@jupyterlab/ui-components/lib/components/windowedlist.d.ts

import { IChangedArgs } from '@jupyterlab/coreutils';
import { IObservableList } from '@jupyterlab/observables';
import { IDisposable } from '@lumino/disposable';
import { Message } from '@lumino/messaging';
import { ISignal, Signal } from '@lumino/signaling';
import { PanelLayout, Widget } from '@lumino/widgets';
/**
 * Windowed list abstract model.
 */
export declare abstract class WindowedListModel implements WindowedList.IModel {
    /**
     * Constructor
     *
     * @param options Constructor options
     */
    constructor(options?: WindowedList.IModelOptions);
    /**
     * Provide a best guess for the widget size at position index
     *
     * #### Notes
     *
     * This function should be very light to compute especially when
     * returning the default size.
     * The default value should be constant (i.e. two calls with `null` should
     * return the same value). But it can change for a given `index`.
     *
     * @param index Widget position
     * @returns Estimated widget size
     */
    abstract estimateWidgetSize: (index: number) => number;
    /**
     * Widget factory for the list items.
     *
     * Caching the resulting widgets should be done by the callee.
     *
     * @param index List index
     * @returns The widget at the given position
     */
    abstract widgetRenderer: (index: number) => Widget;
    /**
     * The overlap threshold used to decide whether to scroll down to an item
     * below the viewport (smart mode). If the item overlap with the viewport
     * is greater or equal this threshold the item is considered sufficiently
     * visible and will not be scrolled to. The value is the number of pixels
     * in overlap if greater than one, or otherwise a fraction of item height.
     * By default the item is scrolled to if not full visible in the viewport.
     */
    readonly scrollDownThreshold: number;
    /**
     * The underlap threshold used to decide whether to scroll up to an item
     * above the viewport (smart mode). If the item part outside the viewport
     * (underlap) is greater than this threshold then the item is considered
     * not sufficiently visible and will be scrolled to.
     * The value is the number of pixels in underlap if greater than one, or
     * otherwise a fraction of the item height.
     * By default the item is scrolled to if not full visible in the viewport.
     */
    readonly scrollUpThreshold: number;
    /**
     * Top padding of the the outer window node.
     */
    paddingTop: number;
    /**
     * List widget height
     */
    get height(): number;
    set height(h: number);
    /**
     * Test whether the model is disposed.
     */
    get isDisposed(): boolean;
    /**
     * Items list to be rendered
     */
    get itemsList(): ISimpleObservableList | null;
    set itemsList(v: ISimpleObservableList | null);
    /**
     * Number of widgets to render in addition to those
     * visible in the viewport.
     */
    get overscanCount(): number;
    set overscanCount(newValue: number);
    /**
     * Viewport scroll offset.
     */
    get scrollOffset(): number;
    set scrollOffset(offset: number);
    /**
     * Total number of widgets in the list
     */
    get widgetCount(): number;
    set widgetCount(newValue: number);
    /**
     * Whether windowing is active or not.
     *
     * This is true by default.
     */
    get windowingActive(): boolean;
    set windowingActive(newValue: boolean);
    /**
     * A signal emitted when any model state changes.
     */
    get stateChanged(): ISignal<WindowedListModel, IChangedArgs<any, any, 'count' | 'estimatedWidgetSize' | 'index' | 'list' | 'overscanCount' | 'windowingActive' | string>>;
    /**
     * Dispose the model.
     */
    dispose(): void;
    /**
     * Get the total list size.
     *
     * @returns Total estimated size
     */
    getEstimatedTotalSize(): number;
    /**
     * Get the scroll offset to display an item in the viewport.
     *
     * By default, the list will scroll as little as possible to ensure the item is fully visible (`auto`).
     * You can control the alignment of the item though by specifying a second alignment parameter.
     * Acceptable values are:
     *
     *   auto - Automatically align with the top or bottom minimising the amount scrolled,
     *          If `alignPreference` is given, follow such preferred alignment.
     *          If item is smaller than the viewport and fully visible, do not scroll at all.
     *   smart - If the item is significantly visible, don't scroll at all (regardless of whether it fits in the viewport).
     *           If the item is less than one viewport away, scroll so that it becomes fully visible (following the `auto` heuristics).
