isZoomed method

# Determining Zoom

It is possible to detect whether a chart has been zoomed in either axis by the use of the `isZoomed` function. If called with no argument, it will report whether either axis has been zoomed. Alternatively it can be called with an argument of either `'x'` or `'y'` and it will report the status of just that axis.

Here's a simple example using `drawCallback` to display the various zoom states whenever the chart is zoomed:

OUTPUT

Zoomed: False

Zoomed X: False

Zoomed Y: False

HTML

      new Dygraph(

      // containing div
      document.getElementById("zoomdiv"),

      // CSV or path to a CSV file.
      "Date,Temperature\n" +
      "2011-01-07,75\n" +
      "2011-01-08,70\n" +
      "2011-01-09,90\n" +
      "2011-01-10,30\n" +
      "2011-01-11,40\n" +
      "2011-01-12,60\n" +
      "2011-01-13,70\n" +
      "2011-01-14,40\n",
      {
        drawCallback: function(me, initial) {
        document.getElementById("zoomed").innerHTML = "" + me.isZoomed();
        document.getElementById("zoomedX").innerHTML = "" + me.isZoomed("x");
        document.getElementById("zoomedY").innerHTML = "" + me.isZoomed("y");
        }
      }
      );

The Tests for zoom operations show a full example of this in action.