CenterOnAndZoomTo Not Working Unless Delayed about mapsui

[pauldendulk]

Thanks a lot for the sample project! This makes things so much easier, and I learn from seeing your code. I like the image layer you use.

In Mapsui changing the viewport depends on the size of the canvas and the extent of the data and this is not known during startup. This is why the Map.Home method was added. This method is called ones those are known. I could fix your problem by writing it like this:

var layer = await CreateLayerAsync(default);
mapControl.Map?.Layers.Add(layer);

double x = -9188151.36056;
double y = 3235144.74039;
var point = new MPoint(x, y);
mapControl.Map.Home = (n) => n.CenterOnAndZoomTo(point, resolution: 1000, 500, Mapsui.Animations.Easing.CubicOut);

MyMapControl = mapControl;
Content = mapControl;

It now starts like this:

Notes:

• I tested on Windows, not on Mac or iOS, but I assume the fix also works there.
• Perhaps we should add this to the FAQ.
• I expect the Mapsui logger to log a warning when CenterOnAndZoom is called too early. I did not see that warning.
• You do not always need to the canvas size, and in this particular case (where resolution and center are set). I think you don't need it. Perhaps we can improve this.

[pauldendulk]

I looked into the last two bullets.

We do not log a warning when the navigator is called while width and height is zero. I think we should add this. It looks like the Navigator.SetViewport method is a good place for this.

Calling CenterOnAndZoom before width and height are set actually works, the viewport is correctly initialized. However, after that, the default Home method does a ZoomToPanBounds() and overrides the earlier CenterOnAndZoom. The initial CenterOnAndZoom actually works if mapControl.Map.Home = (n) => { }; is called before (did this just to test the logic). Anyway, this was just to understand what is happening. Lets leave this like it is. When we add the logger users will understand what is going on.

[nm4568]

Thank you so much for the quick response on this. This makes perfect sense. I updated the code per your example and is working as expected. Just a thought but perhaps the usage of the 'InvalidOperationException' in scenarios like this might be appropriate as well.

[pauldendulk]

Thanks for the suggestion, that might be the best option. I will close this as answered.