Trait RenderSliverMultiBoxAdaptor 

pub trait RenderSliverMultiBoxAdaptor:
    RenderSliver
    + RenderSliverHelpers
    + RenderSliverWithKeepAliveMixin
    + ContainerRenderObjectMixin<ChildType = AnyRenderBox, ParentDataType = SliverMultiBoxAdaptorParentData> {
    // Required methods
    fn adaptor_data(
        self: RenderHandle<Self>,
        app: &App,
    ) -> &RenderSliverMultiBoxAdaptorData;
    fn adaptor_data_mut(
        self: RenderHandle<Self>,
        app: &mut App,
    ) -> &mut RenderSliverMultiBoxAdaptorData;

    // Provided methods
    fn child_manager(
        self: RenderHandle<Self>,
        app: &App,
    ) -> Rc<dyn RenderSliverBoxChildManager> { ... }
    fn setup_parent_data(
        self: RenderHandle<Self>,
        app: &mut App,
        child: AnyRenderObject,
    ) { ... }
    fn debug_child_integrity_enabled(
        self: RenderHandle<Self>,
        app: &App,
    ) -> bool { ... }
    fn set_debug_child_integrity_enabled(
        self: RenderHandle<Self>,
        app: &mut App,
        enabled: bool,
    ) { ... }
    fn debug_assert_child_list_locked(
        self: RenderHandle<Self>,
        app: &App,
    ) -> bool { ... }
    fn debug_verify_child_order(self: RenderHandle<Self>, app: &App) -> bool { ... }
    fn insert(
        self: RenderHandle<Self>,
        app: &mut App,
        child: AnyRenderBox,
        after: Option<AnyRenderBox>,
    ) { ... }
    fn did_adopt_child(
        self: RenderHandle<Self>,
        app: &mut App,
        child: AnyRenderBox,
    ) { ... }
    fn move_child(
        self: RenderHandle<Self>,
        app: &mut App,
        child: AnyRenderBox,
        after: Option<AnyRenderBox>,
    ) { ... }
    fn remove(self: RenderHandle<Self>, app: &mut App, child: AnyRenderBox) { ... }
    fn remove_all(self: RenderHandle<Self>, app: &mut App) { ... }
    fn keep_alive_children(
        self: RenderHandle<Self>,
        app: &App,
    ) -> Vec<AnyRenderBox> { ... }
    fn create_or_obtain_child(
        self: RenderHandle<Self>,
        app: &mut App,
        index: i32,
        after: Option<AnyRenderBox>,
    ) { ... }
    fn destroy_or_cache_child(
        self: RenderHandle<Self>,
        app: &mut App,
        child: AnyRenderBox,
    ) { ... }
    fn did_attach(
        self: RenderHandle<Self>,
        app: &mut App,
        owner: Handle<PipelineOwner>,
    ) { ... }
    fn did_detach(self: RenderHandle<Self>, app: &mut App) { ... }
    fn redepth_children(self: RenderHandle<Self>, app: &mut App) { ... }
    fn visit_children(
        self: RenderHandle<Self>,
        app: &App,
        visitor: &mut dyn FnMut(AnyRenderObject),
    ) { ... }
    fn add_initial_child(
        self: RenderHandle<Self>,
        app: &mut App,
        index: i32,
        layout_offset: f64,
    ) -> bool { ... }
    fn insert_and_layout_leading_child(
        self: RenderHandle<Self>,
        app: &mut App,
        child_constraints: BoxConstraints,
        parent_uses_size: bool,
    ) -> Option<AnyRenderBox> { ... }
    fn insert_and_layout_child(
        self: RenderHandle<Self>,
        app: &mut App,
        child_constraints: BoxConstraints,
        after: Option<AnyRenderBox>,
        parent_uses_size: bool,
    ) -> Option<AnyRenderBox> { ... }
    fn calculate_leading_garbage(
        self: RenderHandle<Self>,
        app: &App,
        first_index: i32,
    ) -> usize { ... }
    fn calculate_trailing_garbage(
        self: RenderHandle<Self>,
        app: &App,
        last_index: i32,
    ) -> usize { ... }
    fn collect_garbage(
        self: RenderHandle<Self>,
        app: &mut App,
        leading_garbage: usize,
        trailing_garbage: usize,
    ) { ... }
    fn index_of(self: RenderHandle<Self>, app: &App, child: AnyRenderBox) -> i32 { ... }
    fn paint_extent_of(
        self: RenderHandle<Self>,
        app: &App,
        child: AnyRenderBox,
    ) -> f64 { ... }
    fn hit_test_children(
        self: RenderHandle<Self>,
        app: &mut App,
        result: &mut SliverHitTestResult<'_>,
        main_axis_position: f64,
        cross_axis_position: f64,
    ) -> bool { ... }
    fn child_main_axis_position(
        self: RenderHandle<Self>,
        app: &App,
        child: AnyRenderObject,
    ) -> f64 { ... }
    fn child_scroll_offset(
        self: RenderHandle<Self>,
        app: &App,
        child: AnyRenderObject,
    ) -> Option<f64> { ... }
    fn paints_child(
        self: RenderHandle<Self>,
        app: &App,
        child: AnyRenderBox,
    ) -> bool { ... }
    fn apply_paint_transform(
        self: RenderHandle<Self>,
        app: &App,
        child: AnyRenderObject,
        transform: &mut Matrix4,
    ) { ... }
    fn paint(
        self: RenderHandle<Self>,
        app: &mut App,
        context: &mut PaintingContext,
        offset: Offset,
    ) { ... }
    fn debug_assert_child_list_is_non_empty_and_contiguous(
        self: RenderHandle<Self>,
        app: &App,
    ) -> bool { ... }
}

