embedded_graphics/primitives/common/
closed_thick_segment_iter.rs

1//! Closed shape thick segment iterator.
2
3use crate::{
4    geometry::Point,
5    primitives::common::{LineJoin, StrokeOffset, ThickSegment},
6};
7
8/// Closed shape thick segments iterator.
9///
10/// Iterates over all line segments in the polyline, returning a 6-sided shape as a [`ThickSegment`]
11/// for each segment. These are tessellated and are used to produce scanline intersections.
12///
13/// Unlike [`ThickSegmentIter`], this iterator closes the shape with a final line between the
14/// start and end points.
15///
16/// [`ThickSegment`]: super::thick_segment::ThickSegment
17/// [`ThickSegmentIter`]: super::thick_segment_iter::ThickSegmentIter
18#[derive(Clone, Debug)]
19#[cfg_attr(feature = "defmt", derive(::defmt::Format))]
20pub struct ClosedThickSegmentIter<'a> {
21    windows: core::slice::Windows<'a, Point>,
22    first_join: LineJoin,
23    start_join: LineJoin,
24    width: u32,
25    stroke_offset: StrokeOffset,
26    points: &'a [Point],
27    stop: bool,
28    idx: usize,
29}
30
31static EMPTY: &[Point; 0] = &[];
32
33impl<'a> ClosedThickSegmentIter<'a> {
34    /// Create a new thick segments iterator.
35    pub fn new(points: &'a [Point], width: u32, stroke_offset: StrokeOffset) -> Self {
36        if let [start, end] = points {
37            // Single line segment.
38            let start_join = LineJoin::start(*start, *end, width, stroke_offset);
39
40            Self {
41                windows: EMPTY.windows(3),
42                start_join,
43                width,
44                stroke_offset,
45                points,
46                stop: false,
47                first_join: start_join,
48                idx: 1,
49            }
50        } else if points.is_empty() {
51            Self::empty()
52        } else {
53            let windows = points.windows(3);
54
55            let start_join = LineJoin::from_points(
56                *points.last().unwrap(),
57                points[0],
58                points[1],
59                width,
60                stroke_offset,
61            );
62
63            Self {
64                windows,
65                start_join,
66                width,
67                stroke_offset,
68                points,
69                stop: false,
70                first_join: start_join,
71                idx: 1,
72            }
73        }
74    }
75
76    /// Empty
77    fn empty() -> Self {
78        Self {
79            windows: EMPTY.windows(3),
80            start_join: LineJoin::empty(),
81            width: 0,
82            stroke_offset: StrokeOffset::None,
83            points: EMPTY,
84            stop: true,
85            first_join: LineJoin::empty(),
86            idx: 1,
87        }
88    }
89}
90
91impl<'a> Iterator for ClosedThickSegmentIter<'a> {
92    type Item = ThickSegment;
93
94    fn next(&mut self) -> Option<Self::Item> {
95        if self.stop {
96            return None;
97        }
98
99        self.idx += 1;
100
101        let end_join = if let Some([start, mid, end]) = self.windows.next() {
102            LineJoin::from_points(*start, *mid, *end, self.width, self.stroke_offset)
103        } else if self.idx == self.points.len() {
104            // The join at the end of the line. This will become the start join of the closing
105            // segment.
106            let start = self.points.get(self.points.len() - 2)?;
107            let mid = self.points.last()?;
108            let end = self.points.first()?;
109
110            LineJoin::from_points(*start, *mid, *end, self.width, self.stroke_offset)
111        } else {
112            // Final closing line between start/end.
113            self.stop = true;
114
115            self.first_join
116        };
117
118        let segment = ThickSegment::new(self.start_join, end_join);
119
120        self.start_join = end_join;
121
122        Some(segment)
123    }
124}
embedded_graphics/primitives/common/closed_thick_segment_iter.rs

embedded_graphics/primitives/common/
closed_thick_segment_iter.rs
