CODEWITHSUNDEEP
javascriptd3.jsdrag-and-drop
altunyurt
altunyurt

Reputation: 2936

D3js: Dragging a group by using one of it's children

Jsfiddle: http://jsfiddle.net/6NBy2/

Code:

var in_editor_drag = d3.behavior.drag()
             .origin(function() {
                var g = this.parentNode;
                return {x: d3.transform(g.getAttribute("transform")).translate[0],
                        y: d3.transform(g.getAttribute("transform")).translate[1]};
            })
            .on("drag", function(d,i) {

                g = this.parentNode;
                translate = d3.transform(g.getAttribute("transform")).translate;
                x = d3.event.dx + translate[0],
                y = d3.event.dy + translate[1];
                d3.select(g).attr("transform", "translate(" + x + "," + y + ")");
                d3.event.sourceEvent.stopPropagation();
            });

svg = d3.select("svg");
d = {x: 20, y: 20 };
groups = svg
        .append("g")
        .attr("transform", "translate(20, 20)");

groups
    .append("rect")
        .attr("x", 0)
        .attr("y", 0)
        .attr("width", 100)
        .attr("height", 100)
        .style("fill", "green")
        .call(in_editor_drag)
        .style("opacity", 0.4);

I'm trying to drag a group by using one of it's children as a handle. Simply, what i'm trying to do is, when a groups child is dragged:

When child dragged, group does not move as expected. It moves less than the dragged distance, and it begins to jump here and there.

What am I doing wrong here?

Edit:

Updated jsfiddle: http://jsfiddle.net/6NBy2/2/

I'm trying to drag the whole group by using one or more of it's children as dragging handles.

Upvotes: 6

Views: 3328

Answers (3)

roland
roland

Reputation: 900

This is an old question, but not really answered. I had exactly the same problem and wanted to drag the group by only one child (not all child elements of the <g>). The problem is, that the d3.event.dx/y is calculated relatively to the position of the <g>. And as soon as the <g> is moved by .attr(“transform”, “translate(x, y)”), the d3.event.dx/dy is adjusted to the new (smaller) value. This results in a jerky movement with approx. the half of the speed of the cursor. I found two possible solutions for this:

First (finally I ended up with this approach):

Append the drag handle rect directly to the svg and not to the <g>. So it is positioned relatively to the <svg> and not to the <g>. Then move both (the <rect> and the <g>) within the on drag function.

var svg = d3.select("svg");
var group = svg
    .append("g").attr("id", "group")
    .attr("transform", "translate(0, 0)");
group
    .append("rect")
    .attr("x", 0)
    .attr("y", 0)
    .attr("width", 100)
    .attr("height", 100)
    .style("fill", "green")
    .style("opacity", 0.4);
group
    .append("text")
    .attr("x", 10)
    .attr("y", 5)
    .attr("dominant-baseline", "hanging")
    .text("drag me");
handle = svg
    .append("rect")
        .data([{
        // Position of the rectangle
        x: 0,
        y: 0
    }]) 
    .attr("class", "draghandle")
    .attr("x", 0)
    .attr("y", 0)
    .attr("width", 100)
    .attr("height", 20)
    .style("fill", "blue")
    .style("opacity", 0.4)
    .attr("cursor", "move")
    .call(d3.drag().on("drag", function (d) {
            console.log("yep");
            d.x += d3.event.dx;
            d.y += d3.event.dy;
            
            // Move handle rect
            d3.select(this)
                .attr("x", function (d) {
                    return d.x;
                })
                .attr("y", function (d) {
                    return d.y;
                });
            
            // Move Group
            d3.select("#group").attr("transform", "translate(" + [d.x, d.y] + ")");
    }));
<body>
    <svg width="400" height="400"></svg>
    <script src="https://d3js.org/d3.v4.min.js"></script>
</body>

Second:

Check on which element the cursor was during the drag event with d3.event.sourceEvent.path[0] and run the drag function only if the handle <rect> was clicked. With this approach, all elements can be grouped within one <g> (no need for an additional <rect> outside the group). The downside of this method is, that the drag is also executed, if the cursor is moved over the drag handle with mouse down.

var svg = d3.select("svg");
var group = svg
    .append("g")
    .data([{
        // Position of the rectangle
        x: 0,
        y: 0
    }])
    .attr("id", "group")
    .attr("transform", function (d) {
            return "translate(" + d.x + ", " + d.y + ")"
    })
    .call(d3.drag().on("drag", function (d) {
        if (d3.event.sourceEvent.target.classList.value === "draghandle") {
            console.log("yep");
            d.x += d3.event.dx;
            d.y += d3.event.dy;
            d3.select(this).attr("transform", function (d) {
                return "translate(" + [d.x, d.y] + ")"
            })
        } else {
            console.log("nope");
            return;
        }
    }));
group
    .append("rect")
    .attr("x", 0)
    .attr("y", 0)
    .attr("width", 100)
    .attr("height", 100)
    .style("fill", "green")
    .style("opacity", 0.4);
group
    .append("text")
    .attr("x", 10)
    .attr("y", 5)
    .attr("dominant-baseline", "hanging")
    .text("drag me");
handle = group
    .append("rect")
    .attr("class", "draghandle")
    .attr("x", 0)
    .attr("y", 0)
    .attr("width", 100)
    .attr("height", 20)
    .style("fill", "blue")
    .style("opacity", 0.4)
    .attr("cursor", "move");
<body>
    <svg width="400" height="400"></svg>
    <script src="https://d3js.org/d3.v4.min.js"></script>
</body>

Upvotes: 6

wuxin
wuxin

Reputation: 11

Use drag.container() to set the container accessor.

See the D3 docs.

Upvotes: 1

FernOfTheAndes
FernOfTheAndes

Reputation: 5015

use g = this; instead of g = this.parentNode;

Upvotes: 0

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