open_gpui/
element.rs

1//! Elements are the workhorses of GPUI. They are responsible for laying out and painting all of
2//! the contents of a window. Elements form a tree and are laid out according to the web layout
3//! standards as implemented by [taffy](https://github.com/DioxusLabs/taffy). Most of the time,
4//! you won't need to interact with this module or these APIs directly. Elements provide their
5//! own APIs and GPUI, or other element implementation, uses the APIs in this module to convert
6//! that element tree into the pixels you see on the screen.
7//!
8//! # Element Basics
9//!
10//! Elements are constructed by calling [`Render::render()`] on the root view of the window,
11//! which recursively constructs the element tree from the current state of the application,.
12//! These elements are then laid out by Taffy, and painted to the screen according to their own
13//! implementation of [`Element::paint()`]. Before the start of the next frame, the entire element
14//! tree and any callbacks they have registered with GPUI are dropped and the process repeats.
15//!
16//! But some state is too simple and voluminous to store in every view that needs it, e.g.
17//! whether a hover has been started or not. For this, GPUI provides the [`Element::PrepaintState`], associated type.
18//!
19//! # Implementing your own elements
20//!
21//! Elements are intended to be the low level, imperative API to GPUI. They are responsible for upholding,
22//! or breaking, GPUI's features as they deem necessary. As an example, most GPUI elements are expected
23//! to stay in the bounds that their parent element gives them. But with [`Window::with_content_mask`],
24//! you can ignore this restriction and paint anywhere inside of the window's bounds. This is useful for overlays
25//! and popups and anything else that shows up 'on top' of other elements.
26//! With great power, comes great responsibility.
27//!
28//! However, most of the time, you won't need to implement your own elements. GPUI provides a number of
29//! elements that should cover most common use cases out of the box and it's recommended that you use those
30//! to construct `components`, using the [`RenderOnce`] trait and the `#[derive(IntoElement)]` macro. Only implement
31//! elements when you need to take manual control of the layout and painting process, such as when using
32//! your own custom layout algorithm or rendering a code editor.
33
34use crate::{
35    App, ArenaBox, AvailableSpace, Bounds, Context, DispatchNodeId, ElementId, FocusHandle,
36    InspectorElementId, LayoutId, Pixels, Point, SharedString, Size, Style, Window,
37    util::FluentBuilder, window::with_element_arena,
38};
39use derive_more::{Deref, DerefMut};
40use std::{
41    any::{Any, type_name},
42    fmt::{self, Debug, Display},
43    mem, panic,
44    sync::Arc,
45};
46
47/// Implemented by types that participate in laying out and painting the contents of a window.
48/// Elements form a tree and are laid out according to web-based layout rules, as implemented by Taffy.
49/// You can create custom elements by implementing this trait, see the module-level documentation
50/// for more details.
51pub trait Element: 'static + IntoElement {
52    /// The type of state returned from [`Element::request_layout`]. A mutable reference to this state is subsequently
53    /// provided to [`Element::prepaint`] and [`Element::paint`].
54    type RequestLayoutState: 'static;
55
56    /// The type of state returned from [`Element::prepaint`]. A mutable reference to this state is subsequently
57    /// provided to [`Element::paint`].
58    type PrepaintState: 'static;
59
60    /// If this element has a unique identifier, return it here. This is used to track elements across frames, and
61    /// will cause a GlobalElementId to be passed to the request_layout, prepaint, and paint methods.
62    ///
63    /// The global id can in turn be used to access state that's connected to an element with the same id across
64    /// frames. This id must be unique among children of the first containing element with an id.
65    fn id(&self) -> Option<ElementId>;
66
67    /// Source location where this element was constructed, used to disambiguate elements in the
68    /// inspector and navigate to their source code.
69    fn source_location(&self) -> Option<&'static panic::Location<'static>>;
70
71    /// Before an element can be painted, we need to know where it's going to be and how big it is.
72    /// Use this method to request a layout from Taffy and initialize the element's state.
