1use smallvec::SmallVec;
2use taffy::style::{Display, Position};
3
4use crate::{
5 point, AnyElement, BorrowWindow, Bounds, Element, LayoutId, ParentElement, Pixels, Point,
6 RenderOnce, Size, Style, WindowContext,
7};
8
9pub struct OverlayState {
10 child_layout_ids: SmallVec<[LayoutId; 4]>,
11}
12
13pub struct Overlay {
14 children: SmallVec<[AnyElement; 2]>,
15 anchor_corner: AnchorCorner,
16 fit_mode: OverlayFitMode,
17 // todo!();
18 anchor_position: Option<Point<Pixels>>,
19 // position_mode: OverlayPositionMode,
20}
21
22/// overlay gives you a floating element that will avoid overflowing the window bounds.
23/// Its children should have no margin to avoid measurement issues.
24pub fn overlay() -> Overlay {
25 Overlay {
26 children: SmallVec::new(),
27 anchor_corner: AnchorCorner::TopLeft,
28 fit_mode: OverlayFitMode::SwitchAnchor,
29 anchor_position: None,
30 }
31}
32
33impl Overlay {
34 /// Sets which corner of the overlay should be anchored to the current position.
35 pub fn anchor(mut self, anchor: AnchorCorner) -> Self {
36 self.anchor_corner = anchor;
37 self
38 }
39
40 /// Sets the position in window co-ordinates
41 /// (otherwise the location the overlay is rendered is used)
42 pub fn position(mut self, anchor: Point<Pixels>) -> Self {
43 self.anchor_position = Some(anchor);
44 self
45 }
46
47 /// Snap to window edge instead of switching anchor corner when an overflow would occur.
48 pub fn snap_to_window(mut self) -> Self {
49 self.fit_mode = OverlayFitMode::SnapToWindow;
50 self
51 }
52}
53
54impl ParentElement for Overlay {
55 fn children_mut(&mut self) -> &mut SmallVec<[AnyElement; 2]> {
56 &mut self.children
57 }
58}
59
60impl Element for Overlay {
61 type State = OverlayState;
62
63 fn layout(
64 &mut self,
65 _: Option<Self::State>,
66 cx: &mut WindowContext,
67 ) -> (crate::LayoutId, Self::State) {
68 let child_layout_ids = self
69 .children
70 .iter_mut()
71 .map(|child| child.layout(cx))
72 .collect::<SmallVec<_>>();
73
74 let mut overlay_style = Style::default();
75 overlay_style.position = Position::Absolute;
76 overlay_style.display = Display::Flex;
77
78 let layout_id = cx.request_layout(&overlay_style, child_layout_ids.iter().copied());
79
80 (layout_id, OverlayState { child_layout_ids })
81 }
82
83 fn paint(
84 self,
85 bounds: crate::Bounds<crate::Pixels>,
86 element_state: &mut Self::State,
87 cx: &mut WindowContext,
88 ) {
89 if element_state.child_layout_ids.is_empty() {
90 return;
91 }
92
93 let mut child_min = point(Pixels::MAX, Pixels::MAX);
94 let mut child_max = Point::default();
95 for child_layout_id in &element_state.child_layout_ids {
96 let child_bounds = cx.layout_bounds(*child_layout_id);
97 child_min = child_min.min(&child_bounds.origin);
98 child_max = child_max.max(&child_bounds.lower_right());
99 }
100 let size: Size<Pixels> = (child_max - child_min).into();
101 let origin = self.anchor_position.unwrap_or(bounds.origin);
102
103 let mut desired = self.anchor_corner.get_bounds(origin, size);
104 let limits = Bounds {
105 origin: Point::zero(),
106 size: cx.viewport_size(),
107 };
108
109 match self.fit_mode {
110 OverlayFitMode::SnapToWindow => {
111 // Snap the horizontal edges of the overlay to the horizontal edges of the window if
112 // its horizontal bounds overflow
113 if desired.right() > limits.right() {
114 desired.origin.x -= desired.right() - limits.right();
115 } else if desired.left() < limits.left() {
116 desired.origin.x = limits.origin.x;
117 }
118
119 // Snap the vertical edges of the overlay to the vertical edges of the window if
120 // its vertical bounds overflow.
