Show D3 link text right-side up - javascript

I have built a D3 force directed visualization with text labels along the links. The one problem I'm running into is these labels appearing upside down when the links are to the left of their source node. Example here:
The code where I position the path and text looks like so:
var nodes = flatten(data);
var links = d3.layout.tree().links(nodes);
var path = vis.selectAll('path.link')
.data(links, function(d) {
return d.target.id;
});
path.enter().insert('svg:path')
.attr({
class: 'link',
id: function(d) {
return 'text-path-' + d.target.id;
},
'marker-end': 'url(#end)'
})
.style('stroke', '#ccc');
var linkText = vis.selectAll('g.link-text').data(links);
linkText.enter()
.append('text')
.append('textPath')
.attr('xlink:href', function(d) {
return '#text-path-' + d.target.id;
})
.style('text-anchor', 'middle')
.attr('startOffset', '50%')
.text(function(d) {return d.target.customerId});
I know I will need to somehow determine the current angle of each path and then set the text position accordingly, but I am not sure how to.
Here is a link to a block based on this issue: http://blockbuilder.org/MattDionis/5f966a5230079d9eb9f4
The answer below has got me about 90% of the way there. Here is what my original visualization looks like with text longer than a couple digit number:
...and here is what it looks like utilizing the tips in the below answer:
So while the text is now "right-side up", it no longer follows the arc.

The arcs you draw are such that their tangent in the middle is exactly the direction of the baseline of the text, AND it is also colinear with the vector that separates the two tree nodes.
We can use that to solve the problem.
A bit of math is needed. First, let's define a function that returns the angle of a vector v with respect to the horizontal axis:
function xAngle(v) {
return Math.atan(v.y/v.x) + (v.x < 0 ? Math.PI : 0);
}
Then, at each tick, let's rotate the text in place by minus the angle of its baseline. First, a few utility functions:
function isFiniteNumber(x) {
return typeof x === 'number' && (Math.abs(x) < Infinity);
}
function isVector(v) {
return isFiniteNumber(v.x) && isFiniteNumber(v.y);
}
and then, in your tick function, add
linkText.attr('transform', function (d) {
// Checks just in case, especially useful at the start of the sim
if (!(isVector(d.source) && isVector(d.target))) {
return '';
}
// Get the geometric center of the text element
var box = this.getBBox();
var center = {
x: box.x + box.width/2,
y: box.y + box.height/2
};
// Get the tangent vector
var delta = {
x: d.target.x - d.source.x,
y: d.target.y - d.source.y
};
// Rotate about the center
return 'rotate('
+ (-180/Math.PI*xAngle(delta))
+ ' ' + center.x
+ ' ' + center.y
+ ')';
});
});
edit: added pic:
edit 2 With straight lines instead of curved arcs (simply <text> instead of <textPath> inside of <text>), you can replace the part of the tick function that concerns linkText with this:
linkText.attr('transform', function(d) {
if (!(isVector(d.source) && isVector(d.target))) {
return '';
}
// Get the geometric center of this element
var box = this.getBBox();
var center = {
x: box.x + box.width / 2,
y: box.y + box.height / 2
};
// Get the direction of the link along the X axis
var dx = d.target.x - d.source.x;
// Flip the text if the link goes towards the left
return dx < 0
? ('rotate(180 '
+ center.x
+ ' ' + center.y
+ ')')
: '';
});
and this is what you get:
Notice how the text gets flipped as the link goes from pointing more to the right to pointing more to the left.
The problem with this is that the text ends up below the link. That can be fixed as follows:
linkText.attr('transform', function(d) {
if (!(isVector(d.source) && isVector(d.target))) {
return '';
}
// Get the geometric center of this element
var box = this.getBBox();
var center = {
x: box.x + box.width / 2,
y: box.y + box.height / 2
};
// Get the vector of the link
var delta = {
x: d.target.x - d.source.x,
y: d.target.y - d.source.y
};
// Get a unitary vector orthogonal to delta
var norm = Math.sqrt(delta.x * delta.x + delta.y * delta.y);
var orth = {
x: delta.y/norm,
y: -delta.x/norm
};
// Replace this with your ACTUAL font size
var fontSize = 14;
// Flip the text and translate it beyond the link line
// if the link goes towards the left
return delta.x < 0
? ('rotate(180 '
+ center.x
+ ' ' + center.y
+ ') translate('
+ (orth.x * fontSize) + ' '
+ (orth.y * fontSize) + ')')
: '';
});
and now the result looks like this:
As you can see, the text sits nicely on top of the line, even when the link points towards the left.
Finally, in order to solve the problem while keeping the arcs AND having the text right side up curved along the arc, I reckon you would need to build two <textPath> elements. One for going from source to target, and one for going the opposite way. You would use the first one when the link goes towards the right (delta.x >= 0) and the second one when the link goes towards the left (delta.x < 0) and I think the result would look nicer and the code would not be necessarily more complicated than the original, just with a bit more logic added.

