[QGIS-Developer] WMTS/XYZ on high DPI screens

[Nyall Dawson]

On Wed, 27 Feb 2019 at 02:24, Martin Dobias <wonder.sk at gmail.com> wrote:

> Other solution would be to introduce a new flag for WMTS/XYZ layers
> where users could set native DPI. By default this flag would be
> disabled, but for services like OSM one could explicitly set their DPI
> to 96 and get the tiles scaled accordingly. This would need an update
> of raster block request API as well where we would also need to
> specify output DPI in addition to output width/height (but that should
> not be a big deal).
>

So I'm guessing this setting would apply in print layouts too?
Regardless of the output resolution, it would be exported as though
it's at 96 dpi?

I have a vague feeling that Sourcepole's albiero fork implemented
something similar to this... some possibly related commits are

https://github.com/sourcepole/kadas-albireo/commit/09bb1c82f296f736ce8ecc07f03b03fc5861ddd3
https://github.com/sourcepole/kadas-albireo/commit/09a4cb0bac5fe8a6c2563f811171804044c60d65
https://github.com/sourcepole/kadas-albireo/commit/09bb1c82f296f736ce8ecc07f03b03fc5861ddd3

Nyall


> This solution could also work nicely with services that provide
> high-res tiles (using 512x512 for each tile instead of 256x256) -
> right now QGIS thinks they are 256x256 so instead of a magnifying
> glass one needs a microscope - you can try it [1]. Setting explicitly
> DPI of high-res tiles to 192 DPI should also fix also that issue.
>
> My only worry is if this setting is not going to be too difficult to
> use for ordinary users... But maybe a combo box would make the choice
> easier: "Normal resolution (96 DPI)" / "High resolution (192 DPI)" /
> "Custom resolution" (with a spin box).
>
> Are there any opinions / ideas how to deal with that?
>
> Cheers
> Martin
>
> [1] https://tile.osmand.net/hd/{z}/{x}/{y}.png
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