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//! A smol library for (s)Rgb color handling. //! //! # Quick-start //! //! To use this in your project, add this to your Cargo.toml: //! //! ```toml //! smol-rgb = "0.1.0" //! ``` //! //! no-std is supported, but requires `libm` to work, like so: //! //! ```toml //! smol-rgb = { version = "0.1.0", default-features = false, features = ["libm"] } //! ``` //! //! We also support two other features: `serde` and `bytemuck`. `serde` support works //! across a variety of backends such as yaml, json, and bincode. //! //! # Who is this library for? //! //! This library is designed for the programmer who: //! - is working with graphics on the GPU (such as games) //! - works entirely or almost entirely with sRGB (if you don't know what that means, that's probably you), //! - and doesn't care about color beyond it "just working" correctly. //! //! This library can also serve as a good starting point to learn more complex color theory. //! //! For users who are comfortable working in color spaces, you should check out the much more //! complicated library [palette](https://github.com/Ogeon/palette). It is significantly //! more complicated, but also equally more capable. //! //! This library, on the other hand, only works with sRGB, and is designed only to help the programmer //! work with sRGB in a simple manner. //! //! # It's not always RGB, but we can make it only sRGB. //! //! Textures, color pickers (like egui or imgui's pickers) are generally in "encoded" sRGB. //! In this library, that means 4 u8s, each of which describe how much `r`, `g`, `b`, and `a` //! should be in an image. On a very technical level, this is a specification called //! IEC 61966-2-1:1999, but you should never remember this again. In this library, this space is //! called `EncodedRgb`. If you use photoshop and use the color picker on a color (generally), //! the number you get out is going to be in encoded sRGB, which this library handles in EncodedRgb. //! That "generally" might have worried you; unless you know you did something odd, however, it shouldn't. //! If you're authoring texture in Photoshop or in Aseprite, you'll be working in sRGB (unless you make //! it so you aren't, but don't do that). //! //! Encoded sRGB is just the bee's knees, except that it's basically useless to *do* things in. //! When you want to *blend* colors (add them, multiply them, basically do anything to them), //! you need to convert those colors into "linear" space. In this library, we call this `LinearColor`. //! Whereas `EncodedRgb` is just 4 u8s, `LinearColor` is 4 f32s, each of which has been transferred //! from "encoded" space to "linear" space. The more complete terms would be that they have been //! transferred from "encoded sRGB" to "linear sRGB", but don't think about it too much -- basically, //! now they're in a place where they can be mixed with each other. //! //! # When does this happen Magically? //! //! Most of the time, in your library or application, your colors will be in `EncodedRgb` //! and you won't think much about it. If you use a tool like egui or imgui-rs, you'll set colors //! from those color picker applets directly into your `EncodedRgb` and call it a day. //! In fact, if you're working in something like Opengl or Vulkan, and you're passing in Colors //! in a Vertex Attribute, you may *still* use `EncodedRgb` in that circumstance, so long as //! you make sure to make that attribute normalized correctly (in [vulkan](https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VkFormat.html), //! and in [opengl](https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/glVertexAttribPointer.xhtml)). //! //! And of course, I've said a few times now that Textures are in EncodedRgb, yet, of course, //! when you access them in a Shader, you can tint them with uniforms easily and correctly, //! so they must also be in linear at that stage, right? //! //! The answer is yes! The GPU, when it samples a texture, will convert it into LinearRgb *for you.