I am trying to make zooming work on my D3 graph.
I have currently found a solution to making my zoom work whilst having an ordinal x-axis, but I have trouble having the x-axis zoom match with the circle and square elements. The more you zoom in, the more "out of place" they become.
Here is a JS fiddle to my current code, where I've attempted to implement my zoom.
http://jsfiddle.net/Vanquiza/c794g977/3/
I would like to know how to properly implement my zoom so that the elements don't go out of place.
Below I've pasted my zoom functions:
var zoom = d3.behavior.zoom()
.scaleExtent([1, 10])
.on("zoom", zoomHandler);
function zoomHandler() {
var translate = zoom.translate(),
scale = zoom.scale();
var tx = Math.min(0, Math.max(width * (1 - scale), translate[0]));
var ty = Math.min(0, Math.max(height * (1 - scale), translate[1]));
zoom.translate([tx, ty]);
//svg.select(".x.axis").call(xAxis);
svg.selectAll(".circleNodes")
.attr("transform", "translate(" + d3.event.translate[0]+",0)scale(" + d3.event.scale + ",1)");
svg.selectAll(".squareNodes")
.attr("transform", "translate(" + d3.event.translate[0]+",0)scale(" + d3.event.scale + ",1)");
svg.select(".x.axis").attr("transform", "translate(" + d3.event.translate[0]+","+(height)+")")
.call(xAxis.scale(x.rangeRoundBands([0, (width * d3.event.scale)],1 * d3.event.scale)));
}
Any help is greatly appretiated!
Remove the transform altogether. All the adjustments can be done by modifying the ordinal scale, accounting for the translation there.
x.rangeBands([d3.event.translate[0], d3.event.translate[0]+(width * d3.event.scale)], 1)
(Switch to using rangeBands() instead of rangeRoundBands() which eliminates the jitter.)
Then you just have to adjust the positions to all the circles and squares and re-render the axis based on this new scale.
svg.select(".x.axis").call(xAxis)
circle.attr("cx", function(d){ return x(d);})
square.attr("x", function(d){ return x(d) - squareSize/2;})
Here's the working jsFiddle
Related
I'm trying to implement drag events in d3 (v6.2), and I'm having some trouble interpreting the d3 x and y coordinates. Consider the following code. When I inspect the console output, it seems to me like, in the drag handler:
event.x and event.y are the SUM of the user (graph) coordinate object locations and the total movement/distance in SVG coordinates?
event.dx and event.dy are indicator that tell you whether since the last update, you've moved left/up (-1), not moved (0), or right/down (1)?
event.subject.x and event.subject.y give the location of the object being dragged?
if I want the current coordinates of the drag (either in user/graph coordinates or SVG coordinates), I need to calculate them myself (see example in code, which seems to work)?
I can't find where the specifics of this are documented. My questions are:
Are the above impressions correct?
If not correct, what's the best way to get the current drag coordinates?
If correct, why would one SUM the values from two different coordinate systems? That doesn't make sense to me.
<html>
<body>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/6.2.0/d3.min.js"></script>
<svg width="500" height="300"></svg>
<style>
circle.circ {
fill: red;
stroke: black;
stroke-width: 1px;
}
</style>
<script>
function dragHandler(e, d){
const objx = scaleX.invert(e.x - d.x + scaleX(d.x))
const objy = scaleY.invert(e.y - d.y + scaleY(d.y))
console.log(`x: ${e.x}, dx: ${e.dx} sx: ${e.subject.x} objx: ${objx}\ny: ${e.y} dy: ${e.dy} sy: ${e.subject.y} objy: ${objy}`)
}
var drag = d3
.drag()
.on('drag', dragHandler)
var x = [{x: 150, y: 150}]
var svg = d3.select("svg")
var margin = {
top: 20,
right: 80,
bottom: 30,
left: 50
}
var width = svg.attr("width") - margin.left - margin.right
var height = svg.attr("height") - margin.top - margin.bottom
g = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")")
var scaleX = d3.scaleLinear().range([0, width]).domain([140, 160])
var scaleY = d3.scaleLinear().range([height, 0]).domain([140, 160])
g.append("g")
.attr("class", "axis axis--x")
.attr("transform", "translate(0," + height + ")")
.call(d3.axisBottom(scaleX));
g.append("g")
.attr("class", "axis axis--y")
.call(d3.axisLeft(scaleY))
var circ = g.selectAll(".circ")
.data(x)
.enter()
.append("circle")
.attr("r", 5)
.attr("cx", function(d) { return scaleX(d.x) })
.attr("cy", function(d) { return scaleY(d.y) })
.attr("class", "circ")
.call(drag);
</script>
</body>
<html>
Your impression is right. You can either
compute the distance in local coordinates as the difference between event.x/y and event.subject.x/y
retrieve the screen distance with event.clickDistance() as a getter
These two work in different coordinate systems.
