Traverse item front to back for input events

api/sixtyfps-cpp/include/sixtyfps.h

@@ -31,6 +31,7 @@ using internal::ComponentVTable;
 using ItemTreeNode = internal::ItemTreeNode<uint8_t>;
 using ComponentRef = VRef<ComponentVTable>;
 using ItemVisitorRefMut = VRefMut<internal::ItemVisitorVTable>;
+using internal::TraversalOrder;
 using internal::EasingCurve;
 using internal::TextHorizontalAlignment;
 using internal::TextVerticalAlignment;
@@ -177,12 +178,13 @@ struct Repeater
         }
     }
 
-    intptr_t visit(ItemVisitorRefMut visitor) const
+    intptr_t visit(TraversalOrder order, ItemVisitorRefMut visitor) const
     {
         for (std::size_t i = 0; i < data.size(); ++i) {
-            VRef<ComponentVTable> ref = item_at(i);
+            int index = order == TraversalOrder::BackToFront ? i : data.size() - 1 - i;
-            if (ref.vtable->visit_children_item(ref, -1, visitor) != -1) {
+            VRef<ComponentVTable> ref = item_at(index);
-                return i;
+            if (ref.vtable->visit_children_item(ref, -1, order, visitor) != -1) {
+                return index;
             }
         }
         return -1;

api/sixtyfps-rs/lib.rs

@@ -87,7 +87,7 @@ pub mod re_exports {
     };
     pub use sixtyfps_corelib::item_tree::{
         item_offset, visit_item_tree, ItemTreeNode, ItemVisitorRefMut, ItemVisitorVTable,
-        VisitChildrenResult,
+        TraversalOrder, VisitChildrenResult,
     };
     pub use sixtyfps_corelib::items::*;
     pub use sixtyfps_corelib::layout::LayoutInfo;

api/sixtyfps-rs/repeater.rs

@@ -43,10 +43,11 @@ where
     /// Call the visitor for each component
     pub fn visit(
         &self,
+        order: sixtyfps_corelib::item_tree::TraversalOrder,
         mut visitor: sixtyfps_corelib::item_tree::ItemVisitorRefMut,
     ) -> sixtyfps_corelib::item_tree::VisitChildrenResult {
         for (i, c) in self.components.borrow().iter().enumerate() {
-            if c.as_ref().visit_children_item(-1, visitor.borrow_mut()).has_aborted() {
+            if c.as_ref().visit_children_item(-1, order, visitor.borrow_mut()).has_aborted() {
                 return sixtyfps_corelib::item_tree::VisitChildrenResult::abort(i, 0);
             }
         }

examples/printerdemo/ui/printerdemo.60

@@ -146,8 +146,6 @@ MainWindow := Rectangle {
             clicked => {
                 if (root.active_page == 0) {
                     root.active_page = idx + 1;
-                } else {
-                    root.active_page = 0;
                 }
             }
         }

sixtyfps_compiler/generator/cpp.rs

@@ -356,7 +356,7 @@ fn handle_repeater(
     repeater_count: i32,
     component_struct: &mut Struct,
     init: &mut Vec<String>,
-    children_repeater_cases: &mut Vec<String>,
+    children_visitor_cases: &mut Vec<String>,
     repeated_input_branch: &mut Vec<String>,
 ) {
     let repeater_id =
@@ -372,8 +372,8 @@ fn handle_repeater(
     };
 
     if repeated.model.is_constant() {
-        children_repeater_cases.push(format!(
+        children_visitor_cases.push(format!(
-            "\n        case {i}: return self->{id}.visit(visitor);",
+            "\n        case {i}: return self->{id}.visit(order, visitor);",
             id = repeater_id,
             i = repeater_count
         ));
@@ -392,14 +392,14 @@ fn handle_repeater(
                 init: None,
             }),
         ));
-        children_repeater_cases.push(format!(
+        children_visitor_cases.push(format!(
             "\n        case {i}: {{
                 if (self->model_{i}.is_dirty()) {{
                     self->model_{i}.evaluate([&] {{
                         self->{id}.update_model({model}, self);
                     }});
                 }}
-                self->{id}.visit(visitor);
+                self->{id}.visit(order, visitor);
                 break;
             }}",
             id = repeater_id,
@@ -667,7 +667,7 @@ fn generate_component(
         ));
     }
 
