1use crate::{
2 AnyElement, AnyEntity, AnyWeakEntity, App, Bounds, ContentMask, Context, Element, ElementId,
3 Entity, EntityId, GlobalElementId, IntoElement, LayoutId, PaintIndex, Pixels,
4 PrepaintStateIndex, Render, Style, StyleRefinement, TextStyle, WeakEntity,
5};
6use crate::{Empty, Window};
7use anyhow::Result;
8use collections::FxHashSet;
9use refineable::Refineable;
10use std::mem;
11use std::{any::TypeId, fmt, ops::Range};
12
13struct AnyViewState {
14 prepaint_range: Range<PrepaintStateIndex>,
15 paint_range: Range<PaintIndex>,
16 cache_key: ViewCacheKey,
17 accessed_entities: FxHashSet<EntityId>,
18}
19
20#[derive(Default)]
21struct ViewCacheKey {
22 bounds: Bounds<Pixels>,
23 content_mask: ContentMask<Pixels>,
24 text_style: TextStyle,
25}
26
27impl<V: Render> Element for Entity<V> {
28 type RequestLayoutState = AnyElement;
29 type PrepaintState = ();
30
31 fn id(&self) -> Option<ElementId> {
32 Some(ElementId::View(self.entity_id()))
33 }
34
35 fn request_layout(
36 &mut self,
37 _id: Option<&GlobalElementId>,
38 window: &mut Window,
39 cx: &mut App,
40 ) -> (LayoutId, Self::RequestLayoutState) {
41 let mut element = self.update(cx, |view, cx| view.render(window, cx).into_any_element());
42 let layout_id = element.request_layout(window, cx);
43 (layout_id, element)
44 }
45
46 fn prepaint(
47 &mut self,
48 _id: Option<&GlobalElementId>,
49 _: Bounds<Pixels>,
50 element: &mut Self::RequestLayoutState,
51 window: &mut Window,
52 cx: &mut App,
53 ) {
54 window.set_view_id(self.entity_id());
55 element.prepaint(window, cx);
56 }
57
58 fn paint(
59 &mut self,
60 _id: Option<&GlobalElementId>,
61 _: Bounds<Pixels>,
62 element: &mut Self::RequestLayoutState,
63 _: &mut Self::PrepaintState,
64 window: &mut Window,
65 cx: &mut App,
66 ) {
67 element.paint(window, cx);
68 }
69}
70
71/// A dynamically-typed handle to a view, which can be downcast to a [Entity] for a specific type.
72#[derive(Clone, Debug)]
73pub struct AnyView {
74 entity: AnyEntity,
75 render: fn(&AnyView, &mut Window, &mut App) -> AnyElement,
76 cached_style: Option<StyleRefinement>,
77}
78
79impl<V: Render> From<Entity<V>> for AnyView {
80 fn from(value: Entity<V>) -> Self {
81 AnyView {
82 entity: value.into_any(),
83 render: any_view::render::<V>,
84 cached_style: None,
85 }
86 }
87}
88
89impl AnyView {
90 /// Indicate that this view should be cached when using it as an element.
91 /// When using this method, the view's previous layout and paint will be recycled from the previous frame if [Context::notify] has not been called since it was rendered.
92 /// The one exception is when [Window::refresh] is called, in which case caching is ignored.
93 pub fn cached(mut self, style: StyleRefinement) -> Self {
94 self.cached_style = Some(style);
95 self
96 }
97
98 /// Convert this to a weak handle.
99 pub fn downgrade(&self) -> AnyWeakView {
100 AnyWeakView {
101 entity: self.entity.downgrade(),
102 render: self.render,
103 }
104 }
105
106 /// Convert this to a [Entity] of a specific type.
107 /// If this handle does not contain a view of the specified type, returns itself in an `Err` variant.
108 pub fn downcast<T: 'static>(self) -> Result<Entity<T>, Self> {
109 match self.entity.downcast() {
110 Ok(entity) => Ok(entity),
111 Err(entity) => Err(Self {
112 entity,
113 render: self.render,
114 cached_style: self.cached_style,
115 }),
116 }
117 }
118
119 /// Gets the [TypeId] of the underlying view.
120 pub fn entity_type(&self) -> TypeId {
121 self.entity.entity_type
122 }
123
124 /// Gets the entity id of this handle.
