1#[cfg(not(feature = "std"))]
2use core_maths::CoreFloat;
3
4use super::buffer::hb_buffer_t;
5use super::hb_font_t;
6use super::ot_shape_plan::hb_ot_shape_plan_t;
7
8pub fn apply(plan: &hb_ot_shape_plan_t, face: &hb_font_t, buffer: &mut hb_buffer_t) -> Option<()> {
9 let trak_mask = plan.trak_mask;
10
11 let ptem = face.points_per_em?;
12 if ptem <= 0.0 {
13 return None;
14 }
15
16 let trak = face.tables().trak?;
17
18 if !buffer.have_positions {
19 buffer.clear_positions();
20 }
21
22 if buffer.direction.is_horizontal() {
23 let tracking = trak.hor_tracking(ptem)?;
24 let advance_to_add = tracking;
25 let offset_to_add = tracking / 2;
26 foreach_grapheme!(buffer, start, end, {
27 if buffer.info[start].mask & trak_mask != 0 {
28 buffer.pos[start].x_advance += advance_to_add;
29 buffer.pos[start].x_offset += offset_to_add;
30 }
31 });
32 } else {
33 let tracking = trak.ver_tracking(ptem)?;
34 let advance_to_add = tracking;
35 let offset_to_add = tracking / 2;
36 foreach_grapheme!(buffer, start, end, {
37 if buffer.info[start].mask & trak_mask != 0 {
38 buffer.pos[start].y_advance += advance_to_add;
39 buffer.pos[start].y_offset += offset_to_add;
40 }
41 });
42 }
43
44 Some(())
45}
46
47trait TrackTableExt {
48 fn hor_tracking(&self, ptem: f32) -> Option<i32>;
49 fn ver_tracking(&self, ptem: f32) -> Option<i32>;
50}
51
52impl TrackTableExt for ttf_parser::trak::Table<'_> {
53 fn hor_tracking(&self, ptem: f32) -> Option<i32> {
54 self.horizontal.tracking(ptem)
55 }
56
57 fn ver_tracking(&self, ptem: f32) -> Option<i32> {
58 self.vertical.tracking(ptem)
59 }
60}
61
62trait TrackTableDataExt {
63 fn tracking(&self, ptem: f32) -> Option<i32>;
64 fn interpolate_at(
65 &self,
66 idx: u16,
67 target_size: f32,
68 track: &ttf_parser::trak::Track,
69 ) -> Option<f32>;
70}
71
72impl TrackTableDataExt for ttf_parser::trak::TrackData<'_> {
73 fn tracking(&self, ptem: f32) -> Option<i32> {
74 // Choose track.
75 let track = self.tracks.into_iter().find(|t| t.value == 0.0)?;
76
77 // Choose size.
78 if self.sizes.is_empty() {
79 return None;
80 }
81
82 let mut idx = self
83 .sizes
84 .into_iter()
85 .position(|s| s.0 >= ptem)
86 .unwrap_or(self.sizes.len() as usize - 1);
87
88 idx = idx.saturating_sub(1);
89
90 self.interpolate_at(idx as u16, ptem, &track)
91 .map(|n| n.round() as i32)
92 }
93
94 fn interpolate_at(
95 &self,
96 idx: u16,
97 target_size: f32,
98 track: &ttf_parser::trak::Track,
99 ) -> Option<f32> {
100 debug_assert!(idx < self.sizes.len() - 1);
101
102 let s0 = self.sizes.get(idx)?.0;
103 let s1 = self.sizes.get(idx + 1)?.0;
104
105 let t = if s0 == s1 {
106 0.0
107 } else {
108 (target_size - s0) / (s1 - s0)
109 };
110
111 let n =
112 t * (track.values.get(idx + 1)? as f32) + (1.0 - t) * (track.values.get(idx)? as f32);
113
114 Some(n)
115 }
116}
117