-    let mut children_visitor_case = vec![];
+    let mut children_visitor_cases = vec![];
     let mut repeated_input_branch = vec![];
     let mut tree_array = vec![];
     let mut repeater_count = 0;
@@ -699,7 +699,7 @@ fn generate_component(
                 repeater_count,
                 &mut component_struct,
                 &mut init,
-                &mut children_visitor_case,
+                &mut children_visitor_cases,
                 &mut repeated_input_branch,
             );
             repeater_count += 1;
@@ -731,15 +731,14 @@ fn generate_component(
         Access::Private,
         Declaration::Function(Function {
             name: "visit_children".into(),
-            signature: "(sixtyfps::ComponentRef component, intptr_t index, sixtyfps::ItemVisitorRefMut visitor) -> intptr_t".into(),
+            signature: "(sixtyfps::ComponentRef component, intptr_t index, sixtyfps::TraversalOrder order, sixtyfps::ItemVisitorRefMut visitor) -> intptr_t".into(),
             is_static: true,
             statements: Some(vec![
-                "static const auto dyn_visit = [] (const uint8_t *base, [[maybe_unused]] sixtyfps::ItemVisitorRefMut visitor, uintptr_t dyn_index) -> int64_t {".to_owned(),
+                "static const auto dyn_visit = [] (const uint8_t *base, sixtyfps::TraversalOrder order, [[maybe_unused]] sixtyfps::ItemVisitorRefMut visitor, uintptr_t dyn_index) -> int64_t {".to_owned(),
                 format!("    [[maybe_unused]] auto self = reinterpret_cast<const {}*>(base);", component_id),
-                // Fixme: this is not the root component
+                format!("    switch(dyn_index) {{ {} }};", children_visitor_cases.join("")),
-                format!("    switch(dyn_index) {{ {} }};", children_visitor_case.join("")),
                 "    return -1; //should not happen\n};".to_owned(),
-                "return sixtyfps::sixtyfps_visit_item_tree(component, item_tree() , index, visitor, dyn_visit);".to_owned(),
+                "return sixtyfps::sixtyfps_visit_item_tree(component, item_tree() , index, order, visitor, dyn_visit);".to_owned(),
             ]),
             ..Default::default()
         }),

sixtyfps_compiler/generator/rust.rs

@@ -230,7 +230,7 @@ fn generate_component(
                     });
                 });
                 repeated_visit_branch.push(quote!(
-                    #repeater_index => self_pinned.#repeater_id.visit(visitor),
+                    #repeater_index => self_pinned.#repeater_id.visit(order, visitor),
                 ));
             } else {
                 let model_name = quote::format_ident!("model_{}", repeater_index);
@@ -244,7 +244,7 @@ fn generate_component(
                                 });
                             });
                         }
-                        self_pinned.#repeater_id.visit(visitor)
+                        self_pinned.#repeater_id.visit(order, visitor)
                     }
                 ));
                 repeated_dynmodel_names.push(model_name);
@@ -438,13 +438,13 @@ fn generate_component(
         }
 