* //! It will also, if you've set up your vertex attributes like above, do the same for those. //! //! Even more confusingly, after your fragment shader is done working in linear colors, it will (generally) //! be converted *back* into EncodedRgb for final output. This is why if you use a color picker on your screen, //! you'll still be getting EncodedRgb colors out! If your monitor itself is in sRgb (and many are), then you'll //! even be displaying those colors in EncodedRgb. //! //! # When do I need to transfer EncodedRgb to LinearRgb myself? //! //! In two circumstances, for most programmers -- when you're blending colors yourself on the CPU, or when //! you're sending a color to a uniform to be blended with another LinearRgb color (like a sampled texture) on the GPU. //! //! You might think to yourself that you commonly sent colors before you read this in "what you're calling 'EncodedRgb'" and //! it worked out just fine. That's probably true! Almost all games have some color error, because it's just so easy to do //! accidentally. However, I might point out that probably you or an artist just fiddled with the encoded color until it //! mixed correctly, so it looked more or less right on the GPU. Or perhaps there was some other weirdness going on! //! //! # A quick final note on alpha //! //! This library uses the term `Rgb` for its color space, which is really `sRgb` with an `alpha` channel. //! We do this for the sake of simplicity -- alpha is almost always desired in grapics applications, and like, come on, //! you can spare the byte. //! //! If this library picks up enough traction, users might want to split it into `Rgb` and `Rgba`. Leave an issue //! if that's desired. #![deny(missing_docs, broken_intra_doc_links)] #![no_std] #[cfg(feature = "std")] extern crate std; use core::fmt; /// A color used in linear applications. On a technical level, /// this color is in sRGB; however, this name is not very clear. /// /// In code, we will say that this Color is `encoded`. This is generally the same /// colorspace that texels in a texture are in. This color space is not valid /// to perform mixing operations *between* colors in, so we must convert this /// color space into a different color, [LinearRgb], with [to_linear](Self::to_linear) /// before we do such operations. #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Default, Hash)] #[repr(C)] pub struct EncodedRgb { /// The red component of the color. pub r: u8, /// The green component of the color. pub g: u8, /// The blue component of the color. pub b: u8, /// The alpha component of the color, normally the opacity in blending operations. pub a: u8, } impl EncodedRgb { /// A basic white (255, 255, 255, 255) with full opacity. pub const WHITE: EncodedRgb = EncodedRgb::new(255, 255, 255, 255); /// A basic black (0, 0, 0, 255) with full opacity. pub const BLACK: EncodedRgb = EncodedRgb::new(0, 0, 0, 255); /// A black (0, 0, 0, 0) with zero opacity. pub const CLEAR: EncodedRgb = EncodedRgb::new(0, 0, 0, 0); /// God's color (255, 0, 255, 255). The color of choice for graphics testing. pub const FUCHSIA: EncodedRgb = EncodedRgb::new(255, 0, 255, 255); /// Creates a new encoded 32bit color. pub const fn new(r: u8, g: u8, b: u8, a: u8) -> Self { Self { r, g, b, a } } /// Transforms this color into the Linear color space. #[inline] pub fn to_linear(self) -> LinearRgb { LinearRgb { r: encoded_to_linear(self.r), g: encoded_to_linear(self.g), b: encoded_to_linear(self.b), a: self.a as f32 / 255.0, } } /// Converts this color to an [f32; 4] array. This is **still in encoded /// space** but they are converted to an f32. This is mostly for compatability /// with other libraries which sometimes need to f32s even while in encoded sRGB. /// /// We use this dedicated function, rather than a `From` or `Into` because /// this is an unusual use of f32s, and in general, this module acts as if /// f32 == Linear and u8 == Encoded, though this is not technically true. #[inline] pub fn to_encoded_f32s(self) -> [f32; 4] { [ self.r as f32 / 255.0, self.g as f32 / 255.0, self.b as f32 / 255.0, self.a as f32 / 255.0, ] } /// Converts this color to an [f32; 4] array. This is **still in encoded /// space** but they are converted to an f32. This is mostly for compatability /// with other libraries which sometimes need to f32s even while in encoded sRGB. /// /// We use this dedicated function, rather than a `From` or `Into` because /// this is an unusual use of f32s, and in general, this module acts as if /// f32 == Linear and u8 == Encoded, though this is not technically true. #[inline] pub fn from_encoded_f32s(input: [f32; 4]) -> Self { Self::new( (input[0] * 255.0) as u8, (input[1] * 255.0) as u8, (input[2] * 255.0) as u8, (input[3] * 255.0) as u8, ) } /// Converts a packed u32 to an encoded rgba struct. /// /// Note, your colors must be in order of `red, green, blue, alpha`. For `bgra` support, /// use `from_bgra_u32`. /// /// This function might also has issues on non-little endian platforms, but look, you're not /// on one of those. #[inline] pub const fn from_rgba_u32(input: u32) -> Self { let bytes = input.to_ne_bytes(); Self { r: bytes[3], g: bytes[2], b: bytes[1], a: bytes[0], } } /// Converts the encoded rgba struct to a packed u32 in `rgba` encoding. /// /// This will output your colors in order of `red, green, blue, alpha`. For `bgra` support, /// use `to_bgra_u32`. /// /// This function might also have issues on non-little endian platforms, but look, you're not /// on one of those. #[inline] pub const fn to_rgba_u32(self) -> u32 { let mut bytes = [0, 0, 0, 0]; bytes[3] = self.r; bytes[2] = self.g; bytes[1] = self.b; bytes[0] = self.a; u32::from_ne_bytes(bytes) } /// Converts a packed u32 to an encoded rgba struct. On little endian platforms, this is a no-op. /// /// Note, your colors must be in order of `blue`, `green`, `red`, `alpha`. /// /// This function might also has issues on non-little endian platforms, but look, you're not /// on one of those probably. #[inline] pub const fn from_bgra_u32(input: u32) -> Self { let bytes = input.to_ne_bytes(); Self { r: bytes[1], g: bytes[2], b: bytes[3], a: bytes[0], } } /// Converts the encoded rgba struct to a packed u32 in `bgra` encoding. /// /// This will output your colors in order of `red, green, blue, alpha`. For `bgra` support, /// use `to_bgra_u32`. /// /// This function might also have issues on non-little endian platforms, but look, you're not /// on one of those. #[inline] pub const fn to_bgra_u32(self) -> u32 { let mut bytes = [0, 0, 0, 0]; bytes[1] = self.r; bytes[2] = self.g; bytes[3] = self.b; bytes[0] = self.a; u32::from_ne_bytes(bytes) } } impl From<(u8, u8, u8, u8)> for EncodedRgb { fn from(o: (u8, u8, u8, u8)) -> Self { Self { r: o.0, g: o.1, b: o.2, a: o.3, } } } impl Into<(u8, u8, u8, u8)> for EncodedRgb { fn into(self) -> (u8, u8, u8, u8) { (self.r, self.g, self.b, self.a) } } impl fmt::Debug for EncodedRgb { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_tuple("EncodedRgb") .field(&self.r) .field(&self.g) .field(&self.b) .field(&self.a) .finish() } } impl fmt::Display for EncodedRgb { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!