mirror of https://github.com/linebender/xilem
152 lines
3.4 KiB
Rust
152 lines
3.4 KiB
Rust
// Copyright 2024 the Xilem Authors
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// SPDX-License-Identifier: Apache-2.0
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//! Model version of Masonry for exploration
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use core::any::Any;
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use xilem_core::{
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DynMessage, MessageResult, Mut, SuperElement, View, ViewElement, ViewId, ViewMarker,
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ViewPathTracker,
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};
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fn app_logic(_: &mut u32) -> impl WidgetView<u32> {
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Button {}
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}
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fn main() {
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let view = app_logic(&mut 10);
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let mut ctx = ViewCtx { path: vec![] };
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let (_widget_tree, _state) = view.build(&mut ctx);
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// TODO: dbg!(widget_tree);
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}
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// Toy version of Masonry
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trait Widget: 'static + Any {
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fn as_mut_any(&mut self) -> &mut dyn Any;
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}
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struct WidgetPod<W: Widget> {
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widget: W,
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}
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struct WidgetMut<'a, W: Widget> {
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value: &'a mut W,
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}
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impl Widget for Box<dyn Widget> {
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fn as_mut_any(&mut self) -> &mut dyn Any {
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self
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}
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}
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// Model version of xilem_masonry (`xilem`)
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// Hmm, this implementation can't exist in `xilem` if `xilem_core` and/or `masonry` are a different crate
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// due to the orphan rules...
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impl<W: Widget> ViewElement for WidgetPod<W> {
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type Mut<'a> = WidgetMut<'a, W>;
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}
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impl ViewMarker for Button {}
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impl<State, Action> View<State, Action, ViewCtx> for Button {
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type Element = WidgetPod<ButtonWidget>;
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type ViewState = ();
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fn build(&self, _ctx: &mut ViewCtx) -> (Self::Element, Self::ViewState) {
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(
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WidgetPod {
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widget: ButtonWidget {},
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},
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(),
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)
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}
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fn rebuild(
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&self,
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_prev: &Self,
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_view_state: &mut Self::ViewState,
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_ctx: &mut ViewCtx,
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_element: Mut<'_, Self::Element>,
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) {
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// Nothing to do
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}
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fn teardown(
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&self,
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_view_state: &mut Self::ViewState,
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_ctx: &mut ViewCtx,
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_element: Mut<'_, Self::Element>,
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) {
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// Nothing to do
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}
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fn message(
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&self,
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_view_state: &mut Self::ViewState,
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_id_path: &[ViewId],
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_message: DynMessage,
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_app_state: &mut State,
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) -> MessageResult<Action> {
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MessageResult::Nop
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}
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}
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struct Button {}
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struct ButtonWidget {}
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impl Widget for ButtonWidget {
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fn as_mut_any(&mut self) -> &mut dyn Any {
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self
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}
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}
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impl<W: Widget> SuperElement<WidgetPod<W>, ViewCtx> for WidgetPod<Box<dyn Widget>> {
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fn upcast(_ctx: &mut ViewCtx, child: WidgetPod<W>) -> Self {
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WidgetPod {
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widget: Box::new(child.widget),
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}
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}
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fn with_downcast_val<R>(
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this: Self::Mut<'_>,
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f: impl FnOnce(<WidgetPod<W> as ViewElement>::Mut<'_>) -> R,
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) -> (Self::Mut<'_>, R) {
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let value = WidgetMut {
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value: this.value.as_mut_any().downcast_mut().expect(
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"this widget should have been created from a child widget of type `W` in `Self::upcast`",
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),
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};
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let ret = f(value);
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(this, ret)
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}
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}
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struct ViewCtx {
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path: Vec<ViewId>,
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}
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impl ViewPathTracker for ViewCtx {
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fn push_id(&mut self, id: ViewId) {
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self.path.push(id);
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}
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fn pop_id(&mut self) {
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self.path.pop();
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}
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fn view_path(&mut self) -> &[ViewId] {
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&self.path
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}
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}
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trait WidgetView<State, Action = ()>:
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View<State, Action, ViewCtx, Element = WidgetPod<Self::Widget>> + Send + Sync
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{
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type Widget: Widget + Send + Sync;
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}
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impl<V, State, Action, W> WidgetView<State, Action> for V
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where
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V: View<State, Action, ViewCtx, Element = WidgetPod<W>> + Send + Sync,
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W: Widget + Send + Sync,
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{
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type Widget = W;
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}
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