[Qgis-user] Simple methodology for user / data / map interactivity?

Brent Wood pcreso at yahoo.com
Thu Feb 23 16:53:45 PST 2017


Sort of in the area you are asking about:

See the Action tool 
Under Windows this can invoke a batch file to display the result of an sql for data about the (Postgis) feature clicked on. Even easier under Linux with a bash script. If one of the fields is an image file, you can create an action to display the image associates with the feature. A useful bit of functionality...
But to do exactly what you are asking, I think the Attribute table does this, so it is a matter of explaining the steps to your users, rather than writing code...

If you select a set of features in a Postgis (or most type of layer) layer rendered on the map, QGIS highlights the selected ones as defined in the project properties. Open the Attribute table for the layer, you will see the selected features, not only highlighted on the map, but also in the attribute list. Click the "move selected features to top" button, and the selected/highlighted features will always be at the top of the list. The attribute table has buttons at the top to zoom & pan to selected features...
Cheers,
Brent


      From: SEGGIE Graeme <gseggie at systra.com>
 To: "Qgis-user at lists.osgeo.org" <Qgis-user at lists.osgeo.org> 
 Sent: Friday, February 24, 2017 6:48 AM
 Subject: [Qgis-user] Simple methodology for user / data / map interactivity?
   
 <!--#yiv2791882570 _filtered #yiv2791882570 {font-family:"Cambria Math";panose-1:2 4 5 3 5 4 6 3 2 4;} _filtered #yiv2791882570 {font-family:Calibri;panose-1:2 15 5 2 2 2 4 3 2 4;}#yiv2791882570 #yiv2791882570 p.yiv2791882570MsoNormal, #yiv2791882570 li.yiv2791882570MsoNormal, #yiv2791882570 div.yiv2791882570MsoNormal {margin:0cm;margin-bottom:.0001pt;font-size:11.0pt;font-family:"Calibri", sans-serif;}#yiv2791882570 a:link, #yiv2791882570 span.yiv2791882570MsoHyperlink {color:#0563C1;text-decoration:underline;}#yiv2791882570 a:visited, #yiv2791882570 span.yiv2791882570MsoHyperlinkFollowed {color:#954F72;text-decoration:underline;}#yiv2791882570 span.yiv2791882570EmailStyle17 {font-family:"Calibri", sans-serif;color:black;font-weight:normal;font-style:normal;text-decoration:none;text-decoration:none;}#yiv2791882570 span.yiv2791882570SpellE {}#yiv2791882570 .yiv2791882570MsoChpDefault {font-family:"Calibri", sans-serif;} _filtered #yiv2791882570 {margin:72.0pt 72.0pt 72.0pt 72.0pt;}#yiv2791882570 div.yiv2791882570WordSection1 {}-->I would like to use QGIS as a visual / interactive front to somePostGIS data and am not sure what the best route to doing so is. Happy to explore further myself, but wanted to get some input on what needs to be joined up to get started on building a little process.    Basically, if I wanted to present a map of features and have a button (like the attribute information one) which a user would click then use to select features, I want this to run a SQL query which to get related features for example and highlight them on the map view, possibly pan to the extent of the newly selected feature set.    Does this sound like a plugin – or would that be taking things too far?    Would the best way for the dynamic layer to be setup, to be a view – empty except when populated by the query and styled to be dominant over the full set of features?     As a simple example, say I had a district zone system of polygons and I wanted a user to be able to click on any polygon, and have all the neighbouring polygons highlighted, centred and fill the map view as fully as possible. What would be the best / simplest approach to this?    Graeme    ========================================================
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