     *           If the item is more than one viewport away, scroll so that it is centered within the viewport (`center` if smaller than viewport, `top-center` otherwise).
     *   center - Align the middle of the item with the middle of the viewport (it only works well for items smaller than the viewport).
     *   top-center - Align the top of the item with the middle of the viewport (works well for items larger than the viewport).
     *   end - Align the bottom of the item to the bottom of the list.
     *   start - Align the top of item to the top of the list.
     *
     * An item is considered significantly visible if:
     *  - it overlaps with the viewport by the amount specified by `scrollDownThreshold` when below the viewport
     *  - it exceeds the viewport by the amount less than specified by `scrollUpThreshold` when above the viewport.
     *
     * @param index Item index
     * @param align Where to align the item in the viewport
     * @param margin The proportion of viewport to add when aligning with the top/bottom of the list.
     * @param precomputed Precomputed values to use when windowing is disabled.
     * @param alignPreference Allows to override the alignment of item when the `auto` heuristic decides that the item needs to be scrolled into view.
     * @returns The needed scroll offset
     */
    getOffsetForIndexAndAlignment(index: number, align?: WindowedList.ScrollToAlign, margin?: number, precomputed?: {
        totalSize: number;
        itemMetadata: WindowedList.ItemMetadata;
        currentOffset: number;
    }, alignPreference?: WindowedList.BaseScrollToAlignment): number;
    /**
     * Compute the items range to display.
     *
     * It returns ``null`` if the range does not need to be updated.
     *
     * @returns The current items range to display
     */
    getRangeToRender(): WindowedList.WindowIndex | null;
    /**
     * Return the viewport top position and height for range spanning from
     * ``startIndex`` to ``stopIndex``.
     *
     * @param startIndex First item in viewport index
     * @param stopIndex Last item in viewport index
     * @returns The viewport top position and its height
     */
    getSpan(startIndex: number, stopIndex: number): [number, number];
    /**
     * WindowedListModel caches offsets and measurements for each index for performance purposes.
     * This method clears that cached data for all items after (and including) the specified index.
     *
     * The list will automatically re-render after the index is reset.
     *
     * @param index
     */
    resetAfterIndex(index: number): void;
    /**
     * Update item sizes.
     *
     * This should be called when the real item sizes has been
     * measured.
     *
     * @param sizes New sizes per item index
     * @returns Whether some sizes changed or not
     */
    setWidgetSize(sizes: {
        index: number;
        size: number;
    }[]): boolean;
    /**
     * Callback on list changes
     *
     * @param list List items
     * @param changes List change
     */
    protected onListChanged(list: IObservableList<Widget>, changes: IObservableList.IChangedArgs<Widget>): void;
    private _getItemMetadata;
    private _findNearestItem;
    private _findNearestItemBinarySearch;
    private _findNearestItemExponentialSearch;
    private _getRangeToRender;
    private _getStartIndexForOffset;
    private _getStopIndexForStartIndex;
    /**
     * Default widget size estimation
     *
     * @deprecated we always use {@link estimateWidgetSize}
     */
    protected _estimatedWidgetSize: number;
    protected _stateChanged: Signal<WindowedListModel, IChangedArgs<any, any, string>>;
    private _currentWindow;
    private _height;
    private _isDisposed;
    private _itemsList;
    private _measuredAllUntilIndex;
    private _overscanCount;
    private _scrollOffset;
    private _widgetCount;
    private _widgetSizers;
    private _windowingActive;
}
/**
 * Windowed list widget
 */
export declare class WindowedList<T extends WindowedList.IModel = WindowedList.IModel, U = any> extends Widget {
    /**
     * Default widget size
     */
    static readonly DEFAULT_WIDGET_SIZE = 50;
    /**
     * Constructor
     *
     * @param options Constructor options
     */
    constructor(options: WindowedList.IOptions<T, U>);
    private _viewportIndicator;
    /**
     * Whether the parent is hidden or not.
     *
     * This should be set externally if a container is hidden to
     * stop updating the widget size when hidden.
     */
    get isParentHidden(): boolean;
    set isParentHidden(v: boolean);
    /**
     * Widget layout
     */
    get layout(): WindowedLayout;
    /**
     * The outer container of the windowed list.
