tlfrd/.block

## .block
license: mit

## README.md

      
    Raw
  

              README.md
            
          
    Learning how to use d3-drag for an interactive "Make a guess" connected dot plot. Dragging is limited to the x-axis and the ends of the line cannot cross over (i.e. their positions cannot be switched). Clicking reset returns the dots to their original positions.

  
## index.html
<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
    .dot {
      fill: white;
      stroke: black;
    }

    .active {
      stroke: red;
    }

    body {
      font-family: monospace;
    }

    a {
      position: absolute;
      top: 20px;
      left: 20px;
    }
  </style>
</head>

<body>
  <a href="#" class="reset-btn">Reset</a>
  <script>
    var margin = {top: 0, right: 0, bottom: 0, left: 0};

    var width = 960 - margin.left - margin.right,
    		height = 500 - margin.top - margin.bottom;

    var svg = d3.select("body").append("svg")
          .attr("width", width + margin.left + margin.right)
          .attr("height", height + margin.top + margin.bottom)
        .append("g")
          .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

    var radius = 20,
        strokewidth = 5;

    var te = d3.easeCubic;

    var dots = [
      {
        type: "min",
        colour: "white",
        x: width / 4,
        y: height / 2
      },
      {
        type: "median",
        colour: "grey",
				x: width / 2,
        y: height / 2
      },
      {
        type: "max",
        colour: "black",
        x: width * 3 / 4,
        y: height / 2
    	}];

    var dotsoriginal = JSON.parse(JSON.stringify(dots));

    var dragbehaviour = d3.drag()
    	.on("start", dragstarted)
    	.on("drag", dragged)
    	.on("end", dragended);

    var labels = svg.selectAll("text")
    	.data(dots)
    .enter().append("text")
    	.attr("x", function(d) { return d.x })
    	.attr("y", function(d) {
        	return height / 2 + (d.type == "min" || d.type == "max" ? 60 : -50)
      })
    	.attr("text-anchor", "middle")
    	.text(function(d) { return "(" + d.x + ", " + d.y + ")" });

    var lineGenerator = d3.line()
    	.x(function(d) { return d.x + (d.type == "min" ? radius : -radius)})
    	.y(function(d) { return d.y });

    var pathString = function() { return lineGenerator(dots) };

    var line = svg.append("path")
    	.attr("class", "line")
    	.attr("d", pathString)
    	.attr("stroke", "black")
    	.style("stroke-width", strokewidth);

    var circles = svg.selectAll("circle")
    	.data(dots)
		.enter().append("circle")
    	.attr("class", "dot")
    	.attr("cx", function(d) { return d.x; })
    	.attr("cy", function(d) { return d.y; })
    	.attr("r", radius)
    	.style("fill", function(d) { return d.colour })
    	.style("stroke-width", strokewidth)
    	.call(dragbehaviour);

    function dragstarted(d) {
      d3.select(this)
        .classed("active", true);
    }

    function dragged(d) {
      var minX, maxX;

      if (d.type == "min") {
        minX = radius + strokewidth;
        maxX = dots[1].x - (radius * 2) - strokewidth;
      } else if (d.type == "median") {
        minX = dots[0].x + (radius * 2) + strokewidth;
        maxX = dots[2].x - (radius * 2) - strokewidth;
      } else {
        minX = dots[1].x + (radius * 2) + strokewidth;
        maxX = width - radius - strokewidth;
      }

      d3.select(this)
      	.attr("cx", d.x = Math.max(minX, Math.min(maxX, d3.event.x)));

      labels
    		.attr("x", function(d) { return d.x })
        .text(function(d) { return "(" + d.x + ", " + d.y + ")" });

      line.attr("d", pathString);
    }

    function dragended(d) {
      d3.select(this)
      	.classed("active", false);
    }

    d3.select(".reset-btn")
    	.on("click", function(d) {
      	d3.event.preventDefault();
      	dots = dotsoriginal;
      	dotsoriginal = JSON.parse(JSON.stringify(dots));

     	 	line.transition()
        	.duration(500)
        	.ease(te)
          .attr("d", pathString);

      	circles.data(dots).transition()
        	.duration(500)
        	.ease(te)
        	.attr("cx", function(d) { return d.x; });

      	labels.data(dots).transition()
        	.duration(500)
        	.ease(te)
        	.attr("x", function(d) { return d.x; })
      		.text(function(d) { return "(" + d.x + ", " + d.y + ")" });
    	});

