hayro_syntax/function/
mod.rs

1//! PDF functions.
2//!
3//! PDF has the concept of functions, representing objects that take a certain number of values
4//! as input, do some processing on them and then return some output.
5
6mod type0;
7mod type2;
8mod type3;
9mod type4;
10
11use crate::function::type0::Type0;
12use crate::function::type2::Type2;
13use crate::function::type3::Type3;
14use crate::function::type4::Type4;
15use crate::object::Dict;
16use crate::object::dict::keys::{DOMAIN, FUNCTION_TYPE, RANGE};
17use crate::object::{Object, dict_or_stream};
18use log::warn;
19use smallvec::SmallVec;
20use std::sync::Arc;
21
22/// The input/output type of functions.
23pub type Values = SmallVec<[f32; 4]>;
24type TupleVec = SmallVec<[(f32, f32); 4]>;
25
26#[derive(Debug)]
27enum FunctionType {
28    Type0(Type0),
29    Type2(Type2),
30    Type3(Type3),
31    Type4(Type4),
32}
33
34/// A PDF function.
35#[derive(Debug, Clone)]
36pub struct Function(Arc<FunctionType>);
37
38impl Function {
39    /// Create a new function.
40    pub fn new(obj: &Object) -> Option<Function> {
41        let (dict, stream) = dict_or_stream(obj)?;
42
43        let function_type = match dict.get::<u8>(FUNCTION_TYPE)? {
44            0 => FunctionType::Type0(Type0::new(&stream?)?),
45            2 => FunctionType::Type2(Type2::new(&dict)?),
46            3 => FunctionType::Type3(Type3::new(&dict)?),
47            4 => FunctionType::Type4(Type4::new(&stream?)?),
48            _ => return None,
49        };
50
51        Some(Self(Arc::new(function_type)))
52    }
53
54    /// Evaluate the function with the given input.
55    pub fn eval(&self, input: Values) -> Option<Values> {
56        match self.0.as_ref() {
57            FunctionType::Type0(t0) => t0.eval(input),
58            FunctionType::Type2(t2) => Some(t2.eval(*input.first()?)),
59            FunctionType::Type3(t3) => t3.eval(*input.first()?),
60            FunctionType::Type4(t4) => Some(t4.eval(input)?),
61        }
62    }
63}
64
65#[derive(Debug, Clone)]
66struct Clamper {
67    domain: TupleVec,
68    range: Option<TupleVec>,
69}
70
71impl Clamper {
72    fn new(dict: &Dict) -> Option<Self> {
73        let domain = dict.get::<TupleVec>(DOMAIN)?;
74        let range = dict.get::<TupleVec>(RANGE);
75
76        Some(Self { domain, range })
77    }
78
79    fn clamp_input(&self, input: &mut [f32]) {
80        if input.len() != self.domain.len() {
81            warn!("the domain of the function didn't match the input arguments");
82        }
83
84        for ((min, max), val) in self.domain.iter().zip(input.iter_mut()) {
85            *val = val.min(*max).max(*min);
86        }
87    }
88
89    fn clamp_output(&self, output: &mut [f32]) {
90        if let Some(range) = &self.range {
91            if range.len() != output.len() {
92                warn!("the range of the function didn't match the output arguments");
93            }
94
95            for ((min, max), val) in range.iter().zip(output.iter_mut()) {
96                *val = val.min(*max).max(*min);
97            }
98        }
99    }
100}
101
102/// Linearly interpolate the value `x`, assuming that it lies within the range `x_min` and `x_max`,
103/// to the range `y_min` and `y_max`.
104pub fn interpolate(x: f32, x_min: f32, x_max: f32, y_min: f32, y_max: f32) -> f32 {
105    y_min + (x - x_min) * (y_max - y_min) / (x_max - x_min)
106}
hayro_syntax/function/mod.rs

hayro_syntax/function/
mod.rs
