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javascriptd3.jstreemarkers

How to have marker end enable to end of path in a d3 tree


Below is my code snippet where I would like to have multiple arrowhead markers at the end of my path pointing it towards the children instead of the parent. But I have been able to point a single arrow marker towards my parent but not a child. Please let me know what needs to be done The below image shows the arrow pointing towards the parent. I would like to have it point towards children.

The below image shows is the plain code without arrow markers Tree Diagram

I would like to see the below image like type functionality to my code Code with markers

<!DOCTYPE html>
<meta charset="UTF-8">
<style>
    .node circle {
        fill: #fff;
        stroke: steelblue;
        stroke-width: 3px;
    }

    .node text {
        font: 12px sans-serif;
    }

    .link {
        fill: none;
        stroke: #ccc;
        stroke-width: 2px;
    }

    .link path {
        fill: none;
        stroke: #ccc;
        stroke-width: 2px;
    }

    .link text {
        font: 12px sans-serif;
        stroke: #333;
        stroke-width: 1;
    }
</style>

<body>

    <!-- load the d3.js library -->
    <script src="https://d3js.org/d3.v4.min.js"></script>
    <script>

        var treeData =
        {
            "name": "Top Level",
            "linkname": "null",
            "children": [
                {
                    "name": "Level 2: A",
                    "linkname": "Link_1",
                    "children": [
                        { "name": "Son of A", "linkname": "Link_2.1" },
                        { "name": "Daughter of A", "linkname": "Link_2.2" }
                    ]
                },
                { "name": "Level 2: B", "linkname": "Link_3", }
            ]
        };

        // Set the dimensions and margins of the diagram
        var margin = { top: 20, right: 90, bottom: 30, left: 90 },
            width = 960 - margin.left - margin.right,
            height = 500 - margin.top - margin.bottom;

        // append the svg object to the body of the page
        // appends a 'group' element to 'svg'
        // moves the 'group' element to the top left margin
        var svg = d3.select("body").append("svg")
            .attr("width", width + margin.right + margin.left)
            .attr("height", height + margin.top + margin.bottom)
            .append("g")
            .attr("transform", "translate("
                + margin.left + "," + margin.top + ")");

        var i = 0,
            duration = 750,
            root;

        // declares a tree layout and assigns the size
        var treemap = d3.tree().size([height, width]);

        // Assigns parent, children, height, depth
        root = d3.hierarchy(treeData, function (d) { return d.children; });
        root.x0 = height / 2;
        root.y0 = 0;

        // Collapse after the second level
        root.children.forEach(collapse);

        update(root);

        // Collapse the node and all it's children
        function collapse(d) {
            if (d.children) {
                d._children = d.children
                d._children.forEach(collapse)
                d.children = null
            }
        }

        function update(source) {

            // Assigns the x and y position for the nodes
            var treeData = treemap(root);

            // Compute the new tree layout.
            var nodes = treeData.descendants(),
                links = treeData.descendants().slice(1);

            // Normalize for fixed-depth.
            nodes.forEach(function (d) {
                d.y = d.depth * 180
            });

            // ****************** Nodes section ***************************

            // Update the nodes...
            var node = svg.selectAll('g.node')
                .data(nodes, function (d) {
                    return d.id || (d.id = ++i);
                });

            // Enter any new modes at the parent's previous position.
            var nodeEnter = node.enter().append('g')
                .attr('class', 'node')
                .attr("transform", function (d) {
                    return "translate(" + source.y0 + "," + source.x0 + ")";
                })
                .on('click', click);

            // Add Circle for the nodes
            nodeEnter.filter(function (d) {
                return (!d.data.type || d.data.type !== 'data');
            }).append('circle')
                .attr('class', 'node')
                .attr('r', 1e-6)
                .style("fill", function (d) {
                    return d._children ? "lightsteelblue" : "#fff";
                });

            nodeEnter.filter(function (d) {
                return (d.data.type && d.data.type === 'data');
            }).append('rect')
                .attr('class', 'node')
                .attr('width', 20)
                .attr('height', 20)
                .attr('y', -10)
                .attr('x', -10)
                .style("fill", function (d) {
                    return d._children ? "lightsteelblue" : "#fff";
                });

            // Add labels for the nodes
            nodeEnter.append('text')
                .attr("dy", "2em")
                .attr("x", function (d) {
                    return d.children || d._children ? 13 : 13;
                })
                .attr("text-anchor", function (d) {
                    return d.children || d._children ? "start" : "start";
                })
                .text(function (d) {
                    return d.data.name;
                });

            // UPDATE
            var nodeUpdate = nodeEnter.merge(node);

            // Transition to the proper position for the node
            nodeUpdate.transition()
                .duration(duration)
                .attr("transform", function (d) {
                    return "translate(" + d.y + "," + d.x + ")";
                });

            // Update the node attributes and style
            nodeUpdate.select('circle.node')
                .attr('r', 10)
                .style("fill", function (d) {
                    return d._children ? "lightsteelblue" : "#fff";
                })
                .attr('cursor', 'pointer');


            // Remove any exiting nodes
            var nodeExit = node.exit().transition()
                .duration(duration)
                .attr("transform", function (d) {
                    return "translate(" + source.y + "," + source.x + ")";
                })
                .remove();

            // On exit reduce the node circles size to 0
            nodeExit.select('circle')
                .attr('r', 1e-6);

            // On exit reduce the opacity of text labels
            nodeExit.select('text')
                .style('fill-opacity', 1e-6);

            // ****************** links section ***************************

            // Update the links...
            var link = svg.selectAll('g.link')
                .data(links, function (d) {
                    return d.id;
                });

            // Enter any new links at the parent's previous position.
            var linkEnter = link.enter().insert('g', 'g')
                .attr("class", "link");

            linkEnter.append('text')
                .attr("class","linkLabels")
                .text(function (d, i) {
                    if (d.parent && d.parent.children.length > 1) {
                        if (!d.parent.index) d.parent.index = 0;
                        return d.data.linkname;
                    }
                })
                .attr("opacity",0)
                .attr('dy', "-1em");

            linkEnter.append('path')
                .attr('d', function (d) {
                    var o = {
                        x: source.x0,
                        y: source.y0
                    }
                    return diagonal(o, o)
                })
                .on("mouseover", function(){
                    d3.select(this.parentNode).select("text").attr("opacity",1);
                })
                .on("mouseleave", function(){
                    d3.select(this.parentNode).select("text").attr("opacity",0);
                })


            // UPDATE
            var linkUpdate = linkEnter.merge(link);

            // Transition back to the parent element position
            linkUpdate.select('path').transition()
                .duration(duration)
                .attr('d', function (d) {
                    return diagonal(d, d.parent)
                });

            linkUpdate.select('text').transition()
                .duration(duration)
                .attr('transform', function (d) {
                    if (d.parent) {
                        return 'translate(' + ((d.parent.y + d.y) / 2) + ',' + ((d.parent.x + d.x) / 2) + ')'
                    }
                })

            // Remove any exiting links
            link.exit().each(function (d) {
                d.parent.index = 0;
            })

            var linkExit = link.exit()
                .transition()
                .duration(duration);

            linkExit.select('path')
                .attr('d', function (d) {
                    var o = {
                        x: source.x,
                        y: source.y
                    }
                    return diagonal(o, o)
                })

            linkExit.select('text')
                .style('opacity', 0);

            linkExit.remove();

            // Store the old positions for transition.
            nodes.forEach(function (d) {
                d.x0 = d.x;
                d.y0 = d.y;
            });

            // Creates a curved (diagonal) path from parent to the child nodes
            function diagonal(s, d) {
                path = `M ${s.y} ${s.x}
                        C ${(s.y + d.y) / 2} ${s.x},
                            ${(s.y + d.y) / 2} ${d.x},
                            ${d.y} ${d.x}`
                return path
            }

            // Toggle children on click.
            function click(d) {
                if (d.children) {
                    d._children = d.children;
                    d.children = null;
                } else {
                    d.children = d._children;
                    d._children = null;
                }
                update(d);
            }
        }


    </script>
</body>

Solution

  • Probably not 100% what you want, but can be a starting point for you, basically I did it by manipulating marker attributes .attr("orient", "auto-start-reverse") check the MDN documentation for more information about this attribute, also refX, and refY finally the path attribute I used marker-start instead of marker-end since in this example the path drawn from the children to the parent not the reverse

    if this is not what you want, there is another stack-overflow question that is a bit close to your case but its not a tree but can help:

