Android components for displaying a graph (nodes and edges, in 2D)?

Question

I'm at the starting point of developing an android app similar to a "mindmap" program (like Thinking Space). It shows some graph nodes (containing text, maybe images) and edges that connecting them. I can take care of graph algorithms, but I have two uncertain points about Android components for displaying these things:

1. The expanded graph will be pretty big, so the user need to be able to scroll both vertically and horizontally. I looked at ScrollView and HorizontalScrollView but they can't scroll both vertically and horizontally. So I hope to know which top level container I should use.

2. I also want the graph to be zoomable with pinch gestures, so that the user can zoom in to a small part of the graph. But I also want the graph nodes to be interactive, so the user can tap on them, typing text into them and move them with fingers. Should I implement each node as a separate View object? If so, how do I make all the nodes zoom together?

Thanks.

Answer 1

I would definitely rely on custom views for this kind of things, they will give you much more freedom and efficiency than using standard layouts.

Implementing a scrollable view is quite easy, and implementing the pinch gesture will be much easier if you're supporting API >= 8 (see ScaleGestureDetector). Making graph elements interactive and editable would be another thing, though.

Something really much better could be creating a custom layout, that would host editable graph elements (custom views) and draw their relations. It would be much more elegant, clean, expandable, maintainable and reusable, but it would need a lot more designing. Yet I'm sure it would be greatly rewarded.

(This would be quite an ambitious project for me, so... good luck!)