Android gestures

[devemux86]

• Scroll (pan)
• Scale
• Scale with focus
• Quick scale (double tap + swipe)
• Fling (kinetic scroll)
• Double tap (zoom with focus)
• Tap (overlay)
• Long press (overlay)

[schildbach]

Here are some takeaways from my PR #687:

• We should remove animations from MapViewPosition entirely. UI animations are very specific to the platform in use. They have their specific look and feel and usually there are already classes to support them. Also threading is handled differently: e.g. on Android you'd prefer to use a Handler rather than spawning a thread.
• The remaining jaggies are due to the fact MapViewPosition keeps a byte zoomLevel and a float scaleFactor separately. That makes it difficult to get simultaneous zooming and panning right. We should think about getting rid of the zoomLevel and only use one single float scaleFactor (maybe rename it to zoomFactor). Of course we can still keep the old methods that deal with the byte values for backwards compatibility.

[devemux86]

1. Not a bad idea, though we'll need to transfer functionality to android / awt modules.
2. Moving from byte to float, meaning like steplessly variable zoom levels Allow for steplessly variable zoom level #75 ?

[devemux86]

With 94623e5 I pushed a set of additions / improvements / fixes with the Mapsforge gestures overhaul.

• New gestures: fling, quick scale
• Improved 'scale with focus'
• Fixed 'double tap'

Any artifacts were mostly eliminated with proper handling of scroll and scale gestures interaction.

[devemux86]

Thilo had expressed some thoughts some years ago, regarding the panning threshold we had active until recently.

How do you find the new Mapsforge gesture handling, do we need a panning threshold?

[schildbach]

I believe the stock GestureDetector handles this all for us already, including quirks for old devices with a bad screen digitizer.

All my test devices certainly do not need an (additional) panning threshold.

[devemux86]

@schildbach thanks for the feedback.

Those were indeed old Android days, just wanting to make sure that now we implemented all the right way.