     */
    get outerNode(): HTMLElement;
    /**
     * Viewport
     */
    get viewportNode(): HTMLElement;
    /**
     * Flag to enable virtual scrollbar.
     */
    get scrollbar(): boolean;
    set scrollbar(enabled: boolean);
    /**
     * The renderer for this windowed list. Set at instantiation.
     */
    protected renderer: WindowedList.IRenderer<U>;
    /**
     * Windowed list view model
     */
    protected get viewModel(): T;
    /**
     * Dispose the windowed list.
     */
    dispose(): void;
    /**
     * Callback on event.
     *
     * @param event Event
     */
    handleEvent(event: Event): void;
    /**
     * Scroll to the specified offset `scrollTop`.
     *
     * @param scrollOffset Offset to scroll
     *
     * @deprecated since v4 This is an internal helper. Prefer calling `scrollToItem`.
     */
    scrollTo(scrollOffset: number): void;
    /**
     * Scroll to the specified item.
     *
     * By default, the list will scroll as little as possible to ensure the item is fully visible (`auto`).
     * You can control the alignment of the item though by specifying a second alignment parameter.
     * Acceptable values are:
     *
     *   auto - Automatically align with the top or bottom minimising the amount scrolled,
     *          If `alignPreference` is given, follow such preferred alignment.
     *          If item is smaller than the viewport and fully visible, do not scroll at all.
     *   smart - If the item is significantly visible, don't scroll at all (regardless of whether it fits in the viewport).
     *           If the item is less than one viewport away, scroll so that it becomes fully visible (following the `auto` heuristics).
     *           If the item is more than one viewport away, scroll so that it is centered within the viewport (`center` if smaller than viewport, `top-center` otherwise).
     *   center - Align the middle of the item with the middle of the viewport (it only works well for items smaller than the viewport).
     *   top-center - Align the top of the item with the middle of the viewport (works well for items larger than the viewport).
     *   end - Align the bottom of the item to the bottom of the list.
     *   start - Align the top of item to the top of the list.
     *
     * @param index Item index to scroll to
     * @param align Type of alignment
     * @param margin In 'smart' mode the viewport proportion to add
     * @param alignPreference Allows to override the alignment of item when the `auto` heuristic decides that the item needs to be scrolled into view.
     */
    scrollToItem(index: number, align?: WindowedList.ScrollToAlign, margin?: number, alignPreference?: WindowedList.BaseScrollToAlignment): Promise<void>;
    /**
     * A message handler invoked on an `'after-attach'` message.
     */
    protected onAfterAttach(msg: Message): void;
    /**
     * A message handler invoked on an `'before-detach'` message.
     */
    protected onBeforeDetach(msg: Message): void;
    /**
     * Callback on scroll event
     *
     * @param event Scroll event
     */
    protected onScroll(event: Event): void;
    /**
     * A message handler invoked on an `'resize-request'` message.
     */
    protected onResize(msg: Widget.ResizeMessage): void;
    /**
     * Callback on view model change
     *
     * @param model Windowed list model
     * @param changes Change
     */
    protected onStateChanged(model: WindowedList.IModel, changes: IChangedArgs<number | boolean, number | boolean, string>): void;
    /**
     * A message handler invoked on an `'update-request'` message.
     *
     * #### Notes
     * The default implementation of this handler is a no-op.
     */
    protected onUpdateRequest(msg: Message): void;
    /**
     * A signal that emits the index when the virtual scrollbar jumps to an item.
     */
    protected jumped: Signal<this, number>;
    private _adjustDimensionsForScrollbar;
    /**
     * Add listeners for viewport, contents and the virtual scrollbar.
     */
    private _addListeners;
    /**
     * Turn off windowing related styles in the viewport.
     */
    private _applyNoWindowingStyles;
    /**
     * Turn on windowing related styles in the viewport.
     */
    private _applyWindowingStyles;
    /**
     * Remove listeners for viewport and contents (but not the virtual scrollbar).
     */
    private _removeListeners;
    /**
     * Update viewport and DOM state.
     */
    private _update;
    /**
     * Handle viewport area resize.
     */
    private _onAreaResize;
    /**
     * Handle viewport content (i.e. items) resize.