73    fn request_layout(
74        &mut self,
75        id: Option<&GlobalElementId>,
76        inspector_id: Option<&InspectorElementId>,
77        window: &mut Window,
78        cx: &mut App,
79    ) -> (LayoutId, Self::RequestLayoutState);
80
81    /// After laying out an element, we need to commit its bounds to the current frame for hitbox
82    /// purposes. The state argument is the same state that was returned from [`Element::request_layout()`].
83    fn prepaint(
84        &mut self,
85        id: Option<&GlobalElementId>,
86        inspector_id: Option<&InspectorElementId>,
87        bounds: Bounds<Pixels>,
88        request_layout: &mut Self::RequestLayoutState,
89        window: &mut Window,
90        cx: &mut App,
91    ) -> Self::PrepaintState;
92
93    /// Once layout has been completed, this method will be called to paint the element to the screen.
94    /// The state argument is the same state that was returned from [`Element::request_layout()`].
95    fn paint(
96        &mut self,
97        id: Option<&GlobalElementId>,
98        inspector_id: Option<&InspectorElementId>,
99        bounds: Bounds<Pixels>,
100        request_layout: &mut Self::RequestLayoutState,
101        prepaint: &mut Self::PrepaintState,
102        window: &mut Window,
103        cx: &mut App,
104    );
105
106    /// Returns the accessible role for this element, if any.
107    /// Elements that return `None` are not included in the accessibility tree.
108    ///
109    /// Note: inclusion in accessibility tree requires non-`None` [`id`][Element::id].
110    ///
111    /// See the [accessibility guide](crate::_accessibility) for an overview.
112    fn a11y_role(&self) -> Option<accesskit::Role> {
113        None
114    }
115
116    /// Write accessibility properties to the given node.
117    /// Called only when `a11y_role()` returns `Some`.
118    ///
119    /// See the [accessibility guide](crate::_accessibility) for an overview.
120    fn write_a11y_info(&self, _node: &mut accesskit::Node) {}
121
122    /// Convert this element into a dynamically-typed [`AnyElement`].
123    fn into_any(self) -> AnyElement {
124        AnyElement::new(self)
125    }
126}
127
128/// Implemented by any type that can be converted into an element.
129pub trait IntoElement: Sized {
130    /// The specific type of element into which the implementing type is converted.
131    /// Useful for converting other types into elements automatically, like Strings
132    type Element: Element;
133
134    /// Convert self into a type that implements [`Element`].
135    fn into_element(self) -> Self::Element;
136
137    /// Convert self into a dynamically-typed [`AnyElement`].
138    fn into_any_element(self) -> AnyElement {
139        self.into_element().into_any()
140    }
141}
142
143impl<T: IntoElement> FluentBuilder for T {}
144
145/// An object that can be drawn to the screen. This is the trait that distinguishes "views" from
146/// other entities. Views are `Entity`'s which `impl Render` and drawn to the screen.
147pub trait Render: 'static + Sized {
148    /// Render this view into an element tree.
149    fn render(&mut self, window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement;
150}
151
152impl Render for Empty {
153    fn render(&mut self, _window: &mut Window, _cx: &mut Context<Self>) -> impl IntoElement {
154        Empty
155    }
156}
157
158/// You can derive [`IntoElement`] on any type that implements this trait.
159/// It is used to construct reusable `components` out of plain data. Think of
160/// components as a recipe for a certain pattern of elements. RenderOnce allows
161/// you to invoke this pattern, without breaking the fluent builder pattern of
162/// the element APIs.
163pub trait RenderOnce: 'static {
164    /// Render this component into an element tree. Note that this method
165    /// takes ownership of self, as compared to [`Render::render()`] method
166    /// which takes a mutable reference.
167    fn render(self, window: &mut Window, cx: &mut App) -> impl IntoElement;
168}
169
170/// This is a helper trait to provide a uniform interface for constructing elements that
171/// can accept any number of any kind of child elements
172pub trait ParentElement {
173    /// Extend this element's children with the given child elements.
174    fn extend(&mut self, elements: impl IntoIterator<Item = AnyElement>);
175
176    /// Add a single child element to this element.
177    fn child(mut self, child: impl IntoElement) -> Self
178    where
179        Self: Sized,
180    {
181        self.extend(std::iter::once(child.into_element().into_any()));
182        self
183    }
184
185    /// Add multiple child elements to this element.