( f, "r: {}, g: {}, b: {}, a: {}, {:x}{:x}{:x}{:x}", self.r, self.g, self.b, self.a, self.r, self.g, self.b, self.a ) } } // we use rgba encoding, for simplicity... impl fmt::LowerHex for EncodedRgb { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { let val = self.to_rgba_u32(); fmt::LowerHex::fmt(&val, f) } } // we use rgba encoding, for simplicity... impl fmt::UpperHex for EncodedRgb { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { let val = self.to_rgba_u32(); fmt::UpperHex::fmt(&val, f) } } /// This is a Color in the `linear` space. This represents /// "linear sRGB". You should use this color space when blending colors on the CPU /// or when sending uniforms to a linear card. /// /// Colors on disc are [EncodedRgb], but to blend them correctly, you need to move them /// into the `linear` color space with [to_linear](EncodedRgb::to_linear). /// /// You *can* directly create this struct, but you probably don't want to. You'd need already /// linear sRGB to correctly make this struct -- that's possible to have, but generally, textures, /// color pickers (like photoshop), and outputted surface (like if you use a Color Picker on a game) /// will all be in the encoded RGB space. Exceptions abound though, so it is possible to directly /// create this color. #[derive(Clone, Copy, PartialEq, PartialOrd, Default)] pub struct LinearRgb { /// The red component of the color. pub r: f32, /// The green component of the color. pub g: f32, /// The blue component of the color. pub b: f32, /// The alpha component of the color, normally the opacity in blending operations. pub a: f32, } impl LinearRgb { /// **You probably don't want to use this function.** /// This creates a color in the LinearColor space directly. For this function to be valid, /// the colors given to this function **must be in the linear space already.** #[inline] pub const fn new(r: f32, g: f32, b: f32, a: f32) -> Self { Self { r, g, b, a } } /// Transforms this color into the Encoded color space. Use this space to serialize /// colors. #[inline] pub fn to_encoded_space(self) -> EncodedRgb { EncodedRgb { r: linear_to_encoded(self.r), g: linear_to_encoded(self.g), b: linear_to_encoded(self.b), a: (self.a * 255.0) as u8, } } /// Creates an array representation of the color. This is useful for sending the color /// to a uniform, but is the same memory representation as `Self`. [LinearRgb] also implements /// Into, but this function is often more convenient. #[inline] pub fn to_array(self) -> [f32; 4] { self.into() } /// Encodes the 4 floats as 16 u8s. This is useful for sending the color /// to a uniform, but is the same memory representation as `Self` -- ie, /// the bits have just been reinterpreted as 16 u8s, but they're still secret floats. #[inline] pub fn to_bits(self) -> [u8; 16] { unsafe { core::mem::transmute(self.to_array()) } } } impl Into<[f32; 4]> for LinearRgb { fn into(self) -> [f32; 4] { [self.r, self.g, self.b, self.a] } } impl From<[f32; 4]> for LinearRgb { fn from(o: [f32; 4]) -> Self { Self::new(o[0], o[1], o[2], o[3]) } } impl Into<(f32, f32, f32, f32)> for LinearRgb { fn into(self) -> (f32, f32, f32, f32) { (self.r, self.g, self.b, self.a) } } impl From<(f32, f32, f32, f32)> for LinearRgb { fn from(o: (f32, f32, f32, f32)) -> Self { Self::new(o.0, o.1, o.2, o.3) } } impl fmt::Debug for LinearRgb { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_tuple("LinearRgb") .field(&self.r) .field(&self.g) .field(&self.b) .field(&self.a) .finish() } } impl fmt::Display for LinearRgb { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!