[mapserver-users] Clickable label

Tue Sep 9 08:10:03 PDT 2014

Neat idea from the GeoServer folks. It's maybe something we could think about.

With tiled maps I wonder if we could cache label references (poly, layer id, feature id) as a by-product of the rendering process and then add that layer back for GetFeature processing.

Steve

________________________________________
From: mapserver-users-bounces at lists.osgeo.org [mapserver-users-bounces at lists.osgeo.org] on behalf of Rahkonen Jukka (Tike) [jukka.rahkonen at mmmtike.fi]
Sent: Tuesday, September 09, 2014 9:50 AM
To: 'mapserver-users at lists.osgeo.org'
Subject: Re: [mapserver-users] Clickable label

Hi,

Geoserver 2.5 came with improved GetFeatureInfo http://blog.geoserver.org/2014/05/21/geoserver-2-5-1-released/
"New implementation of GetFeatureInfo that takes into account symbol shapes, offsets, and dynamic line widths into account"

Just a couple of weeks ago I published a biggish vector layer with about 1300 million features with Mapserver. Actually I published the same data as a bunch of layers with different classification and some layers renders only a couple of classes even at big scale. It feels a bit odd that GetFeatureInfo finds hits even if the map shows only empty space. The customer did not complain so I left the layers as they were but now I think that my case is a bit analogous - What-You-Get-Info-About-Is-Not-What-You-See-On-The-Map.

-Jukka Rahkonen-

Basques, Bob (CI-StPaul) wrote:

> All,
>
> It's probably not the cleanest way to approach it, but maybe a straight
> imagemap type approach.   You use the four corners of the label bounding poly
> and send as an imagemap or json set or id query.
>
> I think the bounding polys need to somehow be thought of as a ad-hoc data
> layer themselves.  Is there a way of sub-selecting feature constructs (that were
> originated by mapserver, like centroids are, into a reusable (on the fly) dataset?
>
> My immediate thoughts were to use a clientside imagemage (which is passe
> these days) and that is where the translation occurs for the bounding boxes, via
> the imagemap generation.
>
> bobb
> ________________________________________
> From: Lime, Steve D (MNIT)
> Sent: Monday, January 20, 2014 9:43 AM
> To: Basques, Bob (CI-StPaul); wiltomap; mapserver-users at lists.osgeo.org
> Subject: RE: [mapserver-users] Clickable label
>
> That or a UTFGrid. I don't believe that support (in master) handles labels but
> maybe it could. In UTFGrid context you wouldn't want to render characters
> anyway, only the bounding polygons. However, because the grid is rendered at a
> lower resolution than the related map label placement consistency might be the
> issue. --Steve ________________________________________
> From: Basques, Bob (CI-StPaul)
> Sent: Friday, January 10, 2014 6:15 PM
> To: Lime, Steve D (MNIT); wiltomap; mapserver-users at lists.osgeo.org
> Subject: RE: [mapserver-users] Clickable label
>
> Steve,
>
> I've been thinking on this thread since it started, I wonder, could you use a
> imagemap template from Mapserver, but populate it with the Label bounding
> polygons?
>
> bobb
>
>
> ________________________________________
> From: mapserver-users-bounces at lists.osgeo.org [mapserver-users-
> bounces at lists.osgeo.org] on behalf of Lime, Steve D (MNIT)
> [Steve.Lime at state.mn.us]
> Sent: Friday, January 10, 2014 4:14 PM
> To: wiltomap; mapserver-users at lists.osgeo.org
> Subject: Re: [mapserver-users] Clickable label
>
>  This can't be done with stock MapServer. Labels are dynamic by nature and are
> the product of a map raw while queries work off the base data. The bridge
> between the map and a query is a conversion from pixels to map coordinates
> based on map size and extent.
>
> You might be able to pull this off using MapScript. For a query you'd have to do
> things in two stages:
>
>   1) Draw the map (in memory) based on the map the user interacted with (same
> extent, size and set of layers) so that a label cache is created.
>   2) Search the label cache based on the query point and based on that pull the
> appropriate feature.
>
> I don't know if step 2 is feasible or not. You used to be able to loop through it,
> not sure about now.
>
> There might be other ways using an image where you render text and label
> backgrounds using the same color, a color that you could map back to a feature
> id. The map would basically contain label polygons in a raster you could, in turn,
> query that raster using point and retrieve a feature id. I have doubts that you
> could match the first image to the second so this would be a huge long shot.
>
> Steve
>
> -----Original Message-----
> From: mapserver-users-bounces at lists.osgeo.org [mailto:mapserver-users-
> bounces at lists.osgeo.org] On Behalf Of wiltomap
> Sent: Friday, January 10, 2014 2:17 AM
> To: mapserver-users at lists.osgeo.org
> Subject: [mapserver-users] Clickable label
>
> Hello all,
>
> I have to display labels instead of points on a layer. The labels rely on an
> attribute value. I would like to click on the label to make an attribute windows
> open up. So far, no problem with mapfile configuration...
>
> The only thing is that the attribute window opens up when I click right in the
> middle of the label. I can use TOLERANCEUNITS and TOLERANCE parameters in
> the mapfile to enlarge the clickable area BUT this means that I can also click
> next to the label and get the attribute window, which I don't want to...
>
> My purpose is to get the attribute window whereever I click on the label (any
> part of it) and not if I click next to it. Would you think about a solution to that ?
>
> I enclose a scrennshot of the mapfile I have worked out so far.
>
>
> Many thanks in advance,
>
> Thomas
>
>
> <http://osgeo-org.1560.x6.nabble.com/file/n5097281/mapfile_label.jpg>
>
>
>
> --
> View this message in context: http://osgeo-org.1560.x6.nabble.com/Clickable-
> label-tp5097281.html
> Sent from the Mapserver - User mailing list archive at Nabble.com.
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