Mind Data

Simple mind mapping application for Android. Create, visualize, and edit interactive force-directed graphs with labeled nodes and edges.

Features

• Force-directed graph layout — nodes repel each other, edges act as springs, central gravity pulls the graph together with friction damping
• Multi-touch gestures — tap to select, drag to pan, pinch to zoom
• Node CRUD — add nodes (with auto-generated random labels), edit labels inline, delete nodes with cascading edge deletion
• Edge creation — toggle connect mode, tap source then target to create edges; tapping an existing pair removes the edge
• 5 edge visual styles — plain, green V, red V, green X, red X (cycled via the arrow button)
• Edge direction — long-press the arrow button to flip connection direction
• Node highlighting — toggle highlight color on selected nodes
• Persistence — each mind map stored in its own SQLite database; node and edge data serialized as BLOBs
• Mind map index — list of saved maps with create, rename, and delete operations
• Haptic feedback — vibration on long-press actions
• Custom fonts — 7 bundled TTF fonts (charm, diablo, primitive, Roboto, under, yuma)

Build

./gradlew assembleDebug

Technical

Package	com.angel.mind
Min SDK	10 (Android 2.3.3 Gingerbread)
Target SDK	10
Compile SDK	18 (Jelly Bean 4.3)
Build tools	29.0.3
Dependencies	None — pure Android SDK

The graph engine runs a physics simulation loop at ~30 FPS via Handler. Nodes are rendered as rounded rectangles with text. Edges are drawn with configurable arrowhead styles using a strategy pattern (EdgePainter subclasses). Multi-touch is handled custom (no gesture detector library) with GC-efficient Matrix pooling.

Architecture

• IndexActivity — launcher listing saved mind maps from an SQLite index
• MindDataActivity — main graph editor with a bottom toolbar
• GraphView — custom View managing rendering, physics, gestures, and graph commands
• GraphDatabase — per-graph SQLite persistence layer
• Node / Edge — data models for graph elements
• EdgePainter + Plain, GreenV, RedV, GreenX, RedX — strategy pattern for edge rendering
• FastRepulsor / NormalRepulsor — node repulsion physics
• EdgeRelaxer / VisibleEdgeRelaxer / CenterEdgeRelaxer — edge spring physics

License

This is an open source project. See the source files for license information.