( f, "r: {}, g: {}, b: {}, a: {}", self.r, self.g, self.b, self.a ) } } impl From<LinearRgb> for EncodedRgb { fn from(o: LinearRgb) -> Self { o.to_encoded_space() } } impl From<EncodedRgb> for LinearRgb { fn from(o: EncodedRgb) -> Self { o.to_linear() } } /// This function takes an encoded u8 and outputs a linear space (linear) sRgb f32. /// /// This is based on <https://bottosson.github.io/posts/colorwrong/> and similar /// transfer functions. /// /// We do this with a LUT rather than actually calculate it, since it's just faster to do /// an array lookup than do the math. /// /// However, in the interest of simplicity, I have left the math which does the conversion commented /// within this function call, if you're like to see the math. pub const fn encoded_to_linear(c: u8) -> f32 { ENCODED_TO_LINEAR_LUT[c as usize] /* If you want to see the encoded to linear function written out (ie, how I made this LUT), it looks like this here: pub fn encoded_to_linear(input: u8) -> f32 { #[cfg(feature = "libm")] use libm::powf; #[cfg(feature = "std")] fn powf(f: f32, e: f32) -> f32 { f.powf(e) } let input = input as f32 / 255.0; if input >= 0.04045 { powf((input + 0.055) / 1.055, 2.4) } else { input / 12.92 } } Thank you very much to @thomcc (@zurr on discord) for helping me with this! */ } /// This is the LUT that we use. You shouldn't really ever need to use directly, but `encoded_to_linear` /// is just a wrapper to index into this LUT. /// /// I have chosen to inline write this, rather than use a build script, because it's a bit simpler. #[rustfmt::skip] pub const ENCODED_TO_LINEAR_LUT: [f32; 256] = [ 0.0, 0.000303527, 0.000607054, 0.000910581, 0.001214108, 0.001517635, 0.001821162, 0.0021246888, 0.002428216, 0.0027317428, 0.00303527, 0.0033465358, 0.0036765074, 0.004024717, 0.004391442, 0.0047769533, 0.0051815165, 0.0056053917, 0.006048833, 0.0065120906, 0.00699541, 0.007499032, 0.008023193, 0.008568126, 0.009134059, 0.009721218, 0.010329823, 0.010960094, 0.011612245, 0.012286488, 0.0129830325, 0.013702083, 0.014443844, 0.015208514, 0.015996294, 0.016807375, 0.017641954, 0.01850022, 0.019382361, 0.020288562, 0.02121901, 0.022173885, 0.023153367, 0.024157632, 0.02518686, 0.026241222, 0.027320892, 0.02842604, 0.029556835, 0.030713445, 0.031896032, 0.033104766, 0.034339808, 0.035601314, 0.03688945, 0.038204372, 0.039546236, 0.0409152, 0.04231141, 0.04373503, 0.045186203, 0.046665087, 0.048171826, 0.049706567, 0.051269457, 0.052860647, 0.054480277, 0.05612849, 0.05780543, 0.059511237, 0.061246052, 0.063010015, 0.064803265, 0.06662594, 0.06847817, 0.070360094, 0.07227185, 0.07421357, 0.07618538, 0.07818742, 0.08021982, 0.08228271, 0.08437621, 0.08650046, 0.08865558, 0.09084171, 0.093058966, 0.09530747, 0.09758735, 0.099898726, 0.10224173, 0.104616486, 0.107023105, 0.10946171, 0.11193243, 0.114435375, 0.116970666, 0.11953843, 0.122138776, 0.12477182, 0.12743768, 0.13013647, 0.13286832, 0.13563333, 0.13843161, 0.14126329, 0.14412847, 0.14702727, 0.14995979, 0.15292615, 0.15592647, 0.15896083, 0.16202937, 0.1651322, 0.1682694, 0.17144111, 0.1746474, 0.17788842, 0.18116425, 0.18447499, 0.18782078, 0.19120169, 0.19461784, 0.19806932, 0.20155625, 0.20507874, 0.20863687, 0.21223076, 0.2158605, 0.2195262, 0.22322796, 0.22696587, 0.23074006, 0.23455058, 0.23839757, 0.24228112, 0.24620132, 0.25015828, 0.2541521, 0.25818285, 0.26225066, 0.2663556, 0.2704978, 0.2746773, 0.27889428, 0.28314874, 0.28744084, 0.29177064, 0.29613826, 0.30054379, 0.3049873, 0.30946892, 0.31398872, 0.31854677, 0.3231432, 0.3277781, 0.33245152, 0.33716363, 0.34191442, 0.34670407, 0.3515326, 0.35640013, 0.3613068, 0.3662526, 0.3712377, 0.37626213, 0.38132602, 0.38642943, 0.39157248, 0.39675522, 0.40197778, 0.4072402, 0.4125426, 0.41788507, 0.42326766, 0.4286905, 0.43415365, 0.43965718, 0.4452012, 0.4507858, 0.45641103, 