Data-defined labeling takes 1560% longer to render

[qgib]

Author Name: Aren Cambre (Aren Cambre)
Original Redmine Issue: 5049
Affected QGIS version: master
Redmine category:labelling

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For the attached SHP, here's how long it takes to render:

• No labels: ~2.5 sec
• Labels with field NAME and no data-defined setting: ~8.0 sec
• Labels with field NAME and data-defined size set to POP_2000: ~41.6 sec

That's a 420% time increase over labeling with no data-defined setting and 1560% longer than no labeling at all.

Time was calculated with stopwatch, between pressing OK on the labeling dialog and when the map finally appears.

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• kx-texas-city-limits-2006-SHP.7z (Aren Cambre)

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Related issue(s): #14818 (relates)
Redmine related issue(s): 5048

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[qgib]

Author Name: Aren Cambre (Aren Cambre)

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I ran this test on a laptop with 8 GB RAM (several GB free) and Intel Core i7 Q720 (1.6 GHz).

[qgib]

Author Name: Aren Cambre (Aren Cambre)

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Related: #14818

[qgib]

Author Name: Marco Hugentobler (@mhugent)

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This is because in POP_2000, there are huge values. If you set the font size e.g. to 1000 (points), you get long rendering times also if the size is not data-defined.
So the longer rendering is only because the labels are larger (over 1000000 points for Houston).

[qgib]

Author Name: Aren Cambre (Aren Cambre)

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Ah, so looks like resolution of #14818 might be necessary to fix this performance issue?

[qgib]

Author Name: Jürgen Fischer (@jef-n)

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Aren Cambre wrote:

Ah, so looks like resolution of #14818 might be necessary to fix this performance issue?

or by using an attribute that is usable as size - eg. by using the field calculator to produce a appropriately scaled value in an additional attribute.

[qgib]

Author Name: Paolo Cavallini (@pcav)

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• fixed_version_id was configured as Version 2.0.0

[qgib]

Author Name: Nyall Dawson (@nyalldawson)

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This might be closable now -- this can be achieved by using an expression for the definition and using the new "scale_linear" function.

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• status_id was changed from Open to Feedback

[qgib]

Author Name: Larry Shaffer (Larry Shaffer)

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Should be fixed with commit 45f374f

Reopen if necessary

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• status_id was changed from Feedback to Resolved
• resolution was changed from to fixed

[qgib]

Author Name: Jürgen Fischer (@jef-n)

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• status_id was changed from Resolved to Closed