D3js:使用其中一个子级拖动组 [英] D3js: Dragging a group by using one of it's children

问题描述

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

代码:

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);

我正在尝试通过使用其中一个孩子作为句柄来拖动一个组.简单地说，我想要做的是，当一个组的孩子被拖动时:

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:

• 获取组的翻译转换
• 从 d3.event.dx、d3.event.dy 获取拖动距离
• 对组的变换属性应用差异

当拖动孩子时，组不会按预期移动.它移动的距离小于拖动的距离，并开始在这里和那里跳跃.

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

我在这里做错了什么?

更新的 jsfiddle:http://jsfiddle.net/6NBy2/2/

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

我正在尝试通过使用一个或多个孩子作为拖动手柄来拖动整个组.

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

推荐答案

这是一个老问题，但没有真正回答.我遇到了完全相同的问题，并且只想将组拖动一个子元素(不是 <g> 的所有子元素).问题是，d3.event.dx/y 是相对于 <g> 的位置计算的.一旦 <g> 被 .attr(transform", translate(x, y)") 移动，d3.event.dx/dy 被调整为新的(较小的)值.这会导致不平稳的运动，大约.光标速度的一半.我为此找到了两种可能的解决方案:

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:

首先(最后我采用了这种方法):

将拖动句柄 rect 直接附加到 svg 而不是 <g>.所以它相对于 <svg> 而不是 <g> 定位.然后在 on drag 函数中同时移动(<rect> 和 <g>).

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>

第二:

使用 d3.event.sourceEvent.path[0] 检查拖动事件期间光标在哪个元素上，仅当句柄 <rect> 时才运行拖动功能代码>被点击.使用这种方法，所有元素都可以在一个 <g> 中进行分组(无需在组外添加额外的 <rect>).这种方法的缺点是，如果鼠标向下移动光标到拖动手柄上，也会执行拖动.

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>

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