         impl sixtyfps::re_exports::Component for #component_id {
-            fn visit_children_item(self: ::core::pin::Pin<&Self>, index: isize, visitor: sixtyfps::re_exports::ItemVisitorRefMut)
+            fn visit_children_item(self: ::core::pin::Pin<&Self>, index: isize, order: sixtyfps::re_exports::TraversalOrder, visitor: sixtyfps::re_exports::ItemVisitorRefMut)
                 -> sixtyfps::re_exports::VisitChildrenResult
             {
                 use sixtyfps::re_exports::*;
-                return sixtyfps::re_exports::visit_item_tree(self, VRef::new_pin(self), Self::item_tree(), index, visitor, visit_dynamic);
+                return sixtyfps::re_exports::visit_item_tree(self, VRef::new_pin(self), Self::item_tree(), index, order, visitor, visit_dynamic);
                 #[allow(unused)]
-                fn visit_dynamic(self_pinned: ::core::pin::Pin<&#component_id>, visitor: ItemVisitorRefMut, dyn_index: usize) -> VisitChildrenResult  {
+                fn visit_dynamic(self_pinned: ::core::pin::Pin<&#component_id>, order: sixtyfps::re_exports::TraversalOrder, visitor: ItemVisitorRefMut, dyn_index: usize) -> VisitChildrenResult  {
                     match dyn_index {
                         #(#repeated_visit_branch)*
                         _ => panic!("invalid dyn_index {}", dyn_index),

sixtyfps_runtime/corelib/abi/datastructures.rs

@@ -5,7 +5,7 @@ use vtable::*;
 use crate::graphics::{HighLevelRenderingPrimitive, Rect, RenderingVariable};
 use crate::input::{InputEventResult, MouseEvent};
 use crate::item_rendering::CachedRenderingData;
-use crate::item_tree::{ItemVisitorVTable, VisitChildrenResult};
+use crate::item_tree::{ItemVisitorVTable, TraversalOrder, VisitChildrenResult};
 use crate::{layout::LayoutInfo, SharedArray};
 
 /// A Component is representing an unit that is allocated together
@@ -18,6 +18,7 @@ pub struct ComponentVTable {
     pub visit_children_item: extern "C" fn(
         core::pin::Pin<VRef<ComponentVTable>>,
         index: isize,
+        order: TraversalOrder,
         visitor: VRefMut<ItemVisitorVTable>,
     ) -> VisitChildrenResult,
 

sixtyfps_runtime/corelib/graphics.rs

@@ -416,6 +416,7 @@ impl<Backend: GraphicsBackend> crate::eventloop::GenericWindow for GraphicsWindo
             // Generate cached rendering data once
             crate::item_tree::visit_items(
                 component,
+                crate::item_tree::TraversalOrder::BackToFront,
                 |_, item, _| {
                     crate::item_rendering::update_item_rendering_data(
                         item,

sixtyfps_runtime/corelib/input.rs

@@ -66,6 +66,7 @@ pub fn process_ungrabbed_mouse_event(
     let mut result = InputEventResult::EventIgnored;
     let item_index = crate::item_tree::visit_items(
         component,
+        crate::item_tree::TraversalOrder::FrontToBack,
         |_, item, offset| -> ItemVisitorResult<Vector2D<f32>> {
             let geom = item.as_ref().geometry();
             let geom = geom.translate(*offset);

sixtyfps_runtime/corelib/item_rendering.rs

@@ -49,6 +49,7 @@ pub(crate) fn render_component_items<Backend: GraphicsBackend>(
 
     crate::item_tree::visit_items(
         component,
+        crate::item_tree::TraversalOrder::BackToFront,
         |_, item, transform| {
             let origin = item.as_ref().geometry().origin;
             let transform =

sixtyfps_runtime/corelib/item_tree.rs

@@ -3,6 +3,13 @@ use crate::ComponentRefPin;
 use core::pin::Pin;
 use vtable::*;
 