     */
    private _onItemResize;
    /**
     * Scroll to the item which was most recently requested.
     *
     * This method ensures that the app scrolls to the item even if a resize event
     * occurs shortly after the scroll. Consider the following sequence of events:
     *
     * 1. User is at the nth cell, presses Shift+Enter (run current cell and
     *    advance to next)
     * 2. App scrolls to the next (n+1) cell
     * 3. The nth cell finishes running and renders the output, pushing the
     *    (n+1) cell down out of view
     * 4. This triggers the resize observer, which calls this method and scrolls
     *    the (n+1) cell back into view
     *
     * On implementation level, this is ensured by scrolling to `this._scrollToItem`
     * which is cleared after a short timeout once the scrolling settles
     * (see `this._resetScrollToItem()`).
     */
    private _scrollBackToItemOnResize;
    /**
     * Clear any outstanding timeout and enqueue scrolling to a new item.
     */
    private _resetScrollToItem;
    /**
     * Render virtual scrollbar.
     */
    private _renderScrollbar;
    private _scrollbarItems;
    /**
     * Handle `pointerdown` events on the virtual scrollbar.
     */
    private _evtPointerDown;
    /**
     * Update the total size
     */
    private _updateTotalSize;
    protected _viewModel: T;
    private _viewportPaddingTop;
    private _viewportPaddingBottom;
    private _innerElement;
    private _isParentHidden;
    private _isScrolling;
    private _needsUpdate;
    private _outerElement;
    private _resetScrollToItemTimeout;
    private _areaResizeObserver;
    private _itemsResizeObserver;
    private _scrollbarElement;
    private _scrollbarResizeObserver;
    private _scrollRepaint;
    private _scrollToItem;
    private _scrollUpdateWasRequested;
    private _updater;
    private _viewport;
}
/**
 * Customized layout for windowed list container.
 */
export declare class WindowedLayout extends PanelLayout {
    /**
     * Constructor
     */
    constructor();
    /**
     * Specialized parent type definition
     */
    get parent(): WindowedList | null;
    set parent(value: WindowedList | null);
    /**
     * Attach a widget to the parent's DOM node.
     *
     * @param index - The current index of the widget in the layout.
     *
     * @param widget - The widget to attach to the parent.
     *
     * #### Notes
     * This method is called automatically by the panel layout at the
     * appropriate time. It should not be called directly by user code.
     *
     * The default implementation adds the widgets's node to the parent's
     * node at the proper location, and sends the appropriate attach
     * messages to the widget if the parent is attached to the DOM.
     *
     * Subclasses may reimplement this method to control how the widget's
     * node is added to the parent's node.
     */
    protected attachWidget(index: number, widget: Widget): void;
    /**
     * Detach a widget from the parent's DOM node.
     *
     * @param index - The previous index of the widget in the layout.
     *
     * @param widget - The widget to detach from the parent.
     *
     * #### Notes
     * This method is called automatically by the panel layout at the
     * appropriate time. It should not be called directly by user code.
     *
     * The default implementation removes the widget's node from the
     * parent's node, and sends the appropriate detach messages to the
     * widget if the parent is attached to the DOM.
     *
     * Subclasses may reimplement this method to control how the widget's
     * node is removed from the parent's node.
     */
    protected detachWidget(index: number, widget: Widget): void;
    /**
     * Move a widget in the parent's DOM node.
     *
     * @param fromIndex - The previous index of the widget in the layout.
     *
     * @param toIndex - The current index of the widget in the layout.
     *
     * @param widget - The widget to move in the parent.
     *
     * #### Notes
     * This method is called automatically by the panel layout at the
     * appropriate time. It should not be called directly by user code.
     *
     * The default implementation moves the widget's node to the proper
     * location in the parent's node and sends the appropriate attach and
     * detach messages to the widget if the parent is attached to the DOM.
     *
     * Subclasses may reimplement this method to control how the widget's
     * node is moved in the parent's node.
     */
    protected moveWidget(fromIndex: number, toIndex: number, widget: Widget): void;
    /**
     * A message handler invoked on an `'update-request'` message.
     *
     * #### Notes
     * This is a reimplementation of the base class method,
     * and is a no-op.
     */
    protected onUpdateRequest(msg: Message): void;
}
/**
 * Windowed list model interface
 */
export interface ISimpleObservableList<T = any> {
    get?: (index: number) => T;
    length: number;
    changed: ISignal<any, IObservableList.IChangedArgs<any>>;
}
/**
 * A namespace for windowed list
 */
export declare namespace WindowedList {
    /**
     * The default renderer class for windowed lists.
     */
    class Renderer<T = any> implements IRenderer<T> {
        /**
         * Create the outer, root element of the windowed list.
         */
        createOuter(): HTMLElement;
        /**
         * Create the virtual scrollbar element.
         */
        createScrollbar(): HTMLOListElement;
        /**
         * Create the virtual scrollbar viewport indicator.
         */
        createScrollbarViewportIndicator(): HTMLElement;
        /**
         * Create an individual item rendered in the scrollbar.
         */
        createScrollbarItem(_: WindowedList, index: number): HTMLLIElement;
        /**
         * Create the viewport element into which virtualized children are added.
         */
        createViewport(): HTMLElement;
    }
    /**
     * The default renderer for windowed lists.
     */
    const defaultRenderer: Renderer<any>;
    /**
     * Windowed list model interface
     */
    interface IModel<T = any> extends IDisposable {
        /**
         * Provide a best guess for the widget size at position index
         *
         * #### Notes
         *
         * This function should be very light to compute especially when
         * returning the default size.
         * The default value should be constant (i.e. two calls with `null` should
         * return the same value). But it can change for a given `index`.
         *
         * @param index Widget position
         * @returns Estimated widget size
         */
        estimateWidgetSize: (index: number) => number;
        /**
         * Get the total list size.
         *
         * @returns Total estimated size
         */
        getEstimatedTotalSize(): number;
        /**
         * Get the scroll offset to display an item in the viewport.
         *
         * By default, the list will scroll as little as possible to ensure the item is fully visible (`auto`).
         * You can control the alignment of the item though by specifying a second alignment parameter.
         * Acceptable values are:
         *
         *   auto - Automatically align with the top or bottom minimising the amount scrolled,
         *          If `alignPreference` is given, follow such preferred alignment.
         *          If item is smaller than the viewport and fully visible, do not scroll at all.
         *   smart - If the item is significantly visible, don't scroll at all (regardless of whether it fits in the viewport).
         *           If the item is less than one viewport away, scroll so that it becomes fully visible (following the `auto` heuristics).
         *           If the item is more than one viewport away, scroll so that it is centered within the viewport (`center` if smaller than viewport, `top-center` otherwise).
         *   center - Align the middle of the item with the middle of the viewport (it only works well for items smaller than the viewport).
         *   top-center - Align the top of the item with the middle of the viewport (works well for items larger than the viewport).
         *   end - Align the bottom of the item to the bottom of the list.
         *   start - Align the top of item to the top of the list.
         *
         * @param index Item index
         * @param align Where to align the item in the viewport
         * @param margin In 'smart' mode the viewport proportion to add
         * @param precomputed Precomputed values to use when windowing is disabled.
         * @param alignPreference Allows to override the alignment of item when the `auto` heuristic decides that the item needs to be scrolled into view.
         * @returns The needed scroll offset
         */
        getOffsetForIndexAndAlignment(index: number, align?: ScrollToAlign, margin?: number, precomputed?: {
            totalSize: number;
            itemMetadata: WindowedList.ItemMetadata;
            currentOffset: number;
        }, alignPreference?: WindowedList.BaseScrollToAlignment): number;
        /**
         * Compute the items range to display.
         *
         * It returns ``null`` if the range does not need to be updated.
         *
         * @returns The current items range to display
         */
        getRangeToRender(): WindowIndex | null;
        /**
         * Return the viewport top position and height for range spanning from
         * ``startIndex`` to ``stopIndex``.
         *
         * @param start First item in viewport index
         * @param stop Last item in viewport index
         * @returns The viewport top position and its height
         */
        getSpan(start: number, stop: number): [number, number];
        /**
         * List widget height
         */
        height: number;
        /**
         * Top padding of the the outer window node.
         */
        paddingTop?: number;
        /**
         * Items list to be rendered
         */
        itemsList: ISimpleObservableList<T> | null;
        /**
         * Number of widgets to render in addition to those
         * visible in the viewport.