Related

build specific icon from data

I want to display a specific icon in different boxes using d3.
I have a data as an array of [x0, y0, x1, y1, vx, vy] where:
x0, y0 is the first corner of a box,
x1, y1 the second corner and
vx, vy two parameters (velocity)
that will be used to generate a SVG path.
I am using:
var boxes = nodeSVGGroup.selectAll("rect").data(nodes).enter().append("rect");
to generate my boxes and this is working well
My problem comes when I want to create the SVG path (icon) and properly render it in each box (it needs to be generated, translated and rotated to fit the center of each box.
I am using a similar pattern i.e.
var selection = nodeSVGGroup.selectAll(".barb").data(nodes);
selection.enter()
.append('g')
.each(function(node, i) {
var vx = node[4];
var vy = node[5];
var speed = Math.sqrt(vx*vx + vy*vy);
var angle = Math.atan2(vx, vy);
// generate a path based on speed. it looks like
// M2 L8 2 M0 0 L1 2 Z
var path = ...
var scale = 0.5*(node[1]-node[0])/8;
var g = d3.select(this).data([path,angle,scale]).enter().append('g');
// still need to add following transforms
// translate(' + node[2] + ', ' + node[3] + ')
// scale(' + scale + ')
// rotate(' + angle + ' ' + 0 + ' ' + 0 + ')
// translate(-8, -2)',
g.append('path').attr('d', function(d){console.log(d); return d[0];})
.attr('vector-effect', 'non-scaling-stroke');
})
.attr('class', 'wind-arrow');
I get the error Uncaught TypeError: Cannot read property 'ownerDocument' of null(…) which seems to be related to this line
.each(function(node, i) {
What am I doing wrong?
The full code is here
It's not entirely clear why are you trying to create an "enter" selection inside an each. I'm not sure if I understand your goals, but you can simply use d3.select(this) to append the path to each group:
d3.select(this).append('path')
.attr('d', path)
Here is the updated fiddle: https://jsfiddle.net/9x169eL1/

How can I fix the coordinate-type change that occurs from dragging in d3?

Right now in my program I have both a drag function and a zoom function.
The problem can best be illustrated in this minimal test case. When the zoom is initiated at first, you may notice that the points in the graph will transition just fine. But, if you drag a point before initiating a zoom, that point will usually travel outside the scope of the graph.
This problem seems to be happening because my coordinates are defined in scaled space centered around the upper left corner. However, after an object is dragged, its coordinates are switched to pixel space, centered around its original coordinates. When a zoom occurs, it will then treat the pixel coordinates as scaled space coordinates relative to the upper left corner, which causes problems.
I would appreciate any tips or pointers and thanks in advance
Drag function:
function dragmove(d) {
var barz = document.querySelector("#visual");
var point = d3.mouse(barz),
tempP = {
x: point[0],
y: point[1]
};
if (this.nodeName === "circle") {
d3.event.sourceEvent.stopPropagation();
var useZoom = $('#zoom').is(":checked");
if (useZoom == false) {
d.usePixels = 1;
d3.select(this).attr("transform", "translate(" + (d.x = tempP.x - xRange(d.initx)) + "," + (d.y = tempP.y - yRange(d.inity)) + ")");
//events to update line to fit dots
updateXs();
redoLine();
updateBars(canvas);
}
} }
Zoom function:
function zoomOut() {
//update axis
yRange.domain([d3.min(lineData, function (d) {
return d.y - 10;
}), d3.max(lineData, function (d) {
return d.y + 10;
})])
yAxisGroup.transition().call(yAxis);
xAxisGroup.transition().attr("transform", "translate(0," + yRange(0) + ")");
//update line
d3.select(".myLine").transition()
.attr("d", lineFunc(lineData));
var c = vis.selectAll("circle")
c.transition()
.attr(circleAttrs)
}

How to move a node along a vector?