    Align Marker on node edges D3 Force Layout

    var treeData = {
      name: "Top Level",
      linkname: "null",
      children: [
        {
          name: "Level 2: A",
          linkname: "Link_1",
          children: [
            { name: "Son of A", linkname: "Link_2.1" },
            { name: "Daughter of A", linkname: "Link_2.2" }
          ]
        },
        { name: "Level 2: B", linkname: "Link_3" }
      ]
    };
    
    // Set the dimensions and margins of the diagram
    var margin = { top: 20, right: 90, bottom: 30, left: 90 },
      width = 960 - margin.left - margin.right,
      height = 500 - margin.top - margin.bottom;
    
    // append the svg object to the body of the page
    // appends a 'group' element to 'svg'
    // moves the 'group' element to the top left margin
    var svg = d3
      .select("body")
      .append("svg")
      .attr("width", width + margin.right + margin.left)
      .attr("height", height + margin.top + margin.bottom)
      .append("g")
      .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
    
    svg
      .append("svg:defs")
      .selectAll("marker")
      .data(["end"]) // Different link/path types can be defined here
      .enter()
      .append("svg:marker") // This section adds in the arrows
      .attr("id", String)
      .attr("viewBox", "0 -5 10 10")
      .attr("refX", 15)
      .attr("refY", 0)
      .attr("markerWidth", 6)
      .attr("markerHeight", 6)
      .attr("orient", "auto-start-reverse")
      .append("svg:path")
      .attr("d", "M0,-5L10,0L0,5");
    
    var i = 0,
      duration = 750,
      root;
    
    // declares a tree layout and assigns the size
    var treemap = d3.tree().size([height, width]);
    
    // Assigns parent, children, height, depth
    root = d3.hierarchy(treeData, function(d) {
      return d.children;
    });
    root.x0 = height / 2;
    root.y0 = 0;
    
    // Collapse after the second level
    root.children.forEach(collapse);
    
    update(root);
    
    // Collapse the node and all it's children
    function collapse(d) {
      if (d.children) {
        d._children = d.children;
        d._children.forEach(collapse);
        d.children = null;
      }
    }
    
    function update(source) {
      // Assigns the x and y position for the nodes
      var treeData = treemap(root);
    
      // Compute the new tree layout.
      var nodes = treeData.descendants(),
        links = treeData.descendants().slice(1);
    
      // Normalize for fixed-depth.
      nodes.forEach(function(d) {
        d.y = d.depth * 180;
      });
    
      // ****************** Nodes section ***************************
    
      // Update the nodes...
      var node = svg.selectAll("g.node").data(nodes, function(d) {
        return d.id || (d.id = ++i);
      });
    
      // Enter any new modes at the parent's previous position.
      var nodeEnter = node
        .enter()
        .append("g")
        .attr("class", "node")
        .attr("transform", function(d) {
          return "translate(" + source.y0 + "," + source.x0 + ")";
        })
        .on("click", click);
    
      // Add Circle for the nodes
      nodeEnter
        .filter(function(d) {
          return !d.data.type || d.data.type !== "data";
        })
        .append("circle")
        .attr("class", "node")
        .attr("r", 1e-6)
        .style("fill", function(d) {
          return d._children ? "lightsteelblue" : "#fff";
        });
    
      nodeEnter
        .filter(function(d) {
          return d.data.type && d.data.type === "data";
        })
        .append("rect")
        .attr("class", "node")
        .attr("width", 20)
        .attr("height", 20)
        .attr("y", -10)
        .attr("x", -10)
        .style("fill", function(d) {
          return d._children ? "lightsteelblue" : "#fff";
        });
    
      // Add labels for the nodes
      nodeEnter
        .append("text")
        .attr("dy", "2em")
        .attr("x", function(d) {
          return d.children || d._children ? 13 : 13;
        })
        .attr("text-anchor", function(d) {
          return d.children || d._children ? "start" : "start";
        })
        .text(function(d) {
          return d.data.name;
        });
    
      // UPDATE
      var nodeUpdate = nodeEnter.merge(node);
    
      // Transition to the proper position for the node
      nodeUpdate
        .transition()
        .duration(duration)
        .attr("transform", function(d) {
          return "translate(" + d.y + "," + d.x + ")";
        });
    