  </script>
</body>

## thumbnail.png

      
    Raw
  

              thumbnail.png
	<!DOCTYPE html>
	<head>
	<meta charset="utf-8">
	<script src="https://d3js.org/d3.v4.min.js"></script>
	<style>
	.dot {
	fill: white;
	stroke: black;
	}

	.active {
	stroke: red;
	}

	body {
	font-family: monospace;
	}

	a {
	position: absolute;
	top: 20px;
	left: 20px;
	}
	</style>
	</head>

	<body>
	<a href="#" class="reset-btn">Reset</a>
	<script>
	var margin = {top: 0, right: 0, bottom: 0, left: 0};

	var width = 960 - margin.left - margin.right,
	height = 500 - margin.top - margin.bottom;

	var svg = d3.select("body").append("svg")
	.attr("width", width + margin.left + margin.right)
	.attr("height", height + margin.top + margin.bottom)
	.append("g")
	.attr("transform", "translate(" + margin.left + "," + margin.top + ")");

	var radius = 20,
	strokewidth = 5;

	var te = d3.easeCubic;

	var dots = [
	{
	type: "min",
	colour: "white",
	x: width / 4,
	y: height / 2
	},
	{
	type: "median",
	colour: "grey",
	x: width / 2,
	y: height / 2
	},
	{
	type: "max",
	colour: "black",
	x: width * 3 / 4,
	y: height / 2
	}];

	var dotsoriginal = JSON.parse(JSON.stringify(dots));

	var dragbehaviour = d3.drag()
	.on("start", dragstarted)
	.on("drag", dragged)
	.on("end", dragended);

	var labels = svg.selectAll("text")
	.data(dots)
	.enter().append("text")
	.attr("x", function(d) { return d.x })
	.attr("y", function(d) {
	return height / 2 + (d.type == "min" \|\| d.type == "max" ? 60 : -50)
	})
	.attr("text-anchor", "middle")
	.text(function(d) { return "(" + d.x + ", " + d.y + ")" });

	var lineGenerator = d3.line()
	.x(function(d) { return d.x + (d.type == "min" ? radius : -radius)})
	.y(function(d) { return d.y });

	var pathString = function() { return lineGenerator(dots) };

	var line = svg.append("path")
	.attr("class", "line")
	.attr("d", pathString)
	.attr("stroke", "black")
	.style("stroke-width", strokewidth);

	var circles = svg.selectAll("circle")
	.data(dots)
	.enter().append("circle")
	.attr("class", "dot")
	.attr("cx", function(d) { return d.x; })
	.attr("cy", function(d) { return d.y; })
	.attr("r", radius)
	.style("fill", function(d) { return d.colour })
	.style("stroke-width", strokewidth)
	.call(dragbehaviour);

	function dragstarted(d) {
	d3.select(this)
	.classed("active", true);
	}

	function dragged(d) {
	var minX, maxX;

	if (d.type == "min") {
	minX = radius + strokewidth;
	maxX = dots[1].x - (radius * 2) - strokewidth;
	} else if (d.type == "median") {
	minX = dots[0].x + (radius * 2) + strokewidth;
	maxX = dots[2].x - (radius * 2) - strokewidth;
	} else {
	minX = dots[1].x + (radius * 2) + strokewidth;
	maxX = width - radius - strokewidth;
	}

	d3.select(this)
	.attr("cx", d.x = Math.max(minX, Math.min(maxX, d3.event.x)));

	labels
	.attr("x", function(d) { return d.x })
	.text(function(d) { return "(" + d.x + ", " + d.y + ")" });

	line.attr("d", pathString);
	}

	function dragended(d) {
	d3.select(this)
	.classed("active", false);
	}

	d3.select(".reset-btn")
	.on("click", function(d) {
	d3.event.preventDefault();
	dots = dotsoriginal;
	dotsoriginal = JSON.parse(JSON.stringify(dots));

	line.transition()
	.duration(500)
	.ease(te)
	.attr("d", pathString);

	circles.data(dots).transition()
	.duration(500)
	.ease(te)
	.attr("cx", function(d) { return d.x; });

	labels.data(dots).transition()
	.duration(500)
	.ease(te)
	.attr("x", function(d) { return d.x; })
	.text(function(d) { return "(" + d.x + ", " + d.y + ")" });
	});

	</script>
	</body>