无法缩放 d3 techanjs

Question

I'm using almost same code which has been used in http://techanjs.org/ . I was trying to add zooming feature in the chart as the developer has rendered the chart in here . But somehow I'm not able to zoom it. I'm getting error selection is not defined in console. I'm using following code to render the chart.https://paste.fedoraproject.org/paste/7gJq9wKL4h4s862EDuxnQQ . I'm sure I'm doing something wrong in here, I would really appreciate if I get any assistance regarding it as I'm still learning D3.

Answer 1

I'd guess the problem is that you are referencing the variable selection but it isn't defined.

Hence -

selection is not defined

selection is the parameter passed into your bigchart function.

But you then use it in your reset , zoomed functions where it is not defined.

//Zoom Begins
 function reset() {
        zoom.scale(1);
        zoom.translate([0,0]);
        selection.call(draw); // this will throw an error
    }

    function zoomed() {
        x.zoomable().domain(d3.event.transform.rescaleX(zoomableInit).domain());
        y.domain(d3.event.transform.rescaleY(yInit).domain());
        yPercent.domain(d3.event.transform.rescaleY(yPercentInit).domain());

        selection.call(draw); // this will throw an error
    }
//Zoom Ends

To fix, either pass the selection to the functions as a parameter (like the other functions) - or else make the selection a property of BigChart so that it can be referenced by the reset and zoomed functions.

ie

 // pass selection to the functions as a parameter

 function reset(selection) {
    zoom.scale(1);
    zoom.translate([0,0]);
    selection.call(draw);
 }

 function zoomed(selection) {
    x.zoomable().domain(d3.event.transform.rescaleX(zoomableInit).domain());
    y.domain(d3.event.transform.rescaleY(yInit).domain());
    yPercent.domain(d3.event.transform.rescaleY(yPercentInit).domain());
    selection.call(draw);
 }

Then when you call the functions obviously you pass in the correct object...eg

zoom = selection.call(d3.zoom().on("zoom", zoomed));

rather than

zoom = d3.zoom().on("zoom", zoomed),