I have a bunch of nodes in a circle around a centre point. I got these positions by drawing arcs first then using the arcs [X,Y] position, populated an array which was used for the positions of the nodes. Using the forcelayout from the javascript library D3.
What I want to do now, if the nodes meet a certain criteria, for example, name starts with L, move them out to the outline of a bigger circle. I have made a simple diagram to explain.
I wish to be able to move from [X2,Y2] to [X3,Y3]. I labelled [X1,Y1] as I am sure you would need this to work out the vector from x1y2 to x2,y2 wish would then be used to calculate the movement along that vector, but I'm unsure how to do this movement
I don't know if the problem is still active, but I'll answer anyway. Since the Problem has a cylindrical symmetry it is best to use polar coordinates. So x,y become r,phi whereas r = sqrt(x^2+y^2) and phi=arctan(y/x). If you want to move a point X(r,phi) in the radial direction by lets say r' you do it by simple adding it to the existing radius. Thus X'=X(r+r',phi)
Here's the way I solved it. I had a variable moveOutso I could toggle between the original node position and the one I move to. So depending on the value of moveOut I alter the scale of movement away from center.
var thisNode = circleViewNode.filter(function(d){
//console.log(d)
return d.origin != 'EquivalenceSets' && d.hasRelationship != true;
});
thisNode.each(function(d){
thisNodeSize = d.thisRadius;
});
if(!moveOut){
thisScale = innerModelRadius - thisNodeSize*1.5;
moveOut = true;
} else {
thisScale = innerModelItemRadius + (outerModelItemRadius - innerModelItemRadius)/2;
moveOut = false;
}
thisNode.each(function(d){
//console.log(d);
var centerOfCircle = [width/2,height/2]; //get center
//var centerOfCircle = [arcCenter.x, arcCenter.y];
var thisPosition = [d.x, d.y]; //get position of current node
//thisVector = [center[0]-thisPosition[0], center[1]-thisPosition[1]],
var thisVector = [thisPosition[0] - centerOfCircle[0], thisPosition[1] - centerOfCircle[1]];
var thisVectorX = thisVector[0];
var thisVectorY = thisVector[1];
var xSquared = Math.pow(thisVector[0],2);
var ySquared = Math.pow(thisVector[1],2);
var normalVector = Math.sqrt(xSquared + ySquared); //using pythagoras theorum to work out length from node pos to center
//console.log(d);
thisVectorX= thisVectorX/normalVector;
thisVectorY= thisVectorY/normalVector;
// d.x = centerOfCircle[0]+(thisVectorX*thisScale);// + -38.5;
// d.y = centerOfCircle[1]+(thisVectorY*thisScale);// + -20;
d.x = centerOfCircle[0]+(thisVectorX*thisScale); //thisScale gives the ability to move back to original pos
d.y = centerOfCircle[1]+(thisVectorY*thisScale);
//}
})
.transition().duration(1000)
.attr("transform", function(d)
{
//console.log(d.hasRelationship);
//console.log(d.y);
return "translate(" + d.x + "," + d.y + ")"; //transition nodes
});

d3 steady horizontal transition along an SVG path

I'm using a d3 attrTween to translate a circle over a path smoothly, similar to this example and as shown in the picture below:
The circle's transition is defined here:
function transition() {
circle.transition()
.duration(2051)
.ease("linear")
.attrTween("transform", translateAlong(path.node()))
}
And the attribute tween is shown here:
function translateAlong(path) {
var l = path.getTotalLength();
return function (d, i, a) {
return function (t) {
var p = path.getPointAtLength(t * l);
return "translate(" + p.x + "," + p.y + ")";
};
};
}
This works well thanks to the SVG method getPointAtLength, which allows us to retrieve coordinates at different lengths of the path. However, I need a different kind of behavior and I've been unable to come up with a solution so far.
I need the circle to animate along the path, but at a steady horizontal speed. Meaning that the circle ought to take as much time to navigate this slice:
As it does with this slice:
Because both slices encompass the same width. On a low level, what I need is to be able to translate any X coordinate with its corresponding Y coordinate along the path. I've looked at all the SVG path methods and I haven't found anything particularly useful here. I'm hoping there's some way in D3 to feed an X coordinate to a d3 line and retrieve its corresponding Y coordinate.
Here's a JSFiddle working as described above. I'd really appreciate any help I can get on this. Thanks!
I ended up creating a lookup array for all my points along the line using getPointAtLength:
var lookup = [];
var granularity = 1000;
var l = path.node().getTotalLength();
for(var i = 1; i <= granularity; i++) {
var p = path.node().getPointAtLength(l * (i/granularity))
lookup.push({
x: p.x,
y: p.y
})
}
Once I had all those points in my lookup table, I used a bisector in my translate tween:
var xBisect = d3.bisector(function(d) { return d.x; }).left;
function translateAlong(path) {
var l = path.getTotalLength();
return function (d, i, a) {
return function (t) {
var index = xBisect(lookup, l * t);
var p = lookup[index];
return "translate(" + p.x + "," + p.y + ")";
};
};
}
And it works as expected! Yahoo!
Fiddle