0.462077, 0.4677838, 0.47353148, 0.47932017, 0.48514995, 0.49102086, 0.49693298, 0.5028865, 0.50888133, 0.5149177, 0.52099556, 0.5271151, 0.5332764, 0.5394795, 0.54572445, 0.55201143, 0.5583404, 0.5647115, 0.57112485, 0.57758045, 0.58407843, 0.59061885, 0.59720176, 0.60382736, 0.61049557, 0.6172066, 0.6239604, 0.63075715, 0.63759685, 0.6444797, 0.65140563, 0.65837485, 0.6653873, 0.67244315, 0.6795425, 0.6866853, 0.69387174, 0.7011019, 0.70837575, 0.7156935, 0.7230551, 0.73046076, 0.7379104, 0.7454042, 0.7529422, 0.7605245, 0.76815116, 0.7758222, 0.7835378, 0.7912979, 0.7991027, 0.80695224, 0.8148466, 0.82278574, 0.8307699, 0.838799, 0.8468732, 0.8549926, 0.8631572, 0.8713671, 0.8796224, 0.8879231, 0.8962694, 0.9046612, 0.91309863, 0.92158186, 0.9301109, 0.9386857, 0.9473065, 0.9559733, 0.9646863, 0.9734453, 0.9822506, 0.9911021, 1.0, ]; /// This function takes an linear space f32 and outputs an encoded sRgb u8. /// /// This is based on <https://bottosson.github.io/posts/colorwrong/> and similar /// transfer functions. pub fn linear_to_encoded(input: f32) -> u8 { #[cfg(feature = "libm")] use libm::powf; #[cfg(feature = "std")] fn powf(f: f32, e: f32) -> f32 { f.powf(e) } let encoded_f32 = if input >= 0.0031308 { 1.055 * powf(input, 1.0 / 2.4) - 0.055 } else { 12.92 * input }; // this multiply to 256 is VERY odd! but otherwise, // 1.0 cannot translate to 1.0. Weirdly, this seems fine actually // in tests. (encoded_f32 * 256.0) as u8 } #[cfg(feature = "bytemuck")] unsafe impl bytemuck::Pod for EncodedRgb {} #[cfg(feature = "bytemuck")] unsafe impl bytemuck::Zeroable for EncodedRgb {} #[cfg(feature = "bytemuck")] unsafe impl bytemuck::Pod for LinearRgb {} #[cfg(feature = "bytemuck")] unsafe impl bytemuck::Zeroable for LinearRgb {} #[cfg(feature = "serde")] const ENCODED_NAME: &str = "Encoded Rgb"; #[cfg(feature = "serde")] impl serde::Serialize for EncodedRgb { fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where S: serde::Serializer, { use serde::ser::SerializeTupleStruct; let mut seq = serializer.serialize_tuple_struct(ENCODED_NAME, 4)?; seq.serialize_field(&self.r)?; seq.serialize_field(&self.g)?; seq.serialize_field(&self.b)?; seq.serialize_field(&self.a)?; seq.end() } } #[cfg(feature = "serde")] impl<'de> serde::Deserialize<'de> for EncodedRgb { fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: serde::Deserializer<'de>, { struct DeserializeColor; impl<'de> serde::de::Visitor<'de> for DeserializeColor { type Value = EncodedRgb; fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result { formatter.write_str("a sequence of u8 colors") } fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error> where A: serde::de::SeqAccess<'de>, { let r = seq .next_element()? .ok_or_else(|| serde::de::Error::invalid_length(0, &self))?; let g = seq .next_element()? .ok_or_else(|| serde::de::Error::invalid_length(1, &self))?; let b = seq .next_element()? .ok_or_else(|| serde::de::Error::invalid_length(2, &self))?; let a = seq .next_element()? .ok_or_else(|| serde::de::Error::invalid_length(3, &self))?; Ok(EncodedRgb { r, g, b, a }) } } deserializer.deserialize_tuple_struct(ENCODED_NAME, 4, DeserializeColor) } } #[cfg(test)] mod tests { use super::*; static_assertions::assert_eq_align!(EncodedRgb, u8); static_assertions::assert_eq_size!(EncodedRgb, [u8; 4]); #[test] fn from_u32s() { let cornwall_blue_in_rgba: u32 = 0x6b9ebeff; let cornwall_blue_in_bgra: u32 = 0xbe9e6bff; let cornwall_encoded = EncodedRgb { r: 107, g: 158, b: 190, a: 255, }; let encoded_rgba = EncodedRgb::from_rgba_u32(cornwall_blue_in_rgba); assert_eq!(encoded_rgba, cornwall_encoded); assert_eq!(encoded_rgba.to_rgba_u32(), cornwall_blue_in_rgba); let encoded_bgra = EncodedRgb::from_bgra_u32(cornwall_blue_in_bgra); assert_eq!