Trait ListDelegate 

pub trait ListDelegate: Sized + 'static {
    type Item: Selectable + IntoElement;

    // Required methods
    fn items_count(&self, section: usize, cx: &App) -> usize;
    fn render_item(
        &mut self,
        ix: IndexPath,
        window: &mut Window,
        cx: &mut Context<'_, ListState<Self>>,
    ) -> Option<Self::Item>;
    fn set_selected_index(
        &mut self,
        ix: Option<IndexPath>,
        window: &mut Window,
        cx: &mut Context<'_, ListState<Self>>,
    );

    // Provided methods
    fn perform_search(
        &mut self,
        query: &str,
        window: &mut Window,
        cx: &mut Context<'_, ListState<Self>>,
    ) -> Task<()> { ... }
    fn sections_count(&self, cx: &App) -> usize { ... }
    fn render_section_header(
        &mut self,
        section: usize,
        window: &mut Window,
        cx: &mut Context<'_, ListState<Self>>,
    ) -> Option<impl IntoElement> { ... }
    fn render_section_footer(
        &mut self,
        section: usize,
        window: &mut Window,
        cx: &mut Context<'_, ListState<Self>>,
    ) -> Option<impl IntoElement> { ... }
    fn render_empty(
        &mut self,
        window: &mut Window,
        cx: &mut Context<'_, ListState<Self>>,
    ) -> impl IntoElement { ... }
    fn render_initial(
        &mut self,
        window: &mut Window,
        cx: &mut Context<'_, ListState<Self>>,
    ) -> Option<AnyElement> { ... }
    fn loading(&self, cx: &App) -> bool { ... }
    fn render_loading(
        &mut self,
        window: &mut Window,
        cx: &mut Context<'_, ListState<Self>>,
    ) -> impl IntoElement { ... }
    fn confirm(
        &mut self,
        secondary: bool,
        window: &mut Window,
        cx: &mut Context<'_, ListState<Self>>,
    ) { ... }
    fn cancel(
        &mut self,
        window: &mut Window,
        cx: &mut Context<'_, ListState<Self>>,
    ) { ... }
    fn is_eof(&self, cx: &App) -> bool { ... }
    fn load_more_threshold(&self) -> usize { ... }
    fn load_more(
        &mut self,
        window: &mut Window,
        cx: &mut Context<'_, ListState<Self>>,
    ) { ... }
}

A delegate for the List.

Required Associated Types

type Item: Selectable + IntoElement

Required Methods

fn items_count(&self, section: usize, cx: &App) -> usize

Return the number of items in the section at the given index.

fn render_item( &mut self, ix: IndexPath, window: &mut Window, cx: &mut Context<'_, ListState<Self>>, ) -> Option<Self::Item>

Render the item at the given index.

Return None will skip the item.

NOTE: Every item should have same height.

fn set_selected_index( &mut self, ix: Option<IndexPath>, window: &mut Window, cx: &mut Context<'_, ListState<Self>>, )

Set the selected index, just store the ix, don’t confirm.

Provided Methods

fn perform_search( &mut self, query: &str, window: &mut Window, cx: &mut Context<'_, ListState<Self>>, ) -> Task<()>

When Query Input change, this method will be called. You can perform search here.

fn sections_count(&self, cx: &App) -> usize

Return the number of sections in the list, default is 1.

fn render_section_header( &mut self, section: usize, window: &mut Window, cx: &mut Context<'_, ListState<Self>>, ) -> Option<impl IntoElement>

Render the section header at the given index, default is None.

NOTE: Every header should have same height.

fn render_section_footer( &mut self, section: usize, window: &mut Window, cx: &mut Context<'_, ListState<Self>>, ) -> Option<impl IntoElement>

Render the section footer at the given index, default is None.

NOTE: Every footer should have same height.

fn render_empty( &mut self, window: &mut Window, cx: &mut Context<'_, ListState<Self>>, ) -> impl IntoElement

Return a Element to show when list is empty.

fn render_initial( &mut self, window: &mut Window, cx: &mut Context<'_, ListState<Self>>, ) -> Option<AnyElement>

Returns Some(AnyElement) to render the initial state of the list.

This can be used to show a view for the list before the user has interacted with it.

For example: The last search results, or the last selected item.

Default is None, that means no initial state.

fn loading(&self, cx: &App) -> bool

Returns the loading state to show the loading view.

fn render_loading( &mut self, window: &mut Window, cx: &mut Context<'_, ListState<Self>>, ) -> impl IntoElement

Returns a Element to show when loading, default is built-in Skeleton loading view.

fn confirm( &mut self, secondary: bool, window: &mut Window, cx: &mut Context<'_, ListState<Self>>, )

Set the confirm and give the selected index, this is means user have clicked the item or pressed Enter.

This will always to set_selected_index before confirm.

fn cancel(&mut self, window: &mut Window, cx: &mut Context<'_, ListState<Self>>)

Cancel the selection, e.g.: Pressed ESC.

fn is_eof(&self, cx: &App) -> bool

Return true to enable load more data when scrolling to the bottom.

Default: true

fn load_more_threshold(&self) -> usize

Returns a threshold value (n entities), of course, when scrolling to the bottom, the remaining number of rows triggers load_more.

This should smaller than the total number of first load rows.

Default: 20 entities (section header, footer and row)

fn load_more( &mut self, window: &mut Window, cx: &mut Context<'_, ListState<Self>>, )

Load more data when the table is scrolled to the bottom.

This will performed in a background task.

This is always called when the table is near the bottom, so you must check if there is more data to load or lock the loading state.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors