Ring Notes

README.md

Annotations created using the d3.ringNote plugin.

d3-ring-note.js

d3.ringNote = function() {
  var draggable = false,
      controlRadius = 15;
  
  var dragCenter = d3.behavior.drag()
    .origin(function(d) { return { x: 0, y: 0}; })
    .on("drag", dragmoveCenter);
  
  var dragRadius = d3.behavior.drag()
    .origin(function(d) { return { x: 0, y: 0 }; })
    .on("drag", dragmoveRadius);
  
  var dragText = d3.behavior.drag()
    .origin(function(d) { return { x: 0, y: 0 }; })
    .on("drag", dragmoveText);
  
  var path = d3.svg.line();
  
  function draw(selection, annotation) {
    
    selection.selectAll(".ring-note").remove();
    
    var gRingNote = selection.selectAll(".ring-note")
        .data(annotation)
      .enter().append("g")
        .attr("class", "ring-note")
        .attr("transform", function(d) {
          return "translate(" + d.cx + "," + d.cy + ")";
        });
    
    var gAnnotation = gRingNote.append("g")
      .attr("class", "annotation");
    
    var circle = gAnnotation.append("circle")
      .attr("r", function(d) { return d.r; });
    
    var line = gAnnotation.append("path")
      .call(updateLine);
      
    var text = gAnnotation.append("text")
      .call(updateText);
    
    if (draggable) {
      
      var gControls = gRingNote.append("g")
        .attr("class", "controls");
      
      // Draggable circle that moves the circle's location
      var center = gControls.append("circle")
        .attr("class", "center")
        .call(styleControl)
        .call(dragCenter);
      
      // Draggable circle that changes the circle's radius
      var radius = gControls.append("circle")
        .attr("class", "radius")
        .attr("cx", function(d) { return d.r; })
        .call(styleControl)
        .call(dragRadius); 
       
      // Make text draggble
      text
        .style("cursor", "move")
        .call(dragText);
    }
    
    return selection;
  }
  
  draw.draggable = function(_) {
    if (!arguments.length) return draggable;
    draggable = _;
    return draw;
  };
  
  // Region in relation to circle, e.g., N, NW, W, SW, etc.
  function getRegion(x, y, r) {
    var px = r * Math.cos(Math.PI/4),
        py = r * Math.sin(Math.PI/4);
    
    var distance = Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2));
    
    if (distance < r) {
      return null;
    }
    else {
      if (x > px) {
        // East
        if (y > py) return "SE"; 
        if (y < -py) return "NE";
        if (x > r) return "E";
        return null;
      }
      else if (x < -px) {
        // West
        if (y > py) return "SW";
        if (y < -py) return "NW";
        if (x < -r) return "W";
        return null;
      }
      else {
        // Center
        if (y > r) return "S";
        if (y < -r) return "N";
      }
    }
  }
  
  function dragmoveCenter(d) {
    var gRingNote = d3.select(this.parentNode.parentNode);
        
    d.cx += d3.event.x;
    d.cy += d3.event.y;
    
    gRingNote
      .attr("transform", function(d) {
        return "translate(" + d.cx + "," + d.cy + ")";
      });
  }
  
  function dragmoveRadius(d) {
    var gRingNote = d3.select(this.parentNode.parentNode),
        gAnnotation = gRingNote.select(".annotation"),
        circle = gAnnotation.select("circle"),
        line = gAnnotation.select("path"),
        text = gAnnotation.select("text"),
        radius = d3.select(this);
    
    d.r += d3.event.dx;
    
    circle.attr("r", function(d) { return d.r; });
    radius.attr("cx", function(d) { return d.r; });
    line.call(updateLine);
    text.call(updateText);
  }
  
  function dragmoveText(d) {
    var gAnnotation = d3.select(this.parentNode),
        line = gAnnotation.select("path"),
        text = d3.select(this);
    
    d.textOffset[0] += d3.event.dx;
    d.textOffset[1] += d3.event.dy;
    
    text.call(updateText);
    line.call(updateLine);
  }
  
  function updateLine(selection) {
    return selection.attr("d", function(d) {
      var x = d.textOffset[0],
          y = d.textOffset[1],
          lineData = getLineData(x, y, d.r);
      return path(lineData);
    });
  }
  
  function getLineData(x, y, r) {
    var region = getRegion(x, y, r);
    
    if (region == null) {
      // No line if text is inside the circle
      return [];
    }
    else {
      // Cardinal directions
      if (region == "N") return [[0, -r], [0, y]];
      if (region == "E") return [[r, 0], [x, 0]];
      if (region == "S") return [[0, r], [0, y]];
      if (region == "W") return [[-r, 0],[x, 0]];
      
      var d0 = r * Math.cos(Math.PI/4),
          d1 = Math.min(Math.abs(x), Math.abs(y)) - d0;
          