A sliver with multiple box children.

RenderSliverMultiBoxAdaptor is a base class for slivers that have multiple box children. The children are managed by a RenderSliverBoxChildManager, which lets implementors create children lazily during layout. Typically implementors will create only those children that are actually needed to fill the SliverConstraints::remaining_paint_extent.

The contract for adding and removing children from this render object is more strict than for normal render objects:

• Children can be removed except during a layout pass if they have already been laid out during that layout pass.
• Children cannot be added except during a call to child_manager, and then only if there is no child corresponding to that index (or the child corresponding to that index was first removed).

See also:

• crate::RenderSliverToBoxAdapter, which has a single box child.
• crate::RenderSliverList, which places its children in a linear array.
• crate::RenderSliverFixedExtentList, which places its children in a linear array with a fixed extent in the main axis.

Required Methods

fn adaptor_data( self: RenderHandle<Self>, app: &App, ) -> &RenderSliverMultiBoxAdaptorData

Mixin field access.

fn adaptor_data_mut( self: RenderHandle<Self>, app: &mut App, ) -> &mut RenderSliverMultiBoxAdaptorData

See adaptor_data.

Provided Methods

fn child_manager( self: RenderHandle<Self>, app: &App, ) -> Rc<dyn RenderSliverBoxChildManager>

The delegate that manages the children of this object.

Rather than having a concrete list of children, a RenderSliverMultiBoxAdaptor uses a RenderSliverBoxChildManager to create children during layout in order to fill the SliverConstraints::remaining_paint_extent.

fn setup_parent_data( self: RenderHandle<Self>, app: &mut App, child: AnyRenderObject, )

The body of Flutter’s setupParentData override.

fn debug_child_integrity_enabled(self: RenderHandle<Self>, app: &App) -> bool

Whether the integrity check is enabled.

The integrity check consists of:

1. Verify that the children index in the child list is in ascending order.
2. Verify that there is no dangling keep-alive child as the result of move_child.

fn set_debug_child_integrity_enabled( self: RenderHandle<Self>, app: &mut App, enabled: bool, )

Sets debug_child_integrity_enabled, immediately performing an integrity check.

fn debug_assert_child_list_locked(self: RenderHandle<Self>, app: &App) -> bool

Flutter’s _debugAssertChildListLocked.

fn debug_verify_child_order(self: RenderHandle<Self>, app: &App) -> bool

Verify that the child list index is in strictly increasing order.

This has no effect in release builds.

fn insert( self: RenderHandle<Self>, app: &mut App, child: AnyRenderBox, after: Option<AnyRenderBox>, )

The body of Flutter’s insert override.

fn did_adopt_child(self: RenderHandle<Self>, app: &mut App, child: AnyRenderBox)

The body of Flutter’s adoptChild override, run after a child joins the child list.

Flutter overrides RenderObject.adoptChild; here the tree operation is not virtual, so the two callers (insert and Dart’s _destroyOrCacheChild, which takes super.adoptChild) decide whether it runs.

fn move_child( self: RenderHandle<Self>, app: &mut App, child: AnyRenderBox, after: Option<AnyRenderBox>, )

The body of Flutter’s move override.

There are two scenarios:

1. The child is not kept alive. The child is in the child list maintained by ContainerRenderObjectMixin. We can call the inherited body and update the parent data with the new slot.

2. The child is kept alive. In this case, the child is no longer in the child list but might be stored in the keep-alive bucket. We need to update the location of the child in the bucket.

fn remove(self: RenderHandle<Self>, app: &mut App, child: AnyRenderBox)

The body of Flutter’s remove override.

fn remove_all(self: RenderHandle<Self>, app: &mut App)

The body of Flutter’s removeAll override.

fn keep_alive_children(self: RenderHandle<Self>, app: &App) -> Vec<AnyRenderBox>

The children currently held in the keep-alive bucket, in insertion order.

fn create_or_obtain_child( self: RenderHandle<Self>, app: &mut App, index: i32, after: Option<AnyRenderBox>, )

Flutter’s _createOrObtainChild.

fn destroy_or_cache_child( self: RenderHandle<Self>, app: &mut App, child: AnyRenderBox, )