125 pub fn entity_id(&self) -> EntityId {
126 self.entity.entity_id()
127 }
128}
129
130impl PartialEq for AnyView {
131 fn eq(&self, other: &Self) -> bool {
132 self.entity == other.entity
133 }
134}
135
136impl Eq for AnyView {}
137
138impl Element for AnyView {
139 type RequestLayoutState = Option<AnyElement>;
140 type PrepaintState = Option<AnyElement>;
141
142 fn id(&self) -> Option<ElementId> {
143 Some(ElementId::View(self.entity_id()))
144 }
145
146 fn request_layout(
147 &mut self,
148 _id: Option<&GlobalElementId>,
149 window: &mut Window,
150 cx: &mut App,
151 ) -> (LayoutId, Self::RequestLayoutState) {
152 if let Some(style) = self.cached_style.as_ref() {
153 let mut root_style = Style::default();
154 root_style.refine(style);
155 let layout_id = window.request_layout(root_style, None, cx);
156 (layout_id, None)
157 } else {
158 let mut element = (self.render)(self, window, cx);
159 let layout_id = element.request_layout(window, cx);
160 (layout_id, Some(element))
161 }
162 }
163
164 fn prepaint(
165 &mut self,
166 global_id: Option<&GlobalElementId>,
167 bounds: Bounds<Pixels>,
168 element: &mut Self::RequestLayoutState,
169 window: &mut Window,
170 cx: &mut App,
171 ) -> Option<AnyElement> {
172 window.set_view_id(self.entity_id());
173 if self.cached_style.is_some() {
174 window.with_element_state::<AnyViewState, _>(
175 global_id.unwrap(),
176 |element_state, window| {
177 let content_mask = window.content_mask();
178 let text_style = window.text_style();
179
180 if let Some(mut element_state) = element_state {
181 if element_state.cache_key.bounds == bounds
182 && element_state.cache_key.content_mask == content_mask
183 && element_state.cache_key.text_style == text_style
184 && !window.dirty_views.contains(&self.entity_id())
185 && !window.refreshing
186 {
187 let prepaint_start = window.prepaint_index();
188 window.reuse_prepaint(element_state.prepaint_range.clone());
189 cx.entities
190 .extend_accessed(&element_state.accessed_entities);
191 let prepaint_end = window.prepaint_index();
192 element_state.prepaint_range = prepaint_start..prepaint_end;
193
194 return (None, element_state);
195 }
196 }
197
198 let refreshing = mem::replace(&mut window.refreshing, true);
199 let prepaint_start = window.prepaint_index();
200 let (mut element, accessed_entities) = cx.detect_accessed_entities(|cx| {
201 let mut element = (self.render)(self, window, cx);
202 element.layout_as_root(bounds.size.into(), window, cx);
203 element.prepaint_at(bounds.origin, window, cx);
204 element
205 });
206 let prepaint_end = window.prepaint_index();
207 window.refreshing = refreshing;
208
209 (
210 Some(element),
211 AnyViewState {
212 accessed_entities,
213 prepaint_range: prepaint_start..prepaint_end,
214 paint_range: PaintIndex::default()..PaintIndex::default(),
215 cache_key: ViewCacheKey {
216 bounds,
217 content_mask,
218 text_style,
219 },
220 },
221 )
222 },
223 )
224 } else {
225 let mut element = element.take().unwrap();
226 element.prepaint(window, cx);
227 Some(element)
228 }
229 }
230
231 fn paint(
232 &mut self,
233 global_id: Option<&GlobalElementId>,
234 _bounds: Bounds<Pixels>,
235 _: &mut Self::RequestLayoutState,
236 element: &mut Self::PrepaintState,
237 window: &mut Window,
238 cx: &mut App,
239 ) {
240 if self.cached_style.is_some() {
241 window.with_element_state::<AnyViewState, _>(
242 global_id.unwrap(),
243 |element_state, window| {
244 let mut element_state = element_state.unwrap();
245
246 let paint_start = window.paint_index();
247
248 if let Some(element) = element {
249 let refreshing = mem::replace(&mut window.refreshing, true);
250 element.paint(window, cx);
251 window.refreshing = refreshing;
252 } else {
253 window.reuse_paint(element_state.paint_range.clone());
254 }
255
256 let paint_end = window.paint_index();
257 element_state.paint_range = paint_start..paint_end;
258
259 ((), element_state)
260 },
261 )
262 } else {
263 element.as_mut().unwrap().paint(window, cx);
264 }
265 }
266}
267
268impl<V: 'static + Render> IntoElement for Entity<V> {
269 type Element = Entity<V>;
270
271 fn into_element(self) -> Self::Element {
272 self
273 }
274}
275
276impl IntoElement for AnyView {
277 type Element = Self;
278
279 fn into_element(self) -> Self::Element {
280 self
281 }
282}
283
284/// A weak, dynamically-typed view handle that does not prevent the view from being released.
285pub struct AnyWeakView {
286 entity: AnyWeakEntity,
287 render: fn(&AnyView, &mut Window, &mut App) -> AnyElement,
288}
289
290impl AnyWeakView {
291 /// Convert to a strongly-typed handle if the referenced view has not yet been released.
292 pub fn upgrade(&self) -> Option<AnyView> {
293 let entity = self.entity.upgrade()?;
294 Some(AnyView {
295 entity,
296 render: self.render,
297 cached_style: None,
298 })
299 }
300}
301
302impl<V: 'static + Render> From<WeakEntity<V>> for AnyWeakView {
303 fn from(view: WeakEntity<V>) -> Self {
304 AnyWeakView {
305 entity: view.into(),
306 render: any_view::render::<V>,
307 }
308 }
309}
310
311impl PartialEq for AnyWeakView {
312 fn eq(&self, other: &Self) -> bool {
313 self.entity == other.entity
314 }
315}
316
317impl std::fmt::Debug for AnyWeakView {
318 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
319 f.debug_struct("AnyWeakView")
320 .field("entity_id", &self.entity.entity_id)
321 .finish_non_exhaustive()
322 }
323}
324
325mod any_view {
326 use crate::{AnyElement, AnyView, App, IntoElement, Render, Window};
327
328 pub(crate) fn render<V: 'static + Render>(
329 view: &AnyView,
330 window: &mut Window,
331 cx: &mut App,
332 ) -> AnyElement {
333 let view = view.clone().downcast::<V>().unwrap();
334 view.update(cx, |view, cx| view.render(window, cx).into_any_element())
335 }
336}
337
338/// A view that renders nothing
339pub struct EmptyView;
340
341impl Render for EmptyView {
342 fn render(&mut self, _window: &mut Window, _cx: &mut Context<Self>) -> impl IntoElement {
343 Empty
344 }
345}