geovation / labelgun Goto Github PK

This may be a temporary glitch, but the link given at

Check out the docs and demos live here

is failing for me

When used in a QtWebkit environment, this fails because of no support for Set, I believe. What's the best approach - a polyfill? Or is there some option in your build process to compile a version compatible with older JS engines?

Other errors might subsequently transpire, but let's fix them as they arise.

It seems very difficult to get to a point where there are no label collisions on the OpenLayers3 example. I think this is more a OpenLayers3 issue than a Labelgun issue. There doesn't appear to be a strict 'this layer has loaded and rendered' event in OL3.

I've added an opacity transition to the style, and this works well. However, this means all overlapping labels initially display on map load, immediately transitioning to fade out.

What would be the easiest way to differentiate calls to hideLabel() made initially from subsequent ones? The transition could then be removed for the subsequent calls.

I think there's a simple enhancement to make this work across multiple layers. PR coming to see whether you think it works.

Warning: slightly rambling ignorant thought follows.

Obviously, Labelgun is mapping-library-agnostic, which is great. It also aims to be extremely efficient, using rbush under the hood. This is also splendid.

However, the Leaflet example doesn't (I think) use Leaflet 1's new L.Tooltip. Is it possible to use it? There would be obvious advantages to using it. It could be that failing to use it compromises performance (a guess).

This one's very odd. If you zoom in Leaflet with a double-click, the label text blurs. Using the + zoom control does not blur it. No idea why.

It would be great to have a simple example in the README. This would be helpful especially to beginners.
I went through the leaflet example but it was hard to understand as there was a lot of configuration being done outside the library.

An example in use with Leaflet.VectorGrid would be incredibly useful. As it stands, L.VectorGrid doesn't handle labelling. There are a couple of open PRs which could enable it, but they all produce one label per feature per tile. This means blurry text if Tooltips with no background are used.

If Labelgun could be implemented, it would automatically get rid of the duplicate labels (this was @perliedman's idea). However, I'm not having any joy implementing it with L.VectorGrid. The Leaflet example uses L.LayerGroup.eachFeature(), but this is not available in L.VectorGrid.

Any help would be very welcome indeed.

I don't know if it's immediately compatible, or if work is needed.

Without Labelgun, I label OL features as follows:

new ol.style.Style({
    text: new ol.style.Text({
    font: '10.725px \'MS Shell Dlg 2\', sans-serif',
    text: labelText,
    textBaseline: 'middle',
    textAlign: textAlign,
    offsetX: offsetX,
    offsetY: offsetY,
    fill: new ol.style.Fill({
        color: 'rgba(0, 0, 0, 1)'
    })
});});

The Labelgun OL4 examples seems to write the text into an SVG:

var iconSVG = "<svg " +
                    "version=\"1.1\" xmlns=\"http://www.w3.org/2000/svg\" " +
                    "x=\"0px\" y=\"0px\" width=\"" + labelWidth + "px\" height=\""+labelHeight+"px\" " +
                    "viewBox=\"0 0 " + labelWidth + " "+labelHeight+"\" " +
                    "enable-background=\"new 0 0 " + labelWidth + " "+labelHeight+"\" >"+
                    "<g>" +
                    "<rect x=\"0\" y=\"0\" width=\"" + labelWidth + "\" height=\""+labelHeight+"\" stroke=\"#000000\" fill=\"" + fillColor + "\" stroke-width=\"2\"></rect>" +
                    "<text x=\"5\" y=\"14\" fill=\"#000000\" font-family=\"Arial\" font-size=\""+labelFontSize+"\" font-weight=\"normal\">" +
                        _.escape(text) +  // We need to escape all the special characters like & etc
                    "</text>" +
                    "</g>" +
                "</svg>";

  var svgURI = encodeURIComponent(iconSVG);
  var src = "data:image/svg+xml;charset=utf-8," + svgURI;

Is this a prerequisite for Labelgun in OL4, or could it be applied to my existing labelling method?

http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/

Labelgun has the ability to set a label to be 'dragged' which in turn makes it's weight infinite and always shown in the collision calculations. An example in Leaflet or OpenLayers would be super!

Here's an example of how you might do it:

   // The last argument is dragged which we set to true
    labelEngine.ingestLabel(
      boundingBox,
      id,
      parseInt(Math.random() * (5 - 1) + 1), // Weight
      label,
      "Test " + id,
      true 
    ); 

I'm not a node user, but the examples require it.

I'm getting this error:

TypeError: layer.getTooltip(...) is undefined
    addLabel file:///C:/Users/tchadwin/Desktop/é/qgis2web_2019_06_17-15_11_29_065534/js/labels.js:29
    resetLabels file:///C:/Users/tchadwin/Desktop/é/qgis2web_2019_06_17-15_11_29_065534/js/labels.js:20
    eachLayer file:///C:/Users/tchadwin/Desktop/é/qgis2web_2019_06_17-15_11_29_065534/js/leaflet.js:5```

Relevant line is:

```javascript
  // This is ugly but there is no getContainer method on the tooltip :(
  var label = layer.getTooltip()._source._tooltip._container;

This implementation was taken from the labelgun Leaflet examples.

I'm assuming this must have occurred with a Leaflet version upgrade, but other than that, I'm in the dark at the moment.

Probably a silly question, but does this work with lines and polygons?

Would be good to prove that updating for some (as opposed to all) labels works as intended. Would also be good to have some test cases for dragging labels.

I feel like this may be under utilized because of how confusing setting it up is.

Also when using browser only getting errors that prevent running.

For one reason or another we have to call this._hideShownCollisions() in order to hide labels that shouldn't be shown (I'd say it effects about 5% of labels). Not sure what the root cause of this is, but obviously a hack and decreases performance so would be A+++ to get rid of.

I'm not sure the new algorithm is as successful as the old. I'm getting frequent overlaps:

I would also say that some plausible candidates for labelling have no label:

It would be great to improve the performance of the library. You can use :

npm run benchmark

to check the general speed of the update function (probably the most crucial for most people).

Haven't quite got to the bottom of it, but something to do with the fact that OL is minifed by closure compiler, the objects have mangled property names. Hard to debug as no actual error is thrown however. Will try to dig in when I have a moment or someone needs it desperately!

In other words, place https://unpkg.com/[email protected]/lib/labelgun.min.js in a /dist directory. Updating it can probably be automated with eg Paver or some such tool.