The client coordinate system is that of the browser viewport. They are just read from the native DOM mousemove event.
The user coordinate system is the one of the thing being dragged, using the same coordinates as those used when writing SVG markup. They are computed from the client coordinates with a transform matrix the SVG API provides. The source code is here.
What you did was the in-between way that normally is not needed: by applying the scaleX/Y transform, you computed the coordinates in the system of the SVG viewBox, i. e. the coordinate system that is found when the viewBox is applied to the outermost <svg> element. That can be the client coordinate system, but only if the attribute is not set, or the width and height values of the element match the contents of the viewBox.
In almost every practical use case, the two will differ. The "Scalable" in SVG is just about that distinction. Leaving out the viewBox like you did deprives you of the possibility to easily scale your grafic as a whole.
Adding to #ccprog's answer above ( that worked for me ). It is also useful to add .container(selection.node) to your drag object. This makes the coordinates work well. Pay attention not to pass the selection but the selection.node() to .container(...).
US map with d3.v3 using Mike Bostock's example:
I want the map to zoom into the marked locations initially when the page loads but the entire map should be rendered so that a user can zoom out if he wants to.
var w = 300;
var h = 280;
//Define map projection
var projection = d3.geo.albersUsa()
.translate([w/2, h/2])
.scale([300]);
//Define path generator
var path = d3.geo.path()
.projection(projection);
//Create SVG element
var svg = d3.select("#map1").append("svg")
.attr("width", w)
.attr("height", h)
var g = svg.append("g");
var tooltip = d3.select("body")
.append("div")
.style("position", "absolute")
.style("z-index", "1000")
.style('opacity', 0)
.style("font-family", "sans-serif")
.style("background-color", "white")
.style("border-radius", "5px")
.style("padding", "10px")
.style('color', '#000')
.style("font-size", "12px");
//Load in GeoJSON data
d3.json("us-states.json", function(json) {
d3.csv("cities.csv", function(error, data) {
g.selectAll("circle")
.data(data)
.enter()
.append("circle")
.attr("cx", function(d) {
return projection([d.longi, d.lati])[0];
})
.attr("cy", function(d) {
return projection([d.longi, d.lati])[1];
})
.attr("r", 4)
.style("fill", "#4F6D88")
.on("mouseover", function(d){
tooltip.transition().style("opacity", 0.9)
.style('left', (d3.event.pageX) + 'px')
.style('top', (d3.event.pageY) + 'px')
.text(d.city)
})
.on("mousemove", function(event){
tooltip.style("top", (event.pageY-10)+"px").style("left",(event.pageX+10)+"px");
})
.on("mouseout", function(){
tooltip.transition().delay(500).style("opacity", 0);
});
});
//Bind data and create one path per GeoJSON feature
g.selectAll("path")
.data(json.features)
.enter()
.append("path")
.attr("d", path);
});
var zoom = d3.behavior.zoom()
.scaleExtent([1, 50])
.on("zoom", function() {
var e = d3.event,
tx = Math.min(0, Math.max(e.translate[0], w - w * e.scale)),
ty = Math.min(0, Math.max(e.translate[1], h - h * e.scale));
zoom.translate([tx, ty]);
g.attr("transform", [
"translate(" + [tx, ty] + ")",
"scale(" + e.scale + ")"
].join(" "));
});
svg.call(zoom)
I have the code to zoom in with scroll which i have pasted above but i want it to zoom on load to those specific locations. How i want it to be:
There are two primary ways to zoom a map in d3:
modify the projection which will re-draw the paths, or
modify the drawn paths with scale and transform.
