[Qgis-developer] Rendering a map in QgsComposition on Win 7 / 8

[pgierski]

Ok, problem solved.

Your hint with the extent setting put me on a right track.

It turns out that I had a total mess with coordinate reference systems beetween layers and projects. QGIS was reprojecting everything on the fly, but I had to double check everything to get it right in the end.

So after all there is no problem with rendering on Win 7/8, it was just my problems with coordinates.

To solve the issue I had to check every time which crs I have in one layer and convert the extent to destination crs (used in map canvas).

This code does the trick:

map_centroid_point_layer_crs = desired_layer.crs()
destination_crs = mapRenderer.destinationCrs()
xform = QgsCoordinateTransform(map_centroid_point_layer_crs, destination_crs)
map_centroid_point_in_dest_crs = xform.transform(map_centroid_point)

# here is the code for calculating the extent
map_width_on_print_mm = 182
map_height_on_print_mm = 160

map_x_min = map_x - (((map_width_on_print_mm * scale) / 1000.0) / 2.0)
map_x_max = map_x + (((map_width_on_print_mm * scale) / 1000.0) / 2.0)
map_y_min = map_y - (((map_height_on_print_mm * scale) / 1000.0) / 2.0)
map_y_max = map_y + (((map_height_on_print_mm * scale) / 1000.0) / 2.0)

rect = QgsRectangle(map_x_min, map_y_min, map_x_max, map_y_max)

Thank again for your help!
--
Cheers, Przemysław Gierski.

Dnia 8 maja 2014 12:39 Nyall Dawson <nyall.dawson at gmail.com> napisał(a):

> On 8 May 2014 20:23, pgierski <pgierski at o2.pl> wrote:
> 
> >
> > composerMap = QgsComposerMap(c,
> > 14.7026,113.85,map_width_on_print_mm,map_height_on_print_mm)
> > composerMap.setFrameEnabled(True)
> > composerMap.setFrameOutlineWidth(0.5)
> > c.addItem(composerMap)
> 
> What if you try explicitly setting composerMap's extent here? ie,
> composerMap.setNewExtent(rect)
> 
> Nyall
>