WIP

gpui/src/presenter.rs

@@ -0,0 +1,370 @@
+use crate::{
+    app::{AppContext, MutableAppContext, WindowInvalidation},
+    elements::Element,
+    platform::Event,
+    Scene,
+};
+use pathfinder_geometry::vector::{vec2f, Vector2F};
+use std::{any::Any, collections::HashMap, rc::Rc};
+
+pub struct Presenter {
+    window_id: usize,
+    rendered_views: HashMap<usize, Box<dyn Element>>,
+    parents: HashMap<usize, usize>,
+    font_cache: Rc<FontCache>,
+    text_layout_cache: LayoutCache,
+    asset_cache: Rc<AssetCache>,
+}
+
+impl Presenter {
+    pub fn new(
+        window_id: usize,
+        font_cache: Rc<FontCache>,
+        asset_cache: Rc<AssetCache>,
+        app: &MutableAppContext,
+    ) -> Self {
+        Self {
+            window_id,
+            rendered_views: app.render_views(window_id).unwrap(),
+            parents: HashMap::new(),
+            font_cache,
+            text_layout_cache: LayoutCache::new(),
+            asset_cache,
+        }
+    }
+
+    fn invalidate(&mut self, invalidation: WindowInvalidation, app: &AppContext) {
+        for view_id in invalidation.updated {
+            self.rendered_views
+                .insert(view_id, app.render_view(self.window_id, view_id).unwrap());
+        }
+        for view_id in invalidation.removed {
+            self.rendered_views.remove(&view_id);
+            self.parents.remove(&view_id);
+        }
+    }
+
+    pub fn build_scene(
+        &mut self,
+        window_size: Vector2F,
+        scale_factor: f32,
+        app: &mut MutableAppContext,
+    ) -> Scene {
+        self.layout(window_size, app.ctx());
+        self.after_layout(app);
+        let scene = self.paint(window_size, scale_factor, app.ctx());
+        self.text_layout_cache.finish_frame();
+        scene
+    }
+
+    fn layout(&mut self, size: Vector2F, app: &AppContext) {
+        if let Some(root_view_id) = app.root_view_id(self.window_id) {
+            let mut layout_ctx = LayoutContext {
+                rendered_views: &mut self.rendered_views,
+                parents: &mut self.parents,
+                font_cache: &self.font_cache,
+                text_layout_cache: &self.text_layout_cache,
+                asset_cache: &self.asset_cache,
+                view_stack: Vec::new(),
+            };
+            layout_ctx.layout(root_view_id, SizeConstraint::strict(size), app);
+        }
+    }
+
+    fn after_layout(&mut self, app: &mut MutableAppContext) {
+        if let Some(root_view_id) = app.root_view_id(self.window_id) {
+            let mut ctx = AfterLayoutContext {
+                rendered_views: &mut self.rendered_views,
+                font_cache: &self.font_cache,
+                text_layout_cache: &self.text_layout_cache,
+            };
+            ctx.after_layout(root_view_id, app);
+        }
+    }
+
+    fn paint(&mut self, size: Vector2F, scale_factor: f32, app: &AppContext) -> Scene {
+        // let mut canvas = Canvas::new(size * scale_factor).get_context_2d(self.font_context.clone());
+        // canvas.scale(scale_factor);
+
+        // if let Some(root_view_id) = app.root_view_id(self.window_id) {
+        //     let mut paint_ctx = PaintContext {
+        //         canvas: &mut canvas,
+        //         font_cache: &self.font_cache,
+        //         text_layout_cache: &self.text_layout_cache,
+        //         rendered_views: &mut self.rendered_views,
+        //     };
+        //     paint_ctx.paint(root_view_id, Vector2F::zero(), app);
+        // }
+
+        // canvas.into_canvas().into_scene()
+        todo!()
+    }
+
+    pub fn responder_chain(&self, app: &AppContext) -> Option<Vec<usize>> {
+        app.focused_view_id(self.window_id).map(|mut view_id| {
+            let mut chain = vec![view_id];
+            while let Some(parent_id) = self.parents.get(&view_id) {
+                view_id = *parent_id;
+                chain.push(view_id);
+            }
+            chain.reverse();
+            chain
+        })
+    }
+
+    pub fn dispatch_event(
+        &self,
+        event: Event,
+        app: &AppContext,
+    ) -> Vec<(usize, &'static str, Box<dyn Any>)> {
+        let mut event_ctx = EventContext {
+            rendered_views: &self.rendered_views,
+            actions: Vec::new(),
+            font_cache: &self.font_cache,
+            text_layout_cache: &self.text_layout_cache,
+            view_stack: Vec::new(),
+        };
+        if let Some(root_view_id) = app.root_view_id(self.window_id) {
+            event_ctx.dispatch_event_on_view(root_view_id, &event, app);
+        }
+        event_ctx.actions
+    }
+}
+
+pub struct LayoutContext<'a> {
+    rendered_views: &'a mut HashMap<usize, Box<dyn Element>>,
+    parents: &'a mut HashMap<usize, usize>,
+    pub font_cache: &'a FontCache,
+    pub text_layout_cache: &'a LayoutCache,
+    pub asset_cache: &'a AssetCache,
+    view_stack: Vec<usize>,
+}
+
+impl<'a> LayoutContext<'a> {
+    fn layout(&mut self, view_id: usize, constraint: SizeConstraint, app: &AppContext) -> Vector2F {
+        if let Some(parent_id) = self.view_stack.last() {
+            self.parents.insert(view_id, *parent_id);
+        }
+        self.view_stack.push(view_id);
+        let mut rendered_view = self.rendered_views.remove(&view_id).unwrap();
+        let size = rendered_view.layout(constraint, self, app);
+        self.rendered_views.insert(view_id, rendered_view);
+        self.view_stack.pop();
+        size
+    }
+}
+
+pub struct AfterLayoutContext<'a> {
+    rendered_views: &'a mut HashMap<usize, Box<dyn Element>>,
+    pub font_cache: &'a FontCache,
+    pub text_layout_cache: &'a LayoutCache,
+}
+
+impl<'a> AfterLayoutContext<'a> {
+    fn after_layout(&mut self, view_id: usize, app: &mut MutableAppContext) {
+        if let Some(mut view) = self.rendered_views.remove(&view_id) {
+            view.after_layout(self, app);
+            self.rendered_views.insert(view_id, view);
+        }
+    }
+}
+
+pub struct PaintContext<'a> {
+    rendered_views: &'a mut HashMap<usize, Box<dyn Element>>,
+    // pub canvas: &'a mut CanvasRenderingContext2D,
+    pub font_cache: &'a FontCache,
+    pub text_layout_cache: &'a LayoutCache,
+}
+
+impl<'a> PaintContext<'a> {
+    fn paint(&mut self, view_id: usize, origin: Vector2F, app: &AppContext) {
+        if let Some(mut tree) = self.rendered_views.remove(&view_id) {
+            tree.paint(origin, self, app);
+            self.rendered_views.insert(view_id, tree);
+        }
+    }
+}
+
+pub struct EventContext<'a> {
+    rendered_views: &'a HashMap<usize, Box<dyn Element>>,
+    actions: Vec<(usize, &'static str, Box<dyn Any>)>,
+    pub font_cache: &'a FontCache,
+    pub text_layout_cache: &'a LayoutCache,
+    view_stack: Vec<usize>,
+}
+
+impl<'a> EventContext<'a> {
+    pub fn dispatch_event_on_view(
+        &mut self,
+        view_id: usize,
+        event: &Event,
+        app: &AppContext,
+    ) -> bool {
+        if let Some(element) = self.rendered_views.get(&view_id) {
+            self.view_stack.push(view_id);
+            let result = element.dispatch_event(event, self, app);
+            self.view_stack.pop();
+            result
+        } else {
+            false
+        }
+    }
+
+    pub fn dispatch_action<A: 'static + Any>(&mut self, name: &'static str, arg: A) {
+        self.actions
+            .push((*self.view_stack.last().unwrap(), name, Box::new(arg)));
+    }
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum Axis {
+    Horizontal,
+    Vertical,
+}
+
+impl Axis {
+    pub fn invert(self) -> Self {
+        match self {
+            Self::Horizontal => Self::Vertical,
+            Self::Vertical => Self::Horizontal,
+        }
+    }
+}
+
+pub trait Vector2FExt {
+    fn along(self, axis: Axis) -> f32;
+}
+
+impl Vector2FExt for Vector2F {
+    fn along(self, axis: Axis) -> f32 {
+        match axis {
+            Axis::Horizontal => self.x(),
+            Axis::Vertical => self.y(),
+        }
+    }
+}
+
+#[derive(Copy, Clone, Debug)]
+pub struct SizeConstraint {
+    pub min: Vector2F,
+    pub max: Vector2F,
+}
+
+impl SizeConstraint {
+    pub fn new(min: Vector2F, max: Vector2F) -> Self {
+        Self { min, max }
+    }
+
+    pub fn strict(size: Vector2F) -> Self {
+        Self {
+            min: size,
+            max: size,
+        }
+    }
+
+    pub fn strict_along(axis: Axis, max: f32) -> Self {
+        match axis {
+            Axis::Horizontal => Self {
+                min: vec2f(max, 0.0),
+                max: vec2f(max, f32::INFINITY),
+            },
+            Axis::Vertical => Self {
+                min: vec2f(0.0, max),
+                max: vec2f(f32::INFINITY, max),
+            },
+        }
+    }
+
+    pub fn max_along(&self, axis: Axis) -> f32 {
+        match axis {
+            Axis::Horizontal => self.max.x(),
+            Axis::Vertical => self.max.y(),
+        }
+    }
+}
+
+pub struct ChildView {
+    view_id: usize,
+    size: Option<Vector2F>,
+    origin: Option<Vector2F>,
+}
+
+impl ChildView {
+    pub fn new(view_id: usize) -> Self {
+        Self {
+            view_id,
+            size: None,
+            origin: None,
+        }
+    }
+}
+
+impl Element for ChildView {
+    fn layout(
+        &mut self,
+        constraint: SizeConstraint,
+        ctx: &mut LayoutContext,
+        app: &AppContext,
+    ) -> Vector2F {
+        let size = ctx.layout(self.view_id, constraint, app);
+        self.size = Some(size);
+        size
+    }
+
+    fn after_layout(&mut self, ctx: &mut AfterLayoutContext, app: &mut MutableAppContext) {
+        ctx.after_layout(self.view_id, app);
+    }
+
+    fn paint(&mut self, origin: Vector2F, ctx: &mut PaintContext, app: &AppContext) {
+        self.origin = Some(origin);
+        ctx.paint(self.view_id, origin, app);
+    }
+
+    fn dispatch_event(&self, event: &Event, ctx: &mut EventContext, app: &AppContext) -> bool {
+        ctx.dispatch_event_on_view(self.view_id, event, app)
+    }
+
+    fn size(&self) -> Option<Vector2F> {
+        self.size
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    // #[test]
+    // fn test_responder_chain() {
+    //     let settings = settings_rx(None);
+    //     let mut app = App::new().unwrap();
+    //     let workspace = app.add_model(|ctx| Workspace::new(Vec::new(), ctx));
+    //     let (window_id, workspace_view) =
+    //         app.add_window(|ctx| WorkspaceView::new(workspace.clone(), settings, ctx));
+
+    //     let invalidations = Rc::new(RefCell::new(Vec::new()));
+    //     let invalidations_ = invalidations.clone();
+    //     app.on_window_invalidated(window_id, move |invalidation, _| {
+    //         invalidations_.borrow_mut().push(invalidation)
+    //     });
+
+    //     let active_pane_id = workspace_view.update(&mut app, |view, ctx| {
+    //         ctx.focus(view.active_pane());
+    //         view.active_pane().id()
+    //     });
+
+    //     app.update(|app| {
+    //         let mut presenter = Presenter::new(
+    //             window_id,
+    //             Rc::new(FontCache::new()),
+    //             Rc::new(AssetCache::new()),
+    //             app,
+    //         );
+    //         for invalidation in invalidations.borrow().iter().cloned() {
+    //             presenter.update(vec2f(1024.0, 768.0), 2.0, Some(invalidation), app);
+    //         }
+
+    //         assert_eq!(
+    //             presenter.responder_chain(app.ctx()).unwrap(),
+    //             vec![workspace_view.id(), active_pane_id]
+    //         );
+    //     });
+    // }
+}