Flutter’s _destroyOrCacheChild.

fn did_attach( self: RenderHandle<Self>, app: &mut App, owner: Handle<PipelineOwner>, )

The body of Flutter’s attach override: attaches the kept-alive children too.

fn did_detach(self: RenderHandle<Self>, app: &mut App)

The body of Flutter’s detach override: detaches the kept-alive children too.

fn redepth_children(self: RenderHandle<Self>, app: &mut App)

The body of Flutter’s redepthChildren override.

fn visit_children( self: RenderHandle<Self>, app: &App, visitor: &mut dyn FnMut(AnyRenderObject), )

The body of Flutter’s visitChildren override: visits the kept-alive children too.

fn add_initial_child( self: RenderHandle<Self>, app: &mut App, index: i32, layout_offset: f64, ) -> bool

Called during layout to create and add the child with the given index and scroll offset.

Calls RenderSliverBoxChildManager::create_child to actually create and add the child if necessary. The child may instead be obtained from a cache; see KeepAliveParentData::keep_alive.

Returns false if there was no cached child and create_child did not add any child, otherwise returns true.

Does not lay out the new child.

fn insert_and_layout_leading_child( self: RenderHandle<Self>, app: &mut App, child_constraints: BoxConstraints, parent_uses_size: bool, ) -> Option<AnyRenderBox>

Called during layout to create, add, and lay out the child before ContainerRenderObjectMixin::first_child.

Returns the new child or None if no child was obtained.

The child that was previously the first child, as well as any subsequent children, may be removed by this call if they have not yet been laid out during this layout pass.

fn insert_and_layout_child( self: RenderHandle<Self>, app: &mut App, child_constraints: BoxConstraints, after: Option<AnyRenderBox>, parent_uses_size: bool, ) -> Option<AnyRenderBox>

Called during layout to create, add, and lay out the child after the given child.

Returns the new child. It is the responsibility of the caller to configure the child’s scroll offset.

Children after the after child may be removed in the process. Only the new child may be added.

fn calculate_leading_garbage( self: RenderHandle<Self>, app: &App, first_index: i32, ) -> usize

Returns the number of children preceding the first_index that need to be garbage collected.

fn calculate_trailing_garbage( self: RenderHandle<Self>, app: &App, last_index: i32, ) -> usize

Returns the number of children following the last_index that need to be garbage collected.

fn collect_garbage( self: RenderHandle<Self>, app: &mut App, leading_garbage: usize, trailing_garbage: usize, )

Called after layout with the number of children that can be garbage collected at the head and tail of the child list.

Children whose KeepAliveParentData::keep_alive property is set to true will be removed to a cache instead of being dropped.

This method also collects any children that were previously kept alive but are now no longer necessary. As such, it should be called every time perform_layout is run, even if the arguments are both zero.

fn index_of(self: RenderHandle<Self>, app: &App, child: AnyRenderBox) -> i32

Returns the index of the given child, as given by the SliverMultiBoxAdaptorParentData::index field of the child’s parent data.

fn paint_extent_of( self: RenderHandle<Self>, app: &App, child: AnyRenderBox, ) -> f64

Returns the dimension of the given child in the main axis, as given by the child’s size.

This is only valid after layout.

fn hit_test_children( self: RenderHandle<Self>, app: &mut App, result: &mut SliverHitTestResult<'_>, main_axis_position: f64, cross_axis_position: f64, ) -> bool

The body of Flutter’s hitTestChildren override.

fn child_main_axis_position( self: RenderHandle<Self>, app: &App, child: AnyRenderObject, ) -> f64

The body of Flutter’s childMainAxisPosition override.

fn child_scroll_offset( self: RenderHandle<Self>, app: &App, child: AnyRenderObject, ) -> Option<f64>

The body of Flutter’s childScrollOffset override.

fn paints_child( self: RenderHandle<Self>, app: &App, child: AnyRenderBox, ) -> bool

Whether the given child is painted, i.e. it is reified and not kept alive off-screen.

Flutter’s paintsChild override; RenderObject.paintsChild is not a virtual here (see PORTING.md).

fn apply_paint_transform( self: RenderHandle<Self>, app: &App, child: AnyRenderObject, transform: &mut Matrix4, )

The body of Flutter’s applyPaintTransform override.

fn paint( self: RenderHandle<Self>, app: &mut App, context: &mut PaintingContext, offset: Offset, )

The body of Flutter’s paint override.

fn debug_assert_child_list_is_non_empty_and_contiguous( self: RenderHandle<Self>, app: &App, ) -> bool

Asserts that the reified child list is not empty and has a contiguous sequence of indices.

Always returns true.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl RenderSliverMultiBoxAdaptor for RenderSliverFixedExtentList

impl RenderSliverMultiBoxAdaptor for RenderSliverGrid

impl RenderSliverMultiBoxAdaptor for RenderSliverList

impl RenderSliverMultiBoxAdaptor for RenderSliverVariedExtentList