[GIS] Can’t pan around the OpenLayers map .. unless there are no Layers under the mouse

openlayers-2

So I've got my map displayed and some Features added to a Layer. All good, etc.

When I try and pan around my map, I can only pan when I left-click the mouse .. hold .. and drag the mouse … when the mouse cursor is NOT over a feature/shape on the vector layer.

Otherwise, the panning works great.

What's the trick to say .. can pan the map at any time / anywhere the mouse cursor is?

Best Answer

This was answered on the main site few years ago.

https://stackoverflow.com/questions/4122160/mouse-drag-on-kml-features-with-openlayers

And in some respects in the OL documentation as well:

http://trac.osgeo.org/openlayers/wiki/SelectFeatureControlMapDragIssues

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[GIS] offset point using openlayers

You are requesting your WFS layer in a different projection than your map and thus forcing OpenLayers to reproject it for you (in the browser). Change the projection of your request to 900913 and it should line up nicely and be much speedier.

OpenLayers – How to Zoom Out Farther Than Max Extent Using Google Maps as Base Layer

This is the default behavior of OpenLayers when using Google layers. The parameter that controls this is wrapDateLine: false. Simply modify your code with this to be able to zoomout further:

    var google_default =  new OpenLayers.Layer.Google("Google Default", {wrapDateLine: false})
    var google_satellite = new OpenLayers.Layer.Google("Google Satellite", {type: google.maps.MapTypeId.SATELLITE, wrapDateLine: false})

When using WFS layers it is a good idea to not use wrapDateLine: false anyway. Otherwise you could end up with your vectors on the wrong side of the DateLine and outside of the visible map.

Update:

You are using a GoogleMaps Layer. This layer already set the maxExtent to the default value -20037508.34,-20037508.34,20037508.34,20037508.34. You don't have to play with that.

In some cases, OpenLayers adjust the minimum (zoomed-out) level to make it fit in your map size. If you are using the wrapDateLine: true (which is the default value with Google layers) in your baseLayer, the zoom level is adjusted to shows a map not wider than its maxExtent.

Now, to answer your original question, to be able to zoom out further, you can:

set wrapDateLine: false in your Google layers
or disable this code directly in OpenLayers (Note that this is not a clean solution):
```
OpenLayers.Map.prototype.adjustZoom = function(zoom) {
    return zoom
}
```

This is the revelant OpenLayers code that prevent you from zooming out further when wrapDateLine is set to true in your layer. This is always called when you zoom in/out with OpenLayers >= 2.13:

 /**
 * Method: adjustZoom
 *
 * Parameters:
 * zoom - {Number} The zoom level to adjust
 *
 * Returns:
 * {Integer} Adjusted zoom level that shows a map not wider than its
 * <baseLayer>'s maxExtent.
 */
adjustZoom: function(zoom) {
    if (this.baseLayer && this.baseLayer.wrapDateLine) {
        var resolution, resolutions = this.baseLayer.resolutions,
            maxResolution = this.getMaxExtent().getWidth() / this.size.w;
        if (this.getResolutionForZoom(zoom) > maxResolution) {
            if (this.fractionalZoom) {
                zoom = this.getZoomForResolution(maxResolution);
            } else {
                for (var i=zoom|0, ii=resolutions.length; i<ii; ++i) {
                    if (resolutions[i] <= maxResolution) {
                        zoom = i;
                        break;
                    }
                }
            } 
        }
    }
    return zoom;
},

Best Answer

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OpenLayers – How to Zoom Out Farther Than Max Extent Using Google Maps as Base Layer

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