Hi devs I face a (IMHO) an API limitation that I'm not sure is a limitation of a feature :)
I'm working adding SLD export for rasters as new feature and some stretching (QgsContrastEnhancement) should be mapped differently if the min/max values has been modified from the real min/max of the image. This can be simply asked to the raster with QgsRasterLayer.statistic(<band number>). The main problem I'm faced is that if statistic is not present it is ALWAYS calculated. This means that if we have big images or a remote one (e.g. COG) this would take long time! I do not analysed any raster provider, but I suppose that min/max values can be estimated asking to raster metadata. IMHO we can have an API like QgsRasterLayer.estimatedStatistic(<band number>) or QgsRasterLayer.statistic(<band number>, estimated=false) that can return metadata values if available. The proposal is valid if there is no a method to get estimated statistic, but I could be wrong and that's the reason of this post. Luigi Pirelli p.s. remember to come to 2019.qgis.es ;) we'll open inscription next monday! ************************************************************************************************** * LinkedIn: https://www.linkedin.com/in/luigipirelli * Stackexchange: http://gis.stackexchange.com/users/19667/luigi-pirelli * GitHub: https://github.com/luipir * Mastering QGIS 2nd Edition: * https://www.packtpub.com/big-data-and-business-intelligence/mastering-qgis-second-edition * Hire me: http://goo.gl/BYRQKg **************************************************************************************************
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