Fractional Zoom using WinForms version

[TAlecksen]

It appears the fractional zoom capability is not working as stated in the code itself. I have attempted to resolve this for a few days now with no luck. Although it works fine when zooming from a 'centered' location, once the map is panned a little and then I attempt to zoom in (with fractional zoom on) the map appears to be off center until the zoom level reaches a whole number again, at which point it gets centered to the correct location.

Does anyone have any insight on how to resolve this? I suspect the fix is in the DrawGraphics method, but I still have a long way to go to understand how the Core.renderOffset is utilized in order to resolve the problem itself.

[radioman]

..yes its a tricky business, offset and scaling matrix is at play

[TAlecksen]

Fantastic control by the way!

Based on what I can see, it looks like the panning is handled by the TranslateTransform. The scaling is handled by the two lines in FromLatLngToLocal:

ret.X = (int)(Core.renderOffset.X + ((Core.renderOffset.X - ret.X) * -MapRenderTransform.Value));
ret.Y = (int)(Core.renderOffset.Y + ((Core.renderOffset.Y - ret.Y) * -MapRenderTransform.Value));

The thing I have not yet figured out is why the Core.renderOffset gets updated correctly when zooming in whole number, but not when the zooming is fractional. Anyone get anywhere with this?

[radioman]

check https://github.com/radioman/greatmaps/blob/master/GMap.NET.Core/GMap.NET.Internals/Core.cs#L670

compensationOffset is equal positionPixel on zoom

[AliFlux]

@TAlecksen, please do share your work if you come across any solution. I've the same issue, and trying to use ScaleTransform but it's tricky and only limited to WPF.

[TAlecksen]

@AliFlux I most certainly will if I manage to get anywhere.