epaint/
stroke.rs

1#![allow(clippy::derived_hash_with_manual_eq)] // We need to impl Hash for f32, but we don't implement Eq, which is fine
2
3use std::{fmt::Debug, sync::Arc};
4
5use emath::GuiRounding as _;
6
7use super::{Color32, ColorMode, Pos2, Rect, emath};
8
9/// Describes the width and color of a line.
10///
11/// The default stroke is the same as [`Stroke::NONE`].
12#[derive(Clone, Copy, Debug, Default, PartialEq)]
13#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
14pub struct Stroke {
15    pub width: f32,
16    pub color: Color32,
17}
18
19impl Stroke {
20    /// Same as [`Stroke::default`].
21    pub const NONE: Self = Self {
22        width: 0.0,
23        color: Color32::TRANSPARENT,
24    };
25
26    #[inline]
27    pub fn new(width: impl Into<f32>, color: impl Into<Color32>) -> Self {
28        Self {
29            width: width.into(),
30            color: color.into(),
31        }
32    }
33
34    /// True if width is zero or color is transparent
35    #[inline]
36    pub fn is_empty(&self) -> bool {
37        self.width <= 0.0 || self.color == Color32::TRANSPARENT
38    }
39
40    /// For vertical or horizontal lines:
41    /// round the stroke center to produce a sharp, pixel-aligned line.
42    pub fn round_center_to_pixel(&self, pixels_per_point: f32, coord: &mut f32) {
43        // If the stroke is an odd number of pixels wide,
44        // we want to round the center of it to the center of a pixel.
45        //
46        // If however it is an even number of pixels wide,
47        // we want to round the center to be between two pixels.
48        //
49        // We also want to treat strokes that are _almost_ odd as it it was odd,
50        // to make it symmetric. Same for strokes that are _almost_ even.
51        //
52        // For strokes less than a pixel wide we also round to the center,
53        // because it will rendered as a single row of pixels by the tessellator.
54
55        let pixel_size = 1.0 / pixels_per_point;
56
57        if self.width <= pixel_size || is_nearest_integer_odd(pixels_per_point * self.width) {
58            *coord = coord.round_to_pixel_center(pixels_per_point);
59        } else {
60            *coord = coord.round_to_pixels(pixels_per_point);
61        }
62    }
63
64    pub(crate) fn round_rect_to_pixel(&self, pixels_per_point: f32, rect: &mut Rect) {
65        // We put odd-width strokes in the center of pixels.
66        // To understand why, see `fn round_center_to_pixel`.
67
68        let pixel_size = 1.0 / pixels_per_point;
69
70        let width = self.width;
71        if width <= 0.0 {
72            *rect = rect.round_to_pixels(pixels_per_point);
73        } else if width <= pixel_size || is_nearest_integer_odd(pixels_per_point * width) {
74            *rect = rect.round_to_pixel_center(pixels_per_point);
75        } else {
76            *rect = rect.round_to_pixels(pixels_per_point);
77        }
78    }
79}
80
81impl<Color> From<(f32, Color)> for Stroke
82where
83    Color: Into<Color32>,
84{
85    #[inline(always)]
86    fn from((width, color): (f32, Color)) -> Self {
87        Self::new(width, color)
88    }
89}
90
91impl std::hash::Hash for Stroke {
92    #[inline(always)]
93    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
94        let Self { width, color } = *self;
95        emath::OrderedFloat(width).hash(state);
96        color.hash(state);
97    }
98}
99
100/// Describes how the stroke of a shape should be painted.
101#[derive(Clone, Copy, Debug, PartialEq, Eq)]
102#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
103pub enum StrokeKind {
104    /// The stroke should be painted entirely inside of the shape
105    Inside,
106
107    /// The stroke should be painted right on the edge of the shape, half inside and half outside.
108    Middle,
109
110    /// The stroke should be painted entirely outside of the shape
111    Outside,
112}
113
114/// Describes the width and color of paths. The color can either be solid or provided by a callback. For more information, see [`ColorMode`]
115///
116/// The default stroke is the same as [`Stroke::NONE`].
