feat(phase-8): implement comprehensive selection system with marching ants
This commit completes Phase 8 of the paint-ui implementation, adding a full
selection system with multiple selection tools, operations, and visual feedback.
**New Files:**
- types/selection.ts: Selection types, masks, and state interfaces
- lib/selection-utils.ts: Selection mask generation and manipulation algorithms
- lib/selection-operations.ts: Copy/cut/paste/delete/fill/stroke operations
- store/selection-store.ts: Selection state management with Zustand
- core/commands/selection-command.ts: Undo/redo commands for selections
- tools/rectangular-selection-tool.ts: Rectangular marquee selection
- tools/elliptical-selection-tool.ts: Elliptical marquee selection
- tools/lasso-selection-tool.ts: Free-form polygon selection
- tools/magic-wand-tool.ts: Color-based flood-fill selection
- components/selection/selection-panel.tsx: Complete selection UI panel
- components/selection/index.ts: Selection components barrel export
**Updated Files:**
- components/canvas/canvas-with-tools.tsx: Added selection tools integration and marching ants animation
- components/editor/editor-layout.tsx: Integrated SelectionPanel into layout
- store/index.ts: Added selection-store export
- store/canvas-store.ts: Renamed Selection to CanvasSelection to avoid conflicts
- tools/index.ts: Added selection tool exports
- types/index.ts: Added selection types export
- types/canvas.ts: Renamed Selection interface to CanvasSelection
**Selection Tools:**
**Marquee Tools:**
- ✨ Rectangular Selection: Click-drag rectangular regions
- ✨ Elliptical Selection: Click-drag elliptical regions
**Free-form Tools:**
- ✨ Lasso Selection: Draw free-form polygon selections
- ✨ Magic Wand: Color-based flood-fill selection with tolerance
**Selection Modes:**
- 🔷 New: Replace existing selection
- ➕ Add: Add to existing selection
- ➖ Subtract: Remove from existing selection
- ⚡ Intersect: Keep only overlapping areas
**Selection Operations:**
- 📋 Copy/Cut/Paste: Standard clipboard operations with selection mask
- 🗑️ Delete: Remove selected pixels
- 🎨 Fill Selection: Fill with current color
- 🖌️ Stroke Selection: Outline selection with current color
- 🔄 Invert Selection: Invert selected/unselected pixels
- ❌ Clear Selection: Deselect all
**Technical Features:**
- Marching ants animation (animated dashed outline at 50ms interval)
- Selection masks using Uint8Array (0-255 values for anti-aliasing)
- Feathering support (0-250px gaussian blur on selection edges)
- Tolerance control for magic wand (0-255 color difference threshold)
- Scanline polygon fill algorithm for lasso tool
- Flood-fill with Set-based visited tracking for magic wand
- Selection bounds calculation for optimized operations
- Keyboard shortcuts (Ctrl+C, Ctrl+X, Ctrl+V, Ctrl+D, Ctrl+Shift+I)
- Undo/redo integration via selection commands
- Non-destructive operations with proper history tracking
**Algorithm Implementations:**
- Rectangular mask: Simple bounds-based pixel marking
- Elliptical mask: Distance formula from ellipse center
- Lasso mask: Scanline polygon fill with edge intersection
- Magic wand: BFS flood-fill with color tolerance matching
- Mask combination: Per-pixel operations (max, subtract, AND)
- Feathering: Separable box blur (horizontal + vertical passes)
- Mask inversion: Per-pixel NOT operation with bounds recalculation
**UI/UX Features:**
- 264px wide selection panel with all tools and operations
- Tool selection with visual feedback (highlighted active tool)
- Selection mode toggles (new/add/subtract/intersect)
- Feather and tolerance sliders with live value display
- Disabled state when no selection exists
- Keyboard shortcut hints next to operations
- Visual marching ants animation (animated dashes)
Build verified: ✓ Compiled successfully in 1302ms
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
Sebastian Krüger
7f1e69559f