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D3 Triggering drag during mousedown

Is there a way to click anywhere in an svg and have an element snap to that location and simultaneously begin dragging?

The closest I've gotten is in the code below. Dragging the circle works and clicking elsewhere will make the circle move to that location, but I can't figure out how to start the drag without releasing the mouse and directly clicking the circle.

More generally, how can I start the drag behavior without directly interacting with the element being dragged?

http://jsfiddle.net/Hj44M/1/

var width = 200,
    height = 200,
    radius = 10;

var drag = d3.behavior.drag()
    .origin(function(d) { return d; })
    .on("dragstart", function(){
        d3.event.sourceEvent.stopPropagation()
    })
    .on("drag", dragmove);

var svg = d3.select("body")
    .data([{x: 100, y : 100}])
    .append('svg')
    .attr("height", 200)
    .attr("widht", 200)
    .on("mousedown", function(){
        circle.each(dragmove)
    });


var circle = svg.append("circle")
    .attr("r", radius)
    .attr("cx", function(d) { return d.x; })
    .attr("cy", function(d) { return d.y; })
    .call(drag);

function dragmove(d) {
    d3.select(this)
    .attr("cx", d.x = Math.max(radius, Math.min(width - radius, d3.event.x)))
    .attr("cy", d.y = Math.max(radius, Math.min(height - radius, d3.event.y)));
}
like image 539
procterw Avatar asked Jan 30 '26 03:01

procterw


1 Answers

UPDATE

I've solved this issue with a sort of brute-force solution: I removed the drag behavior and just added mousedown, mousemove, and mouseup handlers to the svg canvas. This is the functionality I want but I'd still prefer to use d3's drag behavior. If anyone has a more elegant solution do let me know.

http://jsfiddle.net/Hj44M/5/

    var width = 200,
    height = 200,
    radius = 10;

var isDown = false;

var svg = d3.select("body")
    .data([{x: 100, y : 100}])
    .append('svg')
    .attr("height", 200)
    .attr("width", 200)
    .on("mousedown", function(){
        isDown = true;  
        var coordinates = d3.mouse(this);
        circle.each(function(d){
            circle.attr("cx", d.x = coordinates[0])
            circle.attr("cy", d.y = coordinates[1])
        })

    })
    .on("mousemove", function(){
        if(isDown) {
            var coordinates = d3.mouse(this);
            circle.each(function(d){
                circle.attr("cx", d.x = coordinates[0])
                circle.attr("cy", d.y = coordinates[1])
            })
        }
     })
    .on("mouseup", function(){
        isDown = false;
    });     

var circle = svg.append("circle")
    .attr("r", radius)
    .attr("cx", function(d) { return d.x; })
    .attr("cy", function(d) { return d.y; });
like image 73
procterw Avatar answered Feb 01 '26 18:02

procterw



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