Hey everyone!
I’m pretty new to Flutter development and I’m stuck on something. I want to create a canvas-like interface where users can scroll in all directions - up, down, left, right, and even diagonally. Think about how you navigate around in design applications like Canva or Sketch where you can move around freely on an infinite canvas.
I’m not looking for complete code solutions right now, just need some direction on:
- What Flutter widgets would work best for this?
- Any specific approaches or patterns I should consider?
- Are there any gotchas I should watch out for?
Basically I want to place various UI elements on this scrollable area and let users pan around to view different parts. I haven’t started coding yet because I want to make sure I’m heading in the right direction from the beginning.
Thanks for any help!
Here’s another approach: use CustomScrollView with two nested scroll controllers - one for horizontal, one for vertical. I built a map-like interface this way and it worked great. The trick is setting up scroll physics so both controllers work together without fighting each other. Watch out for the scroll listeners though - handle them wrong and you’ll get jittery diagonal scrolling. Compared to InteractiveViewer, you get way more control over scroll boundaries and custom behaviors. The downside? Managing state gets messy since you’re tracking two scroll positions. If you need double-tap zoom or right-click menus, you’ll want custom gesture detection too. And yeah, that coordinate transformation math someone mentioned earlier - definitely plan for it from the start.
Go with InteractiveViewer first - it’s way simpler than building custom scroll stuff. I tried the dual scrollview approach and had to refactor everything after a week. InteractiveViewer handles gestures automatically and transformations are built-in. Only real downside is memory management when your canvas gets massive.
I built something like this for a floor plan editor last year - ran into tons of issues. InteractiveViewer was a lifesaver though. It handles multi-directional scrolling right out of the box, so you just wrap your canvas content and users can pan everywhere naturally. Biggest problem I hit was performance with lots of canvas elements. Flutter tries rendering everything, even off-screen stuff, which destroys your frame rate fast. I fixed it by only rendering widgets actually visible in the current view area - basic viewport culling. Start thinking about coordinate systems early. You’ll constantly convert between screen coordinates and canvas coordinates, especially for selecting elements or handling taps. InteractiveViewer gives you transformation matrices for this, but there’s a learning curve. The math gets messy once you add zoom levels and panning offsets.