121 if desired.bottom() > limits.bottom() {
122 desired.origin.y -= desired.bottom() - limits.bottom();
123 } else if desired.top() < limits.top() {
124 desired.origin.y = limits.origin.y;
125 }
126 }
127 OverlayFitMode::SwitchAnchor => {
128 let mut anchor_corner = self.anchor_corner;
129
130 if desired.left() < limits.left() || desired.right() > limits.right() {
131 anchor_corner = anchor_corner.switch_axis(Axis::Horizontal);
132 }
133
134 if bounds.top() < limits.top() || bounds.bottom() > limits.bottom() {
135 anchor_corner = anchor_corner.switch_axis(Axis::Vertical);
136 }
137
138 // Update bounds if needed
139 if anchor_corner != self.anchor_corner {
140 desired = anchor_corner.get_bounds(origin, size)
141 }
142 }
143 OverlayFitMode::None => {}
144 }
145
146 cx.with_element_offset(desired.origin - bounds.origin, |cx| {
147 for child in self.children {
148 child.paint(cx);
149 }
150 })
151 }
152}
153
154impl RenderOnce for Overlay {
155 type Element = Self;
156
157 fn element_id(&self) -> Option<crate::ElementId> {
158 None
159 }
160
161 fn render_once(self) -> Self::Element {
162 self
163 }
164}
165
166enum Axis {
167 Horizontal,
168 Vertical,
169}
170
171#[derive(Copy, Clone)]
172pub enum OverlayFitMode {
173 SnapToWindow,
174 SwitchAnchor,
175 None,
176}
177
178#[derive(Clone, Copy, PartialEq, Eq)]
179pub enum AnchorCorner {
180 TopLeft,
181 TopRight,
182 BottomLeft,
183 BottomRight,
184}
185
186impl AnchorCorner {
187 fn get_bounds(&self, origin: Point<Pixels>, size: Size<Pixels>) -> Bounds<Pixels> {
188 let origin = match self {
189 Self::TopLeft => origin,
190 Self::TopRight => Point {
191 x: origin.x - size.width,
192 y: origin.y,
193 },
194 Self::BottomLeft => Point {
195 x: origin.x,
196 y: origin.y - size.height,
197 },
198 Self::BottomRight => Point {
199 x: origin.x - size.width,
200 y: origin.y - size.height,
201 },
202 };
203
204 Bounds { origin, size }
205 }
206
207 pub fn corner(&self, bounds: Bounds<Pixels>) -> Point<Pixels> {
208 match self {
209 Self::TopLeft => bounds.origin,
210 Self::TopRight => bounds.upper_right(),
211 Self::BottomLeft => bounds.lower_left(),
212 Self::BottomRight => bounds.lower_right(),
213 }
214 }
215
216 fn switch_axis(self, axis: Axis) -> Self {
217 match axis {
218 Axis::Vertical => match self {
219 AnchorCorner::TopLeft => AnchorCorner::BottomLeft,
220 AnchorCorner::TopRight => AnchorCorner::BottomRight,
221 AnchorCorner::BottomLeft => AnchorCorner::TopLeft,
222 AnchorCorner::BottomRight => AnchorCorner::TopRight,
223 },
224 Axis::Horizontal => match self {
225 AnchorCorner::TopLeft => AnchorCorner::TopRight,
226 AnchorCorner::TopRight => AnchorCorner::TopLeft,
227 AnchorCorner::BottomLeft => AnchorCorner::BottomRight,
228 AnchorCorner::BottomRight => AnchorCorner::BottomLeft,
229 },
230 }
231 }
232}