image/
traits.rs

1//! This module provides useful traits that were deprecated in rust
2
3// Note copied from the stdlib under MIT license
4
5use num_traits::{Bounded, Num, NumCast};
6use std::ops::AddAssign;
7
8use crate::color::{Luma, LumaA, Rgb, Rgba};
9use crate::ExtendedColorType;
10
11/// Types which are safe to treat as an immutable byte slice in a pixel layout
12/// for image encoding.
13pub trait EncodableLayout: seals::EncodableLayout {
14    /// Get the bytes of this value.
15    fn as_bytes(&self) -> &[u8];
16}
17
18impl EncodableLayout for [u8] {
19    fn as_bytes(&self) -> &[u8] {
20        bytemuck::cast_slice(self)
21    }
22}
23
24impl EncodableLayout for [u16] {
25    fn as_bytes(&self) -> &[u8] {
26        bytemuck::cast_slice(self)
27    }
28}
29
30impl EncodableLayout for [f32] {
31    fn as_bytes(&self) -> &[u8] {
32        bytemuck::cast_slice(self)
33    }
34}
35
36/// The type of each channel in a pixel. For example, this can be `u8`, `u16`, `f32`.
37// TODO rename to `PixelComponent`? Split up into separate traits? Seal?
38pub trait Primitive: Copy + NumCast + Num + PartialOrd<Self> + Clone + Bounded {
39    /// The maximum value for this type of primitive within the context of color.
40    /// For floats, the maximum is `1.0`, whereas the integer types inherit their usual maximum values.
41    const DEFAULT_MAX_VALUE: Self;
42
43    /// The minimum value for this type of primitive within the context of color.
44    /// For floats, the minimum is `0.0`, whereas the integer types inherit their usual minimum values.
45    const DEFAULT_MIN_VALUE: Self;
46}
47
48macro_rules! declare_primitive {
49    ($base:ty: ($from:expr)..$to:expr) => {
50        impl Primitive for $base {
51            const DEFAULT_MAX_VALUE: Self = $to;
52            const DEFAULT_MIN_VALUE: Self = $from;
53        }
54    };
55}
56
57declare_primitive!(usize: (0)..Self::MAX);
58declare_primitive!(u8: (0)..Self::MAX);
59declare_primitive!(u16: (0)..Self::MAX);
60declare_primitive!(u32: (0)..Self::MAX);
61declare_primitive!(u64: (0)..Self::MAX);
62
63declare_primitive!(isize: (Self::MIN)..Self::MAX);
64declare_primitive!(i8: (Self::MIN)..Self::MAX);
65declare_primitive!(i16: (Self::MIN)..Self::MAX);
66declare_primitive!(i32: (Self::MIN)..Self::MAX);
67declare_primitive!(i64: (Self::MIN)..Self::MAX);
68declare_primitive!(f32: (0.0)..1.0);
69declare_primitive!(f64: (0.0)..1.0);
70
71/// An `Enlargable::Larger` value should be enough to calculate
72/// the sum (average) of a few hundred or thousand Enlargeable values.
73pub trait Enlargeable: Sized + Bounded + NumCast {
74    type Larger: Copy + NumCast + Num + PartialOrd<Self::Larger> + Clone + Bounded + AddAssign;
75
76    fn clamp_from(n: Self::Larger) -> Self {
77        if n > Self::max_value().to_larger() {
78            Self::max_value()
79        } else if n < Self::min_value().to_larger() {
80            Self::min_value()
81        } else {
82            NumCast::from(n).unwrap()
83        }
84    }
85
86    fn to_larger(self) -> Self::Larger {
87        NumCast::from(self).unwrap()
88    }
89}
90
91impl Enlargeable for u8 {
92    type Larger = u32;
93}
94impl Enlargeable for u16 {
95    type Larger = u32;
96}
97impl Enlargeable for u32 {
98    type Larger = u64;
99}
100impl Enlargeable for u64 {
101    type Larger = u128;
102}
103impl Enlargeable for usize {
104    // Note: On 32-bit architectures, u64 should be enough here.
105    type Larger = u128;
106}
107impl Enlargeable for i8 {
108    type Larger = i32;
109}
110impl Enlargeable for i16 {
111    type Larger = i32;
112}
113impl Enlargeable for i32 {
114    type Larger = i64;
115}
116impl Enlargeable for i64 {
117    type Larger = i128;
118}
119impl Enlargeable for isize {
120    // Note: On 32-bit architectures, i64 should be enough here.
121    type Larger = i128;
122}
123impl Enlargeable for f32 {
124    type Larger = f64;
125}
126impl Enlargeable for f64 {
127    type Larger = f64;
128}
129
130/// Linear interpolation without involving floating numbers.
