriptor;
+pub use logicalscreendescriptor::LogicalScreenDescriptor;
+pub use version::Version;
\ No newline at end of file
diff --git a/src/components/version.rs b/src/components/version.rs
new file mode 100644
index 0000000..a5d688d
--- /dev/null
+++ b/src/components/version.rs
@@ -0,0 +1,13 @@
+pub enum Version {
+	Gif87a,
+	Gif89a
+}
+
+impl From<&Version> for &[u8] {
+	fn from(version: &Version) -> Self {
+		match version {
+			Version::Gif87a => b"GIF87a",
+			Version::Gif89a => b"GIF89a"
+		}
+	}
+}
\ No newline at end of file