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,
7};
8
9pub struct OverlayState {
10 child_layout_ids: SmallVec<[LayoutId; 4]>,
11}
12
13pub struct Overlay<V> {
14 children: SmallVec<[AnyElement<V>; 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<V: 'static>() -> Overlay<V> {
25 Overlay {
26 children: SmallVec::new(),
27 anchor_corner: AnchorCorner::TopLeft,
28 fit_mode: OverlayFitMode::SwitchAnchor,
29 anchor_position: None,
30 }
31}
32
33impl<V> Overlay<V> {
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<V: 'static> ParentElement<V> for Overlay<V> {
55 fn children_mut(&mut self) -> &mut SmallVec<[AnyElement<V>; 2]> {
56 &mut self.children
57 }
58}
59
60impl<V: 'static> Element<V> for Overlay<V> {
61 type State = OverlayState;
62
63 fn layout(
64 &mut self,
65 view_state: &mut V,
66 _: Option<Self::State>,
67 cx: &mut crate::ViewContext<V>,
68 ) -> (crate::LayoutId, Self::State) {
69 let child_layout_ids = self
70 .children
71 .iter_mut()
72 .map(|child| child.layout(view_state, cx))
73 .collect::<SmallVec<_>>();
74
75 let mut overlay_style = Style::default();
76 overlay_style.position = Position::Absolute;
77 overlay_style.display = Display::Flex;
78
79 let layout_id = cx.request_layout(&overlay_style, child_layout_ids.iter().copied());
80
81 (layout_id, OverlayState { child_layout_ids })
82 }
83
84 fn paint(
85 self,
86 bounds: crate::Bounds<crate::Pixels>,
87 view_state: &mut V,
88 element_state: &mut Self::State,
89 cx: &mut crate::ViewContext<V>,
90 ) {
91 if element_state.child_layout_ids.is_empty() {
92 return;
93 }
94
95 let mut child_min = point(Pixels::MAX, Pixels::MAX);
96 let mut child_max = Point::default();
97 for child_layout_id in &element_state.child_layout_ids {
98 let child_bounds = cx.layout_bounds(*child_layout_id);
99 child_min = child_min.min(&child_bounds.origin);
100 child_max = child_max.max(&child_bounds.lower_right());
101 }
102 let size: Size<Pixels> = (child_max - child_min).into();
103 let origin = self.anchor_position.unwrap_or(bounds.origin);
104
105 let mut desired = self.anchor_corner.get_bounds(origin, size);
106 let limits = Bounds {
107 origin: Point::zero(),
108 size: cx.viewport_size(),
109 };
110
111 match self.fit_mode {
112 OverlayFitMode::SnapToWindow => {
113 // Snap the horizontal edges of the overlay to the horizontal edges of the window if
114 // its horizontal bounds overflow
115 if desired.right() > limits.right() {
116 desired.origin.x -= desired.right() - limits.right();
117 } else if desired.left() < limits.left() {
118 desired.origin.x = limits.origin.x;
119 }
120
121 // Snap the vertical edges of the overlay to the vertical edges of the window if
122 // its vertical bounds overflow.
123 if desired.bottom() > limits.bottom() {
124 desired.origin.y -= desired.bottom() - limits.bottom();
125 } else if desired.top() < limits.top() {
126 desired.origin.y = limits.origin.y;
127 }
128 }
129 OverlayFitMode::SwitchAnchor => {
130 let mut anchor_corner = self.anchor_corner;
131
132 if desired.left() < limits.left() || desired.right() > limits.right() {
133 anchor_corner = anchor_corner.switch_axis(Axis::Horizontal);
134 }
135
136 if bounds.top() < limits.top() || bounds.bottom() > limits.bottom() {
137 anchor_corner = anchor_corner.switch_axis(Axis::Vertical);
138 }
139
140 // Update bounds if needed
141 if anchor_corner != self.anchor_corner {
142 desired = anchor_corner.get_bounds(origin, size)
143 }
144 }
145 OverlayFitMode::None => {}
146 }
147
148 cx.with_element_offset(desired.origin - bounds.origin, |cx| {
149 for child in self.children {
150 child.paint(view_state, cx);
151 }
152 })
153 }
154}
155
156impl<V: 'static> RenderOnce<V> for Overlay<V> {
157 type Element = Self;
158
159 fn element_id(&self) -> Option<crate::ElementId> {
160 None
161 }
162
163 fn render_once(self) -> Self::Element {
164 self
165 }
166}
167
168enum Axis {
169 Horizontal,
170 Vertical,
171}
172
173#[derive(Copy, Clone)]
174pub enum OverlayFitMode {
175 SnapToWindow,
176 SwitchAnchor,
177 None,
178}
179
180#[derive(Clone, Copy, PartialEq, Eq)]
181pub enum AnchorCorner {
182 TopLeft,
183 TopRight,
184 BottomLeft,
185 BottomRight,
186}
187
188impl AnchorCorner {
189 fn get_bounds(&self, origin: Point<Pixels>, size: Size<Pixels>) -> Bounds<Pixels> {
190 let origin = match self {
191 Self::TopLeft => origin,
192 Self::TopRight => Point {
193 x: origin.x - size.width,
194 y: origin.y,
195 },
196 Self::BottomLeft => Point {
197 x: origin.x,
198 y: origin.y - size.height,
199 },
200 Self::BottomRight => Point {
201 x: origin.x - size.width,
202 y: origin.y - size.height,
203 },
204 };
205
206 Bounds { origin, size }
207 }
208
209 pub fn corner(&self, bounds: Bounds<Pixels>) -> Point<Pixels> {
210 match self {
211 Self::TopLeft => bounds.origin,
212 Self::TopRight => bounds.upper_right(),
213 Self::BottomLeft => bounds.lower_left(),
214 Self::BottomRight => bounds.lower_right(),
215 }
216 }
217
218 fn switch_axis(self, axis: Axis) -> Self {
219 match axis {
220 Axis::Vertical => match self {
221 AnchorCorner::TopLeft => AnchorCorner::BottomLeft,
222 AnchorCorner::TopRight => AnchorCorner::BottomRight,
223 AnchorCorner::BottomLeft => AnchorCorner::TopLeft,
224 AnchorCorner::BottomRight => AnchorCorner::TopRight,
225 },
226 Axis::Horizontal => match self {
227 AnchorCorner::TopLeft => AnchorCorner::TopRight,
228 AnchorCorner::TopRight => AnchorCorner::TopLeft,
229 AnchorCorner::BottomLeft => AnchorCorner::BottomRight,
230 AnchorCorner::BottomRight => AnchorCorner::BottomLeft,
231 },
232 }
233 }
234}