131pub trait Lerp: Bounded + NumCast {
132    type Ratio: Primitive;
133
134    fn lerp(a: Self, b: Self, ratio: Self::Ratio) -> Self {
135        let a = <Self::Ratio as NumCast>::from(a).unwrap();
136        let b = <Self::Ratio as NumCast>::from(b).unwrap();
137
138        let res = a + (b - a) * ratio;
139
140        if res > NumCast::from(Self::max_value()).unwrap() {
141            Self::max_value()
142        } else if res < NumCast::from(0).unwrap() {
143            NumCast::from(0).unwrap()
144        } else {
145            NumCast::from(res).unwrap()
146        }
147    }
148}
149
150impl Lerp for u8 {
151    type Ratio = f32;
152}
153
154impl Lerp for u16 {
155    type Ratio = f32;
156}
157
158impl Lerp for u32 {
159    type Ratio = f64;
160}
161
162impl Lerp for f32 {
163    type Ratio = f32;
164
165    fn lerp(a: Self, b: Self, ratio: Self::Ratio) -> Self {
166        a + (b - a) * ratio
167    }
168}
169
170/// The pixel with an associated `ColorType`.
171/// Not all possible pixels represent one of the predefined `ColorType`s.
172pub trait PixelWithColorType: Pixel + private::SealedPixelWithColorType {
173    /// This pixel has the format of one of the predefined `ColorType`s,
174    /// such as `Rgb8`, `La16` or `Rgba32F`.
175    /// This is needed for automatically detecting
176    /// a color format when saving an image as a file.
177    const COLOR_TYPE: ExtendedColorType;
178}
179
180impl PixelWithColorType for Rgb<u8> {
181    const COLOR_TYPE: ExtendedColorType = ExtendedColorType::Rgb8;
182}
183impl PixelWithColorType for Rgb<u16> {
184    const COLOR_TYPE: ExtendedColorType = ExtendedColorType::Rgb16;
185}
186impl PixelWithColorType for Rgb<f32> {
187    const COLOR_TYPE: ExtendedColorType = ExtendedColorType::Rgb32F;
188}
189
190impl PixelWithColorType for Rgba<u8> {
191    const COLOR_TYPE: ExtendedColorType = ExtendedColorType::Rgba8;
192}
193impl PixelWithColorType for Rgba<u16> {
194    const COLOR_TYPE: ExtendedColorType = ExtendedColorType::Rgba16;
195}
196impl PixelWithColorType for Rgba<f32> {
197    const COLOR_TYPE: ExtendedColorType = ExtendedColorType::Rgba32F;
198}
199
200impl PixelWithColorType for Luma<u8> {
201    const COLOR_TYPE: ExtendedColorType = ExtendedColorType::L8;
202}
203impl PixelWithColorType for Luma<u16> {
204    const COLOR_TYPE: ExtendedColorType = ExtendedColorType::L16;
205}
206impl PixelWithColorType for LumaA<u8> {
207    const COLOR_TYPE: ExtendedColorType = ExtendedColorType::La8;
208}
209impl PixelWithColorType for LumaA<u16> {
210    const COLOR_TYPE: ExtendedColorType = ExtendedColorType::La16;
211}
212
213/// Prevents down-stream users from implementing the `Primitive` trait
214mod private {
215    use crate::color::*;
216
217    pub trait SealedPixelWithColorType {}
218    impl SealedPixelWithColorType for Rgb<u8> {}
219    impl SealedPixelWithColorType for Rgb<u16> {}
220    impl SealedPixelWithColorType for Rgb<f32> {}
221
222    impl SealedPixelWithColorType for Rgba<u8> {}
223    impl SealedPixelWithColorType for Rgba<u16> {}
224    impl SealedPixelWithColorType for Rgba<f32> {}
225
226    impl SealedPixelWithColorType for Luma<u8> {}
227    impl SealedPixelWithColorType for LumaA<u8> {}
228
229    impl SealedPixelWithColorType for Luma<u16> {}
230    impl SealedPixelWithColorType for LumaA<u16> {}
231}
232
233/// A generalized pixel.
234///
235/// A pixel object is usually not used standalone but as a view into an image buffer.
236pub trait Pixel: Copy + Clone {
237    /// The scalar type that is used to store each channel in this pixel.
238    type Subpixel: Primitive;
239
240    /// The number of channels of this pixel type.
241    const CHANNEL_COUNT: u8;
242
243    /// Returns the components as a slice.
244    fn channels(&self) -> &[Self::Subpixel];
245
246    /// Returns the components as a mutable slice
247    fn channels_mut(&mut self) -> &mut [Self::Subpixel];
248
249    /// A string that can help to interpret the meaning each channel
250    /// See [gimp babl](http://gegl.org/babl/).