+#[repr(u8)]
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub enum TraversalOrder {
+    BackToFront,
+    FrontToBack,
+}
+
 /// The return value of the Component::visit_children_item function
 ///
 /// Represents something like `enum { Continue, Aborted{aborted_at_item: isize} }`.
@@ -114,29 +121,31 @@ pub enum ItemVisitorResult<State> {
 /// Returns the index of the item that cancelled, or -1 if nobody cancelled
 pub fn visit_items<State>(
     component: ComponentRefPin,
+    order: TraversalOrder,
     mut visitor: impl FnMut(ComponentRefPin, Pin<ItemRef>, &State) -> ItemVisitorResult<State>,
     state: State,
 ) -> VisitChildrenResult {
-    visit_internal(component, &mut visitor, -1, &state)
+    visit_internal(component, order, &mut visitor, -1, &state)
 }
 
 fn visit_internal<State>(
     component: ComponentRefPin,
+    order: TraversalOrder,
     visitor: &mut impl FnMut(ComponentRefPin, Pin<ItemRef>, &State) -> ItemVisitorResult<State>,
     index: isize,
     state: &State,
 ) -> VisitChildrenResult {
-    let mut actual_visitor = |component: ComponentRefPin,
+    let mut actual_visitor =
-                              index: isize,
+        |component: ComponentRefPin, index: isize, item: Pin<ItemRef>| -> VisitChildrenResult {
-                              item: Pin<ItemRef>|
+            match visitor(component, item, state) {
-     -> VisitChildrenResult {
+                ItemVisitorResult::Continue(state) => {
-        match visitor(component, item, state) {
+                    visit_internal(component, order, visitor, index, &state)
-            ItemVisitorResult::Continue(state) => visit_internal(component, visitor, index, &state),
+                }
-            ItemVisitorResult::Abort => VisitChildrenResult::abort(index as usize, 0),
+                ItemVisitorResult::Abort => VisitChildrenResult::abort(index as usize, 0),
-        }
+            }
-    };
+        };
     vtable::new_vref!(let mut actual_visitor : VRefMut<ItemVisitorVTable> for ItemVisitor = &mut actual_visitor);
-    component.as_ref().visit_children_item(index, actual_visitor)
+    component.as_ref().visit_children_item(index, order, actual_visitor)
 }
 
 /// Visit the children within an array of ItemTreeNode
@@ -152,8 +161,14 @@ pub fn visit_item_tree<Base>(
     component: ComponentRefPin,
     item_tree: &[ItemTreeNode<Base>],
     index: isize,
+    order: TraversalOrder,
     mut visitor: vtable::VRefMut<ItemVisitorVTable>,
-    visit_dynamic: impl Fn(Pin<&Base>, vtable::VRefMut<ItemVisitorVTable>, usize) -> VisitChildrenResult,
+    visit_dynamic: impl Fn(
+        Pin<&Base>,
+        TraversalOrder,
+        vtable::VRefMut<ItemVisitorVTable>,
+        usize,
+    ) -> VisitChildrenResult,
 ) -> VisitChildrenResult {
     let mut visit_at_index = |idx: usize| -> VisitChildrenResult {
         match &item_tree[idx] {
@@ -162,7 +177,7 @@ pub fn visit_item_tree<Base>(
             }
             ItemTreeNode::DynamicTree { index } => {
                 if let Some(sub_idx) =
-                    visit_dynamic(base, visitor.borrow_mut(), *index).aborted_index()
+                    visit_dynamic(base, order, visitor.borrow_mut(), *index).aborted_index()
                 {
                     VisitChildrenResult::abort(idx, sub_idx)
                 } else {
@@ -176,8 +191,12 @@ pub fn visit_item_tree<Base>(
     } else {
         match &item_tree[index as usize] {
             ItemTreeNode::Item { children_index, chilren_count, .. } => {
-                for c in *children_index..(*children_index + *chilren_count) {
+                for c in 0..*chilren_count {
-                    let maybe_abort_index = visit_at_index(c as usize);
+                    let idx = match order {
+                        TraversalOrder::BackToFront => (*children_index + c),
+                        TraversalOrder::FrontToBack => (*children_index + *chilren_count - c - 1),
+                    } as usize;
+                    let maybe_abort_index = visit_at_index(idx);
                     if maybe_abort_index.has_aborted() {
                         return maybe_abort_index;
                     }
@@ -228,9 +247,11 @@ pub(crate) mod ffi {
         component: Pin<VRef<ComponentVTable>>,
         item_tree: Slice<ItemTreeNode<u8>>,
         index: isize,
+        order: TraversalOrder,
         visitor: VRefMut<ItemVisitorVTable>,
         visit_dynamic: extern "C" fn(
             base: &u8,
+            order: TraversalOrder,
             visitor: vtable::VRefMut<ItemVisitorVTable>,
             dyn_index: usize,
         ) -> VisitChildrenResult,
@@ -240,8 +261,9 @@ pub(crate) mod ffi {
             component,
             item_tree.as_slice(),
             index,
+            order,
             visitor,
-            |a, b, c| visit_dynamic(a.get_ref(), b, c),
+            |a, b, c, d| visit_dynamic(a.get_ref(), b, c, d),
         )
     }
 

