dia.Paper: add viewManagement option

[kumilingus]

• feat(dia.Paper) - add a new viewManagement option to dia.Paper that enables advanced view lifecycle management with lazy initialization and optional disposal of hidden views. The primary purpose is to improve performance in scenarios with large numbers of cells by deferring view creation and potentially disposing views that are not visible.

  • Implementation of a placeholder system for lazy view initialization
  • Introduction of the viewManagement option with lazyInitialize and disposeHidden sub-options

• feat(dia.Paper) - add cellVisibility() callback option to support lazy view initialization

  • Replace the viewport callback with cellVisibility callback

• feat(dia.HighlighterView) - add static has() method to check if a cell view has a highlighter attached

• feat(mvc.View) - custom cid can be provided via constructor

• demo - update async demo with the viewManagement option

[Copilot]

Pull Request Overview

This PR adds a new viewManagement option to dia.Paper that enables advanced view lifecycle management with lazy initialization and optional disposal of hidden views. The primary purpose is to improve performance in scenarios with large numbers of cells by deferring view creation and potentially disposing views that are not visible.

Key changes include:

• Introduction of the viewManagement option with lazyInitialize and disposeHidden sub-options
• Replacement of the viewport callback with a new cellVisibility callback for better consistency
• Implementation of a placeholder system for lazy view initialization
• Addition of view disposal logic when views become hidden

Reviewed Changes

Copilot reviewed 12 out of 13 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
packages/joint-core/src/dia/Paper.mjs	Core implementation of view management features including placeholders, lazy initialization, and view disposal logic
packages/joint-core/src/dia/LinkView.mjs	Refactored to use lazy-loaded source/target views with caching and improved property getters
packages/joint-core/src/mvc/ViewBase.mjs	Added support for custom cid in constructor options
packages/joint-core/src/mvc/View.mjs	Deprecated view flags that moved to Paper
packages/joint-core/src/dia/HighlighterView.mjs	Added has() method to check for highlighter existence
packages/joint-core/src/dia/CellView.mjs	Added cell view marker for type identification
packages/joint-core/src/alg/Deque.mjs	New double-ended queue implementation for efficient view list management
packages/joint-core/test/jointjs/dia/Paper.js	Comprehensive tests for the new view management functionality
packages/joint-core/test/jointjs/mvc.viewBase.js	Tests for custom cid functionality
packages/joint-core/test/jointjs/dia/HighlighterView.js	Tests for the new has() method
packages/joint-core/demo/performance/async.js	Updated demo to use new cellVisibility option
packages/joint-core/demo/performance/async.html	UI improvements for the performance demo

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