      // Update the node attributes and style
      nodeUpdate
        .select("circle.node")
        .attr("r", 10)
        .style("fill", function(d) {
          return d._children ? "lightsteelblue" : "#fff";
        })
        .attr("cursor", "pointer");
    
      // Remove any exiting nodes
      var nodeExit = node
        .exit()
        .transition()
        .duration(duration)
        .attr("transform", function(d) {
          return "translate(" + source.y + "," + source.x + ")";
        })
        .remove();
    
      // On exit reduce the node circles size to 0
      nodeExit.select("circle").attr("r", 1e-6);
    
      // On exit reduce the opacity of text labels
      nodeExit.select("text").style("fill-opacity", 1e-6);
    
      // ****************** links section ***************************
    
      // Update the links...
      var link = svg.selectAll("g.link").data(links, function(d) {
        return d.id;
      });
    
      // Enter any new links at the parent's previous position.
      var linkEnter = link
        .enter()
        .insert("g", "g")
        .attr("class", "link");
    
      linkEnter
        .append("text")
        .attr("class", "linkLabels")
        .text(function(d, i) {
          if (d.parent && d.parent.children.length > 1) {
            if (!d.parent.index) d.parent.index = 0;
            return d.data.linkname;
          }
        })
        .attr("opacity", 0)
        .attr("dy", "-1em");
    
      linkEnter
        .append("path")
        .attr("d", function(d) {
          var o = {
            x: source.x0,
            y: source.y0
          };
          return diagonal(o, o);
        })
        .on("mouseover", function() {
          d3.select(this.parentNode)
            .select("text")
            .attr("opacity", 1);
        })
        .on("mouseleave", function() {
          d3.select(this.parentNode)
            .select("text")
            .attr("opacity", 0);
        })
        .attr("stroke-linecap", "round")
        .attr("marker-start", "url(#end)");
    
      // UPDATE
      var linkUpdate = linkEnter.merge(link);
    
      // Transition back to the parent element position
      linkUpdate
        .select("path")
        .transition()
        .duration(duration)
        .attr("d", function(d) {
          return diagonal(d, d.parent);
        });
    
      linkUpdate
        .select("text")
        .transition()
        .duration(duration)
        .attr("transform", function(d) {
          if (d.parent) {
            return (
              "translate(" +
              (d.parent.y + d.y) / 2 +
              "," +
              (d.parent.x + d.x) / 2 +
              ")"
            );
          }
        });
    
      // Remove any exiting links
      link.exit().each(function(d) {
        d.parent.index = 0;
      });
    
      var linkExit = link
        .exit()
        .transition()
        .duration(duration);
    
      linkExit.select("path").attr("d", function(d) {
        var o = {
          x: source.x,
          y: source.y
        };
        return diagonal(o, o);
      });
    
      linkExit.select("text").style("opacity", 0);
    
      linkExit.remove();
    
      // Store the old positions for transition.
      nodes.forEach(function(d) {
        d.x0 = d.x;
        d.y0 = d.y;
      });
    
      // Creates a curved (diagonal) path from parent to the child nodes
      function diagonal(s, d) {
        path = `M ${s.y} ${s.x}
                C ${(s.y + d.y) / 2} ${s.x},
                    ${(s.y + d.y) / 2} ${d.x},
                    ${d.y} ${d.x}`;
        return path;
      }
    
      // Toggle children on click.
      function click(d) {
        if (d.children) {
          d._children = d.children;
          d.children = null;
        } else {
          d.children = d._children;
          d._children = null;
        }
        update(d);
      }
    }
    .node circle {
      fill: #fff;
      stroke: steelblue;
      stroke-width: 3px;
    }
    
    .node text {
      font: 12px sans-serif;
    }
    
    .link {
      fill: none;
      stroke: #ccc;
      stroke-width: 2px;
    }
    
    .link path {
      fill: none;
      stroke: #ccc;
      stroke-width: 2px;
    }
    
    .link text {
      font: 12px sans-serif;
      stroke: #333;
      stroke-width: 1;
    }
    <!DOCTYPE html>
    <meta charset="UTF-8">
    <style>
        
    </style>
    
    <body>
      <!-- load the d3.js library -->
      <script src="https://d3js.org/d3.v4.min.js"></script>
    </body>