251    const COLOR_MODEL: &'static str;
252
253    /// Returns the channels of this pixel as a 4 tuple. If the pixel
254    /// has less than 4 channels the remainder is filled with the maximum value
255    #[deprecated(since = "0.24.0", note = "Use `channels()` or `channels_mut()`")]
256    fn channels4(
257        &self,
258    ) -> (
259        Self::Subpixel,
260        Self::Subpixel,
261        Self::Subpixel,
262        Self::Subpixel,
263    );
264
265    /// Construct a pixel from the 4 channels a, b, c and d.
266    /// If the pixel does not contain 4 channels the extra are ignored.
267    #[deprecated(
268        since = "0.24.0",
269        note = "Use the constructor of the pixel, for example `Rgba([r,g,b,a])` or `Pixel::from_slice`"
270    )]
271    fn from_channels(
272        a: Self::Subpixel,
273        b: Self::Subpixel,
274        c: Self::Subpixel,
275        d: Self::Subpixel,
276    ) -> Self;
277
278    /// Returns a view into a slice.
279    ///
280    /// Note: The slice length is not checked on creation. Thus the caller has to ensure
281    /// that the slice is long enough to prevent panics if the pixel is used later on.
282    fn from_slice(slice: &[Self::Subpixel]) -> &Self;
283
284    /// Returns mutable view into a mutable slice.
285    ///
286    /// Note: The slice length is not checked on creation. Thus the caller has to ensure
287    /// that the slice is long enough to prevent panics if the pixel is used later on.
288    fn from_slice_mut(slice: &mut [Self::Subpixel]) -> &mut Self;
289
290    /// Convert this pixel to RGB
291    fn to_rgb(&self) -> Rgb<Self::Subpixel>;
292
293    /// Convert this pixel to RGB with an alpha channel
294    fn to_rgba(&self) -> Rgba<Self::Subpixel>;
295
296    /// Convert this pixel to luma
297    fn to_luma(&self) -> Luma<Self::Subpixel>;
298
299    /// Convert this pixel to luma with an alpha channel
300    fn to_luma_alpha(&self) -> LumaA<Self::Subpixel>;
301
302    /// Apply the function ```f``` to each channel of this pixel.
303    fn map<F>(&self, f: F) -> Self
304    where
305        F: FnMut(Self::Subpixel) -> Self::Subpixel;
306
307    /// Apply the function ```f``` to each channel of this pixel.
308    fn apply<F>(&mut self, f: F)
309    where
310        F: FnMut(Self::Subpixel) -> Self::Subpixel;
311
312    /// Apply the function ```f``` to each channel except the alpha channel.
313    /// Apply the function ```g``` to the alpha channel.
314    fn map_with_alpha<F, G>(&self, f: F, g: G) -> Self
315    where
316        F: FnMut(Self::Subpixel) -> Self::Subpixel,
317        G: FnMut(Self::Subpixel) -> Self::Subpixel;
318
319    /// Apply the function ```f``` to each channel except the alpha channel.
320    /// Apply the function ```g``` to the alpha channel. Works in-place.
321    fn apply_with_alpha<F, G>(&mut self, f: F, g: G)
322    where
323        F: FnMut(Self::Subpixel) -> Self::Subpixel,
324        G: FnMut(Self::Subpixel) -> Self::Subpixel;
325
326    /// Apply the function ```f``` to each channel except the alpha channel.
327    fn map_without_alpha<F>(&self, f: F) -> Self
328    where
329        F: FnMut(Self::Subpixel) -> Self::Subpixel,
330    {
331        let mut this = *self;
332        this.apply_with_alpha(f, |x| x);
333        this
334    }
335
336    /// Apply the function ```f``` to each channel except the alpha channel.
337    /// Works in place.
338    fn apply_without_alpha<F>(&mut self, f: F)
339    where
340        F: FnMut(Self::Subpixel) -> Self::Subpixel,
341    {
342        self.apply_with_alpha(f, |x| x);
343    }
344
345    /// Apply the function ```f``` to each channel of this pixel and
346    /// ```other``` pairwise.
347    fn map2<F>(&self, other: &Self, f: F) -> Self
348    where
349        F: FnMut(Self::Subpixel, Self::Subpixel) -> Self::Subpixel;
350
351    /// Apply the function ```f``` to each channel of this pixel and
352    /// ```other``` pairwise. Works in-place.
353    fn apply2<F>(&mut self, other: &Self, f: F)
354    where
355        F: FnMut(Self::Subpixel, Self::Subpixel) -> Self::Subpixel;
356
357    /// Invert this pixel
358    fn invert(&mut self);
359
360    /// Blend the color of a given pixel into ourself, taking into account alpha channels
361    fn blend(&mut self, other: &Self);
362}
363
364/// Private module for supertraits of sealed traits.
365mod seals {
366    pub trait EncodableLayout {}
367
368    impl EncodableLayout for [u8] {}
369    impl EncodableLayout for [u16] {}
370    impl EncodableLayout for [f32] {}
371}
image/traits.rs

image/
traits.rs