sixtyfps_runtime/interpreter/dynamic_component.rs

@@ -9,7 +9,9 @@ use sixtyfps_compilerlib::typeregister::Type;
 use sixtyfps_compilerlib::*;
 use sixtyfps_corelib::abi::datastructures::{ComponentVTable, ItemVTable, WindowProperties};
 use sixtyfps_corelib::graphics::Resource;
-use sixtyfps_corelib::item_tree::{ItemTreeNode, ItemVisitorRefMut, VisitChildrenResult};
+use sixtyfps_corelib::item_tree::{
+    ItemTreeNode, ItemVisitorRefMut, TraversalOrder, VisitChildrenResult,
+};
 use sixtyfps_corelib::items::{Flickable, PropertyAnimation, Rectangle};
 use sixtyfps_corelib::layout::LayoutInfo;
 use sixtyfps_corelib::properties::{InterpolatedPropertyValue, PropertyListenerScope};
@@ -157,6 +159,7 @@ pub struct ComponentDescription {
 unsafe extern "C" fn visit_children_item(
     component: ComponentRefPin,
     index: isize,
+    order: TraversalOrder,
     v: ItemVisitorRefMut,
 ) -> VisitChildrenResult {
     let component_type =
@@ -167,8 +170,9 @@ unsafe extern "C" fn visit_children_item(
         component,
         item_tree.as_slice().into(),
         index,
+        order,
         v,
-        |_, mut visitor, index| {
+        |_, order, mut visitor, index| {
             let rep_in_comp = &component_type.repeater[index];
             let vec = &mut *(component.as_ptr().add(rep_in_comp.offset) as *mut RepeaterVec);
             if let Some(listener_offset) = rep_in_comp.listener {
@@ -205,11 +209,31 @@ unsafe extern "C" fn visit_children_item(
                     });
                 }
             }
-            for (i, x) in vec.iter().enumerate() {
+            match order {
-                if x.borrow().as_ref().visit_children_item(-1, visitor.borrow_mut()).has_aborted() {
+                TraversalOrder::FrontToBack => {
-                    return VisitChildrenResult::abort(i, 0);
+                    for (i, x) in vec.iter().enumerate() {
+                        if x.borrow()
+                            .as_ref()
+                            .visit_children_item(-1, order, visitor.borrow_mut())
+                            .has_aborted()
+                        {
+                            return VisitChildrenResult::abort(i, 0);
+                        }
+                    }
+                }
+                TraversalOrder::BackToFront => {
+                    for (i, x) in vec.iter().enumerate().rev() {
+                        if x.borrow()
+                            .as_ref()
+                            .visit_children_item(-1, order, visitor.borrow_mut())
+                            .has_aborted()
+                        {
+                            return VisitChildrenResult::abort(i, 0);
+                        }
+                    }
                 }
             }
+
             VisitChildrenResult::CONTINUE
         },
     )