         */
        overscanCount: number;
        /**
         * WindowedListModel caches offsets and measurements for each index for performance purposes.
         * This method clears that cached data for all items after (and including) the specified index.
         *
         * The list will automatically re-render after the index is reset.
         *
         * @param index
         */
        resetAfterIndex(index: number): void;
        /**
         * Viewport scroll offset.
         */
        scrollOffset: number;
        /**
         * Update item sizes.
         *
         * This should be called when the real item sizes has been
         * measured.
         *
         * @param sizes New sizes per item index
         * @returns Whether some sizes changed or not
         */
        setWidgetSize(sizes: {
            index: number;
            size: number;
        }[]): boolean;
        /**
         * A signal emitted when any model state changes.
         */
        readonly stateChanged: ISignal<IModel, IChangedArgs<any, any, 'count' | 'index' | 'list' | 'overscanCount' | 'windowingActive' | string>>;
        /**
         * Total number of widgets in the list
         */
        widgetCount: number;
        /**
         * Whether windowing is active or not.
         */
        windowingActive: boolean;
        /**
         * Widget factory for the list items.
         *
         * Caching the resulting widgets should be done by the callee.
         *
         * @param index List index
         * @returns The widget at the given position
         */
        widgetRenderer: (index: number) => Widget;
    }
    /**
     * Windowed list model constructor options
     */
    interface IModelOptions {
        /**
         * Total number of widgets in the list.
         *
         * #### Notes
         * If an observable list is provided this will be ignored.
         */
        count?: number;
        /**
         * Dynamic list of items
         */
        itemsList?: IObservableList<any>;
        /**
         * Number of widgets to render in addition to those
         * visible in the viewport.
         */
        overscanCount?: number;
        /**
         * Whether windowing is active or not.
         *
         * This is true by default.
         */
        windowingActive?: boolean;
    }
    /**
     * Windowed list view constructor options
     */
    interface IOptions<T extends WindowedList.IModel = WindowedList.IModel, U = any> {
        /**
         * Windowed list model to display
         */
        model: T;
        /**
         * Windowed list layout
         */
        layout?: WindowedLayout;
        /**
         * A renderer for the elements of the windowed list.
         */
        renderer?: IRenderer<U>;
        /**
         * Whether the windowed list should display a scrollbar UI.
         */
        scrollbar?: boolean;
    }
    /**
     * A windowed list element renderer.
     */
    interface IRenderer<T = any> {
        /**
         * Create the outer, root element of the windowed list.
         */
        createOuter(): HTMLElement;
        /**
         * Create the virtual scrollbar element.
         */
        createScrollbar(): HTMLElement;
        /**
         * Create the virtual scrollbar viewport indicator.
         */
        createScrollbarViewportIndicator?(): HTMLElement;
        /**
         * Create an individual item rendered in the scrollbar.
         */
        createScrollbarItem(list: WindowedList, index: number, item: T | undefined): HTMLElement | IRenderer.IScrollbarItem;
        /**
         * Create the viewport element into which virtualized children are added.
         */
        createViewport(): HTMLElement;
    }
    /**
     * Renderer statics.
     */
    namespace IRenderer {
        /**
         * Scrollbar item.
         */
        interface IScrollbarItem extends IDisposable {
            /**
             * Render the scrollbar item as an HTML element.
             */
            render: (props: {
                index: number;
            }) => HTMLElement;
            /**
             * Unique item key used for caching.
             */
            key: string;
        }
    }
    /**
     * Item list metadata
     */
    type ItemMetadata = {
        /**
         * Item vertical offset in the container
         */
        offset: number;
        /**
         * Item height
         */
        size: number;
        /**
         * Whether the size is an estimation or a measurement.
         */
        measured?: boolean;
    };
    /**
     * Basic type of scroll alignment
     */
    type BaseScrollToAlignment = 'center' | 'top-center' | 'start' | 'end';
    /**
     * Type of scroll alignment including `auto` and `smart`
     */
    type ScrollToAlign = 'auto' | 'smart' | BaseScrollToAlignment;
    /**
     * Widget range in view port
     */
    type WindowIndex = [number, number, number, number];
}