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3ae422a566
Introduces the necessary base interfaces for representing different focusable contexts within Blockly. The actual logic for utilizing and implementing these interfaces will come in later PRs.
54 lines
1.8 KiB
TypeScript
54 lines
1.8 KiB
TypeScript
/**
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* @license
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* Copyright 2025 Google LLC
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* SPDX-License-Identifier: Apache-2.0
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*/
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import type {IFocusableNode} from './i_focusable_node.js';
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/**
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* Represents a tree of focusable elements with its own active/passive focus
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* context.
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*
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* Note that focus is handled by FocusManager, and tree implementations can have
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* at most one IFocusableNode focused at one time. If the tree itself has focus,
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* then the tree's focused node is considered 'active' ('passive' if another
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* tree has focus).
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*
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* Focus is shared between one or more trees, where each tree can have exactly
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* one active or passive node (and only one active node can exist on the whole
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* page at any given time). The idea of passive focus is to provide context to
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* users on where their focus will be restored upon navigating back to a
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* previously focused tree.
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*/
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export interface IFocusableTree {
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/**
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* Returns the current node with focus in this tree, or null if none (or if
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* the root has focus).
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*
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* Note that this will never return a node from a nested sub-tree as that tree
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* should specifically be called in order to retrieve its focused node.
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*/
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getFocusedNode(): IFocusableNode | null;
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/**
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* Returns the top-level focusable node of the tree.
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*
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* It's expected that the returned node will be focused in cases where
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* FocusManager wants to focus a tree in a situation where it does not
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* currently have a focused node.
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*/
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getRootFocusableNode(): IFocusableNode;
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/**
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* Returns the IFocusableNode corresponding to the select element, or null if
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* the element does not have such a node.
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*
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* The provided element must have a non-null ID that conforms to the contract
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* mentioned in IFocusableNode.
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*/
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findFocusableNodeFor(
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element: HTMLElement | SVGElement,
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): IFocusableNode | null;
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}
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