186    fn children(mut self, children: impl IntoIterator<Item = impl IntoElement>) -> Self
187    where
188        Self: Sized,
189    {
190        self.extend(children.into_iter().map(|child| child.into_any_element()));
191        self
192    }
193}
194
195/// An element for rendering components. An implementation detail of the [`IntoElement`] derive macro
196/// for [`RenderOnce`]
197#[doc(hidden)]
198pub struct Component<C: RenderOnce> {
199    component: Option<C>,
200    #[cfg(debug_assertions)]
201    source: &'static core::panic::Location<'static>,
202}
203
204impl<C: RenderOnce> Component<C> {
205    /// Create a new component from the given RenderOnce type.
206    #[track_caller]
207    pub fn new(component: C) -> Self {
208        Component {
209            component: Some(component),
210            #[cfg(debug_assertions)]
211            source: core::panic::Location::caller(),
212        }
213    }
214}
215
216fn prepaint_component(
217    (element, name): &mut (AnyElement, &'static str),
218    window: &mut Window,
219    cx: &mut App,
220) {
221    window.with_id(ElementId::Name(SharedString::new_static(name)), |window| {
222        element.prepaint(window, cx);
223    })
224}
225
226fn paint_component(
227    (element, name): &mut (AnyElement, &'static str),
228    window: &mut Window,
229    cx: &mut App,
230) {
231    window.with_id(ElementId::Name(SharedString::new_static(name)), |window| {
232        element.paint(window, cx);
233    })
234}
235impl<C: RenderOnce> Element for Component<C> {
236    type RequestLayoutState = (AnyElement, &'static str);
237    type PrepaintState = ();
238
239    fn id(&self) -> Option<ElementId> {
240        None
241    }
242
243    fn source_location(&self) -> Option<&'static core::panic::Location<'static>> {
244        #[cfg(debug_assertions)]
245        return Some(self.source);
246
247        #[cfg(not(debug_assertions))]
248        return None;
249    }
250
251    fn request_layout(
252        &mut self,
253        _id: Option<&GlobalElementId>,
254        _inspector_id: Option<&InspectorElementId>,
255        window: &mut Window,
256        cx: &mut App,
257    ) -> (LayoutId, Self::RequestLayoutState) {
258        window.with_id(ElementId::Name(type_name::<C>().into()), |window| {
259            let mut element = self
260                .component
261                .take()
262                .unwrap()
263                .render(window, cx)
264                .into_any_element();
265
266            let layout_id = element.request_layout(window, cx);
267            (layout_id, (element, type_name::<C>()))
268        })
269    }
270
271    fn prepaint(
272        &mut self,
273        _id: Option<&GlobalElementId>,
274        _inspector_id: Option<&InspectorElementId>,
275        _: Bounds<Pixels>,
276        state: &mut Self::RequestLayoutState,
277        window: &mut Window,
278        cx: &mut App,
279    ) {
280        prepaint_component(state, window, cx);
281    }
282
283    fn paint(
284        &mut self,
285        _id: Option<&GlobalElementId>,
286        _inspector_id: Option<&InspectorElementId>,
287        _: Bounds<Pixels>,
288        state: &mut Self::RequestLayoutState,
289        _: &mut Self::PrepaintState,
290        window: &mut Window,
291        cx: &mut App,
292    ) {
293        paint_component(state, window, cx);
294    }
295}
296
297impl<C: RenderOnce> IntoElement for Component<C> {
298    type Element = Self;
299
300    fn into_element(self) -> Self::Element {
301        self
302    }
303}
304
305/// A globally unique identifier for an element, used to track state across frames.
306#[derive(Deref, DerefMut, Clone, Default, Debug, Eq, PartialEq, Hash)]
307pub struct GlobalElementId(pub(crate) Arc<[ElementId]>);
308
309impl Display for GlobalElementId {
310    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
311        for (i, element_id) in self.0.iter().enumerate() {
312            if i > 0 {
313                write!(f, ".")?;
314            }
315            write!(f, "{}", element_id)?;
316        }
317        Ok(())
318    }
319}
320
321impl GlobalElementId {
322    pub(crate) fn accesskit_node_id(&self) -> accesskit::NodeId {
323        use std::hash::{Hash, Hasher};
324        let mut hasher = std::hash::DefaultHasher::default();
325        self.hash(&mut hasher);
326        accesskit::NodeId(hasher.finish())
327    }
328}
329
330trait ElementObject {
331    fn inner_element(&mut self) -> &mut dyn Any;
332
333    fn request_layout(&mut self, window: &mut Window, cx: &mut App) -> LayoutId;
334
335    fn prepaint(&mut self, window: &mut Window, cx: &mut App);
336
337    fn paint(&mut self, window: &mut Window, cx: &mut App);
338
339    fn layout_as_root(
340        &mut self,
341        available_space: Size<AvailableSpace>,
342        window: &mut Window,
343        cx: &mut App,
344    ) -> Size<Pixels>;
345}
346
347/// A wrapper around an implementer of [`Element`] that allows it to be drawn in a window.
348pub struct Drawable<E: Element> {
349    /// The drawn element.
350    pub element: E,
351    phase: ElementDrawPhase<E::RequestLayoutState, E::PrepaintState>,
352}
353
354#[derive(Default)]
355enum ElementDrawPhase<RequestLayoutState, PrepaintState> {
356    #[default]
357    Start,
358    RequestLayout {
359        layout_id: LayoutId,
360        global_id: Option<GlobalElementId>,
361        inspector_id: Option<InspectorElementId>,
362        request_layout: RequestLayoutState,
363    },
364    LayoutComputed {
365        layout_id: LayoutId,
366        global_id: Option<GlobalElementId>,
367        inspector_id: Option<InspectorElementId>,
368        available_space: Size<AvailableSpace>,
369        request_layout: RequestLayoutState,
370    },
371    Prepaint {
372        node_id: DispatchNodeId,
373        global_id: Option<GlobalElementId>,
374        inspector_id: Option<InspectorElementId>,
375        bounds: Bounds<Pixels>,
376        request_layout: RequestLayoutState,
377        prepaint: PrepaintState,
378    },
379    Painted,
380}
381
382/// A wrapper around an implementer of [`Element`] that allows it to be drawn in a window.
383impl<E: Element> Drawable<E> {
384    pub(crate) fn new(element: E) -> Self {
385        Drawable {
386            element,
387            phase: ElementDrawPhase::Start,
388        }
389    }
390
391    fn request_layout(&mut self, window: &mut Window, cx: &mut App) -> LayoutId {
392        match mem::take(&mut self.phase) {
393            ElementDrawPhase::Start => {
394                let global_id = self.element.id().map(|element_id| {
395                    window.element_id_stack.push(element_id);
396                    GlobalElementId(Arc::from(&*window.element_id_stack))
397                });
398
399                let inspector_id;
400                #[cfg(any(feature = "inspector", debug_assertions))]
401                {
402                    inspector_id = self.element.source_location().map(|source| {
403                        let path = crate::InspectorElementPath {
404                            global_id: GlobalElementId(Arc::from(&*window.element_id_stack)),
405                            source_location: source,
406                        };
407                        window.build_inspector_element_id(path)
408                    });
409                }
410                #[cfg(not(any(feature = "inspector", debug_assertions)))]
411                {
412                    inspector_id = None;
413                }
414
415                let (layout_id, request_layout) = self.element.request_layout(
416                    global_id.as_ref(),
417                    inspector_id.as_ref(),
418                    window,
419                    cx,
420                );
421
422                if global_id.is_some() {
423                    window.element_id_stack.pop();
424                }
425
426                self.phase = ElementDrawPhase::RequestLayout {
427                    layout_id,
428                    global_id,
429                    inspector_id,
430                    request_layout,
431                };
432                layout_id
433            }
434            _ => panic!("must call request_layout only once"),
435        }
436    }
437
438    pub(crate) fn prepaint(&mut self, window: &mut Window, cx: &mut App) {
439        match mem::take(&mut self.phase) {
440            ElementDrawPhase::RequestLayout {
441                layout_id,
442                global_id,
443                inspector_id,
444                mut request_layout,
445            }
446            | ElementDrawPhase::LayoutComputed {
447                layout_id,
448                global_id,
449                inspector_id,
450                mut request_layout,
451                ..
