Bug report #2876
bring back raster legend icons
|Affected QGIS version:||Regression?:||No|
|Operating System:||All||Easy fix?:||No|
|Pull Request or Patch supplied:||Resolution:||fixed|
|Crashes QGIS or corrupts data:||Copied to github as #:||12936|
Icons have been disabled in r13899 because of performance problems while opening projects with many rasters.
Icons are nevertheless very useful.
#2 Updated by Giovanni Manghi over 10 years ago
Why should QGIS draw an icon that represent a, for example, 5000x5000 pixel raster in a space of 16x16?
because when you do raster analisys your rasters (not normal orthophotomaps or militar maps) normally have very different colormaps and with icons they are EASILY identified in the legend.
#3 Updated by William Kyngesburye over 10 years ago
Here's my notes, for the record:
It seems to only affects rasters without overviews. I did a test with a single 1 GiB JP2 and it generates the legend icon nearly instantaneously. A 1.3 GiB tiff without overviews takes a long time, yet the same with overviews is fast. A 200MiB tiff without overviews has a noticable delay, but it's not horrible.
Though the original issue is a small 14MiB vrt with jp2 images, zooming and panning are not affected. Maybe there's something else with a vrt that slows down the legend generation?