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New label tools in QGIS

In cartography, it is a frequent operation to set labels to fixed positions, together with the position of the fix point (left/middle/right, Top, Half, Bottom) that is kept constant in case of font change, rotation or zoom. Therefore, three new editing tools to manipulate text labels are now in the QGIS developer version:

  1. the move label tool drags text labels to a new position

Move label

  1. the rotate label tool is for interactive rotation of labels
  2. the label property tools opens a dialog that lets the user manipulate the data defined properties of a label (and also the text of the label attribute)

Move label

All three tools work on the new labeling engine and data defined labeling needs to be enabled for the layer (e.g. x coordinate attribute / y coordinate attribute for the move tool, rotation for the rotate tool). Additionally, the layer needs to be in edit mode. The new tools are well suited to mix fixed label positions and automated label opsitioning in the same or among several layers. If the x- or y attribute value is NULL, the position is set automatically by the pal library (http://pal.heig-vd.ch/). As soon as a position is manipulated by the move label tool, the position is written into the attribute field and the label position for this feature is fixed. So if a layer does not yet have attribute fields for x, y, you could create two new fields of type double (using the buttons in the vector properties dialog or in the attribute table). Initially, all values will be ‘NULL’ and all the label positions set automatically.

There are further plans to improve the user interface. It could be handy to have the properties dialog always open (non-modal), which would allow faster edits of a large number of labels. And a live text rotation preview is planned too. And yes, if someone likes making real icons, this would be highly appreciated (my graphical skills are somewhat limited…).

Finally I’d like to thank the city of Thun (Switzerland) for funding these tools and sharing it with the rest of the FOSSGIS world.

Testing UMN Mapfiles with QGIS

The Sunday night session of the QGIS hackfest resulted in a new release of the Mapfile Tools plugin.

This QGIS plugin allows you to display an UMN Mapserver mapfile in QGIS without running a Mapserver instance. It depends only on Mapscript (apt-get install python-mapscript on Debian/Ubuntu) and allows you to zoom and pan on the mapfile layer.

In release 0.6, an output window has been added, which shows error messages and detailed layer information. This makes it a convenient tool to test your mapfiles.

qgis-mapfile-tools

QGIS goes 3D

Marco, Matthias and me spent three days at the QGIS hackfest in Wroclaw (pictures). There I got the time to work on the QGIS globe plugin and made a presentation of the current state.

wroclaw

As soon as the threading branch (Martin Dobias’ Google of Summer project) is merged into trunk, the globe should make its way into trunk as well. In the meantime you can compile the QGIS branch from guthub to test the globe. Thanks Vincent for writing step by step build instructions.

Offline editing plugin for QGIS

For data collection, it is a common situation to work with a laptop or a phone offline in the field. Upon returning to the network, the changes need to be synchronized with the master data source, e.g. a PostGIS database. If several persons are working simultaneously on the same datasets, it is difficult to merge the edits by hand, even if people don’t change the same features.

Therefore, Mathias Walker implemented an offline plugin for QGIS. This plugin automates the synchronisation by copying the content of a datasource (usually PostGIS or WFS-T) to a spatialite database and storing the offline edits to dedicated tables. After being connected to the network again, it is possible to apply the offline edits to the master dataset.

To give the plugin a try, unpack the sources, apply the patch ‘qgis_svn.diff’ to a current svn version of QGIS. Then copy the offline_editing folder to $PREFIX/src/plugins and recompile QGIS.

The usage of the plugin is straightforward:

  • Open some vector layers, e.g. from a PostGIS or WFS-T datasource
  • Save the project
  • Press the ‘Convert to offline project’ button and select the layers to save. The content of the layers is saved to spatialite tables.
  • Edit the layers offline
  • After being connected again, upload the changes with the ‘Synchronize’ button

Screenshot

Presumably, the offline editing plugin will be part of the next QGIS version (1.6)