117#[derive(Clone, Debug, PartialEq)]
118#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
119pub struct PathStroke {
120    pub width: f32,
121    pub color: ColorMode,
122    pub kind: StrokeKind,
123}
124
125impl Default for PathStroke {
126    #[inline]
127    fn default() -> Self {
128        Self::NONE
129    }
130}
131
132impl PathStroke {
133    /// Same as [`PathStroke::default`].
134    pub const NONE: Self = Self {
135        width: 0.0,
136        color: ColorMode::TRANSPARENT,
137        kind: StrokeKind::Middle,
138    };
139
140    #[inline]
141    pub fn new(width: impl Into<f32>, color: impl Into<Color32>) -> Self {
142        Self {
143            width: width.into(),
144            color: ColorMode::Solid(color.into()),
145            kind: StrokeKind::Middle,
146        }
147    }
148
149    /// Create a new `PathStroke` with a UV function
150    ///
151    /// The bounding box passed to the callback will have a margin of [`TessellationOptions::feathering_size_in_pixels`](`crate::tessellator::TessellationOptions::feathering_size_in_pixels`)
152    #[inline]
153    pub fn new_uv(
154        width: impl Into<f32>,
155        callback: impl Fn(Rect, Pos2) -> Color32 + Send + Sync + 'static,
156    ) -> Self {
157        Self {
158            width: width.into(),
159            color: ColorMode::UV(Arc::new(callback)),
160            kind: StrokeKind::Middle,
161        }
162    }
163
164    #[inline]
165    pub fn with_kind(self, kind: StrokeKind) -> Self {
166        Self { kind, ..self }
167    }
168
169    /// Set the stroke to be painted right on the edge of the shape, half inside and half outside.
170    #[inline]
171    pub fn middle(self) -> Self {
172        Self {
173            kind: StrokeKind::Middle,
174            ..self
175        }
176    }
177
178    /// Set the stroke to be painted entirely outside of the shape
179    #[inline]
180    pub fn outside(self) -> Self {
181        Self {
182            kind: StrokeKind::Outside,
183            ..self
184        }
185    }
186
187    /// Set the stroke to be painted entirely inside of the shape
188    #[inline]
189    pub fn inside(self) -> Self {
190        Self {
191            kind: StrokeKind::Inside,
192            ..self
193        }
194    }
195
196    /// True if width is zero or color is solid and transparent
197    #[inline]
198    pub fn is_empty(&self) -> bool {
199        self.width <= 0.0 || self.color == ColorMode::TRANSPARENT
200    }
201}
202
203impl<Color> From<(f32, Color)> for PathStroke
204where
205    Color: Into<Color32>,
206{
207    #[inline(always)]
208    fn from((width, color): (f32, Color)) -> Self {
209        Self::new(width, color)
210    }
211}
212
213impl From<Stroke> for PathStroke {
214    fn from(value: Stroke) -> Self {
215        if value.is_empty() {
216            // Important, since we use the stroke color when doing feathering of the fill!
217            Self::NONE
218        } else {
219            Self {
220                width: value.width,
221                color: ColorMode::Solid(value.color),
222                kind: StrokeKind::Middle,
223            }
224        }
225    }
226}
227
228/// Returns true if the nearest integer is odd.
229fn is_nearest_integer_odd(x: f32) -> bool {
230    (x * 0.5 + 0.25).fract() > 0.5
231}
232
233#[test]
234fn test_is_nearest_integer_odd() {
235    assert!(is_nearest_integer_odd(0.6));
236    assert!(is_nearest_integer_odd(1.0));
237    assert!(is_nearest_integer_odd(1.4));
238    assert!(!is_nearest_integer_odd(1.6));
239    assert!(!is_nearest_integer_odd(2.0));
240    assert!(!is_nearest_integer_odd(2.4));
241    assert!(is_nearest_integer_odd(2.6));
242    assert!(is_nearest_integer_odd(3.0));
243    assert!(is_nearest_integer_odd(3.4));
244}
epaint/stroke.rs

epaint/
stroke.rs
