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I set white borders for text (city names) in qgis. If I export the map without white borders it exports quite quickly (png 600 dpi). If I set the white borders it takes hours! Is there any way I can avoid this?

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the qgis Version is Lisboa. Operation system Linux. The text labels are set in the regular Text Tab of the Layer-Properties. See screenshot. In the map composer I didn't change any settings.

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Please give more details on what you mean by 'text.' Is it a label? If so, in what part of the program (map canvas or print composer)? If a label, which labeling tool: regular or advanced? By border, I'm guessing you mean 'buffer'? Which version of QGIS? –  dakcarto Aug 22 '12 at 23:23
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2 Answers

I have a theory based on a discussion about old and new labeling engine and their differences (I'll try to find it again):

In old labeling (which you seem to be using based on your screenshot), buffers are create by copying the label multiple times and offsetting it a little in all directions. This means that there are many more objects on the map if buffering is on. This could cause the export to take much more time.

I would give new labeling from label toolbar a try. I think it uses a different technique.

Update: This bug report seems to be related "Label Buffers Produces Extremely Bloated PDF Export"

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Agree, use the new labelling anyway. Work is being done on it and so the old one will be almost certainly dropped in the next release (finally). –  Giovanni Manghi Aug 23 '12 at 8:08
    
underdark is correct about a different technique in the new labeling engine for creating buffers. While this works well for buffers, the QPainterPath technique causes text to be output as non-text, vector objects, much like choosing a 'Create Outlines' action on text in a graphics programs like Illustrator. This means the text is not editable on output from QGIS to PDF and SVG. –  dakcarto Aug 23 '12 at 16:02
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The new labeling engine seems to work a lot better (Layer | Labeling menu, not the label tab from 'properties'). Just tested this (exporting PDFs from the map composer) on a layer with 246 labelled points using various combinations of buffers (white borders) and the labeling engines.

  • Old engine / no buffer: ~ 1 second, 435 KB file;
  • Old engine / buffered: crashed QGIS twice, no output;
  • New engine / no buffer: ~ 1 second, 341 KB file;
  • New engine / buffered: ~ 1 second, 446 KB file.

Underdark's theory looking correct at this point - stick to new engine!

However - I couldn't get the new engine to rotate the labels 45° for this test.

(QGIS 1.8 on MacOSX, 8GB RAM)

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The label's rotation 'independent of setting data-defined field mappings' is a known issue, and has not yet been addressed in the new labeling engine (see issue #6118). –  dakcarto Aug 23 '12 at 15:55
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