(encoded_bgra, cornwall_encoded); assert_eq!(encoded_bgra.to_bgra_u32(), cornwall_blue_in_bgra); // and finally, check the hex... let rgba_as_hex = std::format!("{:x}", encoded_rgba); assert_eq!(rgba_as_hex, "6b9ebeff"); let rgba_as_hex = std::format!("{:#X}", encoded_rgba); assert_eq!(rgba_as_hex, "0x6B9EBEFF"); } #[test] fn encoding_decoding() { fn encode(input: u8, output: f32) { let o = encoded_to_linear(input); std::println!("Expected {}, got {}", output, o); assert!((o - output).abs() < f32::EPSILON); } fn decode(input: f32, output: u8) { let o = linear_to_encoded(input); assert_eq!(o, output); } encode(66, 0.05448028); encode(0, 0.0); encode(255, 1.0); encode(240, 0.8713671); encode(100, 0.1274377); encode(128, 0.2158605); decode(0.05448028, 66); decode(0.0, 0); decode(1.0, 255); decode(0.1274377, 100); decode(0.8713672, 240); decode(0.2158605, 128); } #[test] #[allow(clippy::float_cmp)] fn test_lut() { // does computation with 64 bits of precision since we can spare it for // the LUT fn srgb_to_linear_high_precision(component: u8) -> f32 { let c = component as f64 / 255.0; (if c > 0.04045 { ((c + 0.055) / 1.055).powf(2.4) } else { c / 12.92 }) as f32 } let expect = (0..=255u8) .map(srgb_to_linear_high_precision) .collect::<std::vec::Vec<_>>(); assert_eq!(expect, ENCODED_TO_LINEAR_LUT); for c in 0..=255u8 { assert_eq!(encoded_to_linear(c), expect[c as usize]); } } #[test] fn serde() { // json let color = EncodedRgb::new(50, 50, 50, 255); let serialized = serde_json::to_string(&color).unwrap(); assert_eq!("[50,50,50,255]", serialized); let deserialized = serde_json::from_str(&serialized).unwrap(); assert_eq!(color, deserialized); // yaml let serialized = serde_yaml::to_string(&color).unwrap(); assert_eq!("---\n- 50\n- 50\n- 50\n- 255\n", serialized); let deserialized = serde_yaml::from_str(&serialized).unwrap(); assert_eq!(color, deserialized); // more yaml (look I use serde_yaml) let start = "---\n- 22\n- 33\n- 100\n- 210"; let color: EncodedRgb = serde_yaml::from_str(start).unwrap(); let base = EncodedRgb::new(22, 33, 100, 210); assert_eq!(color, base); // bad serds let o = serde_yaml::from_str::<EncodedRgb>("[0.2, 50, 50, 255]"); assert!(o.is_err()); let o = serde_yaml::from_str::<EncodedRgb>("[20, 50, 50, 256]"); assert!(o.is_err()); let o = serde_yaml::from_str::<EncodedRgb>("[20, 50, 245]"); assert!(o.is_err()); let o = serde_yaml::from_str::<EncodedRgb>("[-20, 20, 50, 255]"); assert!(o.is_err()); let o = serde_yaml::from_str::<EncodedRgb>("[20, 20, 50, 255, 255]"); assert!(o.is_err()); // and the big chungus, bincode let color = EncodedRgb::new(44, 232, 8, 255); let buff = bincode::serialize(&color).unwrap(); assert_eq!(buff, [44, 232, 8, 255]); let color = EncodedRgb::new(200, 21, 22, 203); let buff = bincode::serialize(&color).unwrap(); assert_eq!(buff, [200, 21, 22, 203]); let round_trip_color: EncodedRgb = bincode::deserialize(&buff).unwrap(); assert_eq!(color, round_trip_color); let buf = [14u8, 12, 3]; let o = bincode::deserialize::<EncodedRgb>(bytemuck::cast_slice(&buf)); assert!(o.is_err()); // okay and now with options, because otherwise it's hard to get errors // out of bincode... use bincode::Options; let deserialize = bincode::DefaultOptions::new(); let buf = [14, 12]; let o = deserialize.deserialize::<EncodedRgb>(bytemuck::cast_slice(&buf)); assert!(o.is_err()); let buf = [14u64]; let o = deserialize.deserialize::<EncodedRgb>(bytemuck::cast_slice(&buf)); assert!(o.is_err()); let buf = [31.0f32]; let o = deserialize.deserialize::<EncodedRgb>(bytemuck::cast_slice(&buf)); // lol, i don't like this. is there a way to make this not work? if you see this // and know the answer, please PR me! assert!(o.is_ok()); } }