Ch. 17 ↩️ Undo, Redo & History

What you'll learn: How DRAW's unified history system works, why text-local undo is separate, and why you can experiment fearlessly.

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History System — Fearless Experimentation

🎯 Goal: Understand the unified undo/redo system.

DRAW has one timeline for everything you do — drawing, transforms, layer ops, palette ops, even the import overlay. Press Ctrl+Z to step backward and Ctrl+Y to step forward.

How history is recorded

History records on mouse release, automatically. There is no manual save-state command, and there is a guard against double-recording on the same frame. Each entry carries a human-readable label — "Brush stroke on Layer 3", "Move 12px on selected layers", "Apply Transform", for a future history panel and comments in QB64PE Project Export.

Multi-layer awareness

When an operation affects multiple layers (a multi-layer select-and-flip, a Smart Erase across visible layers, a group merge, etc.), DRAW records a single composite history step. Smart Erase additionally tracks per-layer erasure so undo / redo behaves intuitively per layer.

Text-local undo

The text tool has its own 128-state local history while you are editing a text layer. Ctrl+Z and Ctrl+Y operate on that local history during text entry — typo experiments don't pollute the global timeline. As soon as you commit (Esc), the entire edit becomes a single global history entry.

Try things

The single biggest productivity unlock in DRAW is: try things. Symmetry, palette ops, blend modes, custom-brush fills, and transform overlays are all undoable. There is no "save first" anxiety — Ctrl+Z always works.

💡 Tip: When you make a destructive-looking change (palette ops, image adjustments), don't try to remember the parameters. Just Ctrl+Z and Ctrl+Y to flip-flop and visually compare.

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➡️ Next: Chapter 18 — Real-World Pixel Art Workflows