If I have a print composer called "ABC", I would like to "tell" its composer that I would like to
- update "Map 0" to simulate the "set to map canvas extent" button activation
- update certain text labels
- activate "export to image"
On the topic of print output from pyQGIS: http://www.qgis.org/pyqgis-cookbook/composer.html (Note: master has
QgsComposition::loadFromTemplate method, which 1.8 has not).
Basically, in 1.8, you have to create the composition (with map, labels, etc.) from scratch in code anyway. So no updates are needed.
Just an update for this question given the QGIS 2 API is a bit better for these things.
Re your 1, if you want to update the maps in a composer, use code such as:
map_item = composition.getComposerItemById('map') map_item.setMapCanvas(canvas) map_item.zoomToExtent(canvas.extent())
Re your 2, use:
Re your 3:- as Underdark suggested, there is example code to export to both images and PDF at the QGIS Python API cookbook:- http://docs.qgis.org/2.8/en/docs/pyqgis_developer_cookbook/composer.html#output-to-a-raster-image