druid_shell/
region.rs

1// Copyright 2020 The Druid Authors.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15use crate::kurbo::{BezPath, Point, Rect, Shape, Vec2};
16
17/// A union of rectangles, useful for describing an area that needs to be repainted.
18#[derive(Clone, Debug)]
19pub struct Region {
20    rects: Vec<Rect>,
21}
22
23impl Region {
24    /// The empty region.
25    pub const EMPTY: Region = Region { rects: Vec::new() };
26
27    /// Returns the collection of rectangles making up this region.
28    #[inline]
29    pub fn rects(&self) -> &[Rect] {
30        &self.rects
31    }
32
33    /// Adds a rectangle to this region.
34    pub fn add_rect(&mut self, rect: Rect) {
35        if rect.area() > 0.0 {
36            self.rects.push(rect);
37        }
38    }
39
40    /// Replaces this region with a single rectangle.
41    pub fn set_rect(&mut self, rect: Rect) {
42        self.clear();
43        self.add_rect(rect);
44    }
45
46    /// Sets this region to the empty region.
47    pub fn clear(&mut self) {
48        self.rects.clear();
49    }
50
51    /// Returns a rectangle containing this region.
52    pub fn bounding_box(&self) -> Rect {
53        if self.rects.is_empty() {
54            Rect::ZERO
55        } else {
56            self.rects[1..]
57                .iter()
58                .fold(self.rects[0], |r, s| r.union(*s))
59        }
60    }
61
62    #[doc(hidden)]
63    #[deprecated(since = "0.7.0", note = "Use bounding_box() instead")]
64    // this existed on the previous Region type, and I've bumped into it
65    // a couple times while updating
66    pub fn to_rect(&self) -> Rect {
67        self.bounding_box()
68    }
69
70    /// Returns `true` if this region has a non-empty intersection with the given rectangle.
71    pub fn intersects(&self, rect: Rect) -> bool {
72        self.rects.iter().any(|r| r.intersect(rect).area() > 0.0)
73    }
74
75    /// Returns `true` if the given `point` is contained within any rectangle in the region.
76    pub fn contains(&self, point: Point) -> bool {
77        self.rects.iter().any(|r| r.contains(point))
78    }
79
80    /// Returns `true` if this region is empty.
81    pub fn is_empty(&self) -> bool {
82        // Note that we only ever add non-empty rects to self.rects.
83        self.rects.is_empty()
84    }
85
86    /// Converts into a Bezier path. Note that this just gives the concatenation of the rectangle
87    /// paths, which is not the smartest possible thing. Also, it's not the right answer for an
88    /// even/odd fill rule.
89    pub fn to_bez_path(&self) -> BezPath {
90        let mut ret = BezPath::new();
91        for rect in self.rects() {
92            // Rect ignores the tolerance.
93            ret.extend(rect.path_elements(0.0));
94        }
95        ret
96    }
97
98    /// Modifies this region by including everything in the other region.
99    pub fn union_with(&mut self, other: &Region) {
100        self.rects.extend_from_slice(&other.rects);
101    }
102
103    /// Modifies this region by intersecting it with the given rectangle.
104    pub fn intersect_with(&mut self, rect: Rect) {
105        // TODO: this would be a good use of the nightly drain_filter function, if it stabilizes
106        for r in &mut self.rects {
107            *r = r.intersect(rect);
108        }
109        self.rects.retain(|r| r.area() > 0.0)
110    }
111}
112
113impl std::ops::AddAssign<Vec2> for Region {
114    fn add_assign(&mut self, rhs: Vec2) {
115        for r in &mut self.rects {
116            *r = *r + rhs;
117        }
118    }
119}
120
121impl std::ops::SubAssign<Vec2> for Region {
122    fn sub_assign(&mut self, rhs: Vec2) {
123        for r in &mut self.rects {
124            *r = *r - rhs;
125        }
126    }
127}
128
129impl From<Rect> for Region {
130    fn from(rect: Rect) -> Region {
131        Region { rects: vec![rect] }
132    }
133}
druid_shell/region.rs

druid_shell/
region.rs