      // Intermediate directions
      if (region == "NE") return [[ d0, -d0], [ d0 + d1, -d0 - d1], [x, y]];
      if (region == "SE") return [[ d0,  d0], [ d0 + d1,  d0 + d1], [x, y]];
      if (region == "SW") return [[-d0,  d0], [-d0 - d1,  d0 + d1], [x, y]];
      if (region == "NW") return [[-d0, -d0], [-d0 - d1, -d0 - d1], [x, y]];
    }
  }
  
  function updateText(selection) {
    return selection.each(function(d) {
      var x = d.textOffset[0],
          y = d.textOffset[1],
          region = getRegion(x, y, d.r),
          textCoords = getTextCoords(x, y, region);
      
      d3.select(this)
        .attr("x", textCoords.x)
        .attr("y", textCoords.y)
        .text(d.text)
        .each(function(d) {
          var x = d.textOffset[0],
              y = d.textOffset[1],
              textAnchor = getTextAnchor(x, y, region);
          
          var dx = textAnchor == "start" ? "0.33em" :
                  textAnchor == "end" ? "-0.33em" : "0";
          
          var dy = textAnchor !== "middle" ? ".33em" :
            ["NW", "N", "NE"].indexOf(region) !== -1 ? "-.33em" : "1em";
          
          var orientation = textAnchor !== "middle" ? undefined :
            ["NW", "N", "NE"].indexOf(region) !== -1 ? "bottom" : "top";
          
          d3.select(this)
            .style("text-anchor", textAnchor)
            .attr("dx", dx)
            .attr("dy", dy)
            .call(wrapText, d.textWidth || 960, orientation);
        });
    });
  }
  
  function getTextCoords(x, y, region) {
    if (region == "N") return { x: 0, y: y };
    if (region == "E") return { x: x, y: 0 };
    if (region == "S") return { x: 0, y: y };
    if (region == "W") return { x: x, y: 0 };
    return { x: x, y: y };
  }
  
  function getTextAnchor(x, y, region) {
    if (region == null) {
      return "middle";
    }
    else {
      // Cardinal directions
      if (region == "N") return "middle";
      if (region == "E") return "start";
      if (region == "S") return "middle";
      if (region == "W") return "end";
      
      var xLonger = Math.abs(x) > Math.abs(y);
      
      // Intermediate directions`
      if (region == "NE") return xLonger ? "start" : "middle";
      if (region == "SE") return xLonger ? "start" : "middle";
      if (region == "SW") return xLonger ? "end" : "middle";
      if (region == "NW") return xLonger ? "end" : "middle"; 
    }
  }
  
  function wrapText(text, width, orientation) {
    text.each(function(d) {
      var text = d3.select(this),
          words = text.text().split(/\s+/).reverse(),
          word,
          line = [],
          lineNumber = 1,
          lineHeight = 1.1, // ems
          x = text.attr("x"),
          dx = text.attr("dx"),
          tspan = text.text(null).append("tspan").attr("x", x).attr("dx", dx);
      while (word = words.pop()) {
        line.push(word);
        tspan.text(line.join(" "));
        if (tspan.node().getComputedTextLength() > width) {
          line.pop();
          tspan.text(line.join(" "));
          line = [word];
          tspan = text.append("tspan")
            .attr("x", x)
            .attr("dx", dx)
            .attr("dy", lineHeight + "em")
            .text(word);
          lineNumber++;
        }
      }
      
      var dy;
      if (orientation == "bottom") { 
        dy = -lineHeight * (lineNumber-1) - .33; 
      }
      else if (orientation == "top") { 
        dy = 1;
      }
      else { 
        dy = -lineHeight * ((lineNumber-1) / 2) + .33; 
      }
      text.attr("dy", dy + "em");
      
    });
  }
  
  function styleControl(selection) {
    selection
      .attr("r", controlRadius)
      .style("fill-opacity", "0")
      .style("stroke", "black")
      .style("stroke-dasharray", "3, 3")
      .style("cursor", "move");
  }
  
  return draw;
};

index.html

<html>
<head>
<style>

html {
  font-family: sans-serif;
  font-size: 12px;
}

label {
  position: absolute;
  top: 15px;
  right: 15px;
}

.annotation circle {
  fill: none;
  stroke: black;
}

.annotation path {
  fill: none;
  stroke: black;
  shape-rendering: crispEdges;
}

.annotation .shaded {
  fill: grey;
  fill-opacity: 0.2;
}

</style>
</head>
<body>
  
<label>
  <input type="checkbox">
  Hide controls
</label>

<script src="https://d3js.org/d3.v3.min.js" charset="utf-8"></script>
<script src="d3-ring-note.js"></script>
<script>

var annotations = [
  {
    "cx": 232,
    "cy": 123,
    "r": 103,
    "text": "This is a \"ring note\"",
    "textOffset": [
      114,
      88
    ]
  },
  {
    "cx": 691,
    "cy": 101,
    "r": 54,
    "text": "Drag this text to move it. Text wraps automatically. Just set the width",
    "textWidth": 150,
    "textOffset": [
      0,
      66
    ]
  },
  {
    "cx": 347,
    "cy": 370,
    "r": 46,
    "text": "Drag the dashed circles to change the annotation's position and size. You can remove these controls after you settle on a final layout",
    "textWidth": 200,
    "textOffset": [
      -68,
      -37
    ]
  },
  {
    "cx": 760,
    "cy": 361,
    "r": 67,
    "text": "Styling individual annotations is straightforward",
    "textWidth": 150,
    "textOffset": [
      -75,
      -5
    ],
    "shaded": true
  }
];

var width = 960,
    height = 500;

var ringNote = d3.ringNote()
  .draggable(true);

var svg = d3.select("body").append("svg")
  .attr("width", width)
  .attr("height", height);
  
var gAnnotations = svg.append("g")
  .attr("class", "annotations")
  .call(ringNote, annotations);

// Styling individual annotations based on bound data
gAnnotations.selectAll(".annotation circle")
  .classed("shaded", function(d) { return d.shaded; });

// Hide or show the controls
var draggable = true;
d3.select("input")
  .on("change", function() {
    ringNote.draggable(draggable = !draggable);
    gAnnotations
        .call(ringNote, annotations)
      .selectAll(".annotation circle")
        .classed("shaded", function(d) { return d.shaded; });
  });

</script>
</body>
</html>

thumbnail.png