owned_ttf_parser/
owned.rs

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1use crate::preparse::{FaceSubtables, PreParsedSubtables};
2#[cfg(not(feature = "std"))]
3use alloc::{boxed::Box, vec::Vec};
4use core::{fmt, marker::PhantomPinned, mem, pin::Pin, slice};
5
6/// An owned version of font [`Face`](struct.Face.html).
7pub struct OwnedFace(Pin<Box<SelfRefVecFace>>);
8
9impl OwnedFace {
10    /// Creates an `OwnedFace` from owned data.
11    ///
12    /// You can set index for font collections. For simple ttf fonts set index to 0.
13    ///
14    /// # Example
15    /// ```
16    /// # use owned_ttf_parser::OwnedFace;
17    /// # let owned_font_data = include_bytes!("../fonts/font.ttf").to_vec();
18    /// let owned_face = OwnedFace::from_vec(owned_font_data, 0).unwrap();
19    /// ```
20    // Note: not `try_from_vec` to better mimic `ttf_parser::Face::from_data`.
21    pub fn from_vec(data: Vec<u8>, index: u32) -> Result<Self, ttf_parser::FaceParsingError> {
22        let inner = SelfRefVecFace::try_from_vec(data, index)?;
23        Ok(Self(inner))
24    }
25
26    pub(crate) fn pre_parse_subtables(self) -> PreParsedSubtables<'static, Self> {
27        // build subtables referencing fake static data
28        let subtables = FaceSubtables::from(match self.0.face.as_ref() {
29            Some(f) => f,
30            None => unsafe { core::hint::unreachable_unchecked() },
31        });
32
33        // bundle everything together so self-reference lifetimes hold
34        PreParsedSubtables {
35            face: self,
36            subtables,
37        }
38    }
39
40    /// Extracts a slice containing the data passed into [`OwnedFace::from_vec`].
41    ///
42    /// # Example
43    /// ```
44    /// # use owned_ttf_parser::OwnedFace;
45    /// # let owned_font_data = include_bytes!("../fonts/font.ttf").to_vec();
46    /// let data_clone = owned_font_data.clone();
47    /// let owned_face = OwnedFace::from_vec(owned_font_data, 0).unwrap();
48    /// assert_eq!(owned_face.as_slice(), data_clone);
49    /// ```
50    pub fn as_slice(&self) -> &[u8] {
51        &self.0.data
52    }
53
54    /// Unwraps the data passed into [`OwnedFace::from_vec`].
55    ///
56    /// # Example
57    /// ```
58    /// # use owned_ttf_parser::OwnedFace;
59    /// # let owned_font_data = include_bytes!("../fonts/font.ttf").to_vec();
60    /// let data_clone = owned_font_data.clone();
61    /// let owned_face = OwnedFace::from_vec(owned_font_data, 0).unwrap();
62    /// assert_eq!(owned_face.into_vec(), data_clone);
63    /// ```
64    pub fn into_vec(self) -> Vec<u8> {
65        self.0.into_vec()
66    }
67}
68
69impl fmt::Debug for OwnedFace {
70    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
71        write!(f, "OwnedFace()")
72    }
73}
74
75impl crate::convert::AsFaceRef for OwnedFace {
76    #[inline]
77    fn as_face_ref(&self) -> &ttf_parser::Face<'_> {
78        self.0.inner_ref()
79    }
80}
81
82impl crate::convert::AsFaceRef for &OwnedFace {
83    #[inline]
84    fn as_face_ref(&self) -> &ttf_parser::Face<'_> {
85        self.0.inner_ref()
86    }
87}
88
89impl crate::convert::FaceMut for OwnedFace {
90    fn set_variation(&mut self, axis: ttf_parser::Tag, value: f32) -> Option<()> {
91        unsafe {
92            let mut_ref = Pin::as_mut(&mut self.0);
93            let mut_inner = mut_ref.get_unchecked_mut();
94            match mut_inner.face.as_mut() {
95                Some(face) => face.set_variation(axis, value),
96                None => None,
97            }
98        }
99    }
100}
101impl crate::convert::FaceMut for &mut OwnedFace {
102    #[inline]
103    fn set_variation(&mut self, axis: ttf_parser::Tag, value: f32) -> Option<()> {
104        (*self).set_variation(axis, value)
105    }
106}
107
108// Face data in a `Vec` with a self-referencing `Face`.
109struct SelfRefVecFace {
110    data: Vec<u8>,
111    face: Option<ttf_parser::Face<'static>>,
112    _pin: PhantomPinned,
113}
114
115impl SelfRefVecFace {
116    /// Creates an underlying face object from owned data.
117    fn try_from_vec(
118        data: Vec<u8>,
119        index: u32,
120    ) -> Result<Pin<Box<Self>>, ttf_parser::FaceParsingError> {
121        let face = Self {
122            data,
123            face: None,
124            _pin: PhantomPinned,
125        };
126        let mut b = Box::pin(face);
127        unsafe {
128            // 'static lifetime is a lie, this data is owned, it has pseudo-self lifetime.
129            let slice: &'static [u8] = slice::from_raw_parts(b.data.as_ptr(), b.data.len());
130            let mut_ref: Pin<&mut Self> = Pin::as_mut(&mut b);
131            let mut_inner = mut_ref.get_unchecked_mut();
132            mut_inner.face = Some(ttf_parser::Face::parse(slice, index)?);
133        }
134        Ok(b)
135    }
136
137    // Must not leak the fake 'static lifetime that we lied about earlier to the
138    // compiler. Since the lifetime 'a will not outlive our owned data it's
139    // safe to provide Face<'a>
140    #[inline]
141    #[allow(clippy::needless_lifetimes)] // explicit is nice as it's important 'static isn't leaked
142    fn inner_ref<'a>(self: &'a Pin<Box<Self>>) -> &'a ttf_parser::Face<'a> {
143        // Safety: if you have a ref `face` is always Some
144        unsafe { self.face.as_ref().unwrap_unchecked() }
145    }
146
147    fn into_vec(self: Pin<Box<Self>>) -> Vec<u8> {
148        // Safety: safe as `face` is dropped.
149        let mut me = unsafe { Pin::into_inner_unchecked(self) };
150        me.face.take(); // ensure dropped before taking `data`
151        mem::take(&mut me.data)
152    }
153}
154
155impl Drop for SelfRefVecFace {
156    fn drop(&mut self) {
157        self.face.take(); // ensure dropped before `data`
158    }
159}
owned_ttf_parser/owned.rs

owned_ttf_parser/
owned.rs
