[ios] Fix toCamera.centerCoordinate in shouldChangeFromCamera

[fabian-guerra]

Fixes #10391

[1ec5]

This change only works when the zoom gesture is centered over the map view. It doesn’t work when attempting to zoom with an uncentered anchor.

The good news is that we no longer need to implement a change-and-revert dance or write manual conversion math here, because mbgl::Map::latLngBoundsForCamera() can give us the answer more directly as of #8510.

[1ec5]

This change conflates the anchor point of a zoom with the map view’s center coordinate: #10391 (comment).

[1ec5]

The good news is that we no longer need to implement a change-and-revert dance or write manual conversion math here, because mbgl::Map::latLngBoundsForCamera() can give us the answer more directly as of #8510.

To expand on this, the anchor when zooming apparently affects the CameraOptions’ padding:

mapbox-gl-native/src/mbgl/map/transform.cpp

Lines 345 to 347 in 91dabd0

	if (anchor) {
	camera.padding = EdgeInsets(anchor->y, anchor->x, state.size.height - anchor->y, state.size.width - anchor->x);
	}

So if we set a similar padding on the CameraOptions we pass into mbgl::Map::latLngBoundsForCamera(), then feed the resulting LatLngBounds into -[MGLMapView cameraThatFitsCoordinateBounds:edgePadding:], that should get us the camera we’re looking for. It won’t necessarily be accurate on a tilted map, but I don’t think our existing conversions are accurate in that case, either.

[1ec5]

Also, please make corresponding changes to the macOS implementation of MGLMapView, if applicable. Thanks!

[fabian-guerra]

@1ec5 looks like we didn't implement the camera projection on mac I will port cameraByZoomingToZoomLevel, cameraByRotatingToDirection, cameraByTiltingToPitch, cameraByPanningWithTranslation

[1ec5]

Return this expression directly instead of creating a local variable for it.

[1ec5]

Use the fully qualified syntax so that jazzy will autolink these references in the front page of the API reference:

Fixed an issue where the same value was passed in as the oldCamera and newCamera parameters to the -[MGLMapViewDelegate mapView:shouldChangeFromCamera:toCamera:] method.

[1ec5]

looks like we didn't implement the camera projection on mac I will port cameraByZoomingToZoomLevel, cameraByRotatingToDirection, cameraByTiltingToPitch, cameraByPanningWithTranslation

It may not be strictly necessary to implement any of these methods on macOS: since AppKit handles drift panning for us, we can do the set-and-revert dance without any real consequences. But keeping the implementations as similar as possible could make it easier to factor out the camera implementation into a platform-agnostic class in the future, so perhaps we can implement that functionality as tail work.