Modifying the projection is easiest in d3v4 with fitSize or fitExtent - though you would need to turn your points into geojson. You can also manually calculate the translate and scale values to update a projection (see this answer by Mike Bostock which explains this common d3v3 approach).
Alternatively, you can modify the drawn paths by calling the zoom function - this question asked yesterday has an excellent example of doing so (in d3v4). Or you can calculate and apply the zoom manually and then update the zoom to indicate the current scale and translate. I'll use the common method of modifying a d3v3 projection mentioned above (with Mike's answer) and apply it to the transform on the paths - rather than modifying the projection. Though it should not be difficult to see how my answer could be changed to modify the projection instead.
First you need to determine the maximum difference between the x and y coordinates of your points. If dealing with two points, this will be fairly easy:
var data = [[-100,45],[-110,45]];
var p1 = projection(data[0]);
var p2 = projection(data[1]);
var dx = Math.abs(p1[0] - p2[0]);
var dy = Math.abs(p1[1] - p2[1]);
I'm assuming a simple data format for the sake of a shorter answer. Also, if dealing with many points, this would be a bit more complex. One potential option would be to place your points in geojson and get the bounding box of the points.
Now we need to find out the centroid of the points - in the case of two points this is just the average of the x and y values:
var x = (p1[0] + p2[0])/2;
var y = (p1[1] + p2[1])/2;
Next we need to calculate a new scale, while also determining if the scale is restricted by the difference in x values of the coordinates or the difference in y values of the coordinates:
var scale = 0.9 / Math.max( dx/w , dy/h );
The 0.9 reduces the scale slightly, it is the same as 0.9 * scale and allows a variable amount of margin. The value returned by dx/w is one over the scale value we need to stretch the difference across the width of the svg container.
(it would probably make more sense written like: var scale = 0.9 * Math.min(w/dx,h/dy); - we want to limit the zoom by the lowest scale value and multiply it by some percentage to give margins. But the other representation is ubiquitous in online examples)
Now we have a scale, we only need to determine a translate. To do so we find out how far we need to re-position the values held in the x and y variables so that those values would be centered:
var translate = [w/2 - scale * x, h/2-scale*y];
Now you can set the initial scale and translate of the map:
g.attr("transform", "translate("+translate+")scale("+scale+")");
But, you probably want to update the zoom parameters on page load to reflect the initial zoom and translate:
zoom.translate(translate);
zoom.scale(scale);
This way when you zoom in or out from the initial view, the change is relative to your initial zoom.
Now all you have to do is include the above code when you add the points. Note that this technique might require some modification if you want to return to the initial position.
I created a polar scatter plot using D3.js (based on this post) .
I would like to add the functionality to zoom and pan. I've seen examples for rectangular plots, but nothing for zooming/panning on circular plots.
I am just a beginner with using D3 so I'm a little lost. Can anyone help/offer suggestions?
I'm not entirely sure what your goal is, but I tried something below.
First you should add zoom behaviour. I used the r scale for both your x and y directions like:
var zoomBeh = d3.behavior.zoom()
.x(r)
.y(r)
.on("zoom", zoom);
And call the zoom behaviour into your svg:
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height)
.append("g")
.attr("transform", "translate(" + width / 2 + "," + height / 2 + ")")
.call(zoomBeh);
Finally you should make a zoom function.
function zoom() {
var t = svg.transition().duration(750);
svg.selectAll(".point").transition(t)
.attr("transform", function(d) {
var coors = line([d]).slice(1).slice(0, -1);
return "translate(" + coors + ")"
})
}
Here is an updated fiddle. It's a little bit staggering, I'm not sure why yet.
I am trying to use an svg-clippath with d3.js and the zoom behaviour.
The following code creates a rectangle, which will then be clipped by a rectangualar clipping region.