452            } => {
453                if let Some(element_id) = self.element.id() {
454                    window.element_id_stack.push(element_id);
455                    debug_assert_eq!(&*global_id.as_ref().unwrap().0, &*window.element_id_stack);
456                }
457
458                let bounds = window.layout_bounds(layout_id);
459                let mut pushed_a11y_node = false;
460                if window.a11y.is_active() {
461                    if let Some(global_id) = global_id.as_ref() {
462                        if let Some(role) = self.element.a11y_role() {
463                            let node_id = global_id.accesskit_node_id();
464                            let mut node = accesskit::Node::new(role);
465                            let scale = window.scale_factor();
466                            node.set_bounds(accesskit::Rect {
467                                x0: (bounds.origin.x.0 * scale) as f64,
468                                y0: (bounds.origin.y.0 * scale) as f64,
469                                x1: ((bounds.origin.x.0 + bounds.size.width.0) * scale) as f64,
470                                y1: ((bounds.origin.y.0 + bounds.size.height.0) * scale) as f64,
471                            });
472                            self.element.write_a11y_info(&mut node);
473                            window.a11y.node_bounds.insert(node_id, bounds);
474                            pushed_a11y_node = window.a11y.nodes.push(node_id, node);
475                        }
476                    }
477                }
478
479                let node_id = window.next_frame.dispatch_tree.push_node();
480                let prepaint = self.element.prepaint(
481                    global_id.as_ref(),
482                    inspector_id.as_ref(),
483                    bounds,
484                    &mut request_layout,
485                    window,
486                    cx,
487                );
488                window.next_frame.dispatch_tree.pop_node();
489
490                if pushed_a11y_node {
491                    window.a11y.nodes.pop();
492                }
493
494                if global_id.is_some() {
495                    window.element_id_stack.pop();
496                }
497
498                self.phase = ElementDrawPhase::Prepaint {
499                    node_id,
500                    global_id,
501                    inspector_id,
502                    bounds,
503                    request_layout,
504                    prepaint,
505                };
506            }
507            _ => panic!("must call request_layout before prepaint"),
508        }
509    }
510
511    pub(crate) fn paint(
512        &mut self,
513        window: &mut Window,
514        cx: &mut App,
515    ) -> (E::RequestLayoutState, E::PrepaintState) {
516        match mem::take(&mut self.phase) {
517            ElementDrawPhase::Prepaint {
518                node_id,
519                global_id,
520                inspector_id,
521                bounds,
522                mut request_layout,
523                mut prepaint,
524                ..
525            } => {
526                if let Some(element_id) = self.element.id() {
527                    window.element_id_stack.push(element_id);
528                    debug_assert_eq!(&*global_id.as_ref().unwrap().0, &*window.element_id_stack);
529                }
530
531                window.next_frame.dispatch_tree.set_active_node(node_id);
532                self.element.paint(
533                    global_id.as_ref(),
534                    inspector_id.as_ref(),
535                    bounds,
536                    &mut request_layout,
537                    &mut prepaint,
538                    window,
539                    cx,
540                );
541
542                if global_id.is_some() {
543                    window.element_id_stack.pop();
544                }
545
546                self.phase = ElementDrawPhase::Painted;
547                (request_layout, prepaint)
548            }
549            _ => panic!("must call prepaint before paint"),
550        }
551    }
552
553    pub(crate) fn layout_as_root(
554        &mut self,
555        available_space: Size<AvailableSpace>,
556        window: &mut Window,
557        cx: &mut App,
558    ) -> Size<Pixels> {
559        if matches!(&self.phase, ElementDrawPhase::Start) {
560            self.request_layout(window, cx);
561        }
562
563        let layout_id = match mem::take(&mut self.phase) {
564            ElementDrawPhase::RequestLayout {
565                layout_id,
566                global_id,
567                inspector_id,
568                request_layout,
569            } => {
570                window.compute_layout(layout_id, available_space, cx);
571                self.phase = ElementDrawPhase::LayoutComputed {
572                    layout_id,
573                    global_id,
574                    inspector_id,
575                    available_space,
576                    request_layout,
577                };
578                layout_id
579            }
580            ElementDrawPhase::LayoutComputed {
581                layout_id,
582                global_id,
583                inspector_id,
584                available_space: prev_available_space,
585                request_layout,
586            } => {
587                if available_space != prev_available_space {
588                    window.compute_layout(layout_id, available_space, cx);
589                }
590                self.phase = ElementDrawPhase::LayoutComputed {
591                    layout_id,
592                    global_id,
593                    inspector_id,
594                    available_space,
595                    request_layout,
596                };
597                layout_id
598            }
599            _ => panic!("cannot measure after painting"),
600        };
601
602        window.layout_bounds(layout_id).size
603    }
604}
605
606impl<E> ElementObject for Drawable<E>
607where
608    E: Element,
609    E::RequestLayoutState: 'static,
610{
611    fn inner_element(&mut self) -> &mut dyn Any {
612        &mut self.element
613    }
614
615    #[inline]
616    fn request_layout(&mut self, window: &mut Window, cx: &mut App) -> LayoutId {
617        Drawable::request_layout(self, window, cx)
618    }
619
620    #[inline]
621    fn prepaint(&mut self, window: &mut Window, cx: &mut App) {
622        Drawable::prepaint(self, window, cx);
623    }
624
625    #[inline]
626    fn paint(&mut self, window: &mut Window, cx: &mut App) {
627        Drawable::paint(self, window, cx);
628    }
629
630    #[inline]
631    fn layout_as_root(
632        &mut self,
633        available_space: Size<AvailableSpace>,
634        window: &mut Window,
635        cx: &mut App,
636    ) -> Size<Pixels> {
637        Drawable::layout_as_root(self, available_space, window, cx)
638    }
639}
640
641/// A dynamically typed element that can be used to store any element type.
642pub struct AnyElement(ArenaBox<dyn ElementObject>);
643
644impl AnyElement {
645    pub(crate) fn new<E>(element: E) -> Self
646    where
647        E: 'static + Element,
648        E::RequestLayoutState: Any,
649    {
650        let element = with_element_arena(|arena| arena.alloc(|| Drawable::new(element)))
651            .map(|element| element as &mut dyn ElementObject);
652        AnyElement(element)
653    }
654
655    /// Attempt to downcast a reference to the boxed element to a specific type.
656    pub fn downcast_mut<T: 'static>(&mut self) -> Option<&mut T> {
657        self.0.inner_element().downcast_mut::<T>()
658    }
659
660    /// Request the layout ID of the element stored in this `AnyElement`.
661    /// Used for laying out child elements in a parent element.
662    pub fn request_layout(&mut self, window: &mut Window, cx: &mut App) -> LayoutId {
663        self.0.request_layout(window, cx)
664    }
665
666    /// Prepares the element to be painted by storing its bounds, giving it a chance to draw hitboxes and
667    /// request autoscroll before the final paint pass is confirmed.
668    pub fn prepaint(&mut self, window: &mut Window, cx: &mut App) -> Option<FocusHandle> {
669        let focus_assigned = window.next_frame.focus.is_some();
670
671        self.0.prepaint(window, cx);
672
673        if !focus_assigned && let Some(focus_id) = window.next_frame.focus {
674            return FocusHandle::for_id(focus_id, &cx.focus_handles);
675        }
676
677        None
678    }
679
680    /// Paints the element stored in this `AnyElement`.
681    pub fn paint(&mut self, window: &mut Window, cx: &mut App) {
682        self.0.paint(window, cx);
683    }
684
685    /// Performs layout for this element within the given available space and returns its size.
686    pub fn layout_as_root(
687        &mut self,
688        available_space: Size<AvailableSpace>,
689        window: &mut Window,
690        cx: &mut App,
691    ) -> Size<Pixels> {
692        self.0.layout_as_root(available_space, window, cx)
693    }
694
695    /// Prepaints this element at the given absolute origin.
696    /// If any element in the subtree beneath this element is focused, its FocusHandle is returned.
697    pub fn prepaint_at(
698        &mut self,
699        origin: Point<Pixels>,
700        window: &mut Window,
701        cx: &mut App,
702    ) -> Option<FocusHandle> {
703        window.with_absolute_element_offset(origin, |window| self.prepaint(window, cx))
704    }
705
706    /// Performs layout on this element in the available space, then prepaints it at the given absolute origin.
707    /// If any element in the subtree beneath this element is focused, its FocusHandle is returned.
708    pub fn prepaint_as_root(
709        &mut self,
710        origin: Point<Pixels>,
711        available_space: Size<AvailableSpace>,
712        window: &mut Window,
713        cx: &mut App,
714    ) -> Option<FocusHandle> {
715        self.layout_as_root(available_space, window, cx);
716        window.with_absolute_element_offset(origin, |window| self.prepaint(window, cx))
717    }
718}
719
720impl Element for AnyElement {
721    type RequestLayoutState = ();
722    type PrepaintState = ();
723
724    fn id(&self) -> Option<ElementId> {
725        None
726    }
727
728    fn source_location(&self) -> Option<&'static panic::Location<'static>> {
729        None
730    }
731
732    fn request_layout(
733        &mut self,
734        _: Option<&GlobalElementId>,
735        _inspector_id: Option<&InspectorElementId>,
736        window: &mut Window,
737        cx: &mut App,
738    ) -> (LayoutId, Self::RequestLayoutState) {
739        let layout_id = self.request_layout(window, cx);
740        (layout_id, ())
741    }
742
743    fn prepaint(
744        &mut self,
745        _: Option<&GlobalElementId>,
746        _inspector_id: Option<&InspectorElementId>,
747        _: Bounds<Pixels>,
748        _: &mut Self::RequestLayoutState,
749        window: &mut Window,
750        cx: &mut App,
751    ) {
752        self.prepaint(window, cx);
753    }
754
755    fn paint(
756        &mut self,
757        _: Option<&GlobalElementId>,
758        _inspector_id: Option<&InspectorElementId>,
759        _: Bounds<Pixels>,
760        _: &mut Self::RequestLayoutState,
761        _: &mut Self::PrepaintState,
762        window: &mut Window,
763        cx: &mut App,
764    ) {
765        self.paint(window, cx);
766    }
767}
768
769impl IntoElement for AnyElement {
770    type Element = Self;
771
772    fn into_element(self) -> Self::Element {
773        self
774    }
775
776    fn into_any_element(self) -> AnyElement {
777        self
778    }
779}
780
781/// The empty element, which renders nothing.
782pub struct Empty;
783
784impl IntoElement for Empty {
785    type Element = Self;
786
787    fn into_element(self) -> Self::Element {
788        self
789    }
790}
791
792impl Element for Empty {
793    type RequestLayoutState = ();
794    type PrepaintState = ();
795
796    fn id(&self) -> Option<ElementId> {
797        None
798    }
799
800    fn source_location(&self) -> Option<&'static panic::Location<'static>> {
801        None
802    }
803
804    fn request_layout(
805        &mut self,
806        _id: Option<&GlobalElementId>,
807        _inspector_id: Option<&InspectorElementId>,
808        window: &mut Window,
809        cx: &mut App,
810    ) -> (LayoutId, Self::RequestLayoutState) {
811        (
812            window.request_layout(
813                Style {
814                    display: crate::Display::None,
815                    ..Default::default()
816                },
817                None,
818                cx,
819            ),
820            (),
821        )
822    }
823
824    fn prepaint(
825        &mut self,
826        _id: Option<&GlobalElementId>,
827        _inspector_id: Option<&InspectorElementId>,
828        _bounds: Bounds<Pixels>,
829        _state: &mut Self::RequestLayoutState,
830        _window: &mut Window,
831        _cx: &mut App,
832    ) {
833    }
834
835    fn paint(
836        &mut self,
837        _id: Option<&GlobalElementId>,
838        _inspector_id: Option<&InspectorElementId>,
839        _bounds: Bounds<Pixels>,
840        _request_layout: &mut Self::RequestLayoutState,
841        _prepaint: &mut Self::PrepaintState,
842        _window: &mut Window,
843        _cx: &mut App,
844    ) {
845    }
846}
open_gpui/element.rs

open_gpui/
element.rs
