Allow zooming only with a pressed modifier key

[NicolasGoeddel]

Hi,

when I create a nearly page filling graph with the zoom functionality enabled, it is nearly impossible to find a spot where is no canvas to scroll the page. It would be nice if one could set a modifier key like Alt, Ctrl or Shift to enable zooming with the scroll wheel.

If there is already such a functionality, can you please give me an example application?

[NicolasGoeddel]

I tried to change the enabled property with some key binds but although the property gets changed it does not enable the zooming functionality.

The graphs object stores all my graphs on the page and I iterate through them to change the state of the zoom.

  $(document).keydown(function(event) {
    if (event.shiftKey) {
      for (var g in graphs) {
        graphs[g].options.plugins.zoom.zoom.enabled = true;
        console.log('enabled');
      }
    }
  });

  $(document).keyup(function(event) {
    if (event.shiftKey) {
      for (var g in graphs) {
        graphs[g].options.plugins.zoom.zoom.enabled = false;
        console.log('disabled');
      }
    }
  });

[KoalaBear84]

What if you also add? Here it works. Without it, is sometimes does not work as expected, with the update it does.

graphs[g].update();

[etimberg]

A wheel modifier key was added in #382