On Wed, Feb 27, 2019 at 1:03 PM Matthias Kuhn <matth...@opengis.ch> wrote: > > > > I am wondering if we should have three options for tile resolutions: > > - standard (96 DPI) ... autoscaled, for 256x256 tiles for XYZ tiles > > - high res (192 DPI) ... autoscaled, for 512x512 tiles for XYZ tiles > > - undefined ... not scaled > > Sounds reasonable. > > I can see the following options for what a data provider can offer: > > * A predefined set of available DPI from the server (e.g. XYZ) > > * Manually specify DPI (e.g. as WMS parameter "DPI=300") > > * No scaling available
Right. > Some dataproviders might know what they can offer (WMS might include > that in the GetCapabilities, AFS maybe?), others might need > configuration on layer / data provider properties (XYZ, preconfigured > through QMS or ,qml/.qlr files). As mentioned in my earlier email, WMS, WMTS, XYZ have no way to tell the true DPI of tiles (as far as I know). AMS does but QGIS does not take it into account. > I assume that it's also not always desired to get the maximum resolution. > > E.g. in HighRes atlas printing a WMS via a network connection with > "DPI=3000" parameter could be very slow, so the API should be prepared > to specify > > * "data source DPI", i.e. what's requested from the provider > > * and output device DPI, i.e. what it's scaled to for screen/paper To specify output device DPI there's already QgsRasterDataProvider::setDpi() call which is also used when drawing raster layers. I am not sure how do you mean it with specification of "data source DPI" ... if I have a tileset with 96 DPI, do you mean that option should allow overriding of the source DPI? In any case, here's my take on fixing three problems in one go: - correct rendering of XYZ tiles on high res screen (and in print output) - correct rendering of high resolution XYZ tiles (on any screen) https://github.com/qgis/QGIS/pull/9296 The PR does not address scaling issues with WMTS layers. Compared to XYZ layers where one connection = one tile layer, with WMTS there may be multiple tile layers within one connection, each with different DPI - and as mentioned above, WMTS does not provide information about DPI. Cheers Martin _______________________________________________ QGIS-Developer mailing list QGIS-Developer@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer