Implement update_scrolls pass

masonry/src/contexts.rs

@@ -59,7 +59,6 @@ pub struct EventCtx<'a> {
     pub(crate) widget_children: ArenaMutChildren<'a, Box<dyn Widget>>,
     pub(crate) allow_pointer_capture: bool,
     pub(crate) is_handled: bool,
-    pub(crate) request_pan_to_child: Option<Rect>,
 }
 
 /// A context provided to the [`lifecycle`] method on widgets.
@@ -600,8 +599,20 @@ impl EventCtx<'_> {
     }
 
     /// Send a signal to parent widgets to scroll this widget into view.
-    pub fn request_pan_to_this(&mut self) {
-        self.request_pan_to_child = Some(self.widget_state.layout_rect());
+    pub fn request_scroll_to_this(&mut self) {
+        let rect = self.widget_state.layout_rect();
+        self.global_state
+            .scroll_request_targets
+            .push((self.widget_state.id, rect));
+    }
+
+    /// Send a signal to parent widgets to scroll this area into view.
+    ///
+    /// `rect` is in local coordinates.
+    pub fn request_scroll_to(&mut self, rect: Rect) {
+        self.global_state
+            .scroll_request_targets
+            .push((self.widget_state.id, rect));
     }
 
     // TODO - Remove

masonry/src/passes/event.rs

@@ -54,7 +54,6 @@ fn run_event_pass<E>(
             widget_children: widget_mut.children,
             allow_pointer_capture,
             is_handled: false,
-            request_pan_to_child: None,
         };
         let widget = widget_mut.item;
 
@@ -194,41 +193,3 @@ pub(crate) fn root_on_access_event(
 
     handled
 }
-
-// These functions were carved out of WidgetPod code during a previous refactor
-// The general "pan to child" logic needs to be added back in.
-#[cfg(FALSE)]
-fn pan_to_child() {
-    // TODO - there's some dubious logic here
-    if let Some(target_rect) = inner_ctx.request_pan_to_child {
-        self.pan_to_child(parent_ctx, target_rect);
-        let (state, _) = parent_ctx
-            .widget_state_children
-            .get_child_mut(id)
-            .expect("WidgetPod: inner widget not found in widget tree");
-        let new_rect = target_rect.with_origin(target_rect.origin() + state.origin.to_vec2());
-        parent_ctx.request_pan_to_child = Some(new_rect);
-    }
-}
-
-#[cfg(FALSE)]
-fn pan_to_child(&mut self, parent_ctx: &mut EventCtx, rect: Rect) {
-    let id = self.id().to_raw();
-    let (widget, widget_token) = parent_ctx
-        .widget_children
-        .get_child_mut(id)
-        .expect("WidgetPod: inner widget not found in widget tree");
-    let (state, state_token) = parent_ctx
-        .widget_state_children
-        .get_child_mut(id)
-        .expect("WidgetPod: inner widget not found in widget tree");
-    let mut inner_ctx = LifeCycleCtx {
-        global_state: parent_ctx.global_state,
-        widget_state: state,
-        widget_state_children: state_token,
-        widget_children: widget_token,
-    };
-    let event = LifeCycle::RequestPanToChild(rect);
-
-    widget.lifecycle(&mut inner_ctx, &event);
-}

masonry/src/passes/update.rs

@@ -202,3 +202,31 @@ pub(crate) fn run_update_disabled_pass(root: &mut RenderRoot) {
     let (root_widget, root_state) = root.widget_arena.get_pair_mut(root.root.id());
     update_disabled_for_widget(&mut root.state, root_widget, root_state, false);
 }
+
+// ----------------
+
+// This pass will update scroll positions in cases where a widget has requested to be
+// scrolled into view (usually a textbox getting text events).
+// Each parent that implements scrolling will update its scroll position to ensure the
+// child is visible. (If the target area is larger than the parent, the parent will try
+// to show the top left of that area.)
+pub(crate) fn run_update_scroll_pass(root: &mut RenderRoot) {
+    let _span = info_span!("update_scroll").entered();
+
+    let scroll_request_targets = std::mem::take(&mut root.state.scroll_request_targets);
+    for (target, rect) in scroll_request_targets {
+        let mut target_rect = rect;
+
+        run_targeted_update_pass(root, Some(target), |widget, ctx| {
+            let event = LifeCycle::RequestPanToChild(rect);
+            widget.lifecycle(ctx, &event);
+
+            // TODO - We should run the compose method after this, so
+            // translations are updated and the rect passed to parents
+            // is more accurate.
+
+            let state = &ctx.widget_state;
+            target_rect = target_rect + state.translation + state.origin.to_vec2();
+        });
+    }
+}

masonry/src/render_root.rs

@@ -7,7 +7,7 @@ use accesskit::{ActionRequest, Tree, TreeUpdate};
 use parley::fontique::{self, Collection, CollectionOptions};
 use parley::{FontContext, LayoutContext};
 use tracing::{info_span, warn};
-use vello::kurbo::{self, Point};
+use vello::kurbo::{self, Point, Rect};
 use vello::Scene;
 
 #[cfg(not(target_arch = "wasm32"))]
@@ -24,7 +24,9 @@ use crate::passes::compose::root_compose;
 use crate::passes::event::{root_on_access_event, root_on_pointer_event, root_on_text_event};
 use crate::passes::mutate::{mutate_widget, run_mutate_pass};
 use crate::passes::paint::root_paint;
-use crate::passes::update::{run_update_disabled_pass, run_update_pointer_pass};
+use crate::passes::update::{
+    run_update_disabled_pass, run_update_pointer_pass, run_update_scroll_pass,
+};
 use crate::text::TextBrush;
 use crate::tree_arena::TreeArena;
 use crate::widget::WidgetArena;
@@ -55,11 +57,13 @@ pub struct RenderRoot {
     pub(crate) widget_arena: WidgetArena,
 }
 
+// TODO - Document these fields.
 pub(crate) struct RenderRootState {
     pub(crate) debug_logger: DebugLogger,
     pub(crate) signal_queue: VecDeque<RenderRootSignal>,
     pub(crate) focused_widget: Option<WidgetId>,
     pub(crate) next_focused_widget: Option<WidgetId>,
+    pub(crate) scroll_request_targets: Vec<(WidgetId, Rect)>,
     pub(crate) hovered_path: Vec<WidgetId>,
     pub(crate) pointer_capture_target: Option<WidgetId>,
     pub(crate) cursor_icon: CursorIcon,
@@ -132,6 +136,7 @@ impl RenderRoot {
                 signal_queue: VecDeque::new(),
                 focused_widget: None,
                 next_focused_widget: None,
+                scroll_request_targets: Vec::new(),
                 hovered_path: Vec::new(),
                 pointer_capture_target: None,
                 cursor_icon: CursorIcon::Default,
@@ -547,6 +552,10 @@ impl RenderRoot {
             self.state.debug_logger.layout_tree.root = Some(self.root.id().to_raw() as u32);
         }
 
+        if !self.state.scroll_request_targets.is_empty() {
+            run_update_scroll_pass(self);
+        }
+
         if self.root_state().needs_compose && !self.root_state().needs_layout {
             root_compose(self, widget_state);
         }

masonry/src/widget/portal.rs

@@ -145,6 +145,26 @@ impl<W: Widget> Portal<W> {
             false
         }
     }
+
+    // Note - Rect is in child coordinates
+    // TODO - Merge with pan_viewport_to
+    // Right now these functions are just different enough to be a pain to merge.
+    fn pan_viewport_to_raw(&mut self, portal_size: Size, content_size: Size, target: Rect) -> bool {
+        let viewport = Rect::from_origin_size(self.viewport_pos, portal_size);
+
+        let new_pos_x = compute_pan_range(
+            viewport.min_x()..viewport.max_x(),
+            target.min_x()..target.max_x(),
+        )
+        .start;
+        let new_pos_y = compute_pan_range(
+            viewport.min_y()..viewport.max_y(),
+            target.min_y()..target.max_y(),
+        )
+        .start;
+
+        self.set_viewport_pos_raw(portal_size, content_size, Point::new(new_pos_x, new_pos_y))
+    }
 }
 
 // --- MARK: WIDGETMUT ---
@@ -315,8 +335,29 @@ impl<W: Widget> Widget for Portal<W> {
             LifeCycle::WidgetAdded => {
                 ctx.register_as_portal();
             }
-            //TODO
-            //LifeCycle::RequestPanToChild(target_rect) => {}
+            LifeCycle::RequestPanToChild(target) => {
+                let portal_size = ctx.size();
+                let content_size = ctx.get_raw_ref(&mut self.child).ctx().layout_rect().size();
+
+                self.pan_viewport_to_raw(portal_size, content_size, *target);
+                ctx.request_compose();
+
+                // TODO - There's a lot of code here that's duplicated from the `MouseWheel`
+                // event in `on_pointer_event`.
+                // Because this code directly manipulates child widgets, it's hard to factor
+                // it out.
+                let mut scrollbar = ctx.get_raw_mut(&mut self.scrollbar_vertical);
+                scrollbar.widget().cursor_progress =
+                    self.viewport_pos.y / (content_size - portal_size).height;
+                scrollbar.ctx().request_paint();
+
+                std::mem::drop(scrollbar);
+
+                let mut scrollbar = ctx.get_raw_mut(&mut self.scrollbar_horizontal);
+                scrollbar.widget().cursor_progress =
+                    self.viewport_pos.x / (content_size - portal_size).width;
+                scrollbar.ctx().request_paint();
+            }
             _ => {}
         }
 
@@ -424,10 +465,6 @@ impl<W: Widget> Widget for Portal<W> {
         }
 
         ctx.current_node().set_clips_children();
-        ctx.current_node()
-            .push_child(self.scrollbar_horizontal.id().into());
-        ctx.current_node()
-            .push_child(self.scrollbar_vertical.id().into());
     }
 
     fn children_ids(&self) -> SmallVec<[WidgetId; 16]> {

masonry/src/widget/textbox.rs

@@ -13,6 +13,7 @@ use vello::{
     peniko::{BlendMode, Color},
     Scene,
 };
+use winit::event::Ime;
 
 use crate::widget::{LineBreaking, WidgetMut};
 use crate::{
@@ -205,8 +206,13 @@ impl Widget for Textbox {
 
     fn on_text_event(&mut self, ctx: &mut EventCtx, event: &TextEvent) {
         let result = self.editor.text_event(ctx, event);
-        // If focused on a link and enter pressed, follow it?
         if result.is_handled() {
+            // Some platforms will send a lot of spurious Preedit events.
+            // We only want to request a scroll on user input.
+            if !matches!(event, TextEvent::Ime(Ime::Preedit(preedit, ..)) if preedit.is_empty()) {
+                // TODO - Use request_scroll_to with cursor rect
+                ctx.request_scroll_to_this();
+            }
             ctx.set_handled();
             // TODO: only some handlers need this repaint
             ctx.request_layout();