OpenLayers Integration: Larger tile sizes for higher resolution monitors

[andreasneumann]

It would be useful to render larger tiles for high-dpi monitors.

One could have a switch depending on the screen size. E.g. when a browser window is larger than 2000 px on either width or height, then the tile size could switch from 256 px tiles to 512 px tiles.

of course, this is also low priority.

[boardend]

If your concern is about using all the physical pixels available on a high dpi device, then this is already in place (see the QgisXYZDataSource). The pixelRatio is detected/managed by OpenLayers, multiplied with the default tile size (which is 265px in a xyz source) and also passed to the qgis-js renderXYZTile-function to be taken into account for symbols and fonts. So on a HighDPI device (window.devicePixelRatio = 2) one will get 512px (physical pixels) tiles which will be rendered to 256 CSS pixels (the same principle as demonstrated in the High DPI WMTS example)

If your concern is about the amount of parallel renderXYZTile-function calls, we could also go for a custom and dynamic TileGrid with an increased tile size on large maps. But this would mean that we're not in the commonly used XYZ scheme anymore and that the layer has to be recreated when the map size changes (demonstrated in the WMS 512x256 Tiles example)

We could also try to make the QgisCanvasDataSource cache the rendered tiles, as demonstrated in the Tiled WMS example.

[boardend]

We should definitely switch to 512x512px tiles (based on the feedback of Andreas Hocevar)