AmCharts AmMap - Set starting location for zoom actions - amcharts

Question

I would like to use the "zoomToMapObject" method based on a selection on a dropdown menu.
For some reason the start zoom location is the middle of the map and not the set the geoPoint.
(The zooming works but the start location make it look a bit weird.)
My current approach looks like this:
const duration = this.chart.zoomToMapObject(selectedPoloygon, this.countryZoom, true).duration;
setTimeout(() => {
this.chart.homeGeoPoint = geoPoint;
this.chart.homeZoomLevel = this.countryZoom;
}, duration);
this.handleCountrySelection(selectedPoloygon);
Somehow even setting the homeGeoPoint / homeZoomLevel doesn't affect next zoom actions.
**UPDATE: Workaround heavy cost (from 1300 nodes to over 9000) **
I examined the problem a step further. It seems the middle point gets set when I push a new mapImageSeries into the map.
My workarround currently is to draw all points on the map and hide them.
Then after I select a country I change the state to visible.
However this approach is very costly. The DOM-Nodes rises from 1300 to ~ 9100.
My other approach with creating them after a country has been selected AND the zoom animation finished was much more
effective. But due to the map starting every time for a center location it is not viable? Or did I do s.th. wrong?
Here is my current code which is not performant:
// map.ts
export class MapComponent implements AfterViewInit, OnDestroy {
imageSeriesMap = {};
// ... standard map initialization ( not in zone of course )
// creating the "MapImages" which is very costly
this.dataService.getCountries().forEach(country => {
const imageSeriesKey = country.id;
const imageSeriesVal = chart.series.push(new am4maps.MapImageSeries()); // takes arround 1-2 ms -> 300 x 2 ~ 500 ms.
const addressForCountry = this.dataService.filterAddressToCountry(country.id); // returns "DE" or "FR" for example.
const imageSeriesTemplate = imageSeriesVal.mapImages.template;
const circle = imageSeriesTemplate.createChild(am4core.Circle);
circle.radius = 4;
circle.fill = am4core.color(this.colorRed);
circle.stroke = am4core.color('#FFFFFF');
circle.strokeWidth = 2;
circle.nonScaling = true;
circle.tooltipText = '{title}';
imageSeriesTemplate.propertyFields.latitude = 'latitude';
imageSeriesTemplate.propertyFields.longitude = 'longitude';
imageSeriesVal.data = addressForCountry.map(address => {
return {
latitude: Number.parseFloat(address.lat),
longitude: Number.parseFloat(address.long),
title: address.company
};
});
imageSeriesVal.visible = false;
this.imageSeriesMap[imageSeriesKey] = imageSeriesVal;
});
// clicking on the map
onSelect(country) {
this.imageSeriesMap[country].visible = true;
setTimeout( () => {
const chartPolygons = <any>this.chart.series.values[0];
const polygon = chartPolygons.getPolygonById(country);
const anim = this.chart.zoomToMapObject(polygon, 1, true, 1000);
anim.events.on('animationended', () => {});
this.handleCountrySelection(polygon);
}, 100);
});
}
handleCountrySelection(polygon: am4maps.MapPolygon) {
if (this.selectedPolygon && this.selectedPolygon !== polygon) {
this.selectedPolygon.isActive = false;
}
polygon.isActive = true;
const geoPoint: IGeoPoint = {
latitude: polygon.latitude,
longitude: polygon.longitude
};
this.chart.homeGeoPoint = geoPoint;
this.chart.homeZoomLevel = this.countryZoom;
this.selectedPolygon = polygon;
}
}

Answer 1

Thanks to your thorough followup I was able to replicate the issue. The problem you were having is triggered by any one of these steps:
dynamically pushing a MapImageSeries to the chart
dynamically creating a MapImage via data (also please note in the pastebind you provided, data expects an array, I had to change that while testing)
In either step, the chart will fully zoom out as if resetting itself. I'm going to look into why this is happening and if it can be changed, so in the meantime let's see if the workaround below will work for you.
If we only use a single MapImageSeries set in advance (I don't particularly see a reason to have multiple MapImageSeries, would one not do?), that eliminates problem 1 from occurring. Asides from data, we can create() MapImages manually via mapImageSeries.mapImages.create(); then assign their latitude and longitude properties manually, too. With that, problem 2 does not occur either, and we seem to be good.
Here's a demo with a modified version of the pastebin:
https://codepen.io/team/amcharts/pen/c460241b0efe9c8f6ab1746f44d666af
The changes are that the MapImageSeries code is taken out of the createMarkers function so it only happens once:
const mapImageSeries = chart.series.push(new am4maps.MapImageSeries());
const imageSeriesTemplate = mapImageSeries.mapImages.template;
const circle = imageSeriesTemplate.createChild(am4core.Circle);
circle.radius = 10;
circle.fill = am4core.color('#ff0000');
circle.stroke = am4core.color('#FFFFFF');
circle.strokeWidth = 2;
circle.nonScaling = true;
circle.tooltipText = 'hi';
In this case, there's no need to pass chart to createMarkers and return it, so I've passed polygon instead just to demo dynamic latitude/longitudes, I also assign our new MapImage to the polygon's data (dataItem.dataContext) so we can refer to it later. Here's the new body of createMarkers:
function createMarkers(polygon) {
console.log('calling createMarkers');
if ( !polygon.dataItem.dataContext.redDot) {
const dataItem = polygon.dataItem;
// Object notation for making a MapImage
const redDot = mapImageSeries.mapImages.create();
// Note the lat/long are direct properties
redDot.id = `reddot-${dataItem.dataContext.id}`;
// attempt to make a marker in the middle of the country (note how this is inaccurate for US since we're getting the center for a rectangle, but it's not a rectangle)
redDot.latitude = dataItem.north - (dataItem.north - dataItem.south)/2;
redDot.longitude = dataItem.west - (dataItem.west - dataItem.east)/2;;
dataItem.dataContext.redDot = redDot;
}
}
There's no need for the animationended event or anything, it just works since there is no longer anything interfering with your code. You should also have your performance back.
Will this work for you?
Original answer prior to question's edits below:
I am unable to replicate the behavior you mentioned. Also, I don't know what this.countryZoom is.
Just using the following in a button handler...
chart.zoomToMapObject(polygon);
...seems to zoom just fine to the country, regardless of the current map position/zoomLevel.
If you need to time something after the zoom animation has ended, the zoomToMapObject returns an Animation, you can use its 'animationended' event, e.g.
const animation = this.chart.zoomToMapObject(selectedPoloygon, this.countryZoom, true);
animation.events.on("animationended", () => {
// ...
});
Here's an example with all that with 2 external <button>s, one for zooming to USA and the other Brazil:
https://codepen.io/team/amcharts/pen/c1d1151803799c3d8f51afed0c6eb61d
Does this help? If not, could you possibly provide a minimal example so we can replicate the issue you're having?