<svg class="chart"></svg>
<script>
var width = 800;
var height = 600;
var svg = d3.select(".chart")
.attr("width", width)
.attr("height", height)
.append("g");
var clip = svg.append("defs")
.append("clipPath")
.attr("id","clip")
.append("rect")
.attr("width",200)
.attr("height",200)
.attr("x",100)
.attr("y",100);
var zoom = d3.behavior.zoom().
on("zoom",zoomed);
function zoomed(){
container.attr("transform", "translate(" + d3.event.translate
+")scale(" + d3.event.scale + ")");
container.attr("clip-path","url(#clip)");
}
svg.call(zoom);
var container = svg.append("g")
.attr("clip-path","url(#clip)");
var rect = container.append("rect")
//.attr("clip-path","url(#clip)")
.attr("class","bar")
.attr("x",150)
.attr("y",150)
.attr("width",350)
.attr("height",350);
</script>
What I want is for the clipping to be applied again after zooming / moving (so that I cannot
move the rectangle outh of the clipping region, which right now i can do without any problems.) How do I do that?
I am assuming that the current behaviour is caused by the fact that the clipping is applied before the transformation.
I had the same problem and spent the last couple of hours trying to figure out a solution. Apparently, the clip-path operates on the object prior to transformation. So I tried to reverse-transform the clip object when performing the zoom transformation, and this worked !
It is something in the spirit of:
var clip_orig_x = 100, clip_orig_y = 100;
function zoomed() {
var t = d3.event.translate;
var s = d3.event.scale;
// standard zoom transformation:
container.attr("transform", "translate(" + t +")scale(" + s + ")");
// the trick: reverse transform the clip object!
clip.attr("transform", "scale(" + 1/s + ")")
.attr("x", clip_orig_x - t[0])
.attr("y", clip_orig_y - t[1]);
}
where clip is the rectangle in the clipPath. Because of interactions between zooming and translation, you need to set "x" and "y" explicitly instead of using transform.
I am sure experienced d3 programmers out there will come up with a better solution, but this works !
I have this map in d3
http://107.170.20.64/
that renders topojson with a custom projection and path, like this
var projection = d3.geo.mercator().translate([width / 2, height / 2]).scale(width * 185).center([-89.99, 29.975]);
var path = d3.geo.path().projection(projection);
I am trying to adapt it so that it pans and zooms using Bostock's tutorial. Here is the function that fires once the topojson loads (showing my adaptations of Bostock's method):
function ready(error, us) {
var zoom = d3.behavior.zoom()
.translate([0, 0])
.scale(1)
.scaleExtent([1, 8])
.on("zoom", zoomed);
var features = svg.append("g");
features.append("g")
.attr("class", "precincts")
.selectAll("path")
.data(topojson.feature(us, us.objects.orleansgeojson).features)
.enter().append("path")
.attr("class", (function(d) {
return wards.get(d.id) + " precinct";
}))
.attr("title", (function(d) {
return votesone.get(d.id) + "-" + votestwo.get(d.id);
}))
.attr("id", function(d) {
return d.id;
})
.attr("d", path);
svg.append("rect")
.attr("class", "overlay")
.attr("width", width)
.attr("height", height)
.call(zoom);
function zoomed() {
features.attr("transform", "translate(" + d3.event.translate + ")scale(" + d3.event.scale + ")");
features.select(".precinct").style("stroke-width", 1.5 / d3.event.scale + "px");
}
Somehow, zoomed is never getting called. If I set a breakpoint on zoomed it never catches. I think that the final append to svg calls zoom which somehow sets up a d3 behavior that creates listeners for mouse events and calls the zoomed function. That's what I understand so far about what is going on (clarification or detailed answers would be great). Is the problem that the listeners are not getting set? If so, how do I debug why they are not getting set? The overlay shows up in my svg -- it just does not seem to be picking up mouse events.
The problem in your case is unrelated to the zoom behaviour. You're setting the z-index of the div containing the map to be -1. This means that it's behind the containing div, which gets all the mouse events. So the map is "obscured" by the element that contains it.
To fix, either set the z-index of the map div to be higher than -1, or set the z-index of all the containing elements (including the body) to be -1 or less.