Issue
Zoom doesn't work when I invoke drag at first. Dragging doesn't work when I call the zoom in the first place.
I am writing these codes with Ionic Framework 6 version (Angular).
const w = window.screen.width;
const h = window.screen.height;
const scl: any = Math.min(w, h) / 2.5;
const sensitivity = 75;
const projection: any = d3.geoOrthographic()
.scale(scl)
.translate([ w/2, h/2 ]);
const initialScale = projection.scale();
let path = d3.geoPath()
.projection(projection);
const svg: any = d3.select('#globe')
.append('svg')
.attr('width', w)
.attr('height', h);
const map = svg.append('g');
const drag: any = d3.drag()
.on('drag', (event) => {
const rotate = projection.rotate();
const k = sensitivity / projection.scale();
projection.rotate([
rotate[0] + event.dx * k,
rotate[1] - event.dy * k
]);
path = d3.geoPath().projection(projection);
svg.selectAll('path').attr('d', path);
});
svg.call(drag);
const zoom: any = d3.zoom()
.scaleExtent([1, 10])
.on('zoom', (event) => {
if (event.transform.k > 0.3) {
projection.scale(initialScale * event.transform.k);
path = d3.geoPath().projection(projection);
svg.selectAll('path').attr('d', path);
map.attr('r', projection.scale());
} else {
event.transform.k = 0.3;
}
});
svg.call(zoom).on('dblclick.zoom', null);
Thanks in advance.
I tried map.call()
instead of hammer.js and svg.call()
but I can't run both functions at the same time.
Solution
I solved the problem. In d3.js, I added a filter to the zoom and drag, and made them act according to the number of touches.
Filtering for zoom
const zoom: any = d3.zoom()
.filter((event) => event.touches && event.touches.length === 2)
Filtering for drag
const drag: any = d3.drag()
.filter((event) => !(event.touches && event.touches.length === 2))
Important: You must call zoom first, then drag.
Answered By - imdecoder
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