How to Build a High‑Performance, Multi‑Touch Canvas Drawing Board from Scratch

This article walks through creating a fully customizable, high‑performance HTML5 canvas drawing board for online teaching, covering devicePixelRatio handling, responsive layout, touch and mouse event processing, drawing pipelines, multi‑touch support, erasing modes, caching strategies, undo/redo, and brush extensions, all with complete React code examples.

CanvasUndo Redodrawing

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How to Build a High‑Performance, Multi‑Touch Canvas Drawing Board from Scratch

Sohu Tech Products

Apr 7, 2021 · Frontend Development

Understanding Notion’s Block‑Based Editor Architecture and Operations

The article explains how Notion implements a block‑tree data model and a controlled contenteditable editor using React, detailing the data layer, operation (op) system, rendering components, selection handling, text styling, and copy‑paste mechanisms, all backed by transactional undo/redo logic.

Block ModelNotionReact

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Understanding Notion’s Block‑Based Editor Architecture and Operations

Programmer DD

Sep 13, 2020 · Mobile Development

How iOS Implements Undo/Redo with Command & Observer Patterns

This article explains how iOS keyboards achieve undo and redo functionality by combining the Command and Observer design patterns, illustrates their class structures, and shows how the NSUndoManager leverages these patterns to manage undo and redo stacks in Cocoa Touch applications.

Command PatternDesign PatternsMobile Development

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How iOS Implements Undo/Redo with Command & Observer Patterns