Adjusting scale of a group to ensure shapes inside are as big as possible in d3 js

I'm using d3 tree layout similar to this example: http://bl.ocks.org/mbostock/4339083
I implemented a search box that when typing, centers your screen on a virtual "average" position of all the appropriate nodes.
I want to adjust the scale, so that selected nodes will be
All Visible
As zoomed in as possible.
If the search match is exactly 1, simulate the clicking on the node, else center to this virtual position.
if (matches[0].length === 1) {
click(matches.datum(), 0, 0, false);
}
else {
var position = GetAveragePosition(matches);
centerToPosition(position.x, position.y, 1);
}
This is what the centerToPosition function looks like:
function centerToPosition(x0, y0, newScale) {
if (typeof newScale == "undefined") {
scale = zoomListener.scale();
}
else {
scale = newScale;
}
var x = y0 * -1; //not sure why this is.. but it is
var y = x0 * -1;
x = x * scale + viewerWidth / 2;
y = y * scale + viewerHeight / 2;
d3.select('g').transition()
.duration(duration)
.attr("transform", "translate(" + x + "," + y + ")scale(" + scale + ")");
zoomListener.scale(scale);
zoomListener.translate([x, y]);
}
So how can I calculate the new scale? I tried different variations by taking the extents of the data points
var xExtent = d3.extent(matches.data(), function (d) {
return d.x0;
});
var yExtent = d3.extent(matches.data(), function (d) {
return d.y0;
});
Also tried looking at the transform properties of the group before centering the screen.
var components = d3.transform(svgGroup.attr("transform"));
I'll try to add a js fiddle soon!
EDIT: Here it is: http://jsfiddle.net/7SJqC/
Interesting project.
The method of determining the appropriate scale to fit a collection of points is fairly straightforward, although it took me quite a while to figure out why it wasn't working for me -- I hadn't clued in to the fact that (since you were drawing the tree horizontally) "x" from the tree layout represented vertical position, and "y" represented horizontal position, so I was getting apparently arbitrary results.
With that cleared up, to figure out the zoom you simply need to find the height and width (in data-coordinates) of the area you want to display, and compare that with the height and width of the viewport (or whatever your original max and min dimensions are).
ScaleFactor = oldDomain / newDomain
Generally, you don't want to distort the image with different horizontal and vertical scales, so you figure out the scale factor separately for width and height and take the minimum (so the entire area will fit in the viewport).
You can use the d3 array functions to figure out the extent of positions in each direction, and then find the middle of the extent adding max and min and dividing by two.
var matches = d3.selectAll(".selected");
/*...*/
if ( matches.empty() ) {
centerToPosition(0, 0, 1); //reset
}
else if (matches.size() === 1) {
click(matches.datum(), 0, 0, false);
}
else {
var xExtent = d3.extent(matches.data(), function (d) {
return d.x0;
});
var yExtent = d3.extent(matches.data(), function (d) {
return d.y0;
});
//note: the "x" values are used to set VERTICAL position,
//while the "y" values are setting the HORIZONTAL position
var potentialXZoom = viewerHeight/(xExtent[1] - xExtent[0] + 20);
var potentialYZoom = viewerWidth/(yExtent[1] - yExtent[0] + 150);
//The "20" and "150" are for height and width of the labels
//You could (should) replace with calculated values
//or values stored in variables
centerToPosition( (xExtent[0] + xExtent[1])/2,
(yExtent[0] + yExtent[1])/2,
Math.min(potentialXZoom, potentialYZoom)
);
}
http://jsfiddle.net/7SJqC/2/

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